201
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Yang TT, Liu Y, Tan S, Wang WX, Wang X. The role of intestinal microbiota of the marine fish (Acanthopagrus latus) in mercury biotransformation. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 277:116768. [PMID: 33647808 DOI: 10.1016/j.envpol.2021.116768] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/15/2021] [Accepted: 02/13/2021] [Indexed: 06/12/2023]
Abstract
Both inorganic (IHg) and organic (MeHg) forms of Hg can be converted into each other by methylation or demethylation, leading to changes of Hg speciation and distribution in fish. However, Hg biotransformation in fish is not thoroughly understood and the key factors in this process are unclear. The present study investigated the in vivo Hg transformation in a marine fish (Acanthopagrus latus) and explored the roles of intestinal microbiota in Hg biotransformation. We first demonstrated that Hg methylation or demethylation occurred in the fish gut under dietary IHg or MeHg exposure, respectively. The demethylation was observed to be faster than methylation, suggesting that demethylation could significantly influence the Hg speciation in fish. This study also strongly suggested that intestinal microbiota played a predominant role in Hg biotransformation and thus significantly affected the overall Hg accumulation and distribution in fish body. The richness of Hg methylators or demethylators was elevated under IHg or MeHg treatment, respectively. Furthermore, the intestinal microbiota composition was also altered by Hg exposure. This study highlights the importance of intestinal microbiota in Hg biotransformation in fish body, and suggests that modulating the gut microbiome could be a possible solution to minimize Hg contamination in fish.
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Affiliation(s)
- Tao-Tao Yang
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Yong Liu
- Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, 510300, China
| | - Sha Tan
- State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resource, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, PR China
| | - Wen-Xiong Wang
- School of Energy and Environment, State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China; Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518057, China
| | - Xun Wang
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, 510642, China.
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202
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Du B, Li P, Feng X, Yin R, Zhou J, Maurice L. Monthly variations in mercury exposure of school children and adults in an industrial area of southwestern China. ENVIRONMENTAL RESEARCH 2021; 196:110362. [PMID: 33169691 DOI: 10.1016/j.envres.2020.110362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 10/15/2020] [Accepted: 10/16/2020] [Indexed: 06/11/2023]
Abstract
Recent studies have shown that rice consumption can be the major pathway for human methylmercury (MeHg) exposure in inland China. However, few studies have considered the susceptible population of school children's exposure through rice ingestion. In this study, monthly variations in total Hg (THg)/MeHg concentrations in rice, fish, hair, and urine samples were studied to evaluate the Hg (both THg and MeHg) exposure in Guiyang, a typical industrial area with high anthropogenic emission of Hg. A total of 17 primary school (school A) students, 29 middle school (school B) students, and 46 guardians participated in this study for one year. Hair THg, hair MeHg, and urine THg concentrations ranged from 355-413 ng g-1, 213-236 ng g-1, and 469-518 ng g-1 Creatinine (ng·g-1 Cr), respectively, and no significant differences were observed between different genders and age groups. Hair and urine Hg concentrations showed slightly higher values in the cold season (October to February) than the hot season (March to September), but without significant difference. High monthly variability of individual hair and urine Hg concentrations suggested that long-term study could effectively decrease the uncertainty. The school students showed significantly higher urine THg concentrations than adults due to children's unique physiological structure and behaviors. Probable daily intake (PDI) of MeHg via rice and fish ingestion averaged at 0.0091, 0.0090, and 0.0079 μg kg-1 d-1 for school A students, school B students, and their guardians, respectively, which means that 86%, 84%, and 87% of the PDI were originated from rice ingestion, respectively. Therefore, more attention should be paid to children as a susceptible population. The results indicated low risk of Hg exposure via rice and fish consumption for urban residents in a Chinese industrial city.
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Affiliation(s)
- Buyun Du
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, Nanjing, 210042, China
| | - Ping Li
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
| | - Runsheng Yin
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Jun Zhou
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Laurence Maurice
- Observatoire Midi-Pyrénées, Laboratoire Géosciences Environnement Toulouse, IRD-CNRS-Université Toulouse, 14 Avenue Edouard Belin, Toulouse, 31400, France
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203
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Goñez-Rodríguez L, Johs A, Lowe KA, Carter KE, Löffler FE, Mayes MA. Evaluation of engineered sorbents for the sorption of mercury from contaminated bank soils: a column study. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:22651-22663. [PMID: 33420931 PMCID: PMC8113147 DOI: 10.1007/s11356-020-12073-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 12/13/2020] [Indexed: 06/12/2023]
Abstract
As a global environmental pollutant, mercury (Hg) threatens our water resources and presents a substantial risk to human health. The rate and extent of immobilization of Hg2+ (hereafter, Hg) on engineered sorbents (Thiol-SAMMS®, pine biochar, SediMite™, Organoclay™ PM-199, and quartz sand as a control) was evaluated using flow-through column experiments. The effectiveness of the sorbents was based on (1) the percentage of Hg removed in relation to the total amount of Hg passing the sorbent column, and (2) the rate of Hg uptake compared to the nonreactive tracer bromide (Br-). All sorbents removed Hg to a certain extent, but none of the sorbents removed all the Hg introduced to the columns. Thiol-SAMMS showed the highest mean percentage of Hg removed (87% ± 2.9%), followed by Organoclay PM-199 (71% ± 0.4%), pine biochar (57% ± 22.3%), SediMite (61% ± 0.8%), and the control quartz sand (11% ± 5.6%). Thiol-SAMMS was the only sorbent to exhibit retardation of Hg in comparison to the conservative tracer Br-. For the remaining sorbents, Br- along with low concentrations of Hg were eluted within the first 3 pore volumes, indicating limited retardation of Hg. Overall, removal of Hg by sorbents was substantial, suggesting that sorbents might be suitable for deployment in contaminated environments. High concentrations of DOM leaching from the soil columns likely influenced the speciation of Hg and inhibited sorption to the sorbents. Incomplete removal of Hg by any sorbent suggests that additional optimization is needed to increase efficiency.
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Affiliation(s)
- Leroy Goñez-Rodríguez
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37830, USA
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN, 37996, USA
| | - Alexander Johs
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37830, USA
| | - Kenneth A Lowe
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37830, USA
| | - Kimberly E Carter
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN, 37996, USA
| | - Frank E Löffler
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN, 37996, USA
- Department of Microbiology, University of Tennessee, Knoxville, TN, 37996, USA
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, 37996, USA
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Melanie A Mayes
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37830, USA.
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204
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Dai SS, Yang Z, Tong Y, Chen L, Liu SY, Pan R, Li Y, Zhang CJ, Liu YR, Huang Q. Global distribution and environmental drivers of methylmercury production in sediments. JOURNAL OF HAZARDOUS MATERIALS 2021; 407:124700. [PMID: 33333388 DOI: 10.1016/j.jhazmat.2020.124700] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/11/2020] [Accepted: 11/25/2020] [Indexed: 06/12/2023]
Abstract
Neurotoxic methylmercury (MeHg) in environments poses substantial risks to human health. Saturated sediments are basic sources of MeHg in food chains; however, distribution patterns and environmental drivers of MeHg at a global scale remain largely unexplored. Here, we characterized global patterns of MeHg distribution and environmental drivers of MeHg production based on 495 sediment samples across five typical ecosystems from the literature (1995-2018) and our own field survey. Our results showed the MeHg concentration ranged from 0.009 to 55.7 μg kg-1 across the different ecosystems, and the highest MeHg concentration and Hg methylation potential were from the sediments of paddy and marine environments, respectively. Further, using combined analysis of random forest and structural equation modeling, we identified temperature and precipitation as important regulators of MeHg production after accounting for the well-known drivers including Hg availability and sediment geochemistry. More importantly, we found increased MeHg production in sediments with elevated mean annual Hg precipitation, and warmer temperature could also accelerate MeHg production by facilitating activities of microbial methylators. Together, this work advances our understanding of global MeHg distribution in sediments and environmental drivers, which are fundamental to the prediction and management of MeHg production and its potential health risk globally.
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Affiliation(s)
- Shu-Shen Dai
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Ziming Yang
- Department of Chemistry, Oakland University, Rochester, MI 48309, United States
| | - Yindong Tong
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Long Chen
- Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Si-Yuan Liu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Rong Pan
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Yanbin Li
- Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Cui-Jing Zhang
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Wuhan 430070, China.
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; Hubei Key Laboratory of Soil Environment and Pollution Remediation, Wuhan 430070, China
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205
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Carrell AA, Schwartz GE, Cregger MA, Gionfriddo CM, Elias DA, Wilpiszeski RL, Klingeman DM, Wymore AM, Muller KA, Brooks SC. Nutrient Exposure Alters Microbial Composition, Structure, and Mercury Methylating Activity in Periphyton in a Contaminated Watershed. Front Microbiol 2021; 12:647861. [PMID: 33815336 PMCID: PMC8017159 DOI: 10.3389/fmicb.2021.647861] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 02/22/2021] [Indexed: 01/04/2023] Open
Abstract
The conversion of mercury (Hg) to monomethylmercury (MMHg) is a critical area of concern in global Hg cycling. Periphyton biofilms may harbor significant amounts of MMHg but little is known about the Hg-methylating potential of the periphyton microbiome. Therefore, we used high-throughput amplicon sequencing of the 16S rRNA gene, ITS2 region, and Hg methylation gene pair (hgcAB) to characterize the archaea/bacteria, fungi, and Hg-methylating microorganisms in periphyton communities grown in a contaminated watershed in East Tennessee (United States). Furthermore, we examined how nutrient amendments (nitrate and/or phosphate) altered periphyton community structure and function. We found that bacterial/archaeal richness in experimental conditions decreased in summer and increased in autumn relative to control treatments, while fungal diversity generally increased in summer and decreased in autumn relative to control treatments. Interestingly, the Hg-methylating communities were dominated by Proteobacteria followed by Candidatus Atribacteria across both seasons. Surprisingly, Hg methylation potential correlated with numerous bacterial families that do not contain hgcAB, suggesting that the overall microbiome structure of periphyton communities influences rates of Hg transformation within these microbial mats. To further explore these complex community interactions, we performed a microbial network analysis and found that the nitrate-amended treatment resulted in the highest number of hub taxa that also corresponded with enhanced Hg methylation potential. This work provides insight into community interactions within the periphyton microbiome that may contribute to Hg cycling and will inform future research that will focus on establishing mixed microbial consortia to uncover mechanisms driving shifts in Hg cycling within periphyton habitats.
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Affiliation(s)
- Alyssa A Carrell
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Grace E Schwartz
- Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN, United States.,Department of Chemistry, Wofford College, Spartanburg, SC, United States
| | - Melissa A Cregger
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Caitlin M Gionfriddo
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States.,Smithsonian Environmental Research Center, Edgewater, MD, United States
| | - Dwayne A Elias
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Regina L Wilpiszeski
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Dawn M Klingeman
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Ann M Wymore
- Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN, United States
| | - Katherine A Muller
- Pacific Northwest National Laboratory, Earth Systems Science Division, Richland, WA, United States
| | - Scott C Brooks
- Oak Ridge National Laboratory, Environmental Science Division, Oak Ridge, TN, United States
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206
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Wall JD, Zane GM, Juba TR, Kuehl JV, Ray J, Chhabra SR, Trotter VV, Shatsky M, De León KB, Keller KL, Bender KS, Butland G, Arkin AP, Deutschbauer AM. Deletion Mutants, Archived Transposon Library, and Tagged Protein Constructs of the Model Sulfate-Reducing Bacterium Desulfovibrio vulgaris Hildenborough. Microbiol Resour Announc 2021; 10:e00072-21. [PMID: 33737356 PMCID: PMC7975874 DOI: 10.1128/mra.00072-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 02/17/2021] [Indexed: 11/20/2022] Open
Abstract
The dissimilatory sulfate-reducing deltaproteobacterium Desulfovibrio vulgaris Hildenborough (ATCC 29579) was chosen by the research collaboration ENIGMA to explore tools and protocols for bringing this anaerobe to model status. Here, we describe a collection of genetic constructs generated by ENIGMA that are available to the research community.
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Affiliation(s)
- Judy D Wall
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Grant M Zane
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Thomas R Juba
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Jennifer V Kuehl
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Jayashree Ray
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Swapnil R Chhabra
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Valentine V Trotter
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Maxim Shatsky
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Kara B De León
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Kimberly L Keller
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Kelly S Bender
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Gareth Butland
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Adam P Arkin
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Adam M Deutschbauer
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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207
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Leclerc M, Harrison MC, Storck V, Planas D, Amyot M, Walsh DA. Microbial Diversity and Mercury Methylation Activity in Periphytic Biofilms at a Run-of-River Hydroelectric Dam and Constructed Wetlands. mSphere 2021; 6:e00021-21. [PMID: 33731467 PMCID: PMC8546676 DOI: 10.1128/msphere.00021-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/24/2021] [Indexed: 01/04/2023] Open
Abstract
Periphytic biofilms have the potential to greatly influence the microbial production of the neurotoxicant monomethylmercury in freshwaters although few studies have simultaneously assessed periphyton mercury methylation and demethylation rates and the microbial communities associated with these transformations. We performed a field study on periphyton from a river affected by run-of-river power plants and artificial wetlands in a boreal landscape (Québec, Canada). In situ incubations were performed on three sites using environmental concentrations of isotopically enriched monomethylmercury (MM198Hg) and inorganic mercury (200Hg) for demethylation and methylation rate measurements. Periphytic microbial communities were investigated through 16S rRNA gene analyses and metagenomic screenings for the hgcA gene, involved in mercury methylation. Positive mercury methylation rates ([5.9 ± 3.4] × 10-3 day-1) were observed only in the wetlands, and demethylation rates averaged 1.78 ± 0.21 day-1 for the three studied sites. The 16S rRNA gene analyses revealed Proteobacteria as the most abundant phylum across all sites (36.3% ± 1.4%), from which families associated with mercury methylation were mostly found in the wetland site. Metagenome screening for HgcA identified 24 different hgcA sequences in the constructed wetland site only, associated with 8 known families, where the iron-reducing Geobacteraceae were the most abundant. This work brings new information on mercury methylation in periphyton from habitats of impacted rivers, associating it mostly with putative iron-reducing bacteria.IMPORTANCE Monomethylmercury (MMHg) is a biomagnifiable neurotoxin of global concern with risks to human health mostly associated with fish consumption. Hydroelectric reservoirs are known to be sources of MMHg many years after their impoundment. Little is known, however, on run-of-river dams flooding smaller terrestrial areas, although their numbers are expected to increase considerably worldwide in decades to come. Production of MMHg is associated mostly with anaerobic processes, but Hg methylation has been shown to occur in periphytic biofilms located in oxic zones of the water column. Therefore, in this study, we investigated in situ production of MMHg by periphytic communities in habitats impacted by the construction of a run-of-river dam by combining transformation rate measurements with genomic approaches targeting hgcAB genes, responsible for mercury methylation. These results provide extended knowledge on mercury methylators in river ecosystems impacted by run-of-river dams in temperate habitats.
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Affiliation(s)
- Maxime Leclerc
- GRIL, Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada
- GRIL, Département de Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | | | - Veronika Storck
- GRIL, Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada
- Department of Biology, Concordia University, Montréal, Québec, Canada
| | - Dolors Planas
- GRIL, Département de Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Marc Amyot
- GRIL, Département de Sciences Biologiques, Université de Montréal, Montréal, Québec, Canada
| | - David A Walsh
- Department of Biology, Concordia University, Montréal, Québec, Canada
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208
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Gilmour CC, Soren AB, Gionfriddo CM, Podar M, Wall JD, Brown SD, Michener JK, Urriza MSG, Elias DA. Pseudodesulfovibrio mercurii sp. nov., a mercury-methylating bacterium isolated from sediment. Int J Syst Evol Microbiol 2021; 71. [PMID: 33570484 DOI: 10.1099/ijsem.0.004697] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The sulfate-reducing, mercury-methylating strain ND132T was isolated from the brackish anaerobic bottom sediments of Chesapeake Bay, USA. Capable of high levels of mercury (Hg) methylation, ND132T has been widely used as a model strain to study the process and to determine the genetic basis of Hg methylation. Originally called Desulfovibrio desulfuricans ND132T on the basis of an early partial 16S rRNA sequence, the strain has never been formally described. Phylogenetic and physiological traits place this strain within the genus Pseudodesulfovibrio, in the recently reclassified phylum Desulfobacterota (formerly Deltaproteobacteria). ND132T is most closely related to Pseudodesulfovibrio hydrargyri BerOc1T and Pseudodesulfovibrio indicus J2T. Analysis of average nucleotide identity (ANI) of whole-genome sequences showed roughly 88 % ANI between P. hydrargyri BerOc1T and ND132T, and 84 % similarity between ND132T and P. indicus J2T. These cut-off scores <95 %, along with a multi-gene phylogenetic analysis of members of the family Desulfovibrionacea, and differences in physiology indicate that all three strains represent separate species. The Gram-stain-negative cells are vibrio-shaped, motile and not sporulated. ND132T is a salt-tolerant mesophile with optimal growth in the laboratory at 32 °C, 2 % salinity, and pH 7.8. The DNA G+C content of the genomic DNA is 65.2 %. It is an incomplete oxidizer of short chain fatty acids, using lactate, pyruvate and fumarate with sulfate or sulfite as the terminal electron acceptors. ND132T can respire fumarate using pyruvate as an electron donor. The major fatty acids are iso-C15 : 0, anteiso-C15 : 0, iso-C17 : 0, iso-C17 : 1ω9c and anteiso-C17 : 0. We propose the classification of strain ND132T (DSM 110689, ATCC TSD-224) as the type strain Pseudodesulfovibrio mercurii sp. nov.
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Affiliation(s)
| | | | - Caitlin M Gionfriddo
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA.,Smithsonian Environmental Research Center, Edgewater, Maryland, USA
| | - Mircea Podar
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Judy D Wall
- Department of Biochemistry, University of Missouri, Columbia, Missouri, USA
| | - Steven D Brown
- Present address: LanzaTech, Skokie, Illinois, USA.,Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Joshua K Michener
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | | | - Dwayne A Elias
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
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209
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Liem-Nguyen V, Skyllberg U, Björn E. Methylmercury formation in boreal wetlands in relation to chemical speciation of mercury(II) and concentration of low molecular mass thiols. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:142666. [PMID: 33059147 DOI: 10.1016/j.scitotenv.2020.142666] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 09/22/2020] [Accepted: 09/22/2020] [Indexed: 06/11/2023]
Abstract
Methylmercury (MeHg) is a neurotoxin formed from inorganic divalent mercury (HgII) via microbial methylation, and boreal wetlands have been identified as major sources of MeHg. There is however a lack of studies investigating the relationship between the chemical speciation of HgII and MeHg formation in such environments, in particular regarding to role of thiol compounds. We determined HgII methylation potentials, kmeth, in boreal wetland soils using two HgII isotope tracers: 198Hg(OH)2(aq) and HgII bonded to thiol groups in natural organic matter, 200HgII-NOM(ads), representing HgII sources with high and low availability for methylation. The 198Hg(OH)2(aq) tracer was consistently methylated to a 5-fold higher extent than 200HgII-NOM(ads), independent of environmental conditions. This suggests that the concentration of HgII in porewater was a decisive factor for HgII methylation. A comprehensive thermodynamic speciation model (including HgII complexes with inorganic sulfide (H2S), polysulfides (H2Sn), thiols associated with natural organic matter (NOM-RSH) and specific low molecular mass thiols (LMM-RSH) provided new insights on the speciation of HgII in boreal wetland porewaters, but did not demonstrate any clear relationship between kmeth and the calculated chemical speciation. In contrast, significant positive relationships were observed between kmeth and the sum of LMM thiol compounds of biological origin. We suggest two possible mechanisms underlying these correlations: 1) LMM thiols kinetically control the size and composition of the HgII pool available for microbial uptake, and/or 2) LMM thiols are produced by microbes such that the correlation reflects a relation between microbial activity and MeHg formation.
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Affiliation(s)
- Van Liem-Nguyen
- Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden; Laboratory of Advanced Materials Chemistry, Advanced Institute of Materials Science, Ton Duc Thang University, Ho Chi Minh City, Viet Nam
| | - Ulf Skyllberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
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210
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Complete Genome Sequence of Desulfobulbus oligotrophicus Prop6, an Anaerobic Deltabacterota Strain That Lacks Mercury Methylation Capability. Microbiol Resour Announc 2021; 10:10/5/e00002-21. [PMID: 33541869 PMCID: PMC7862947 DOI: 10.1128/mra.00002-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Desulfobulbus oligotrophicus Prop6 is a sulfate-reducing, propionate-oxidizing Deltabacterota (formerly Deltaproteobacteria) strain from sewage sludge. Desulfobulbus species are found in anoxic environments, in animal microbiota, and some produce the neurotoxin methylmercury. The 3.1-Mbp D. oligotrophicus genome sequence enables studies of diverse environmental adaptations and the evolutionary genomics of mercury methylation mechanisms.
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211
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Song W, Xiong H, Qi R, Wang S, Yang Y. Effect of salinity and algae biomass on mercury cycling genes and bacterial communities in sediments under mercury contamination: Implications of the mercury cycle in arid regions. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 269:116141. [PMID: 33290948 DOI: 10.1016/j.envpol.2020.116141] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/22/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
Lakes in arid regions are experiencing mercury pollution via air deposition and surface runoff, posing a threat to ecosystem safety and human health. Furthermore, salinity and organic matter input could influence the mercury cycle and composition of bacterial communities in the sediment. In this study, the effects of salinity and algae biomass as an important organic matter on the genes (merA and hgcA) involved in the mercury cycle under mercury contamination were investigated. Archaeal merA and hgcA were not detected in sediments of lake microcosms, indicating that bacteria rather than archaea played a crucial role in mercury reduction and methylation. The high content of mercury (300 ng g-1) could reduce the abundance of both merA and hgcA. The effects of salinity and algae biomass on mercury cycling genes depended on the gene type and dose. A higher input of algae biomass (250 mg L-1) led to an increase of merA abundance, but a decrease of hgcA abundance. All high inputs of mercury, salinity, and algae biomass decreased the richness and diversity of bacterial communities in sediment. Further analysis indicated that higher mercury (300 ng g-1) led to an increased relative abundance of mercury methylators, such as Ruminococcaceae, Bacteroidaceae, and Veillonellaceae. Under saline conditions (10 and 30 g L-1), the richness of specific bacteria associated with mercury reduction (Halomonadaceae) and methylation (Syntrophomonadaceae) increased compared to the control. The input of algae biomass led to an increase in the specific bacterial communities associated with the mercury cycle and the richness of bacteria involved in the decomposition of organic matter. These results provide insight into mercury cycle-related genes and bacterial communities in the sediments of lakes in arid regions.
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Affiliation(s)
- Wenjuan Song
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Heigang Xiong
- College of Applied Arts and Science of Beijing Union University, Beijing, 100191, China
| | - Ran Qi
- Command Center of Comprehensive Natural Resources Survey, China Geological Survey, Beijing, 100055, China; Institute of Geological Survey, China University of Geosciences, Wuhan, 430074, China
| | - Shuzhi Wang
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China
| | - Yuyi Yang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China
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212
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Wang T, Yang G, Du H, Guo P, Sun T, An S, Wang D, Ma M. Migration characteristics and potential determinants of mercury in long-term decomposing litterfall of two subtropical forests. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 208:111402. [PMID: 33068979 DOI: 10.1016/j.ecoenv.2020.111402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 09/11/2020] [Accepted: 09/20/2020] [Indexed: 06/11/2023]
Abstract
It is of great importance to elucidate the mechanism of mercury (Hg) migration in the forest litterfall so as to clearly understand global Hg deposition. However, it is still unclear for the migration and transformation of Hg in different forest litters during long-term decomposition. Therefore, the dynamics of total Hg (THg), methylmercury (MeHg), carbon, nitrogen, microbial biomass carbon and nitrogen in the litterfall of the evergreen broadleaf (EB) and mixed broadleaf-conifer (MBC) forests, southwest China were investigated, aiming to understand the migration characteristics of Hg in the two-year decomposing litterfall. Results showed that carbon decreased, while nitrogen accumulated slightly in the process of litterfall decomposition. THg levels in the second year of the EB and MBC forests decreased by 16.9% and 11.3%, while MeHg levels reduced by 141.4% and 210.7% respectively comparing with those in the first year. The total percentage of hydrochloric acid-soluble mercury (Hg-h) and water-soluble mercury (Hg-w) had a significant impact on the migration of THg and MeHg in the two forest stands. The C/N ratio in the EB forest bore a positive correlation with THg and MeHg levels, whereas that in the MBC forest was adverse. Besides, microbial biomass C and N were positively related with THg and MeHg levels in both the EB and MBC forests. It is proposed that THg and MeHg accumulation in the second year drastically decreased probably due to finite nutritional conditions, which implies that Hg accumulation risks alleviate with degradation time.
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Affiliation(s)
- Tao Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Southwest University, Chongqing 400715, China
| | - Guang Yang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Southwest University, Chongqing 400715, China
| | - Hongxia Du
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Bio-resource for Bioenergy, Southwest University, Chongqing 400715, China
| | - Pan Guo
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Southwest University, Chongqing 400715, China
| | - Tao Sun
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Southwest University, Chongqing 400715, China
| | - Siwei An
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Southwest University, Chongqing 400715, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Southwest University, Chongqing 400715, China
| | - Ming Ma
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Bio-resource for Bioenergy, Southwest University, Chongqing 400715, China.
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213
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Cao D, Chen W, Xiang Y, Mi Q, Liu H, Feng P, Shen H, Zhang C, Wang Y, Wang D. The efficiencies of inorganic mercury bio-methylation by aerobic bacteria under different oxygen concentrations. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 207:111538. [PMID: 33254400 DOI: 10.1016/j.ecoenv.2020.111538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 10/15/2020] [Accepted: 10/18/2020] [Indexed: 06/12/2023]
Abstract
Limited information is available about the bio-methylation of inorganic mercury (iHg) under aerobic conditions. In this study, two γ-proteobacteria strains (P. fluorescens TGR-B2 and P. putida TGR-B4) were obtained from the soil of The Three Gorges Reservoir (TGR), demonstrating effective aerobic transformation capacities of iHg into methylmercury (MeHg). Based on periodical changes in soil oxygen content of the TGR, a culture system was established, in which 300 ng Hg (II) L-1 and O2 were set at 7%, 14%, and 21%, respectively. Results indicated that the two strains differed significantly in bacterial growth rate and MeHg production. The kinetic model of MeHg showed typical characteristics of a "two-staged" process: The first stage was dominated by bio-methylation, which was shown by increasing of net MeHg content. Moreover, the second stage was dominated by bio-demethylation, which decreased net MeHg content. Thus, we hypothesized that the mechanism of aerobic bacterial iHg bio-methylation: (1) should inefficiency compared to anaerobic bacteria i.e.SRB, which were regulated by hgcA/B gene clusters, (2) might be regarded as a passive stress response and depended on the bacterial iHg intoxication threshold and MeHg tolerance threshold.
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Affiliation(s)
- Dan Cao
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Weihong Chen
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Yuping Xiang
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Qianfen Mi
- Biological Science Research Center of Southwest University, Chongqing 400715, China
| | - Hang Liu
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - PengYu Feng
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Hong Shen
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China.
| | - Cheng Zhang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China
| | - Yongmin Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China
| | - Dingyong Wang
- College of Resources and Environment, Southwest University, Chongqing 400715, China; Biological Science Research Center of Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400715, China.
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214
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Khose RV, Chakraborty G, Bondarde MP, Wadekar PH, Ray AK, Some S. Red-fluorescent graphene quantum dots from guava leaf as a turn-off probe for sensing aqueous Hg(ii). NEW J CHEM 2021. [DOI: 10.1039/d0nj06259f] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, we have prepared red-fluorescent graphene quantum dots and utilized as a highly selective and sensitive fluorescence turn-off probe for detection of the toxic metal ion Hg2+ from guava leaf extract.
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Affiliation(s)
- Rahul V. Khose
- Department of Speciality chemicals Technology
- Institute of Chemical Technology
- Mumbai 400019
- India
| | - Goutam Chakraborty
- Laser and Plasma Technology Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
| | - Mahesh P. Bondarde
- Department of Speciality chemicals Technology
- Institute of Chemical Technology
- Mumbai 400019
- India
| | - Pravin H. Wadekar
- Department of Speciality chemicals Technology
- Institute of Chemical Technology
- Mumbai 400019
- India
| | - Alok K. Ray
- Laser and Plasma Technology Division
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
- Professor
| | - Surajit Some
- Department of Speciality chemicals Technology
- Institute of Chemical Technology
- Mumbai 400019
- India
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215
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Zhang G, Yin D, He T, Xu Y, Ran S, Zhou X, Tian X, Wang Y. Mercury Bioaccumulation in Freshwater Snails as Influenced by Soil Composition. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2021; 106:153-159. [PMID: 33392685 DOI: 10.1007/s00128-020-03071-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Soil properties largely control the fate of mercury (Hg), including the synthesis of neurovirulent methylmercury (MeHg). Here, the freshwater snail (Cipangopaludina cahayensis), a snail species commonly bred in flooded farmland, was used in a test of biotoxicity exposure to explore the effects of soil components on Hg bioavailability. The results show that snails incubated on the surface of slightly Hg-polluted flooded soil (2.0 mg/kg) have MeHg concentrations of 7.9 ± 1.5 mg/kg, which greatly exceed the limit of contaminants in food in China (0.5 mg/kg). The addition of ferrous disulfide can significantly increase the MeHg concentrations in soils while reducing the concentrations of total Hg (THg) and MeHg levels in snails by 59.1% and 64.3%, respectively. Peat-derived fulvic acid has the capacity to reduce the MeHg concentrations in soils and snails by 23.8% and 33.2%, respectively, whereas it increases the dissolved Hg levels in overlying water by 104.3%. Moreover, Fe-Mn oxides and humic acid can consistently reduce THg and MeHg concentrations in snails. Overall, freshwater snails bred in Hg-polluted areas may suffer from a high risk of Hg exposure, and importantly, some soil components such as ferrous disulfide and humic acid have strong inhibitory effects on Hg bioaccumulation in snails.
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Affiliation(s)
- Ge Zhang
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Deliang Yin
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China.
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China.
- Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, 550025, China.
| | - Tianrong He
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China.
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China.
- Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang, 550025, China.
| | - Yiyuan Xu
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Shu Ran
- College of Resources and Environment, Guizhou University, Guiyang, 550025, China
| | - Xian Zhou
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Xiang Tian
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
| | - Yan Wang
- Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China
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216
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Lozano M, Murcia M, Soler-Blasco R, González L, Iriarte G, Rebagliato M, Lopez-Espinosa MJ, Esplugues A, Ballester F, Llop S. Exposure to mercury among 9-year-old children and neurobehavioural function. ENVIRONMENT INTERNATIONAL 2021; 146:106173. [PMID: 33096466 DOI: 10.1016/j.envint.2020.106173] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 09/14/2020] [Accepted: 09/30/2020] [Indexed: 05/28/2023]
Abstract
Mercury (Hg) is an environmental neurotoxicant whose main route of exposure in humans is the consumption of seafood. The aim of this study was to explore the relationship between Hg exposure at 9 years old and behaviour assessed at 9 and 11 years old. Study subjects were mother-child pairs participating in the INMA (Environment and Childhood) Project in Valencia (Spain). Total Hg (THg) was measured in hair samples from the children at 9 years old. Behaviour and emotions were assessed at 9 (n = 472) years and 11 (n = 385) years of age using the Child Behaviour Checklist test (CBCL) and the Conners Parents Rating Scale-Revised: Short Form (CPRS-R:S). Furthermore, the attention function was assessed by the Attention Network Test at 11 years old. Socio-demographic, lifestyle and dietary information was collected through questionnaires during pregnancy and childhood. Polymorphism in BDNF, APOE and GSTP1 were genotyped in cord blood DNA. Multivariable negative binomial regression models were built in order to study the association between THg concentrations and the scores obtained by the children at 9 and 11 years old. Effect modification by sex and genetic polymorphisms was assessed. The association between Hg levels and CBCL scores was positive (worse neurobehavioural development) for the CBCL internalizing and total problem scales (Incidence Rate Ratio [95% confidence interval] = 1.07 [1.01, 1.13] and 1.05 [0.99, 1.11], respectively). The association between Hg and the externalizing and total problems CBCL scales and the Attention Deficit Hyperactivity Disorder (ADHD) index of the CPRS-R:S was different according to sex, with boys obtaining worse scores with increasing Hg, compared to girls. Statistically significant interactions were also observed for genetic polymorphisms affecting the association between early exposure to Hg and both CBCL and CPRS-R:S scores. In conclusion, postnatal Hg exposure is associated with poorer neurobehavioural development in 9- and 11-year-old children. Sex and the presence of certain genetic polymorphisms modified this association.
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Affiliation(s)
- Manuel Lozano
- Preventive Medicine and Public Health, Food Sciences, Toxicology and Forensic Medicine Department, Universitat de València, Valencia, Spain
| | - Mario Murcia
- Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Servicio de Análisis de Sistemas de Información Sanitaria, Conselleria de Sanitat, Generalitat Valenciana, Valencia, Spain
| | - Raquel Soler-Blasco
- Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Valencia, Spain
| | - Llúcia González
- Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain
| | - Gorka Iriarte
- Laboratorio de Salud Pública, Alava, Vitoria Gasteiz, Spain
| | - Marisa Rebagliato
- Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Department of Medicine, Universitat Jaume I, Castelló, Spain
| | - Maria-Jose Lopez-Espinosa
- Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Department of Nursing School, Universitat de València, Valencia, Spain
| | - Ana Esplugues
- Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Department of Nursing School, Universitat de València, Valencia, Spain.
| | - Ferran Ballester
- Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Department of Nursing School, Universitat de València, Valencia, Spain
| | - Sabrina Llop
- Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de València, Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain
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217
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Cozannet M, Borrel G, Roussel E, Moalic Y, Allioux M, Sanvoisin A, Toffin L, Alain K. New Insights into the Ecology and Physiology of Methanomassiliicoccales from Terrestrial and Aquatic Environments. Microorganisms 2020; 9:E30. [PMID: 33374130 PMCID: PMC7824343 DOI: 10.3390/microorganisms9010030] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/19/2020] [Accepted: 12/21/2020] [Indexed: 12/19/2022] Open
Abstract
Members of the archaeal order Methanomassiliicoccales are methanogens mainly associated with animal digestive tracts. However, environmental members remain poorly characterized as no representatives not associated with a host have been cultivated so far. In this study, metabarcoding screening combined with quantitative PCR analyses on a collection of diverse non-host-associated environmental samples revealed that Methanomassiliicoccales were very scarce in most terrestrial and aquatic ecosystems. Relative abundance of Methanomassiliicoccales and substrates/products of methanogenesis were monitored during incubation of environmental slurries. A sediment slurry enriched in Methanomassiliicoccales was obtained from a freshwater sample. It allowed the reconstruction of a high-quality metagenome-assembled genome (MAG) corresponding to a new candidate species, for which we propose the name of Candidatus 'Methanomassiliicoccus armoricus MXMAG1'. Comparison of the annotated genome of MXMAG1 with the published genomes and MAGs from Methanomassiliicoccales belonging to the 2 known clades ('free-living'/non-host-associated environmental clade and 'host-associated'/digestive clade) allowed us to explore the putative physiological traits of Candidatus 'M. armoricus MXMAG1'. As expected, Ca. 'Methanomassiliicoccus armoricus MXMAG1' had the genetic potential to produce methane by reduction of methyl compounds and dihydrogen oxidation. This MAG encodes for several putative physiological and stress response adaptations, including biosynthesis of trehalose (osmotic and temperature regulations), agmatine production (pH regulation), and arsenic detoxication, by reduction and excretion of arsenite, a mechanism that was only present in the 'free-living' clade. An analysis of co-occurrence networks carried out on environmental samples and slurries also showed that Methanomassiliicoccales detected in terrestrial and aquatic ecosystems were strongly associated with acetate and dihydrogen producing bacteria commonly found in digestive habitats and which have been reported to form syntrophic relationships with methanogens.
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Affiliation(s)
- Marc Cozannet
- Laboratoire de Microbiologie des Environnements Extrêmes LM2E, Univ Brest, CNRS, IFREMER, IRP 1211 MicrobSea, UMR 6197, IUEM, Rue Dumont d’Urville, F-29280 Plouzané, France; (M.C.); (E.R.); (Y.M.); (M.A.); (A.S.); (L.T.)
| | - Guillaume Borrel
- Unit Evolutionary Biology of the Microbial Cell, Department of Microbiology, Institute Pasteur, 75015 Paris, France;
| | - Erwan Roussel
- Laboratoire de Microbiologie des Environnements Extrêmes LM2E, Univ Brest, CNRS, IFREMER, IRP 1211 MicrobSea, UMR 6197, IUEM, Rue Dumont d’Urville, F-29280 Plouzané, France; (M.C.); (E.R.); (Y.M.); (M.A.); (A.S.); (L.T.)
| | - Yann Moalic
- Laboratoire de Microbiologie des Environnements Extrêmes LM2E, Univ Brest, CNRS, IFREMER, IRP 1211 MicrobSea, UMR 6197, IUEM, Rue Dumont d’Urville, F-29280 Plouzané, France; (M.C.); (E.R.); (Y.M.); (M.A.); (A.S.); (L.T.)
| | - Maxime Allioux
- Laboratoire de Microbiologie des Environnements Extrêmes LM2E, Univ Brest, CNRS, IFREMER, IRP 1211 MicrobSea, UMR 6197, IUEM, Rue Dumont d’Urville, F-29280 Plouzané, France; (M.C.); (E.R.); (Y.M.); (M.A.); (A.S.); (L.T.)
| | - Amandine Sanvoisin
- Laboratoire de Microbiologie des Environnements Extrêmes LM2E, Univ Brest, CNRS, IFREMER, IRP 1211 MicrobSea, UMR 6197, IUEM, Rue Dumont d’Urville, F-29280 Plouzané, France; (M.C.); (E.R.); (Y.M.); (M.A.); (A.S.); (L.T.)
| | - Laurent Toffin
- Laboratoire de Microbiologie des Environnements Extrêmes LM2E, Univ Brest, CNRS, IFREMER, IRP 1211 MicrobSea, UMR 6197, IUEM, Rue Dumont d’Urville, F-29280 Plouzané, France; (M.C.); (E.R.); (Y.M.); (M.A.); (A.S.); (L.T.)
| | - Karine Alain
- Laboratoire de Microbiologie des Environnements Extrêmes LM2E, Univ Brest, CNRS, IFREMER, IRP 1211 MicrobSea, UMR 6197, IUEM, Rue Dumont d’Urville, F-29280 Plouzané, France; (M.C.); (E.R.); (Y.M.); (M.A.); (A.S.); (L.T.)
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218
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Peterson BD, McDaniel EA, Schmidt AG, Lepak RF, Janssen SE, Tran PQ, Marick RA, Ogorek JM, DeWild JF, Krabbenhoft DP, McMahon KD. Mercury Methylation Genes Identified across Diverse Anaerobic Microbial Guilds in a Eutrophic Sulfate-Enriched Lake. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:15840-15851. [PMID: 33228362 PMCID: PMC9741811 DOI: 10.1021/acs.est.0c05435] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Mercury (Hg) methylation is a microbially mediated process that converts inorganic Hg into bioaccumulative, neurotoxic methylmercury (MeHg). The metabolic activity of methylating organisms is highly dependent on biogeochemical conditions, which subsequently influences MeHg production. However, our understanding of the ecophysiology of methylators in natural ecosystems is still limited. Here, we identified potential locations of MeHg production in the anoxic, sulfidic hypolimnion of a freshwater lake. At these sites, we used shotgun metagenomics to characterize microorganisms with the Hg-methylation gene hgcA. Putative methylators were dominated by hgcA sequences divergent from those in well-studied, confirmed methylators. Using genome-resolved metagenomics, we identified organisms with hgcA (hgcA+) within the Bacteroidetes and the recently described Kiritimatiellaeota phyla. We identified hgcA+ genomes derived from sulfate-reducing bacteria, but these accounted for only 22% of hgcA+ genome coverage. The most abundant hgcA+ genomes were from fermenters, accounting for over half of the hgcA gene coverage. Many of these organisms also mediate hydrolysis of polysaccharides, likely from cyanobacterial blooms. This work highlights the distribution of the Hg-methylation genes across microbial metabolic guilds and indicate that primary degradation of polysaccharides and fermentation may play an important but unrecognized role in MeHg production in the anoxic hypolimnion of freshwater lakes.
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Affiliation(s)
- Benjamin D. Peterson
- Environmental Science & Technology Program, University of Wisconsin - Madison, 660 N. Park Street, Madison, WI 53706, USA
- Corresponding author:
| | - Elizabeth A. McDaniel
- Department of Bacteriology, University of Wisconsin - Madison, 1550 Linden Drive, Madison, WI 53706, USA
| | - Anna G. Schmidt
- Department of Bacteriology, University of Wisconsin - Madison, 1550 Linden Drive, Madison, WI 53706, USA
| | - Ryan F. Lepak
- Environmental Science & Technology Program, University of Wisconsin - Madison, 660 N. Park Street, Madison, WI 53706, USA
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
- U.S. Environmental Protection Agency Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, 6201 Congdon Blvd, Duluth, MN 55804, USA
| | - Sarah E. Janssen
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
| | - Patricia Q. Tran
- Department of Bacteriology, University of Wisconsin - Madison, 1550 Linden Drive, Madison, WI 53706, USA
- Department of Integrative Biology, University of Wisconsin - Madison, 250 N. Mills St.Madison, WI 53706, USA
| | - Robert A. Marick
- Department of Biochemistry, University of Wisconsin - Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - Jacob M. Ogorek
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
| | - John F. DeWild
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
| | - David P. Krabbenhoft
- U.S. Geological Survey, Upper Midwest Water Science Center, Mercury Research Laboratory, 8505 Research Way, Middleton, WI 53562, USA
| | - Katherine D. McMahon
- Department of Bacteriology, University of Wisconsin - Madison, 1550 Linden Drive, Madison, WI 53706, USA
- Department of Civil and Environmental Engineering, University of Wisconsin – Madison, 1415 Engineering Drive, Madison WI 53706, USA
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Hao X, Zhu J, Rensing C, Liu Y, Gao S, Chen W, Huang Q, Liu YR. Recent advances in exploring the heavy metal(loid) resistant microbiome. Comput Struct Biotechnol J 2020; 19:94-109. [PMID: 33425244 PMCID: PMC7771044 DOI: 10.1016/j.csbj.2020.12.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 12/03/2020] [Accepted: 12/05/2020] [Indexed: 12/18/2022] Open
Abstract
Heavy metal(loid)s exert selective pressure on microbial communities and evolution of metal resistance determinants. Despite increasing knowledge concerning the impact of metal pollution on microbial community and ecological function, it is still a challenge to identify a consistent pattern of microbial community composition along gradients of elevated metal(loid)s in natural environments. Further, our current knowledge of the microbial metal resistome at the community level has been lagging behind compared to the state-of-the-art genetic profiling of bacterial metal resistance mechanisms in a pure culture system. This review provides an overview of the core metal resistant microbiome, development of metal resistance strategies, and potential factors driving the diversity and distribution of metal resistance determinants in natural environments. The impacts of biotic factors regulating the bacterial metal resistome are highlighted. We finally discuss the advances in multiple technologies, research challenges, and future directions to better understand the interface of the environmental microbiome with the metal resistome. This review aims to highlight the diversity and wide distribution of heavy metal(loid)s and their corresponding resistance determinants, helping to better understand the resistance strategy at the community level.
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Affiliation(s)
- Xiuli Hao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
- Corresponding authors at: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Jiaojiao Zhu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Christopher Rensing
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Ying Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Shenghan Gao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Wenli Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Huazhong Agricultural University, Wuhan 430070, China
- Corresponding authors at: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China.
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220
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Cai W, Jin J, Dang F, Shi W, Zhou D. Mercury methylation from mercury selenide particles in soils. JOURNAL OF HAZARDOUS MATERIALS 2020; 400:123248. [PMID: 32585526 DOI: 10.1016/j.jhazmat.2020.123248] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 05/17/2020] [Accepted: 06/16/2020] [Indexed: 06/11/2023]
Abstract
Selenium-inhibited monomethylmercury (MeHg) production is an attractive strategy for mitigating the risks of MeHg exposure. However, it is poorly understood the methylation potential of mercury selenide (HgSe) particles during their aging in soils and sediments. Net MeHg production in three floodplain soils amended with different geochemical species of mercury selenides, i.e., dissolved inorganic mercury freshly mixed with selenite (Hg(II)+Se(IV)), HgSe nanoparticles (45.2 ± 0.5 nm) and microparticles (> 1 μm) is examined. Among mercury types, the methylation from nanoparticulate HgSe was similar to (0.05 - 0.5 % vs. 0.1 - 0.4 %, yellow brown soil) or 12.9 - 21.0 times lower (0.02 - 0.1 vs. 0.6 - 1.5 %, black soil) than that from Hg(II)+Se(IV); however, net MeHg production from HgSe nanoparticles (0.02 - 0.5 %) was 1.9 - 15.5 times greater than HgSe microparticles (< 0.05 %) in all soils. Furthermore, net MeHg production from nanoparticulate HgSe varied significantly among soil types, attributable to differences in soil organic matter contents (2.4-5.8%) and microbial methylator community among soils. These results address the importance of geochemical intermediates of mercury selenide precipitation reactions and soil properties in MeHg production, and develop Se-based remediation strategy to minimize negative effects of MeHg on environmental and human health.
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Affiliation(s)
- Weiping Cai
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jingmei Jin
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; College of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, China
| | - Fei Dang
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
| | - Weilin Shi
- College of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, China
| | - Dongmei Zhou
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China
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221
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Feng W, Liu J, Huang L, Tan Y, Peng C. Gut microbiota as a target to limit toxic effects of traditional Chinese medicine: Implications for therapy. Biomed Pharmacother 2020; 133:111047. [PMID: 33378954 DOI: 10.1016/j.biopha.2020.111047] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 11/11/2020] [Accepted: 11/19/2020] [Indexed: 12/17/2022] Open
Abstract
Traditional Chinese medicines (TCMs) are medicines that are widely used in oriental countries under the guidance of ancient Chinese medicinal philosophies. With thousands of years of experiences in fighting against diseases, TCMs are gaining increasing importance in the world. Although the efficacy of TCMs is well recognized in clinic, the toxicity of TCMs has become a serious issue around the world in recent years. In general, the toxicity of TCMs is caused by the toxic medicinal compounds and contaminants in TCMs such as pesticides, herbicides, and heavy metals. Recent studies have demonstrated that gut microbiota can interact with TCMs and thus influence the toxicity of TCMs. However, there is no focused review on gut microbiota and the toxicity of TCMs. Here, we summarized the influences of the gut microbiota on the toxicity of medicinal compounds in TCMs and the corresponding mechanisms were offered. Then, we discussed the relationships between gut microbiota and the TCM contaminants. In addition, we discussed the methods of manipulating gut microbiota to reduce the toxicity of TCMs. At the end of this review, the perspectives on gut microbiota and the toxicity of TCMs were also discussed.
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Affiliation(s)
- Wuwen Feng
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China; State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Juan Liu
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Lihua Huang
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China; State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Yuzhu Tan
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China; State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Cheng Peng
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China; State Key Laboratory of Characteristic Chinese Medicine Resources in Southwest China, Chengdu University of Traditional Chinese Medicine, Chengdu, China.
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222
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Wang Q, Zhang L, Liang X, Yin X, Zhang Y, Zheng W, Pierce EM, Gu B. Rates and Dynamics of Mercury Isotope Exchange between Dissolved Elemental Hg(0) and Hg(II) Bound to Organic and Inorganic Ligands. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:15534-15545. [PMID: 33196184 DOI: 10.1021/acs.est.0c06229] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Mercury (Hg) isotope exchange is a common process in biogeochemical transformations of Hg in the environment, but it is unclear whether and at what rates dissolved elemental Hg(0)aq may exchange with divalent Hg(II) bound to various organic and inorganic ligands in water. Using enriched stable isotopes, we investigated the rates and dynamics of isotope exchange between 202Hg(0)aq and 201Hg(II) bound to organic and inorganic ligands with varying chemical structures and binding affinities. Time-dependent exchange reactions were followed by isotope compositional changes using both inductively coupled plasma mass spectrometry and Zeeman cold vapor atomic absorption spectrometry. Rapid, spontaneous isotope exchange (<1 h) was observed between 202Hg(0)aq and 201Hg(II) bound to chloride (Cl-), ethylenediaminetetraacetate (EDTA), and thiols, such as cysteine (CYS), glutathione (GSH), and 2,3-dimercaptopropanesulfonic acid (DMPS) at a thiol ligand-to-Hg(II) molar ratio of 1:1. Without external reductants or oxidants, the exchange resulted in transfer of two electrons and redistribution of Hg isotopes bound to the ligand but no net changes of chemical species in the system. However, an increase in the ligand-to-Hg(II) ratio decreased the exchange rates due to the formation of 2:1 or higher thiol:Hg(II) chelated complexes, but had no effects on exchange rates with 201Hg(II) bound to EDTA or Cl-. The exchange between 202Hg(0)aq and 201Hg(II) bound to dissolved organic matter (DOM) showed an initially rapid followed by a slower exchange rate, likely resulting from Hg(II) complexation with both low- and high-affinity binding functional groups on DOM (e.g., carboxylates vs bidentate thiolates). These results demonstrate that Hg(0)aq readily exchanges with Hg(II) bound to various ligands and highlight the importance of considering exchange reactions in experimental enriched Hg isotope tracer studies or in natural abundance Hg isotope studies in environmental matrices.
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Affiliation(s)
- Quanying Wang
- Key Laboratory of Wet Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Lijie Zhang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Xujun Liang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Xiangping Yin
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Yaoling Zhang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Wang Zheng
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Eric M Pierce
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
- Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, Tennessee 37996, United States
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223
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Siedlewicz G, Korejwo E, Szubska M, Grabowski M, Kwasigroch U, Bełdowski J. Presence of mercury and methylmercury in Baltic Sea sediments, collected in ammunition dumpsites. MARINE ENVIRONMENTAL RESEARCH 2020; 162:105158. [PMID: 33065518 DOI: 10.1016/j.marenvres.2020.105158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 07/07/2020] [Accepted: 09/18/2020] [Indexed: 06/11/2023]
Abstract
Methylmercury (MeHg) is the most toxic and dangerous form of mercury occurring in the environment. MeHg is highly bioaccumulative in organisms and undergoes biomagnification via the food chain. In the Baltic Sea munition dumpsites, methylmercury can be formed from mercury fulminate contained in primary explosives, as environmental conditions there favour methylation. MeHg in analysed sediments ranged from 19 to 2362 pg g-1d.w., the concentration of mercury (HgTOT) ranged from 4 to 294 ng g-1 d.w., and the values of MeHg/Hg ratio ranged from 0.1 to 2.0%. The obtained results confirmed that munition dumpsites are a source of mercury. The concentration of MeHg is elevated in a wider area than immediately next to dumped munitions. Presented results suggest that physical processes responsible for sediment and near-bottom water movement are diffusing MeHg signal, making munition dumpsites rather a diffuse source of MeHg than a number of point sources associated with particular munitions.
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Affiliation(s)
- Grzegorz Siedlewicz
- Institute of Oceanology of the Polish Academy of Sciences, Ul. Powstańców Warszawy 55, Sopot, 81-712, Poland
| | - Ewa Korejwo
- Institute of Oceanology of the Polish Academy of Sciences, Ul. Powstańców Warszawy 55, Sopot, 81-712, Poland
| | - Marta Szubska
- Institute of Oceanology of the Polish Academy of Sciences, Ul. Powstańców Warszawy 55, Sopot, 81-712, Poland
| | - Miłosz Grabowski
- Institute of Oceanology of the Polish Academy of Sciences, Ul. Powstańców Warszawy 55, Sopot, 81-712, Poland
| | - Urszula Kwasigroch
- Institute of Oceanography, University of Gdańsk, Ul. Piłsudskiego 46, 81-378, Gdynia, Poland
| | - Jacek Bełdowski
- Institute of Oceanology of the Polish Academy of Sciences, Ul. Powstańców Warszawy 55, Sopot, 81-712, Poland.
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224
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Branfireun BA, Cosio C, Poulain AJ, Riise G, Bravo AG. Mercury cycling in freshwater systems - An updated conceptual model. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 745:140906. [PMID: 32758756 DOI: 10.1016/j.scitotenv.2020.140906] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 06/11/2023]
Abstract
The widely accepted conceptual model of mercury (Hg) cycling in freshwater lakes (atmospheric deposition and runoff of inorganic Hg, methylation in bottom sediments and subsequent bioaccumulation and biomagnification in biota) is practically accepted as common knowledge. There is mounting evidence that the dominant processes that regulate inputs, transformations, and bioavailability of Hg in many lakes may be missing from this picture, and the fixation on the temperate stratified lake archetype is impeding our exploration of understudied, but potentially important sources of methylmercury to freshwater lakes. In this review, the importance of understudied biogeochemical processes and sites of methylmercury production are highlighted, including the complexity of redox transformations of Hg within the lake system itself, the complex assemblage of microbes found in biofilms and periphyton (two vastly understudied important sources of methylmercury in many freshwater ecosystems), and the critical role of autochthonous and allochthonous dissolved organic matter which mediates the net supply of methylmercury from the cellular to catchment scale. A conceptual model of lake Hg in contrasting lakes and catchments is presented, highlighting the importance of the autochthonous and allochthonous supply of dissolved organic matter, bioavailable inorganic mercury and methylmercury and providing a framework for future convergent research at the lab and field scales to establish more mechanistic process-based relationships within and among critical compartments that regulate methylmercury concentrations in freshwater ecosystems.
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Affiliation(s)
- Brian A Branfireun
- Department of Biology and Centre for Environment & Sustainability, The University of Western Ontario, London, Canada.
| | - Claudia Cosio
- Université de Reims Champagne-Ardenne, UMR I-02 SEBIO, Reims, France
| | | | - Gunnhild Riise
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| | - Andrea G Bravo
- Spanish National Research Council | CSIC, Institut de Ciències del Mar, Barcelona, Spain.
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225
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Jones DS, Johnson NW, Mitchell CPJ, Walker GM, Bailey JV, Pastor J, Swain EB. Diverse Communities of hgcAB+ Microorganisms Methylate Mercury in Freshwater Sediments Subjected to Experimental Sulfate Loading. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:14265-14274. [PMID: 33138371 DOI: 10.1021/acs.est.0c02513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Methylmercury (MeHg) is a bioaccumulative neurotoxin produced by certain sulfate-reducing bacteria and other anaerobic microorganisms. Because microorganisms differ in their capacity to methylate mercury, the abundance and distribution of methylating populations may determine MeHg production in the environment. We compared rates of MeHg production and the distribution of hgcAB genes in epilimnetic sediments from a freshwater lake that were experimentally amended with sulfate levels from 7 to 300 mg L-1. The most abundant hgcAB sequences were associated with clades of Methanomicrobia, sulfate-reducing Deltaproteobacteria, Spirochaetes, and unknown environmental sequences. The hgcAB+ communities from higher sulfate amendments were less diverse and had relatively more Deltaproteobacteria, whereas the communities from lower amendments were more diverse with a larger proportion of hgcAB sequences affiliated with other clades. Potential methylation rate constants varied 52-fold across the experiment. Both potential methylation rate constants and % MeHg were the highest in sediments from the lowest sulfate amendments, which had the most diverse hgcAB+ communities and relatively fewer hgcAB genes from clades associated with sulfate reduction. Although pore water sulfide concentration covaried with hgcAB diversity across our experimental sulfate gradient, major changes in the community of hgcAB+ organisms occurred prior to a significant buildup of sulfide in pore waters. Our results indicate that methylating communities dominated by diverse anaerobic microorganisms that do not reduce sulfate can produce MeHg as effectively as communities dominated by sulfate-reducing populations.
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Affiliation(s)
- Daniel S Jones
- BioTechnology Institute, University of Minnesota, Saint Paul 55108, Minnesota, United States
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis 55455, Minnesota, United States
- Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology, Socorro 87801, New Mexico, United States
- National Cave and Karst Research Institute, Carlsbad, New Mexico 88220, United States
| | - Nathan W Johnson
- Department of Civil Engineering, University of Minnesota Duluth, Duluth, Minnesota 55812, United States
| | - Carl P J Mitchell
- Department of Physical and Environmental Sciences, University of Toronto-Scarborough, Toronto, Ontario M1C 1A4, Canada
| | - Gabriel M Walker
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis 55455, Minnesota, United States
| | - Jake V Bailey
- Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis 55455, Minnesota, United States
| | - John Pastor
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota 55812, United States
| | - Edward B Swain
- Minnesota Pollution Control Agency, Saint Paul, Minnesota 55155, United States
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226
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Duan H, Yu L, Tian F, Zhai Q, Fan L, Chen W. Gut microbiota: A target for heavy metal toxicity and a probiotic protective strategy. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 742:140429. [PMID: 32629250 DOI: 10.1016/j.scitotenv.2020.140429] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/02/2020] [Accepted: 06/20/2020] [Indexed: 06/11/2023]
Abstract
There is growing epidemiological evidence that heavy metals (HMs) may contribute to the progression of various metabolic diseases and that the etiology and progression of these diseases is partly due to HM-induced perturbations of the gut microbiota. Importantly, the gut microbiota are the first line of defense against the toxic effects of HMs, and there is a bidirectional relationship between the two. Thus, HM exposure alters the composition and metabolic profile of the gut microbiota at the functional level, and in turn, the gut microbiota alter the uptake and metabolism of HMs by acting as a physical barrier to HM absorption and by altering the pH, oxidative balance, and concentrations of detoxification enzymes or proteins involved in HM metabolism. Moreover, the gut microbiota can affect the integrity of the intestinal barrier, which may also in turn affect the absorption of HMs. Specifically, probiotic have been shown to reduce the absorption of HMs in the intestinal tract via the enhancement of intestinal HM sequestration, detoxification of HMs in the gut, changing the expression of metal transporter proteins, and maintaining the gut barrier function. This review is a summary of the bidirectional relationship between HMs and gut microbiota and of the probiotic-based protective strategies against HM-induced gut dysbiosis, with reference to strategies used in the food industry or for medically alleviating HM toxicity.
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Affiliation(s)
- Hui Duan
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China; National Engineering Research Center for Functional Food, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Leilei Yu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China; International Joint Research Laboratory for Probiotics at Jiangnan University, Wuxi, Jiangsu 214122, China.
| | - Fengwei Tian
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China; International Joint Research Laboratory for Probiotics at Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Qixiao Zhai
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China; International Joint Research Laboratory for Probiotics at Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Liuping Fan
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China; National Engineering Research Center for Functional Food, Jiangnan University, Wuxi, Jiangsu 214122, China.
| | - Wei Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China; National Engineering Research Center for Functional Food, Jiangnan University, Wuxi, Jiangsu 214122, China; International Joint Research Laboratory for Probiotics at Jiangnan University, Wuxi, Jiangsu 214122, China
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227
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Isaure MP, Albertelli M, Kieffer I, Tucoulou R, Petrel M, Gontier E, Tessier E, Monperrus M, Goñi-Urriza M. Relationship Between Hg Speciation and Hg Methylation/Demethylation Processes in the Sulfate-Reducing Bacterium Pseudodesulfovibrio hydrargyri: Evidences From HERFD-XANES and Nano-XRF. Front Microbiol 2020; 11:584715. [PMID: 33154741 PMCID: PMC7591507 DOI: 10.3389/fmicb.2020.584715] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 09/17/2020] [Indexed: 01/09/2023] Open
Abstract
Microorganisms are key players in the transformation of mercury into neurotoxic methylmercury (MeHg). Nevertheless, this mechanism and the opposite MeHg demethylation remain poorly understood. Here, we explored the impact of inorganic mercury (IHg) and MeHg concentrations from 0.05 to 50 μM on the production and degradation of MeHg in two sulfate-reducing bacteria, Pseudodesulfovibrio hydrargyri BerOc1 able to methylate and demethylate mercury and Desulfovibrio desulfuricans G200 only able to demethylate MeHg. MeHg produced by BerOc1 increased with increasing IHg concentration with a maximum attained for 5 μM, and suggested a saturation of the process. MeHg was mainly found in the supernatant suggesting its export from the cell. Hg L3-edge High- Energy-Resolution-Fluorescence-Detected-X-ray-Absorption-Near-Edge-Structure spectroscopy (HERFD-XANES) identified MeHg produced by BerOc1 as MeHg-cysteine2 form. A dominant tetracoordinated βHgS form was detected for BerOc1 exposed to the lowest IHg concentrations where methylation was detected. In contrast, at the highest exposure (50 μM) where Hg methylation was abolished, Hg species drastically changed suggesting a role of Hg speciation in the production of MeHg. The tetracoordinated βHgS was likely present as nano-particles as suggested by transmission electron microscopy combined to X-ray energy dispersive spectroscopy (TEM-X-EDS) and nano-X ray fluorescence (nano-XRF). When exposed to MeHg, the production of IHg, on the contrary, increased with the increase of MeHg exposure until 50 μM for both BerOc1 and G200 strains, suggesting that demethylation did not require intact biological activity. The formed IHg species were identified as various tetracoordinated Hg-S forms. These results highlight the important role of thiol ligands and Hg coordination in Hg methylation and demethylation processes.
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Affiliation(s)
- Marie-Pierre Isaure
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, MIRA, IPREM, Pau, France
| | - Marine Albertelli
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, MIRA, IPREM, Pau, France
| | - Isabelle Kieffer
- FAME-UHD, BM16 Beamline, European Synchrotron Radiation Facility (ESRF), BP220, Grenoble, France.,CNRS, IRD, Irstea, Météo France, OSUG, FAME, Université Grenoble Alpes, Grenoble, France
| | - Rémi Tucoulou
- ID16B Beamline, European Synchrotron Radiation Facility (ESRF), BP220, Grenoble, France
| | - Melina Petrel
- Bordeaux Imaging Center UMS 3420 CNRS - US4 INSERM, Université de Bordeaux, Pôle d'imagerie Électronique, Bordeaux, France
| | - Etienne Gontier
- Bordeaux Imaging Center UMS 3420 CNRS - US4 INSERM, Université de Bordeaux, Pôle d'imagerie Électronique, Bordeaux, France
| | - Emmanuel Tessier
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, MIRA, IPREM, Pau, France
| | - Mathilde Monperrus
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, MIRA, IPREM, Anglet, France
| | - Marisol Goñi-Urriza
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, MIRA, IPREM, Pau, France
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228
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Pinto DV, Raposo RS, Matos GA, Alvarez-Leite JI, Malva JO, Oriá RB. Methylmercury Interactions With Gut Microbiota and Potential Modulation of Neurogenic Niches in the Brain. Front Neurosci 2020; 14:576543. [PMID: 33224022 PMCID: PMC7670038 DOI: 10.3389/fnins.2020.576543] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/24/2020] [Indexed: 12/13/2022] Open
Affiliation(s)
- Daniel V Pinto
- Laboratory of Tissue Healing, Ontogeny and Nutrition, Department of Morphology, School of Medicine, Institute of Biomedicine, Federal University of Ceara, Fortaleza, Brazil
| | - Ramon S Raposo
- Experimental Biology Core, University of Fortaleza, Fortaleza, Brazil
| | - Gabriella A Matos
- Laboratory of Tissue Healing, Ontogeny and Nutrition, Department of Morphology, School of Medicine, Institute of Biomedicine, Federal University of Ceara, Fortaleza, Brazil
| | - Jacqueline I Alvarez-Leite
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - João O Malva
- Center for Innovative Biomedicine and Biotechnology (CIBB), Faculty of Medicine, Institute of Pharmacology and Experimental Therapeutics, Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, Coimbra, Portugal
| | - Reinaldo B Oriá
- Laboratory of Tissue Healing, Ontogeny and Nutrition, Department of Morphology, School of Medicine, Institute of Biomedicine, Federal University of Ceara, Fortaleza, Brazil
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229
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Gionfriddo CM, Wymore AM, Jones DS, Wilpiszeski RL, Lynes MM, Christensen GA, Soren A, Gilmour CC, Podar M, Elias DA. An Improved hgcAB Primer Set and Direct High-Throughput Sequencing Expand Hg-Methylator Diversity in Nature. Front Microbiol 2020; 11:541554. [PMID: 33123100 PMCID: PMC7573106 DOI: 10.3389/fmicb.2020.541554] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 08/25/2020] [Indexed: 01/27/2023] Open
Abstract
The gene pair hgcAB is essential for microbial mercury methylation. Our understanding of its abundance and diversity in nature is rapidly evolving. In this study we developed a new broad-range primer set for hgcAB, plus an expanded hgcAB reference library, and used these to characterize Hg-methylating communities from diverse environments. We applied this new Hg-methylator database to assign taxonomy to hgcA sequences from clone, amplicon, and metagenomic datasets. We evaluated potential biases introduced in primer design, sequence length, and classification, and suggest best practices for studying Hg-methylator diversity. Our study confirms the emerging picture of an expanded diversity of HgcAB-encoding microbes in many types of ecosystems, with abundant putative mercury methylators Nitrospirae and Chloroflexi in several new environments including salt marsh and peat soils. Other common microbes encoding HgcAB included Phycisphaerae, Aminicenantes, Spirochaetes, and Elusimicrobia. Combined with high-throughput amplicon specific sequencing, the new primer set also indentified novel hgcAB sequences similar to Lentisphaerae, Bacteroidetes, Atribacteria, and candidate phyla WOR-3 and KSB1 bacteria. Gene abundance data also corroborate the important role of two "classic" groups of methylators (Deltaproteobacteria and Methanomicrobia) in many environments, but generally show a scarcity of hgcAB+ Firmicutes. The new primer set was developed to specifically target hgcAB sequences found in nature, reducing degeneracy and providing increased sensitivity while maintaining broad diversity capture. We evaluated mock communities to confirm primer improvements, including culture spikes to environmental samples with variable DNA extraction and PCR amplification efficiencies. For select sites, this new workflow was combined with direct high-throughput hgcAB sequencing. The hgcAB diversity generated by direct amplicon sequencing confirmed the potential for novel Hg-methylators previously identified using metagenomic screens. A new phylogenetic analysis using sequences from freshwater, saline, and terrestrial environments showed Deltaproteobacteria HgcA sequences generally clustered among themselves, while metagenome-resolved HgcA sequences in other phyla tended to cluster by environment, suggesting horizontal gene transfer into many clades. HgcA from marine metagenomes often formed distinct subtrees from those sequenced from freshwater ecosystems. Overall the majority of HgcA sequences branch from a cluster of HgcAB fused proteins related to Thermococci, Atribacteria (candidate division OP9), Aminicenantes (OP8), and Chloroflexi. The improved primer set and library, combined with direct amplicon sequencing, provide a significantly improved assessment of the abundance and diversity of hgcAB+ microbes in nature.
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Affiliation(s)
- Caitlin M Gionfriddo
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Ann M Wymore
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Daniel S Jones
- BioTechnology Institute, University of Minnesota, St. Paul, MN, United States.,Department of Earth Sciences, Minneapolis, MN, United States
| | - Regina L Wilpiszeski
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Mackenzie M Lynes
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Geoff A Christensen
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Ally Soren
- Smithsonian Environmental Research Center, Edgewater, MD, United States
| | | | - Mircea Podar
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Dwayne A Elias
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States
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230
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Tang Z, Fan F, Deng S, Wang D. Mercury in rice paddy fields and how does some agricultural activities affect the translocation and transformation of mercury - A critical review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 202:110950. [PMID: 32800226 DOI: 10.1016/j.ecoenv.2020.110950] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/22/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
Human exposure to methylmercury (MeHg) through rice consumption is raising health concerns. It has long been recognized that MeHg found in rice grain predominately originated from paddy soil. Anaerobic conditions in paddy fields promote Hg methylation, potentially leading to high MeHg concentrations in rice grain. Understanding the transformation and migration of Hg in the rice paddy system, as well as the effects of farming activities, are keys to assessing risks and developing potential mitigation strategies. Therefore, this review examines the current state of knowledge on: 1) sources of Hg in paddy fields; 2) how MeHg and inorganic Hg (IHg) are transformed (including abiotic and biotic processes); 3) how IHg and MeHg enter and translocate in rice plants; and 4) how regular farming activities (including the application of fertilizer, cultivation methods, choice of cultivar), affect Hg cycling in the paddy field system. Current issues and controversies on Hg transformation and migration in the paddy field system are also discussed.
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Affiliation(s)
- Zhenya Tang
- Faculty of Environmental Science & Engineering, Kunming University of Science &Technology, Kunming, China; Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, Southwest University, Chongqing, China.
| | - Fangling Fan
- School of Energy and Environment Science, Yunnan Normal University, Kunming, China.
| | - Shiping Deng
- Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK, USA.
| | - Dingyong Wang
- Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin, Southwest University, Chongqing, China; State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, College of Resources and Environment, Southwest University, Chongqing, China.
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231
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Gustin MS, Bank MS, Bishop K, Bowman K, Branfireun B, Chételat J, Eckley CS, Hammerschmidt CR, Lamborg C, Lyman S, Martínez-Cortizas A, Sommar J, Tsui MTK, Zhang T. Mercury biogeochemical cycling: A synthesis of recent scientific advances. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 737:139619. [PMID: 32783819 PMCID: PMC7430064 DOI: 10.1016/j.scitotenv.2020.139619] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 05/23/2023]
Abstract
The focus of this paper is to briefly discuss the major advances in scientific thinking regarding: a) processes governing the fate and transport of mercury in the environment; b) advances in measurement methods; and c) how these advances in knowledge fit in within the context of the Minamata Convention on Mercury. Details regarding the information summarized here can be found in the papers associated with this Virtual Special Issue of STOTEN.
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Affiliation(s)
- Mae Sexauer Gustin
- Department of Natural Resources and Environmental Science, University of Nevada, Reno, NV 89439, USA.
| | - Michael S Bank
- Department of Contaminants and Biohazards, Institute of Marine Research, Bergen, Norway; Department of Environmental Conservation, University of Massachusetts, Amherst, MA 01255, USA
| | - Kevin Bishop
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 75007 Uppsala, Sweden
| | - Katlin Bowman
- Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, CA 95039, USA; University of California Santa Cruz, Ocean Sciences Department, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Brian Branfireun
- Department of Biology and Centre for Environment and Sustainability, Western University, London, Canada
| | - John Chételat
- Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Ottawa, ON K1A 0H3, Canada
| | - Chris S Eckley
- U.S. Environmental Protection Agency, Region-10, 1200 6th Ave, Seattle, WA 98101, USA
| | - Chad R Hammerschmidt
- Wright State University, Department of Earth and Environmental Sciences, 3640 Colonel Glenn Highway, Dayton, OH 45435, USA
| | - Carl Lamborg
- University of California Santa Cruz, Ocean Sciences Department, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Seth Lyman
- Bingham Research Center, Utah State University, 320 N Aggie Blvd., Vernal, UT, USA
| | - Antonio Martínez-Cortizas
- EcoPast (GI-1553), Facultade de Bioloxía, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Jonas Sommar
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Martin Tsz-Ki Tsui
- Department of Biology, University of North Carolina at Greensboro, Greensboro, NC 27402, USA
| | - Tong Zhang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin 300350, China
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232
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Capo E, Bravo AG, Soerensen AL, Bertilsson S, Pinhassi J, Feng C, Andersson AF, Buck M, Björn E. Deltaproteobacteria and Spirochaetes-Like Bacteria Are Abundant Putative Mercury Methylators in Oxygen-Deficient Water and Marine Particles in the Baltic Sea. Front Microbiol 2020; 11:574080. [PMID: 33072037 PMCID: PMC7536318 DOI: 10.3389/fmicb.2020.574080] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/25/2020] [Indexed: 11/13/2022] Open
Abstract
Methylmercury (MeHg), a neurotoxic compound biomagnifying in aquatic food webs, can be a threat to human health via fish consumption. However, the composition and distribution of the microbial communities mediating the methylation of mercury (Hg) to MeHg in marine systems remain largely unknown. In order to fill this knowledge gap, we used the Baltic Sea Reference Metagenome (BARM) dataset to study the abundance and distribution of the genes involved in Hg methylation (the hgcAB gene cluster). We determined the relative abundance of the hgcAB genes and their taxonomic identity in 81 brackish metagenomes that cover spatial, seasonal and redox variability in the Baltic Sea water column. The hgcAB genes were predominantly detected in anoxic water, but some hgcAB genes were also detected in hypoxic and normoxic waters. Phylogenetic analysis identified putative Hg methylators within Deltaproteobacteria, in oxygen-deficient water layers, but also Spirochaetes-like and Kiritimatiellaeota-like bacteria. Higher relative quantities of hgcAB genes were found in metagenomes from marine particles compared to free-living communities in anoxic water, suggesting that such particles are hotspot habitats for Hg methylators in oxygen-depleted seawater. Altogether, our work unveils the diversity of the microorganisms with the potential to mediate MeHg production in the Baltic Sea and pinpoint the important ecological niches for these microorganisms within the marine water column.
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Affiliation(s)
- Eric Capo
- Department of Chemistry, Umeå University, Umeå, Sweden.,Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Andrea G Bravo
- Institut de Ciències del Mar (ICM-CSIC), Barcelona, Spain
| | - Anne L Soerensen
- Department of Environmental Research and Monitoring, Swedish Museum of Natural History, Stockholm, Sweden
| | - Stefan Bertilsson
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jarone Pinhassi
- Centre for Ecology and Evolution in Microbial Model Systems - EEMiS, Linnaeus University, Kalmar, Sweden
| | - Caiyan Feng
- Department of Chemistry, Umeå University, Umeå, Sweden
| | - Anders F Andersson
- Department of Gene Technology, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
| | - Moritz Buck
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, Umeå, Sweden
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233
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Li Z, Mascarenhas R, Twahir UT, Kallon A, Deb A, Yaw M, Penner-Hahn J, Koutmos M, Warncke K, Banerjee R. An Interprotein Co-S Coordination Complex in the B 12-Trafficking Pathway. J Am Chem Soc 2020; 142:16334-16345. [PMID: 32871076 DOI: 10.1021/jacs.0c06590] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The CblC and CblD chaperones are involved in early steps in the cobalamin trafficking pathway. Cobalamin derivatives entering the cytoplasm are converted by CblC to a common cob(II)alamin intermediate via glutathione-dependent alkyltransferase or reductive elimination activities. Cob(II)alamin is subsequently converted to one of two biologically active alkylcobalamins by downstream chaperones. The function of CblD has been elusive although it is known to form a complex with CblC under certain conditions. Here, we report that CblD provides a sulfur ligand to cob(II)alamin bound to CblC, forming an interprotein coordination complex that rapidly oxidizes to thiolato-cob(III)alamin. Cysteine scanning mutagenesis and EPR spectroscopy identified Cys-261 on CblD as the sulfur donor. The unusual interprotein Co-S bond was characterized by X-ray absorption spectroscopy and visualized in the crystal structure of the human CblD thiolato-cob(III)alamin complex. Our study provides insights into how cobalamin coordination chemistry could be utilized for cofactor translocation in the trafficking pathway.
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Affiliation(s)
- Zhu Li
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | - Romila Mascarenhas
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | - Umar T Twahir
- Department of Physics, Emory University, Atlanta, Georgia 30322-2430, United States
| | - Albert Kallon
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | - Aniruddha Deb
- Departments of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Madeline Yaw
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | - James Penner-Hahn
- Departments of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Markos Koutmos
- Departments of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kurt Warncke
- Department of Physics, Emory University, Atlanta, Georgia 30322-2430, United States
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
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234
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Biotransformation fate and sustainable mitigation of a potentially toxic element of mercury from environmental matrices. ARAB J CHEM 2020. [DOI: 10.1016/j.arabjc.2020.06.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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235
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McDaniel EA, Peterson BD, Stevens SLR, Tran PQ, Anantharaman K, McMahon KD. Expanded Phylogenetic Diversity and Metabolic Flexibility of Mercury-Methylating Microorganisms. mSystems 2020; 5:e00299-20. [PMID: 32817383 PMCID: PMC7438021 DOI: 10.1128/msystems.00299-20] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/29/2020] [Indexed: 11/23/2022] Open
Abstract
Methylmercury is a potent bioaccumulating neurotoxin that is produced by specific microorganisms that methylate inorganic mercury. Methylmercury production in diverse anaerobic bacteria and archaea was recently linked to the hgcAB genes. However, the full phylogenetic and metabolic diversity of mercury-methylating microorganisms has not been fully unraveled due to the limited number of cultured experimentally verified methylators and the limitations of primer-based molecular methods. Here, we describe the phylogenetic diversity and metabolic flexibility of putative mercury-methylating microorganisms by hgcAB identification in publicly available isolate genomes and metagenome-assembled genomes (MAGs) as well as novel freshwater MAGs. We demonstrate that putative mercury methylators are much more phylogenetically diverse than previously known and that hgcAB distribution among genomes is most likely due to several independent horizontal gene transfer events. The microorganisms we identified possess diverse metabolic capabilities spanning carbon fixation, sulfate reduction, nitrogen fixation, and metal resistance pathways. We identified 111 putative mercury methylators in a set of previously published permafrost metatranscriptomes and demonstrated that different methylating taxa may contribute to hgcA expression at different depths. Overall, we provide a framework for illuminating the microbial basis of mercury methylation using genome-resolved metagenomics and metatranscriptomics to identify putative methylators based upon hgcAB presence and describe their putative functions in the environment.IMPORTANCE Accurately assessing the production of bioaccumulative neurotoxic methylmercury by characterizing the phylogenetic diversity, metabolic functions, and activity of methylators in the environment is crucial for understanding constraints on the mercury cycle. Much of our understanding of methylmercury production is based on cultured anaerobic microorganisms within the Deltaproteobacteria, Firmicutes, and Euryarchaeota. Advances in next-generation sequencing technologies have enabled large-scale cultivation-independent surveys of diverse and poorly characterized microorganisms from numerous ecosystems. We used genome-resolved metagenomics and metatranscriptomics to highlight the vast phylogenetic and metabolic diversity of putative mercury methylators and their depth-discrete activities in thawing permafrost. This work underscores the importance of using genome-resolved metagenomics to survey specific putative methylating populations of a given mercury-impacted ecosystem.
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Affiliation(s)
- Elizabeth A McDaniel
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Benjamin D Peterson
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sarah L R Stevens
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, Wisconsin, USA
- American Family Insurance Data Science Institute, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Patricia Q Tran
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Karthik Anantharaman
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Katherine D McMahon
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
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236
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Zaporski J, Jamison M, Zhang L, Gu B, Yang Z. Mercury methylation potential in a sand dune on Lake Michigan's eastern shoreline. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 729:138879. [PMID: 32371207 DOI: 10.1016/j.scitotenv.2020.138879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 04/17/2020] [Accepted: 04/19/2020] [Indexed: 06/11/2023]
Abstract
Lake Michigan hosts the largest freshwater sand dune system in the world and is economically important for the fishery industry and tourism. Due to industrial pollution and atmospheric mercury (Hg) deposition, toxic levels of methylmercury (MeHg) have been found in the Lake biota, but little information is known regarding MeHg sources and Hg methylation potential in the shoreline sand dunes. We conducted anaerobic incubation experiments with beach sands collected from Ludington, Michigan, and examined the effects of organic carbon substrate addition, inorganic nitrogen, and mineral magnetite on Hg methylation. Despite nutrient poor and low-organic carbon conditions, appreciable Hg methylation activity coupled with carbon degradation was observed in the sands. Addition of acetate as a carbon source substantially increased MeHg production from 2 to 380 ng/kg sediment while acetate was rapidly degraded in the first 19 days of incubation. Ammonium addition showed little influence on carbon degradation or Hg methylation, whereas iron oxide addition (~1% dry weight) significantly inhibited both carbon degradation and MeHg production (by up to 90%), highlighting strongly coupled interactions between microbes, carbon substrates, and minerals. This research demonstrates the potential of microbial Hg methylation in the sand dunes, which may play a role in MeHg input and bioaccumulation in the Lake Michigan ecosystem.
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Affiliation(s)
- Jared Zaporski
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA
| | - Megan Jamison
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA
| | - Lijie Zhang
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
| | - Ziming Yang
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA.
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237
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Schaefer JK, Kronberg R, Björn E, Skyllberg U. Anaerobic guilds responsible for mercury methylation in boreal wetlands of varied trophic status serving as either a methylmercury source or sink. Environ Microbiol 2020; 22:3685-3699. [DOI: 10.1111/1462-2920.15134] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 06/16/2020] [Indexed: 11/30/2022]
Affiliation(s)
- Jeffra K Schaefer
- Department of Environmental Sciences Rutgers University 14 College Farm Road, New Brunswick NJ 08901 USA
| | - Rose‐Marie Kronberg
- Department of Forest Ecology and Management Swedish University of Agricultural Sciences Umeå SE‐901 83 Sweden
| | - Erik Björn
- Department of Chemistry Umeå University Umeå SE‐901 87 Sweden
| | - Ulf Skyllberg
- Department of Forest Ecology and Management Swedish University of Agricultural Sciences Umeå SE‐901 83 Sweden
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238
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Genome-Resolved Metagenomics and Detailed Geochemical Speciation Analyses Yield New Insights into Microbial Mercury Cycling in Geothermal Springs. Appl Environ Microbiol 2020; 86:AEM.00176-20. [PMID: 32414793 DOI: 10.1128/aem.00176-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 05/07/2020] [Indexed: 12/18/2022] Open
Abstract
Geothermal systems emit substantial amounts of aqueous, gaseous, and methylated mercury, but little is known about microbial influences on mercury speciation. Here, we report results from genome-resolved metagenomics and mercury speciation analysis of acidic warm springs in the Ngawha Geothermal Field (<55°C, pH <4.5), Northland Region, Aotearoa New Zealand. Our aim was to identify the microorganisms genetically equipped for mercury methylation, demethylation, or Hg(II) reduction to volatile Hg(0) in these springs. Dissolved total and methylated mercury concentrations in two adjacent springs with different mercury speciation ranked among the highest reported from natural sources (250 to 16,000 ng liter-1 and 0.5 to 13.9 ng liter-1, respectively). Total solid mercury concentrations in spring sediments ranged from 1,274 to 7,000 μg g-1 In the context of such ultrahigh mercury levels, the geothermal microbiome was unexpectedly diverse and dominated by acidophilic and mesophilic sulfur- and iron-cycling bacteria, mercury- and arsenic-resistant bacteria, and thermophilic and acidophilic archaea. By integrating microbiome structure and metagenomic potential with geochemical constraints, we constructed a conceptual model for biogeochemical mercury cycling in geothermal springs. The model includes abiotic and biotic controls on mercury speciation and illustrates how geothermal mercury cycling may couple to microbial community dynamics and sulfur and iron biogeochemistry.IMPORTANCE Little is currently known about biogeochemical mercury cycling in geothermal systems. The manuscript presents a new conceptual model, supported by genome-resolved metagenomic analysis and detailed geochemical measurements. The model illustrates environmental factors that influence mercury cycling in acidic springs, including transitions between solid (mineral) and aqueous phases of mercury, as well as the interconnections among mercury, sulfur, and iron cycles. This work provides a framework for studying natural geothermal mercury emissions globally. Specifically, our findings have implications for mercury speciation in wastewaters from geothermal power plants and the potential environmental impacts of microbially and abiotically formed mercury species, particularly where they are mobilized in spring waters that mix with surface or groundwaters. Furthermore, in the context of thermophilic origins for microbial mercury volatilization, this report yields new insights into how such processes may have evolved alongside microbial mercury methylation/demethylation and the environmental constraints imposed by the geochemistry and mineralogy of geothermal systems.
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239
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Sokolovskaya OM, Shelton AN, Taga ME. Sharing vitamins: Cobamides unveil microbial interactions. Science 2020; 369:369/6499/eaba0165. [PMID: 32631870 DOI: 10.1126/science.aba0165] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Microbial communities are essential to fundamental processes on Earth. Underlying the compositions and functions of these communities are nutritional interdependencies among individual species. One class of nutrients, cobamides (the family of enzyme cofactors that includes vitamin B12), is widely used for a variety of microbial metabolic functions, but these structurally diverse cofactors are synthesized by only a subset of bacteria and archaea. Advances at different scales of study-from individual isolates, to synthetic consortia, to complex communities-have led to an improved understanding of cobamide sharing. Here, we discuss how cobamides affect microbes at each of these three scales and how integrating different approaches leads to a more complete understanding of microbial interactions.
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Affiliation(s)
- Olga M Sokolovskaya
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Amanda N Shelton
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Michiko E Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, USA.
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240
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Song Y, Adediran GA, Jiang T, Hayama S, Björn E, Skyllberg U. Toward an Internally Consistent Model for Hg(II) Chemical Speciation Calculations in Bacterium-Natural Organic Matter-Low Molecular Mass Thiol Systems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:8094-8103. [PMID: 32491838 PMCID: PMC7467648 DOI: 10.1021/acs.est.0c01751] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
To advance the scientific understanding of bacteria-driven mercury (Hg) transformation processes in natural environments, thermodynamics and kinetics of divalent mercury Hg(II) chemical speciation need to be understood. Based on Hg LIII-edge extended X-ray absorption fine structure (EXAFS) spectroscopic information, combined with competitive ligand exchange (CLE) experiments, we determined Hg(II) structures and thermodynamic constants for Hg(II) complexes formed with thiol functional groups in bacterial cell membranes of two extensively studied Hg(II) methylating bacteria: Geobacter sulfurreducens PCA and Desulfovibrio desulfuricans ND132. The Hg EXAFS data suggest that 5% of the total number of membranethiol functionalities (Mem-RStot = 380 ± 50 μmol g-1 C) are situated closely enough to be involved in a 2-coordinated Hg(Mem-RS)2 structure in Geobacter. The remaining 95% of Mem-RSH is involved in mixed-ligation Hg(II)-complexes, combining either with low molecular mass (LMM) thiols like Cys, Hg(Cys)(Mem-RS), or with neighboring O/N membrane functionalities, Hg(Mem-RSRO). We report log K values for the formation of the structures Hg(Mem-RS)2, Hg(Cys)(Mem-RS), and Hg(Mem-RSRO) to be 39.1 ± 0.2, 38.1 ± 0.1, and 25.6 ± 0.1, respectively, for Geobacter and 39.2 ± 0.2, 38.2 ± 0.1, and 25.7 ± 0.1, respectively, for ND132. Combined with results obtained from previous studies using the same methodology to determine chemical speciation of Hg(II) in the presence of natural organic matter (NOM; Suwannee River DOM) and 15 LMM thiols, an internally consistent thermodynamic data set is created, which we recommend to be used in studies of Hg transformation processes in bacterium-NOM-LMM thiol systems.
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Affiliation(s)
- Yu Song
- Department
of Forest Ecology and Management, Swedish
University of Agricultural Science, SE-901 83 Umeå, Sweden
| | | | - Tao Jiang
- Department
of Forest Ecology and Management, Swedish
University of Agricultural Science, SE-901 83 Umeå, Sweden
| | - Shusaku Hayama
- Diamond
Light Source, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Erik Björn
- Department
of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
| | - Ulf Skyllberg
- Department
of Forest Ecology and Management, Swedish
University of Agricultural Science, SE-901 83 Umeå, Sweden
- . Phone: +46 (0)90-786 84 60
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241
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Sun R, Yuan J, Sonke JE, Zhang Y, Zhang T, Zheng W, Chen S, Meng M, Chen J, Liu Y, Peng X, Liu C. Methylmercury produced in upper oceans accumulates in deep Mariana Trench fauna. Nat Commun 2020; 11:3389. [PMID: 32636418 PMCID: PMC7341844 DOI: 10.1038/s41467-020-17045-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 06/08/2020] [Indexed: 12/04/2022] Open
Abstract
Monomethylmercury (MMHg) is a potent toxin that bioaccumulates and magnifies in marine food webs. Recent studies show abundant methylated Hg in deep oceans (>1000 m), yet its origin remains uncertain. Here we measured Hg isotope compositions in fauna and surface sediments from the Mariana Trench. The trench fauna at 7000-11000 m depth all have substantially positive mass-independent fractionation of odd Hg isotopes (odd-MIF), which can be generated only in the photic zone via MMHg photo-degradation. Given the identical odd-MIF in trench fauna and North Pacific upper ocean (<1000 m) biota MMHg, we suggest that the accumulated Hg in trench fauna originates exclusively from MMHg produced in upper oceans, which penetrates to depth by sorption to sinking particles. Our findings reveal little in-situ MMHg production in deep oceans and imply that anthropogenic Hg released at the Earth's surface is much more pervasive across deep oceans than was previously thought.
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Affiliation(s)
- Ruoyu Sun
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 300072, Tianjin, China
| | - Jingjing Yuan
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 300072, Tianjin, China
| | - Jeroen E Sonke
- Laboratoire Géosciences Environnement Toulouse, CNRS/Institute for Research and Development/Université Paul Sabatier-Toulouse III, 31400, Toulouse, France
| | - Yanxu Zhang
- School of Atmospheric Sciences, Nanjing University, 210023, Jiangsu, China
| | - Tong Zhang
- College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, 38 Tongyan Rd., 300350, Tianjin, China
| | - Wang Zheng
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 300072, Tianjin, China
| | - Shun Chen
- Deep Sea Science Division, Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, 572000, Sanya, Hainan, China
| | - Mei Meng
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 300072, Tianjin, China
| | - Jiubin Chen
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 300072, Tianjin, China
| | - Yi Liu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 300072, Tianjin, China.
| | - Xiaotong Peng
- Deep Sea Science Division, Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, 572000, Sanya, Hainan, China.
| | - Congqiang Liu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, 300072, Tianjin, China
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242
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Zhou XQ, Hao YY, Gu B, Feng J, Liu YR, Huang Q. Microbial Communities Associated with Methylmercury Degradation in Paddy Soils. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:7952-7960. [PMID: 32437137 DOI: 10.1021/acs.est.0c00181] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Bioaccumulation of the neurotoxin methylmercury (MeHg) in rice has raised worldwide concerns because of its risks to human health. Certain microorganisms are able to degrade MeHg in pure cultures, but the roles and diversities of the microbial communities in MeHg degradation in rice paddy soils are unknown. Using a series of microcosms, we investigated MeHg degradation in paddy soils from Hunan, Guizhou, and Hubei provinces, representing three major rice production regions in China, and further characterized one of the soils from the Hunan Province for microbial communities associated with MeHg degradation. Microbial demethylation was observed in all three soils, demonstrated by significantly more MeHg degraded in the unsterilized soils than in the sterilized controls. More demethylation occurred in water-saturated soils than in unsaturated soils, but the addition of molybdate and bromoethanesulfonic acid as the respective inhibitors of sulfate reducing bacteria and methanogens showed insignificant effects on MeHg degradation. However, the addition of Cu enhanced MeHg degradation and the enrichment of Xanthomonadaceae in the unsaturated soil. 16S rRNA Illumina sequencing and metatranscriptomic analyses of the Hunan soil consistently revealed that Catenulisporaceae, Frankiaceae, Mycobacteriaceae, and Thermomonosporaceae were among the most likely microbial taxa in influencing MeHg degradation in the paddy soil, and they were confirmed by combined analyses of the co-occurrence network, random forest modeling, and linear discriminant analysis of the effect size. Our results shed additional light onto the roles of microbial communities in MeHg degradation in paddy soils and its subsequent bioaccumulation in rice grains.
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Affiliation(s)
- Xin-Quan Zhou
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Yun-Yun Hao
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Baohua Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jiao Feng
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Yu-Rong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Wuhan 430070, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Key Laboratory of Soil Environment and Pollution Remediation, Wuhan 430070, China
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243
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Tada Y, Marumoto K, Takeuchi A. Nitrospina-Like Bacteria Are Potential Mercury Methylators in the Mesopelagic Zone in the East China Sea. Front Microbiol 2020; 11:1369. [PMID: 32719662 PMCID: PMC7347909 DOI: 10.3389/fmicb.2020.01369] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 05/27/2020] [Indexed: 11/18/2022] Open
Abstract
In natural environments, the production of neurotoxic and bioaccumulative methylmercury (MeHg) is mediated by microorganisms carrying the genes hgcA and hgcB. However, the contribution of these microorganisms to mercury (Hg) methylation or MeHg accumulation in the ocean is poorly understood. Here we determined the total Hg (THg) and MeHg concentrations in seawater samples and conducted a metagenomic survey of the hgcAB genes and functional modules involved in metabolic pathways in the East China Sea (ECS). In the metagenomic analyses, we used paired-end reads and assembled contigs for hgcAB enumeration and phylogenetic analyses in the seawater column. To evaluate the relative abundance of hgcAB in the metagenomic data, we estimated the abundance of recA (single-copy gene of bacteria) as well and then compared them. Moreover, the profiles of prokaryotic community composition were analyzed by 16S rRNA gene (V4 region) deep-sequencing. In the mesopelagic layers, the hgcA sequences were detected, and there was a positive correlation between hgcA abundance relative to the recA and MeHg concentrations. Thus, the quantification of the hgcA sequences could provide valuable information to evaluate the potential environments of microbial MeHg accumulation in the seawater column. A phylogenetic analysis using the assembled contigs revealed that all of the hgcA sequences in the mesopelagic layers were affiliated with Nitrospina-like sequences. The 16S rRNA gene analysis revealed that Nitrospinae were abundant in the mesopelagic layers. Although the lineages of Deltaproteobacteria, Firmicutes, and Spirochaetes were detected in the seawater column, their hgcAB sequences were not detected in our metagenomes, despite the fact that they are closely related to previously identified Hg methylators. The metabolic pathway analysis revealed that the modules related to sulfur and methane metabolism were prominent in the mesopelagic layers. However, no hgcA sequences affiliated with sulfate-reducing bacteria (SRB) or methanogens were detected in these layers, suggesting that these bacteria could not be strongly involved in the Hg accumulation in the seawater column. Our results indicate that Nitrospina-like bacteria with hgcAB genes could play a critical role in microbial Hg accumulation in the oxygenated mesopelagic layers of the ECS.
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Affiliation(s)
- Yuya Tada
- Department of Environment and Public Health, National Institute for Minamata Disease, Kumamoto, Japan
| | - Kohji Marumoto
- Department of Environment and Public Health, National Institute for Minamata Disease, Kumamoto, Japan
| | - Akinori Takeuchi
- Center for Environmental Measurement and Analysis, National Institute for Environmental Studies, Ibaraki, Japan
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244
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Using Mixed Active Capping to Remediate Multiple Potential Toxic Metal Contaminated Sediment for Reducing Environmental Risk. WATER 2020. [DOI: 10.3390/w12071886] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this study, kaolinite, carbon black (CB), iron sulfide (FeS), hydroxyapatite (HAP), and oyster shell powder (OSP) were selected as potentially ideal amendments to immobilize metals in sediment, including Ni, Cr, Cu, Zn, and Hg. In aqueous batch experiments, the five adsorbents were tested for capturing the five potential toxic metals individually at various concentrations. HAP and OSP showed the largest removal efficiencies towards Ni (OSP: 76.47%), Cr (OSP: 100.00%), Cu (HAP: 98.39%), and Zn (HAP: 64.56%), with CB taking the third place. In contrast, FeS and CB played a more significant role in Hg removal (FeS: 100.00%; CB: 86.40%). In the modified six-column microcosm experiments, five mixing ratios based on various considerations using the five adsorbent materials were tested; the water samples were collected and analyzed every week for 135 days. Results showed that caps including CB could immobilize the release of Hg and methylmercury (MeHg) better than those with FeS. More economical caps, namely, with a higher portion of OSP in the mixed capping, could not reach comparable effects to those with more HAP for immobilizing Ni, but performed almost the same for the other four metals. All columns with active caps showed greater metal immobilization as compared to the controlled column without caps.
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245
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Azaroff A, Goñi Urriza M, Gassie C, Monperrus M, Guyoneaud R. Marine mercury-methylating microbial communities from coastal to Capbreton Canyon sediments (North Atlantic Ocean). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 262:114333. [PMID: 32443198 DOI: 10.1016/j.envpol.2020.114333] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 03/01/2020] [Accepted: 03/04/2020] [Indexed: 06/11/2023]
Abstract
Microbial mercury (Hg) methylation transforms inorganic mercury to neurotoxic methylmercury (MeHg) mainly in aquatic anoxic environments. Sampling challenges in marine ecosystems, particularly in submarine canyons, leads to a lack of knowledge about the Hg methylating microbia in marine sediments. A previous study showed an enrichment of mercury species in sediments from the Capbreton Canyon where both geochemical parameters and microbial activities constrained the net MeHg production. In order to characterize Hg-methylating microbial communities from coastal to deeper sediments, we analysed the diversity of microorganisms' (16S rDNA-based sequencing) and Hg methylators (hgcA based cloning and sequencing). Both, 16S rDNA and hgcA gene analysis demonstrated that the putative Hg-methylating prokaryotes were likely within the Deltaproteobacteria, dominated by sulfur-compounds based reducing bacteria (mainly sulfate reducers). Additionally, others clades were also identified as carrying HgcA gene, such as, Chloroflexi, Spirochaetes, Elusimicrobia, PVC superphylum (Plantomycetes, Verrucomicrobia and Chlamydiae) and Euryarchaea. Nevertheless, 61% of the hgcA sequences were not assigned to specific clade, indicating that further studies are needed to understand the implication of new microorganisms carrying hgcA in the Hg methylation in marine environments. These first results suggest that sulfur cycle drives the Hg-methylation in marine ecosystem.
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Affiliation(s)
- Alyssa Azaroff
- Universite de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM-MIRA, UMR 5254, 64600 Anglet, France
| | - Marisol Goñi Urriza
- Universite de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM-MIRA Environmental Microbiology, UMR 5254, 64000, Pau, France
| | - Claire Gassie
- Universite de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM-MIRA Environmental Microbiology, UMR 5254, 64000, Pau, France
| | - Mathilde Monperrus
- Universite de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM-MIRA, UMR 5254, 64600 Anglet, France
| | - Rémy Guyoneaud
- Universite de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM-MIRA Environmental Microbiology, UMR 5254, 64000, Pau, France.
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246
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Cooper CJ, Zheng K, Rush KW, Johs A, Sanders BC, Pavlopoulos GA, Kyrpides NC, Podar M, Ovchinnikov S, Ragsdale SW, Parks JM. Structure determination of the HgcAB complex using metagenome sequence data: insights into microbial mercury methylation. Commun Biol 2020; 3:320. [PMID: 32561885 PMCID: PMC7305189 DOI: 10.1038/s42003-020-1047-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 05/27/2020] [Indexed: 11/09/2022] Open
Abstract
Bacteria and archaea possessing the hgcAB gene pair methylate inorganic mercury (Hg) to form highly toxic methylmercury. HgcA consists of a corrinoid binding domain and a transmembrane domain, and HgcB is a dicluster ferredoxin. However, their detailed structure and function have not been thoroughly characterized. We modeled the HgcAB complex by combining metagenome sequence data mining, coevolution analysis, and Rosetta structure calculations. In addition, we overexpressed HgcA and HgcB in Escherichia coli, confirmed spectroscopically that they bind cobalamin and [4Fe-4S] clusters, respectively, and incorporated these cofactors into the structural model. Surprisingly, the two domains of HgcA do not interact with each other, but HgcB forms extensive contacts with both domains. The model suggests that conserved cysteines in HgcB are involved in shuttling HgII, methylmercury, or both. These findings refine our understanding of the mechanism of Hg methylation and expand the known repertoire of corrinoid methyltransferases in nature. Connor J. Cooper et al. expressed HgcA and HgcB in Escherichia coli and modeled the structure of the HgcAB complex by combining metagenome sequence data, coevolution analysis, and ab initio structure calculations. This study provides insights into the biochemical mechanism of mercury (Hg) methylation.
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Affiliation(s)
- Connor J Cooper
- Graduate School of Genome Science and Technology, University of Tennessee, F225 Walters Life Science, Knoxville, TN, 37996, USA.,Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831-6038, USA
| | - Kaiyuan Zheng
- Department of Biological Chemistry, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI, 48109-0606, USA
| | - Katherine W Rush
- Department of Biological Chemistry, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI, 48109-0606, USA
| | - Alexander Johs
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831-6038, USA
| | - Brian C Sanders
- Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831-6038, USA
| | - Georgios A Pavlopoulos
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.,Institute for Fundamental Biomedical Research, Biomedical Science Research Center "Alexander Fleming", 34 Fleming Street, 16672, Vari, Greece
| | - Nikos C Kyrpides
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory Berkeley, California, USA
| | - Mircea Podar
- Graduate School of Genome Science and Technology, University of Tennessee, F225 Walters Life Science, Knoxville, TN, 37996, USA.,Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831-6038, USA
| | - Sergey Ovchinnikov
- John Harvard Distinguished Science Fellowship Program, Harvard University, Cambridge, MA, 02138, USA
| | - Stephen W Ragsdale
- Department of Biological Chemistry, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI, 48109-0606, USA
| | - Jerry M Parks
- Graduate School of Genome Science and Technology, University of Tennessee, F225 Walters Life Science, Knoxville, TN, 37996, USA. .,Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37831-6038, USA.
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247
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Luo H, Cheng Q, Pan X. Photochemical behaviors of mercury (Hg) species in aquatic systems: A systematic review on reaction process, mechanism, and influencing factor. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 720:137540. [PMID: 32143045 DOI: 10.1016/j.scitotenv.2020.137540] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/23/2020] [Accepted: 02/23/2020] [Indexed: 06/10/2023]
Abstract
The fate and transport of Hg species in natural aquatic environment are strongly affected by photochemical transformation of Hg0, Hg2+, and MeHg. Migration of Hg is determined by its complexation with organic and inorganic ligands that are widely present in the water. The presence of dissolved organic matter (DOM) is closely related to photochemical reactions of Hg. DOM can strongly bind to mercury (e.g., Hg2+ and MeHg), thus affecting its speciation, mobility and toxicity, eventually dominating its bioavailability. This review summarizes extensive studies on photochemical behaviors of Hg including: (1) photo-oxidation; (2) photo-reduction; (3) photochemical methylation; and (4) MeHg photo-degradation. Photo-oxidation of Hg0 is mostly caused by oxidative free radicals (e.g., •OH, CO3•-, O3, and 1O2), while photo-reduction of Hg2+ is more complicated and it involves two pathways: (1) primary processes (direct photolysis of Hg2+ or ligand-metal charge transfer of Hg2+-DOM complex); and (2) secondary processes (reduction of Hg2+-DOM complex induced by free radicals derived from DOM photolysis). Photochemical methylation of inorganic Hg occurs as follows: (1) Hg2+ complexes with methyl donors (e.g., acetic acid, tert-butyl, alcohols, etc.) to form intermediates, followed by (2) an intramolecular methyl transfer. MeHg photo-degradation is the leading pathway for MeHg demethylation and it primarily proceeds via four different pathways. The information on DOM was also mentioned, but DOM is not the only factor that affects the photochemical behaviors of Hg. Other influencing factors such as: (1) pH value; (2) dissolved oxygen; (3) cations (Fe3+, K+) and anions (NO3-, HCO3-, CO32-, Cl-); and (4) suspended substance cannot be ignored.
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Affiliation(s)
- Hongwei Luo
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China
| | - Qianqian Cheng
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China
| | - Xiangliang Pan
- Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
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248
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Liu J, Wang D, Zhang J, Liem-Nguyen V, Huang R, Jiang T. Evaluation of Hg methylation in the water-level-fluctuation zone of the Three Gorges Reservoir region by using the MeHg/Hg T ratio. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 195:110468. [PMID: 32200146 DOI: 10.1016/j.ecoenv.2020.110468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/05/2020] [Accepted: 03/09/2020] [Indexed: 06/10/2023]
Abstract
In the recent decade, the hydroelectric reservoir is identified as a methylmercury (MeHg) hotspot and gained much attention. The artificial water level management in the Three Gorges Reservoir (TGR) in China formed a water-level-fluctuation zone (WLFZ) undergoing flooding drying rotations annually. However, the mercury (Hg) methylation and major geochemical driving factors at different elevations in the WLFZ remain unclear. Here we use total Hg (HgT) normalized MeHg (MeHg/HgT ratio) to evaluate Hg methylation degree in a one-year field study at 155, 165 m elevations in the WLFZ and with >175 m elevation as the reference. Results demonstrate that MeHg/HgT ratio at the WLFZ could reach 4.1% in soils, and both 155 and 165 m elevations have a higher Hg methylation degree than the >175 m elevation. However, the differences in MeHg/HgT ratios both in soils and waters between 155 and 165 m elevations are not significant. This indicates the influence of different submerging periods on the MeHg/HgT at the WLFZ elevations is not observed. The significant correlation between the MeHg/HgT ratio and soil organic carbon (SOC) content implies a MeHg retention in re-exposed soils after flooding. Decoupling of MeHg/HgT ratios between submerged soil and overlying water are found at both elevations and therefore make MeHg/HgT in waters alone cannot be used to evaluate Hg methylation degree in this study. The calculation of HgT and MeHg partitioning coefficient (Kd) found an immobilization of MeHg by submerged soils at the WLFZ during the flooding period. Major geochemical factors, determined through principal component analysis (PCA), in affecting Hg methylation are the redox cycling of sulfur and the distribution of organic matters in the WLFZ.
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Affiliation(s)
- Jiang Liu
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400716, China; Centre for Earth Observation Science, Department of Environment and Geography, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
| | - Dingyong Wang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400716, China.
| | - Jinzhong Zhang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400716, China.
| | - Van Liem-Nguyen
- Laboratory of Advanced Materials Chemistry, Advanced Institute of Materials Science, Ton Duc Thang University, Ho Chi Minh City, Vietnam; Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
| | - Rong Huang
- College of Resources, Sichuan Agricultural University, Chengdu, 611130, China.
| | - Tao Jiang
- Interdisciplinary Research Centre for Agriculture Green Development in Yangtze River Basin, College of Resources and Environment, Southwest University, Chongqing, 400716, China.
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249
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Villar E, Cabrol L, Heimbürger-Boavida LE. Widespread microbial mercury methylation genes in the global ocean. ENVIRONMENTAL MICROBIOLOGY REPORTS 2020. [PMID: 32090489 DOI: 10.1101/648329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Methylmercury is a neurotoxin that bioaccumulates from seawater to high concentrations in marine fish, putting human and ecosystem health at risk. High methylmercury levels have been found in the oxic subsurface waters of all oceans, but only anaerobic microorganisms have been shown to efficiently produce methylmercury in anoxic environments. The microaerophilic nitrite-oxidizing bacteria Nitrospina have previously been suggested as possible mercury methylating bacteria in Antarctic sea ice. However, the microorganisms responsible for processing inorganic mercury into methylmercury in oxic seawater remain unknown. Here, we show metagenomic and metatranscriptomic evidence that the genetic potential for microbial methylmercury production is widespread in oxic seawater. We find high abundance and expression of the key mercury methylating genes hgcAB across all ocean basins, corresponding to the taxonomic relatives of known mercury methylating bacteria from Deltaproteobacteria, Firmicutes and Chloroflexi. Our results identify Nitrospina as the predominant and widespread microorganism carrying and actively expressing hgcAB. The highest hgcAB abundance and expression occurs in the oxic subsurface waters of the global ocean where the highest MeHg concentrations are typically observed.
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Affiliation(s)
- Emilie Villar
- Aix Marseille Université, Univ Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288, Marseille, France
- Sorbonne Université, Université Pierre et Marie Curie - Paris 6, CNRS, UMR 7144 (AD2M), Station Biologique de Roscoff, Place Georges Teissier, CS90074, Roscoff, 29688, France
| | - Léa Cabrol
- Aix Marseille Université, Univ Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288, Marseille, France
- Instituto de Ecologia y Biodiversidad, Departamento de Ciencias Ecologicas, Facultad de Ciencias, Universidad de Chile, Santiago de Chile, Chile
| | - Lars-Eric Heimbürger-Boavida
- Aix Marseille Université, Univ Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288, Marseille, France
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250
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Zhao L, Meng B, Feng X. Mercury methylation in rice paddy and accumulation in rice plant: A review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 195:110462. [PMID: 32179234 DOI: 10.1016/j.ecoenv.2020.110462] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/07/2020] [Accepted: 03/08/2020] [Indexed: 06/10/2023]
Abstract
The bioavailability and toxicity of mercury (Hg) are dependent on its chemical speciation, in which methylmercury (MeHg) is the most toxic compound. Inorganic Hg can be transformed into MeHg in anaerobic conditions. Subsequent accumulation and biomagnification in the food chain pose a potential threat to human health. Previous studies have confirmed that paddy soil is an important site for MeHg production, and rice fields are an important source of MeHg in terrestrial ecosystems. Rice (Oryza sativa L.) is recently confirmed as a potential bioaccumulator plant of MeHg. Understanding the behaviour of Hg in rice paddies is important, particularly the mechanisms involved in Hg sources, uptake, toxicity, detoxification, and accumulation in crops. This review highlights the issue of MeHg-contaminated rice, and presents the current understanding of the Hg cycling in the rice paddy ecosystem, including the mechanism and processes of Hg species accumulation in rice plants and Hg methylation/demethylation processes in rice paddies and the primary controlling factors. The review also identified various research gaps in previous studies and proposes future research objectives to reduce the impact of Hg-contamination in rice crops.
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Affiliation(s)
- Lei Zhao
- School of Management Science, Guizhou University of Finance and Economics, Guiyang, 550025, PR China; State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, PR China
| | - Bo Meng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, PR China.
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550002, PR China.
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