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Wang H, Zhang L, Cui H, Ma X, Li Z, Liang B, Wang AJ. Mechanisms linking triclocarban biotransformation to functional response and antimicrobial resistome evolution in wastewater treatment systems. WATER RESEARCH 2024; 260:121909. [PMID: 38878310 DOI: 10.1016/j.watres.2024.121909] [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: 03/22/2024] [Revised: 05/28/2024] [Accepted: 06/06/2024] [Indexed: 07/27/2024]
Abstract
Evaluating the role of antimicrobials biotransformation in the regulation of metabolic functions and antimicrobial resistance evolution in wastewater biotreatment systems is crucial to ensuring water security. However, the associated mechanisms remain poorly understood. Here, we investigate triclocarban (TCC, one of the typical antimicrobials) biotransformation mechanisms and the dynamic evolution of systemic function disturbance and antimicrobial resistance risk in a complex anaerobic hydrolytic acidification (HA)-anoxic (ANO)/oxic (O) process. We mined key functional genes involved in the TCC upstream (reductive dechlorination and amide bonds hydrolysis) and downstream (chloroanilines catabolism) biotransformation pathways by metagenomic sequencing. Acute and chronic stress of TCC inhibit the production of volatile fatty acids (VFAs), NH4+ assimilation, and nitrification. The biotransformation of TCC via a single pathway cannot effectively relieve the inhibition of metabolic functions (e.g., carbon and nitrogen transformation and cycling) and enrichment of antimicrobial resistance genes (ARGs). Importantly, the coexistence of TCC reductive dechlorination and hydrolysis pathways and subsequent ring-opening catabolism play a critical role for stabilization of systemic metabolic functions and partial control of antimicrobial resistance risk. This study provides new insights into the mechanisms linking TCC biotransformation to the dynamic evolution of systemic functions and risks, and highlights critical regulatory information for enhanced control of TCC risks in complex biotreatment systems.
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Affiliation(s)
- Hao Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Liying Zhang
- State Key Laboratory of Urban Water Resource and Environment, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Hanlin Cui
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; State Key Laboratory of Urban Water Resource and Environment, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Xiaodan Ma
- State Key Laboratory of Urban Water Resource and Environment, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China
| | - Zhiling Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Bin Liang
- State Key Laboratory of Urban Water Resource and Environment, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China.
| | - Ai-Jie Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; State Key Laboratory of Urban Water Resource and Environment, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China.
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2
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Bulka O, Picott K, Mahadevan R, Edwards EA. From mec cassette to rdhA: a key Dehalobacter genomic neighborhood in a chloroform and dichloromethane-transforming microbial consortium. Appl Environ Microbiol 2024; 90:e0073224. [PMID: 38819127 PMCID: PMC11218628 DOI: 10.1128/aem.00732-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 05/20/2024] [Indexed: 06/01/2024] Open
Abstract
Chloroform (CF) and dichloromethane (DCM) are groundwater contaminants of concern due to their high toxicity and inhibition of important biogeochemical processes such as methanogenesis. Anaerobic biotransformation of CF and DCM has been well documented but typically independently of one another. CF is the electron acceptor for certain organohalide-respiring bacteria that use reductive dehalogenases (RDases) to dechlorinate CF to DCM. In contrast, known DCM degraders use DCM as their electron donor, which is oxidized using a series of methyltransferases and associated proteins encoded by the mec cassette to facilitate the entry of DCM to the Wood-Ljungdahl pathway. The SC05 culture is an enrichment culture sold commercially for bioaugmentation, which transforms CF via DCM to CO2. This culture has the unique ability to dechlorinate CF to DCM using electron equivalents provided by the oxidation of DCM to CO2. Here, we use metagenomic and metaproteomic analyses to identify the functional genes involved in each of these transformations. Though 91 metagenome-assembled genomes were assembled, the genes for an RDase-named acdA-and a complete mec cassette were found to be encoded on a single contig belonging to Dehalobacter. AcdA and critical Mec proteins were also highly expressed by the culture. Heterologously expressed AcdA dechlorinated CF and other chloroalkanes but had 100-fold lower activity on DCM. Overall, the high expression of Mec proteins and the activity of AcdA suggest a Dehalobacter capable of dechlorination of CF to DCM and subsequent mineralization of DCM using the mec cassette. IMPORTANCE Chloroform (CF) and dichloromethane (DCM) are regulated groundwater contaminants. A cost-effective approach to remove these pollutants from contaminated groundwater is to employ microbes that transform CF and DCM as part of their metabolism, thus depleting the contamination as the microbes continue to grow. In this work, we investigate bioaugmentation culture SC05, a mixed microbial consortium that effectively and simultaneously degrades both CF and DCM coupled to the growth of Dehalobacter. We identified the functional genes responsible for the transformation of CF and DCM in SC05. These genetic biomarkers provide a means to monitor the remediation process in the field.
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Affiliation(s)
- Olivia Bulka
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Katherine Picott
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Radhakrishnan Mahadevan
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Elizabeth A. Edwards
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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3
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Zhao S, Rogers MJ, Ding C, Xu G, He J. Interspecies Mobility of Organohalide Respiration Gene Clusters Enables Genetic Bioaugmentation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:4214-4225. [PMID: 38373236 DOI: 10.1021/acs.est.3c09171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Anthropogenic organohalide pollutants pose a severe threat to public health and ecosystems. In situ bioremediation using organohalide respiring bacteria (OHRB) offers an environmentally friendly and cost-efficient strategy for decontaminating organohalide-polluted sites. The genomic structures of many OHRB suggest that dehalogenation traits can be horizontally transferred among microbial populations, but their occurrence among anaerobic OHRB has not yet been demonstrated experimentally. This study isolates and characterizes a novel tetrachloroethene (PCE)-dechlorinating Sulfurospirillum sp. strain SP, distinguishing itself among anaerobic OHRB by showcasing a mechanism essential for horizontal dissemination of reductive dehalogenation capabilities within microbial populations. Its genetic characterization identifies a unique plasmid (pSULSP), harboring reductive dehalogenase and de novo corrinoid biosynthesis operons, functions critical to organohalide respiration, flanked by mobile elements. The active mobility of these elements was demonstrated through genetic analyses of spontaneously emerging nondehalogenating variants of strain SP. More importantly, bioaugmentation of nondehalogenating microcosms with pSULSP DNA triggered anaerobic PCE dechlorination in taxonomically diverse bacterial populations. Our results directly support the hypothesis that exposure to anthropogenic organohalide pollutants can drive the emergence of dehalogenating microbial populations via horizontal gene transfer and demonstrate a mechanism by which genetic bioaugmentation for remediation of organohalide pollutants could be achieved in anaerobic environments.
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Affiliation(s)
- Siyan Zhao
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Matthew J Rogers
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Chang Ding
- Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research─UFZ, Permoserstraße, 15, Leipzig 04318, Germany
| | - Guofang Xu
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Jianzhong He
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore 117576, Singapore
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4
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Liu G, Chen K, Wu Z, Ji Y, Lu L, Liu S, Li ZL, Ji R, Liu SJ, Jiang J, Qiao W. Genome-Centric Metatranscriptomic Characterization of a Humin-Facilitated Anaerobic Tetrabromobisphenol A-Dehalogenating Consortium. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:1299-1311. [PMID: 38113523 DOI: 10.1021/acs.est.3c06118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Tetrabromobisphenol A (TBBPA), a widely used brominated flame retardant in electronics manufacturing, has caused global contamination due to improper e-waste disposal. Its persistence, bioaccumulation, and potential carcinogenicity drive studies of its transformation and underlying (a)biotic interactions. This study achieved an anaerobic enrichment culture capable of reductively dehalogenating TBBPA to the more bioavailable bisphenol A. 16S rRNA gene amplicon sequencing and quantitative PCR confirmed that successive dehalogenation of four bromide ions from TBBPA was coupled with the growth of both Dehalobacter sp. and Dehalococcoides sp. with growth yields of 5.0 ± 0.4 × 108 and 8.6 ± 4.6 × 108 cells per μmol Br- released (N = 3), respectively. TBBPA dehalogenation was facilitated by solid humin and reduced humin, which possessed the highest organic radical signal intensity and reducing groups -NH2, and maintained the highest dehalogenation rate and dehalogenator copies. Genome-centric metatranscriptomic analyses revealed upregulated putative TBBPA-dehalogenating rdhA (reductive dehalogenase) genes with humin amendment, cprA-like Dhb_rdhA1 gene in Dehalobacter species, and Dhc_rdhA1/Dhc_rdhA2 genes in Dehalococcoides species. The upregulated genes of lactate fermentation, de novo corrinoid biosynthesis, and extracellular electron transport in the humin amended treatment also stimulated TBBPA dehalogenation. This study provided a comprehensive understanding of humin-facilitated organohalide respiration.
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Affiliation(s)
- Guiping Liu
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, Nanjing 210095, China
| | - Kai Chen
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, Nanjing 210095, China
| | - Zhiming Wu
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, Nanjing 210095, China
| | - Yanhan Ji
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, Nanjing 210095, China
| | - Lianghua Lu
- Jiangsu Provincial Academy of Environmental Science, Jiangsu Provincial Key Laboratory of Environmental Engineering, Nanjing 210036, China
| | - Songmeng Liu
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, Nanjing 210095, China
| | - Zhi-Ling Li
- State Key Laboratory of Urban Water Resources and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Rong Ji
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China
| | - Shuang-Jiang Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jiandong Jiang
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, Nanjing 210095, China
| | - Wenjing Qiao
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, Nanjing 210095, China
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5
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Dang H, Ewald JM, Mattes TE. Genome-Resolved Metagenomics and Metatranscriptomics Reveal Insights into the Ecology and Metabolism of Anaerobic Microbial Communities in PCB-Contaminated Sediments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:16386-16398. [PMID: 37856784 PMCID: PMC10621002 DOI: 10.1021/acs.est.3c05439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 10/02/2023] [Accepted: 10/02/2023] [Indexed: 10/21/2023]
Abstract
Growth of organohalide-respiring bacteria such as Dehalococcoides mccartyi on halogenated organics (e.g., polychlorinated biphenyls (PCBs)) at contaminated sites or in enrichment culture requires interaction and support from other microbial community members. To evaluate naturally occurring interactions between Dehalococcoides and key supporting microorganisms (e.g., production of H2, acetate, and corrinoids) in PCB-contaminated sediments, metagenomic and metatranscriptomic sequencing was conducted on DNA and RNA extracted from sediment microcosms, showing evidence of both Dehalococcoides growth and PCB dechlorination. Using a genome-resolved approach, 160 metagenome-assembled genomes (MAGs), including three Dehalococcoides MAGs, were recovered. A novel reductive dehalogenase gene, distantly related to the chlorophenol dehalogenase gene cprA (pairwise amino acid identity: 23.75%), was significantly expressed. Using MAG gene expression data, 112 MAGs were assigned functional roles (e.g., corrinoid producers, acetate/H2 producers, etc.). A network coexpression analysis of all 160 MAGs revealed correlations between 39 MAGs and the Dehalococcoides MAGs. The network analysis also showed that MAGs assigned with functional roles that support Dehalococcoides growth (e.g., corrinoid assembly, and production of intermediates required for corrinoid synthesis) displayed significant coexpression correlations with Dehalococcoides MAGs. This work demonstrates the power of genome-resolved metagenomic and metatranscriptomic analyses, which unify taxonomy and function, in investigating the ecology of dehalogenating microbial communities.
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Affiliation(s)
- Hongyu Dang
- Department of Civil and Environmental
Engineering, 4105 Seamans Center, University
of Iowa, Iowa City, Iowa 52242, United States
| | - Jessica M. Ewald
- Department of Civil and Environmental
Engineering, 4105 Seamans Center, University
of Iowa, Iowa City, Iowa 52242, United States
| | - Timothy E. Mattes
- Department of Civil and Environmental
Engineering, 4105 Seamans Center, University
of Iowa, Iowa City, Iowa 52242, United States
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Hnatko JP, Liu C, Elsey JL, Dong S, Fortner JD, Pennell KD, Abriola LM, Cápiro NL. Microbial Reductive Dechlorination by a Commercially Available Dechlorinating Consortium Is Not Inhibited by Perfluoroalkyl Acids (PFAAs) at Field-Relevant Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023. [PMID: 37216485 DOI: 10.1021/acs.est.2c04815] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Perfluoroalkyl acids (PFAAs) have been shown to inhibit biodegradation (i.e., organohalide respiration) of chlorinated ethenes. The potential negative impacts of PFAAs on microbial species performing organohalide respiration, particularly Dehalococcoides mccartyi (Dhc), and the efficacy of in situ bioremediation are a critical concern for comingled PFAA-chlorinated ethene plumes. Batch reactor (no soil) and microcosm (with soil) experiments, containing a PFAA mixture and bioaugmented with KB-1, were completed to assess the impact of PFAAs on chlorinated ethene organohalide respiration. In batch reactors, PFAAs delayed complete biodegradation of cis-1,2-dichloroethene (cis-DCE) to ethene. Maximum substrate utilization rates (a metric for quantifying biodegradation rates) were fit to batch reactor experiments using a numerical model that accounted for chlorinated ethene losses to septa. Fitted values for cis-DCE and vinyl chloride biodegradation were significantly lower (p < 0.05) in batch reactors containing ≥50 mg/L PFAAs. Examination of reductive dehalogenase genes implicated in ethene formation revealed a PFAA-associated change in the Dhc community from cells harboring the vcrA gene to those harboring the bvcA gene. Organohalide respiration of chlorinated ethenes was not impaired in microcosm experiments with PFAA concentrations of 38.7 mg/L and less, suggesting that a microbial community containing multiple strains of Dhc is unlikely to be inhibited by PFAAs at lower, environmentally relevant concentrations.
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Affiliation(s)
- Jason P Hnatko
- Environmental Resources Management (ERM), Boston, Massachusetts 02108, United States
| | - Chen Liu
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Jack L Elsey
- Department of Civil and Environmental Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Sheng Dong
- Department of Civil and Environmental Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - John D Fortner
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
| | - Kurt D Pennell
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Linda M Abriola
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Natalie L Cápiro
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853, United States
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7
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Xu G, Zhao X, Zhao S, Rogers MJ, He J. Salinity determines performance, functional populations, and microbial ecology in consortia attenuating organohalide pollutants. THE ISME JOURNAL 2023; 17:660-670. [PMID: 36765150 PMCID: PMC10119321 DOI: 10.1038/s41396-023-01377-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 01/25/2023] [Accepted: 01/31/2023] [Indexed: 02/12/2023]
Abstract
Organohalide pollutants are prevalent in coastal regions due to extensive intervention by anthropogenic activities, threatening public health and ecosystems. Gradients in salinity are a natural feature of coasts, but their impacts on the environmental fate of organohalides and the underlying microbial communities remain poorly understood. Here we report the effects of salinity on microbial reductive dechlorination of tetrachloroethene (PCE) and polychlorinated biphenyls (PCBs) in consortia derived from distinct environments (freshwater and marine sediments). Marine-derived microcosms exhibited higher halotolerance during PCE and PCB dechlorination, and a halotolerant dechlorinating culture was enriched from these microcosms. The organohalide-respiring bacteria (OHRB) responsible for PCE and PCB dechlorination in marine microcosms shifted from Dehalococcoides to Dehalobium when salinity increased. Broadly, lower microbial diversity, simpler co-occurrence networks, and more deterministic microbial community assemblages were observed under higher salinity. Separately, we observed that inhibition of dechlorination by high salinity could be attributed to suppressed viability of Dehalococcoides rather than reduced provision of substrates by syntrophic microorganisms. Additionally, the high activity of PCE dechlorinating reductive dehalogenases (RDases) in in vitro tests under high salinity suggests that high salinity likely disrupted cellular components other than RDases in Dehalococcoides. Genomic analyses indicated that the capability of Dehalobium to perform dehalogenation under high salinity was likely owing to the presence of genes associated with halotolerance in its genomes. Collectively, these mechanistic and ecological insights contribute to understanding the fate and bioremediation of organohalide pollutants in environments with changing salinity.
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Affiliation(s)
- Guofang Xu
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore
- NUS Graduate School - Integrative Sciences and Engineering Programme (ISEP), National University of Singapore, Singapore, 119077, Singapore
| | - Xuejie Zhao
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Siyan Zhao
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Matthew J Rogers
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Jianzhong He
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore.
- NUS Graduate School - Integrative Sciences and Engineering Programme (ISEP), National University of Singapore, Singapore, 119077, Singapore.
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8
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Palmer M, Covington JK, Zhou EM, Thomas SC, Habib N, Seymour CO, Lai D, Johnston J, Hashimi A, Jiao JY, Muok AR, Liu L, Xian WD, Zhi XY, Li MM, Silva LP, Bowen BP, Louie K, Briegel A, Pett-Ridge J, Weber PK, Tocheva EI, Woyke T, Northen TR, Mayali X, Li WJ, Hedlund BP. Thermophilic Dehalococcoidia with unusual traits shed light on an unexpected past. THE ISME JOURNAL 2023:10.1038/s41396-023-01405-0. [PMID: 37041326 DOI: 10.1038/s41396-023-01405-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 03/22/2023] [Accepted: 03/27/2023] [Indexed: 04/13/2023]
Abstract
Although the phylum Chloroflexota is ubiquitous, its biology and evolution are poorly understood due to limited cultivability. Here, we isolated two motile, thermophilic bacteria from hot spring sediments belonging to the genus Tepidiforma and class Dehalococcoidia within the phylum Chloroflexota. A combination of cryo-electron tomography, exometabolomics, and cultivation experiments using stable isotopes of carbon revealed three unusual traits: flagellar motility, a peptidoglycan-containing cell envelope, and heterotrophic activity on aromatics and plant-associated compounds. Outside of this genus, flagellar motility has not been observed in Chloroflexota, and peptidoglycan-containing cell envelopes have not been described in Dehalococcoidia. Although these traits are unusual among cultivated Chloroflexota and Dehalococcoidia, ancestral character state reconstructions showed flagellar motility and peptidoglycan-containing cell envelopes were ancestral within the Dehalococcoidia, and subsequently lost prior to a major adaptive radiation of Dehalococcoidia into marine environments. However, despite the predominantly vertical evolutionary histories of flagellar motility and peptidoglycan biosynthesis, the evolution of enzymes for degradation of aromatics and plant-associated compounds was predominantly horizontal and complex. Together, the presence of these unusual traits in Dehalococcoidia and their evolutionary histories raise new questions about the timing and selective forces driving their successful niche expansion into global oceans.
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Affiliation(s)
- Marike Palmer
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.
| | - Jonathan K Covington
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - En-Min Zhou
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, 510275, Guangzhou, People's Republic of China
- Key Laboratory of Microbial Diversity in Southwest China of Ministry of Education, Yunnan Institute of Microbiology, School of Life Sciences, Yunnan University, 650091, Kunming, People's Republic of China
| | - Scott C Thomas
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA
| | - Neeli Habib
- Key Laboratory of Microbial Diversity in Southwest China of Ministry of Education, Yunnan Institute of Microbiology, School of Life Sciences, Yunnan University, 650091, Kunming, People's Republic of China
- Department of Microbiology, Shaheed Benazir Bhutto Women University, Peshawar, Khyber Pakhtunkhwa (KPK), Pakistan
| | - Cale O Seymour
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Dengxun Lai
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Juliet Johnston
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Ameena Hashimi
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Jian-Yu Jiao
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, 510275, Guangzhou, People's Republic of China
| | - Alise R Muok
- Institute of Biology, Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - Lan Liu
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, 510275, Guangzhou, People's Republic of China
| | - Wen-Dong Xian
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, 510275, Guangzhou, People's Republic of China
| | - Xiao-Yang Zhi
- Key Laboratory of Microbial Diversity in Southwest China of Ministry of Education, Yunnan Institute of Microbiology, School of Life Sciences, Yunnan University, 650091, Kunming, People's Republic of China
| | - Meng-Meng Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, 510275, Guangzhou, People's Republic of China
| | - Leslie P Silva
- The Department of Energy Joint Genome Institute, Berkeley, CA, 94720, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Benjamin P Bowen
- The Department of Energy Joint Genome Institute, Berkeley, CA, 94720, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Katherine Louie
- The Department of Energy Joint Genome Institute, Berkeley, CA, 94720, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ariane Briegel
- Institute of Biology, Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - Jennifer Pett-Ridge
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
- Life and Environmental Sciences, University of California Merced, Merced, CA, 95343, USA
- Innovative Genomics Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Peter K Weber
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Elitza I Tocheva
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Tanja Woyke
- The Department of Energy Joint Genome Institute, Berkeley, CA, 94720, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Life and Environmental Sciences, University of California Merced, Merced, CA, 95343, USA
| | - Trent R Northen
- The Department of Energy Joint Genome Institute, Berkeley, CA, 94720, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Xavier Mayali
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Wen-Jun Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, 510275, Guangzhou, People's Republic of China
| | - Brian P Hedlund
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.
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9
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Qiao W, Liu G, Li M, Su X, Lu L, Ye S, Wu J, Edwards EA, Jiang J. Complete Reductive Dechlorination of 4-Hydroxy-chlorothalonil by Dehalogenimonas Populations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:12237-12246. [PMID: 35951369 DOI: 10.1021/acs.est.2c02574] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile, TePN) is one of the most widely used fungicides all over the world. Its major environmental transformation product 4-hydroxy-chlorothalonil (4-hydroxy-2,5,6-trichloroisophthalonitrile, 4-OH-TPN) is more persistent, mobile, and toxic and is frequently detected at a higher concentration in various habitats compared to its parent compound TePN. Further microbial transformation of 4-OH-TPN has never been reported. In this study, we demonstrated that 4-OH-TPN underwent complete microbial reductive dehalogenation to 4-hydroxy-isophthalonitrile via 4-hydroxy-dichloroisophthalonitrile and 4-hydroxy-monochloroisophthalonitrile. 16S rRNA gene amplicon sequencing demonstrated that Dehalogenimonas species was enriched from 6% to 17-22% after reductive dechlorination of 77.24 μmol of 4-OH-TPN. Meanwhile, Dehalogenimonas copies increased by one order of magnitude and obtained a yield of 1.78 ± 1.47 × 108 cells per μmol Cl- released (N = 6), indicating that 4-OH-TPN served as the terminal electron acceptor for organohalide respiration of Dehalogenimonas species. A draft genome of Dehalogenimonas species was assembled through metagenomic sequencing, which harbors 30 putative reductive dehalogenase genes. Syntrophobacter, Acetobacterium, and Methanosarcina spp. were found to be the major non-dechlorinating populations in the microbial community, who might play important roles in the reductive dechlorination of 4-OH-TPN by the Dehalogenimonas species. This study first reports that Dehalogenimonas sp. can also respire on the seemingly dead-end product of TePN, paving the way to complete biotransformation of the widely present TePN and broadening the substrate spectrum of Dehalogenimonas sp. to polychlorinated hydroxy-benzonitrile.
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Affiliation(s)
- Wenjing Qiao
- Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Guiping Liu
- Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Mengya Li
- Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiaojing Su
- Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Lianghua Lu
- Jiangsu Provincial Academy of Environmental Science, Jiangsu Provincial Key Laboratory of Environmental Engineering, Nanjing 210036, China
| | - Shujun Ye
- Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
| | - Jichun Wu
- Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
| | - Elizabeth A Edwards
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto M5S 3E5, Canada
| | - Jiandong Jiang
- Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
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10
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Zhao S, Ding C, Xu G, Rogers MJ, Ramaswamy R, He J. Diversity of organohalide respiring bacteria and reductive dehalogenases that detoxify polybrominated diphenyl ethers in E-waste recycling sites. THE ISME JOURNAL 2022; 16:2123-2131. [PMID: 35710945 PMCID: PMC9381789 DOI: 10.1038/s41396-022-01257-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 05/20/2022] [Accepted: 05/26/2022] [Indexed: 11/09/2022]
Abstract
Widespread polybrominated diphenyl ethers (PBDEs) contamination poses risks to human health and ecosystems. Bioremediation is widely considered to be a less ecologically disruptive strategy for remediation of organohalide contamination, but bioremediation of PBDE-contaminated sites is limited by a lack of knowledge about PBDE-dehalogenating microbial populations. Here we report anaerobic PBDE debromination in microcosms established from geographically distinct e-waste recycling sites. Complete debromination of a penta-BDE mixture to diphenyl ether was detected in 16 of 24 investigated microcosms; further enrichment of these 16 microcosms implicated microbial populations belonging to the bacterial genera Dehalococcoides, Dehalogenimonas, and Dehalobacter in PBDE debromination. Debrominating microcosms tended to contain either both Dehalogenimonas and Dehalobacter or Dehalococcoides alone. Separately, complete debromination of a penta-BDE mixture was also observed by axenic cultures of Dehalococcoides mccartyi strains CG1, CG4, and 11a5, suggesting that this phenotype may be fairly common amongst Dehalococcoides. PBDE debromination in these isolates was mediated by four reductive dehalogenases not previously known to debrominate PBDEs. Debromination of an octa-BDE mixture was less prevalent and less complete in microcosms. The PBDE reductive dehalogenase homologous genes in Dehalococcoides genomes represent plausible molecular markers to predict PBDE debromination in microbial communities via their prevalence and transcriptions analysis.
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Affiliation(s)
- Siyan Zhao
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Chang Ding
- Helmholtz Centre for Environmental Research - UFZ, Environmental Biotechnology, Permoserstraße 15, 04318, Leipzig, Germany
| | - Guofang Xu
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore
- NUS Graduate School - Integrative Sciences and Engineering Programme (ISEP), National University of Singapore, Singapore, 119077, Singapore
| | - Matthew J Rogers
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Rajaganesan Ramaswamy
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore
- NUS Graduate School - Integrative Sciences and Engineering Programme (ISEP), National University of Singapore, Singapore, 119077, Singapore
| | - Jianzhong He
- Department of Civil and Environmental Engineering, National University of Singapore, Singapore, 117576, Singapore.
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11
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Asai M, Yoshida N, Kusakabe T, Ismaeil M, Nishiuchi T, Katayama A. Dehalococcoides mccartyi NIT01, a novel isolate, dechlorinates high concentrations of chloroethenes by expressing at least six different reductive dehalogenases. ENVIRONMENTAL RESEARCH 2022; 207:112150. [PMID: 34619124 DOI: 10.1016/j.envres.2021.112150] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/07/2021] [Accepted: 09/27/2021] [Indexed: 06/13/2023]
Abstract
This study presents the isolation of a novel strain of Dehalococcoides mccartyi, NIT01, which can completely dechlorinate up to 4.0 mM of trichloroethene to ethene via 1,2-cis-dichroroethene and vinyl chloride within 25 days. Strain NIT01 dechlorinated chloroethenes (CEs) at a temperature range of 25-32 °C and pH range of 6.5-7.8. The activity of the strain was inhibited by salt at more than 1.3% and inactivated by 1 h exposure to 2.0% air or 0.5 ppm hypochlorous acid. The genome of NIT01 was highly similar to that of the Dehalococcoides strains DCMB5, GT, 11a5, CBDB1, and CG5, and all included identical 16S rRNA genes. Moreover, NIT01 had 19 rdhA genes including NIT01-rdhA7 and rdhA13, which are almost identical to vcrA and pceA that encode known dehalogenases for tetrachloroethene and vinyl chloride, respectively. We also extracted RdhAs from the membrane fraction of NIT01 using 0.5% n-dodecyl-β-d-maltoside and separated them by anion exchange chromatography to identify those involved in CE dechlorination. LC/MS identification of the LDS-PAGE bands and RdhA activities in the fractions indicated cellular expression of six RdhAs. NIT01-RdhA7 (VcrA) and NIT01-RdhA15 were highly detected and NIT01-RdhA6 was the third-most detected. Among these three RdhAs, NIT01-RdhA15 and NIT01-RdhA6 had no biochemically identified relatives and were suggested to be novel functional dehalogenases for CEs. The expression of multiple dehalogenases may support bacterial tolerance to high concentrations of CEs.
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Affiliation(s)
- Masaki Asai
- Department of Civil and Environmental Engineering, Nagoya Institute of Technology (Nitech), Gokiso-Cho, Showa-Ku, Nagoya, Aichi, Japan
| | - Naoko Yoshida
- Department of Civil and Environmental Engineering, Nagoya Institute of Technology (Nitech), Gokiso-Cho, Showa-Ku, Nagoya, Aichi, Japan.
| | - Toshiya Kusakabe
- Department of Civil and Environmental Engineering, Nagoya Institute of Technology (Nitech), Gokiso-Cho, Showa-Ku, Nagoya, Aichi, Japan
| | - Mohamed Ismaeil
- Department of Environmental Engineering and Architecture, Graduate School of Environmental Studies, Nagoya University, Nagoya, 464-8603, Japan; Department of Microbiology, Faculty of Science, Ain Shams University, Cairo, Egypt
| | - Takumi Nishiuchi
- Division of Integrated Omics Research, Kanazawa University, Ishikawa, Japan
| | - Arata Katayama
- Department of Environmental Engineering and Architecture, Graduate School of Environmental Studies, Nagoya University, Nagoya, 464-8603, Japan
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12
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Xu G, Zhao S, Chen C, Zhao X, Ramaswamy R, He J. Dehalogenation of Polybrominated Diphenyl Ethers and Polychlorinated Biphenyls Catalyzed by a Reductive Dehalogenase in Dehalococcoides mccartyi Strain MB. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:4039-4049. [PMID: 35298122 DOI: 10.1021/acs.est.1c05170] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) are notorious persistent organic pollutants. However, few organohalide-respiring bacteria that harbor reductive dehalogenases (RDases) capable of dehalogenating these pollutants have been identified. Here, we report reductive dehalogenation of penta-BDEs and PCBs byDehalococcoides mccartyi strain MB. The PCE-pregrown cultures of strain MB debrominated 86.6 ± 7.4% penta-BDEs to di- to tetra-BDEs within 5 days. Similarly, extensive dechlorination of Aroclor1260 and Aroclor1254 was observed in the PCE-pregrown cultures of strain MB, with the average chlorine per PCB decreasing from 6.40 ± 0.02 and 5.40 ± 0.03 to 5.98 ± 0.11 and 5.19 ± 0.07 within 14 days, respectively; para-substituents were preferentially dechlorinated from PCBs. Moreover, strain MB showed distinct enantioselective dechlorination of different chiral PCB congeners. Dehalogenation activity and cell growth were maintained during the successive transfer of cultures when amended with penta-BDEs as the sole electron acceptors but not when amended with only PCBs, suggesting metabolic and co-metabolic dehalogenation of these compounds, respectively. Transcriptional analysis, proteomic profiling, and in vitro activity assays indicated that MbrA was involved in dehalogenating PCE, PCBs, and PBDEs. Interestingly, resequencing of mbrA in strain MB identified three nonsynonymous mutations within the nucleotide sequence, although the consequences of which remain unknown. The substrate versatility of MbrA enabled strain MB to dechlorinate PCBs in the presence of either penta-BDEs or PCE, suggesting that co-metabolic dehalogenation initiated by multifunctional RDases may contribute to PCB attenuation at sites contaminated with multiple organohalide pollutants.
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Affiliation(s)
- Guofang Xu
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore 117576, Singapore
- NUS Graduate School - Integrative Sciences and Engineering Programme (ISEP), National University of Singapore, Singapore 119077, Singapore
| | - Siyan Zhao
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore 117576, Singapore
| | - Chen Chen
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore 117576, Singapore
| | - Xuejie Zhao
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore 117576, Singapore
| | - Rajaganesan Ramaswamy
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore 117576, Singapore
- NUS Graduate School - Integrative Sciences and Engineering Programme (ISEP), National University of Singapore, Singapore 119077, Singapore
| | - Jianzhong He
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore 117576, Singapore
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13
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Comparative Genomic Analysis Reveals Preserved Features in Organohalide-Respiring Sulfurospirillum Strains. mSphere 2022; 7:e0093121. [PMID: 35196120 PMCID: PMC8865925 DOI: 10.1128/msphere.00931-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Sulfurospirillum species strains are frequently detected in various pristine and contaminated environments and participate in carbon, sulfur, nitrogen, and halogen elements cycling. Recently we obtained the complete genome sequences of two newly isolated Sulfurospirillum strains, ACSDCE and ACSTCE, capable of dechlorinating tetrachloroethene to cis-1,2-dichloroethene and trichloroethene under low-pH conditions, but a detailed analysis of these two genomes in reference to other Sulfurospirillum genomes for an improved understanding of Sulfurospirillum evolution and ecophysiology has not been accomplished. Here, we performed phylogenetic and pangenome analyses with 12 completed Sulfurospirillum genomes, including those of strain ACSTCE and strain ACSDCE, to unravel the evolutionary and metabolic potentials in the genus Sulfurospirillum. Based on 16S rRNA gene and whole-genome phylogenies, strains ACSTCE, ACSDCE, and JPD-1 could be clustered into a single species, proposed as “Candidatus Sulfurospirillum acididehalogenans.” TimeTree analysis suggested that the organohalide-respiring (OHR) Sulfurospirillum might acquire the ability to use chlorinated electron acceptors later than other energy conservation processes. Nevertheless, the ambiguity of the phylogenetic relations among Sulfurospirillum strains complicated the interpretation of acquisition and loss of metabolic traits. Interestingly, all OHR Sulfurospirillum genomes except the ones of Sulfurospirillum multivorans strains harbor a well-aligned and conserved region comprising the genetic components required for the organohalide respiration chain. Pangenome results further revealed that a total of 34,620 gene products, annotated from the 12 Sulfurospirillum genomes, can be classified into 4,118 homolog families and 2,075 singleton families. Various Sulfurospirillum species strains have conserved metabolisms as well as individual enzymes and biosynthesis capabilities. For instance, only the OHR Sulfurospirillum species strains possess the quinone-dependent pyruvate dehydrogenase (PoxB) gene, and only “Ca. Sulfurospirillum acididehalogenans” strains harbor urea transporter and urease genes. The plasmids found in strain ACSTCE and strain ACSDCE feature genes coding for type II toxin-antitoxin systems and transposases and are promising tools for the development of robust gene editing tools for Sulfurospirillum. IMPORTANCE Organohalide-respiring bacteria (OHRB) play critical roles in the detoxification of chlorinated pollutants and bioremediation of subsurface environments (e.g., groundwater and sediment) impacted by anthropogenic chlorinated solvents. The majority of known OHRB cannot perform reductive dechlorination below neutral pH, hampering the applications of OHRB for remediating acidified groundwater due to fermentation and reductive dechlorination. Previously we isolated two Sulfurospirillum strains, ACSTCE and ACSDCE, capable of dechlorinating tetrachloroethene under acidic conditions (e.g., pH 5.5), and obtained the complete genomes of both strains. Notably, two plasmid sequences were identified in the genomes of strain ACSTCE and strain ACSDCE that may be conducive to unraveling the genetic modification mechanisms in the genus Sulfurospirillum. Our findings improve the current understanding of Sulfurospirillum species strains regarding their biogeographic evolution, genome dynamics, and functional diversity. This study has applied values for the bioremediation of toxic and persistent organohalide pollutants in low-pH environments.
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14
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Differentiating closely affiliated Dehalococcoides lineages by a novel genetic marker identified via computational pangenome analysis. Appl Environ Microbiol 2021; 88:e0218121. [PMID: 34910572 DOI: 10.1128/aem.02181-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
As a group, Dehalococcoides dehalogenate a wide range of organohalide pollutants but the range of organohalide compounds that can be utilized for reductive dehalogenation differs among the Dehalococcoides strains. Dehalococcoides lineages cannot be reliably disambiguated in mixed communities using typical phylogenetic markers, which often confounds bioremediation efforts. Here, we describe a computational approach to identify Dehalococcoides genetic markers with improved discriminatory resolution. Screening core genes from the Dehalococcoides pangenome for degree of similarity and frequency of 100% identity found a candidate genetic marker encoding a bacterial neuraminidase repeat (BNR)-containing protein of unknown function. This gene exhibits the fewest completely identical amino acid sequences and among the lowest average amino acid sequence identity in the core pangenome. Primers targeting BNR could effectively discriminate between 40 available BNR sequences (in silico) and 10 different Dehalococcoides isolates (in vitro). Amplicon sequencing of BNR fragments generated from 22 subsurface soil samples revealed a total of 109 amplicon sequence variants, suggesting a high diversity of Dehalococcoides distributed in environment. Therefore, the BNR gene can serve as an alternative genetic marker to differentiate strains of Dehalococcoides in complicated microbial communities. Importance The challenge of discriminating between phylogenetically similar but functionally distinct bacterial lineages is particularly relevant to the development of technologies seeking to exploit the metabolic or physiological characteristics of specific members of bacterial genera. A computational approach was developed to expedite screening of potential genetic markers among phylogenetically affiliated bacteria. Using this approach, a gene encoding a bacterial neuraminidase repeat (BNR)-containing protein of unknown function was selected and evaluated as a genetic marker to differentiate strains of Dehalococcoides, an environmentally relevant genus of bacteria whose members can transform and detoxify a range of halogenated organic solvents and persistent organic pollutants, in complex microbial communities to demonstrate the validity of the approach. Moreover, many apparently phylogenetically distinct, currently uncharacterized Dehalococcoides were detected in environmental samples derived from contaminated sites.
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15
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Heterologous expression of active Dehalobacter spp. respiratory reductive dehalogenases in Escherichia coli. Appl Environ Microbiol 2021; 88:e0199321. [PMID: 34851719 DOI: 10.1128/aem.01993-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Reductive dehalogenases (RDases) are a family of redox enzymes that are required for anaerobic organohalide respiration, a microbial process that is useful in bioremediation. Structural and mechanistic studies of these enzymes have been greatly impeded due to challenges in RDase heterologous expression, potentially because of their cobamide-dependence. There have been a few successful attempts at RDase production in unconventional heterologous hosts, but a robust method has yet to be developed. Here we outline a novel respiratory RDase expression system using Escherichia coli. The overexpression of E. coli's cobamide transport system, btu, and anaerobic expression conditions were found to be essential for production of active RDases from Dehalobacter - an obligate organohalide respiring bacterium. The expression system was validated on six enzymes with amino acid sequence identities as low as 28%. Dehalogenation activity was verified for each RDase by assaying cell-free extracts of small-scale expression cultures on various chlorinated substrates including chloroalkanes, chloroethenes, and hexachlorocyclohexanes. Two RDases, TmrA from Dehalobacter sp. UNSWDHB and HchA from Dehalobacter sp. HCH1, were purified by nickel affinity chromatography. Incorporation of the cobamide and iron-sulfur cluster cofactors was verified; though, the precise cobalamin incorporation could not be determined due to variance between methodologies, and the specific activity of TmrA was consistent with that of the native enzyme. The heterologous expression of respiratory RDases, particularly from obligate organohalide respiring bacteria, has been extremely challenging and unreliable. Here we present a relatively straightforward E. coli expression system that has performed well for a variety of Dehalobacter spp. RDases. IMPORTANCE Understanding microbial reductive dehalogenation is important to refine the global halogen cycle and to improve bioremediation of halogenated contaminants; however, studies of the family of enzymes responsible are limited. Characterization of reductive dehalogenase enzymes has largely eluded researchers due to the lack of a reliable and high-yielding production method. We are presenting an approach to express reductive dehalogenase enzymes from Dehalobacter, a key group of organisms used in bioremediation, in E. coli. This expression system will propel the study of reductive dehalogenases by facilitating their production and isolation, allowing researchers to pursue more in-depth questions about the activity and structure of these enzymes. This platform will also provide a starting point to improve the expression of reductive dehalogenases from many other organisms.
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16
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Matturro B, Zeppilli M, Lai A, Majone M, Rossetti S. Metagenomic Analysis Reveals Microbial Interactions at the Biocathode of a Bioelectrochemical System Capable of Simultaneous Trichloroethylene and Cr(VI) Reduction. Front Microbiol 2021; 12:747670. [PMID: 34659183 PMCID: PMC8516407 DOI: 10.3389/fmicb.2021.747670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/09/2021] [Indexed: 01/04/2023] Open
Abstract
Bioelectrochemical systems (BES) are attractive and versatile options for the bioremediation of organic or inorganic pollutants, including trichloroethylene (TCE) and Cr(VI), often found as co-contaminants in the environment. The elucidation of the microbial players' role in the bioelectroremediation processes for treating multicontaminated groundwater is still a research need that attracts scientific interest. In this study, 16S rRNA gene amplicon sequencing and whole shotgun metagenomics revealed the leading microbial players and the primary metabolic interactions occurring in the biofilm growing at the biocathode where TCE reductive dechlorination (RD), hydrogenotrophic methanogenesis, and Cr(VI) reduction occurred. The presence of Cr(VI) did not negatively affect the TCE degradation, as evidenced by the RD rates estimated during the reactor operation with TCE (111±2 μeq/Ld) and TCE/Cr(VI) (146±2 μeq/Ld). Accordingly, Dehalococcoides mccartyi, the primary biomarker of the RD process, was found on the biocathode treating both TCE (7.82E+04±2.9E+04 16S rRNA gene copies g-1 graphite) and TCE/Cr(VI) (3.2E+07±2.37E+0716S rRNA gene copies g-1 graphite) contamination. The metagenomic analysis revealed a selected microbial consortium on the TCE/Cr(VI) biocathode. D. mccartyi was the sole dechlorinating microbe with H2 uptake as the only electron supply mechanism, suggesting that electroactivity is not a property of this microorganism. Methanobrevibacter arboriphilus and Methanobacterium formicicum also colonized the biocathode as H2 consumers for the CH4 production and cofactor suppliers for D. mccartyi cobalamin biosynthesis. Interestingly, M. formicicum also harbors gene complexes involved in the Cr(VI) reduction through extracellular and intracellular mechanisms.
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Affiliation(s)
| | - Marco Zeppilli
- Department of Chemistry, Sapienza University of Rome, Rome, Italy
| | - Agnese Lai
- Department of Chemistry, Sapienza University of Rome, Rome, Italy
| | - Mauro Majone
- Department of Chemistry, Sapienza University of Rome, Rome, Italy
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Identification of Reductive Dehalogenases That Mediate Complete Debromination of Penta- and Tetrabrominated Diphenyl Ethers in Dehalococcoides spp. Appl Environ Microbiol 2021; 87:e0060221. [PMID: 34160266 DOI: 10.1128/aem.00602-21] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Polybrominated diphenyl ethers (PBDEs) are persistent, highly toxic, and widely distributed environmental pollutants. The microbial populations and functional reductive dehalogenases (RDases) responsible for PBDE debromination in anoxic systems remain poorly understood, which confounds bioremediation of PBDE-contaminated sites. Here, we report a PBDE-debrominating enrichment culture dominated by a previously undescribed Dehalococcoides mccartyi population. A D. mccartyi strain, designated TZ50, whose genome contains 25 putative RDase-encoding genes, was isolated from the debrominating enrichment culture. Strain TZ50 dehalogenated a mixture of pentabrominated diphenyl ether (penta-BDE) and tetra-BDE congeners (total BDEs, 1.48 μM) to diphenyl ether within 2 weeks (0.58 μM Br-/day) via ortho- and meta-bromine elimination; strain TZ50 also dechlorinated tetrachloroethene (PCE) to vinyl chloride and ethene (260.2 μM Cl-/day). Results of native PAGE, proteomic profiling, and in vitro enzymatic activity assays implicated the involvement of three RDases in PBDE and PCE dehalogenation. TZ50_0172 (PteATZ50) and TZ50_1083 (TceATZ50) were responsible for the debromination of penta- and tetra-BDEs to di-BDE. TZ50_0172 and TZ50_1083 were also implicated in the dechlorination of PCE to trichloroethene (TCE) and of TCE to vinyl chloride/ethene, respectively. The other expressed RDase, TZ50_0090 (designated BdeA), was associated with the debromination of di-BDE to diphenyl ether, but its role in PCE dechlorination was unclear. Comparatively few RDases are known to be involved in PBDE debromination, and the identification of PteATZ50, TceATZ50, and BdeA provides additional information for evaluating debromination potential at contaminated sites. Moreover, the ability of PteATZ50 and TceATZ50 to dehalogenate both PBDEs and PCE makes strain TZ50 a suitable candidate for the remediation of cocontaminated sites. IMPORTANCE The ubiquity, toxicity, and persistence of polybrominated diphenyl ethers (PBDEs) in the environment have drawn significant public and scientific interest to the need for the remediation of PBDE-contaminated ecosystems. However, the low bioavailability of PBDEs in environmental compartments typically limits bioremediation of PBDEs and has long impeded the study of anaerobic microbial PBDE removal. In the current study, a novel Dehalococcoides mccartyi strain, dubbed strain TZ50, that expresses RDases that mediate organohalide respiration of both PBDEs and chloroethenes was isolated and characterized. Strain TZ50 could potentially be used to remediate multiple cooccurring organohalides in contaminated systems.
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18
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A Microcosm Treatability Study for Evaluating Wood Mulch-Based Amendments as Electron Donors for Trichloroethene (TCE) Reductive Dechlorination. WATER 2021. [DOI: 10.3390/w13141949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this study, wood mulch-based amendments were tested in a bench-scale microcosm experiment in order to assess the treatability of saturated soils and groundwater from an industrial site contaminated by chlorinated ethenes. Wood mulch was tested alone as the only electron donor in order to assess its potential for stimulating the biological reductive dechlorination. It was also tested in combination with millimetric iron filings in order to assess the ability of the additive to accelerate/improve the bioremediation process. The efficacy of the selected amendments was compared with that of unamended control microcosms. The results demonstrated that wood mulch is an effective natural and low-cost electron donor to stimulate the complete reductive dechlorination of chlorinated solvents to ethene. Being a side-product of the wood industry, mulch can be used in environmental remediation, an approach which perfectly fits the principles of circular economy and addresses the compelling needs of a sustainable and low environmental impact remediation. The efficacy of mulch was further improved by the co-presence of iron filings, which accelerated the conversion of vinyl chloride into the ethene by increasing the H2 availability rather than by catalyzing the direct abiotic dechlorination of contaminants. Chemical analyses were corroborated by biomolecular assays, which confirmed the stimulatory effect of the selected amendments on the abundance of Dehalococcoides mccartyi and related reductive dehalogenase genes. Overall, this paper further highlights the application potential and environmental sustainability of wood mulch-based amendments as low-cost electron donors for the biological treatment of chlorinated ethenes.
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Matturro B, Majone M, Aulenta F, Rossetti S. Correlations between maximum reductive dechlorination rates and specific biomass parameters in Dehalococcoides mccartyi consortia enriched on chloroethenes PCE, TCE and cis-1,2-DCE. FEMS Microbiol Ecol 2021; 97:6253249. [PMID: 33899920 DOI: 10.1093/femsec/fiab064] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 04/23/2021] [Indexed: 01/04/2023] Open
Abstract
One of the challenges to implementing the modeling of the biological reductive dechlorination (RD) process is the evaluation of biological parameters that represent the abundance/activity levels of the microorganisms involved in the biodegradation of chloroethenes. Here we report a combined analysis of kinetic and specific biomass parameters conducted on three dechlorinating consortia enriched on PCE, TCE and cis-1,2-DCE. In these consortia, Dehalococcoides mccartyi (Dhc) represented ≥70% of the bacterial population identified via 16S rRNA gene amplicon sequencing. Quantitative biomolecular methods were used to generate specific biomass parameters targeting either the Dhc population (16S rRNA genes or cells) or specific genes encoding RD process-involved reductive dehalogenases. The correlation factor between the abundance of active Dhc cells or tceA gene copies and maximum RD rates allowed to predict an increment of 7E+09 of active Dhc cells or 5E+09 tceA gene copies/L under controlled conditions. Diversely, the utilization of gene transcripts as biomass parameters for RD modeling did not provide reliable correlations with kinetic performances. This study provides valuable insights for further modeling of the RD process through the utilization of specific biomass parameters.
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Affiliation(s)
- B Matturro
- Water Research Institute, IRSA-CNR, Via Salaria km 29.300, Monterotondo (RM) 00015, Italy
| | - M Majone
- Department of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - F Aulenta
- Water Research Institute, IRSA-CNR, Via Salaria km 29.300, Monterotondo (RM) 00015, Italy
| | - S Rossetti
- Water Research Institute, IRSA-CNR, Via Salaria km 29.300, Monterotondo (RM) 00015, Italy
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Toth CRA, Luo F, Bawa N, Webb J, Guo S, Dworatzek S, Edwards EA. Anaerobic Benzene Biodegradation Linked to the Growth of Highly Specific Bacterial Clades. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:7970-7980. [PMID: 34041904 DOI: 10.1021/acs.est.1c00508] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Reliance on bioremediation to remove benzene from anoxic environments has proven risky for decades but for unknown reasons. Research has revealed a strong link between anaerobic benzene biodegradation and the enrichment of highly specific microbes, including Thermincola in the family Peptococcaceae and the deltaproteobacterial Candidate Sva0485 clade. Using aquifer materials from Canadian Forces Base Borden, we compared five bioremediation approaches in batch microcosms. Under conditions simulating natural attenuation or sulfate biostimulation, benzene was not degraded after 1-2 years of incubation and no enrichment of known benzene-degrading microbes occurred. In contrast, nitrate-amended microcosms reported benzene biodegradation coincident with significant growth of Thermincola spp., along with a functional gene presumed to catalyze anaerobic benzene carboxylation (abcA). Inoculation with 2.5% of a methanogenic benzene-degrading consortium containing Sva0485 (Deltaproteobacteria ORM2) resulted in benzene biodegradation in the presence of sulfate or under methanogenic conditions. The presence of other hydrocarbon co-contaminants decreased the rates of benzene degradation by a factor of 2 to 4. Tracking the abundance of the abcA gene and 16S rRNA genes specific for benzene-degrading Thermincola and Sva0485 is recommended to monitor benzene bioremediation in anoxic groundwater systems to further uncover growth-rate-limiting conditions for these two intriguing phylotypes.
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Affiliation(s)
- Courtney R A Toth
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Fei Luo
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Nancy Bawa
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Jennifer Webb
- SiREM, 130 Stone Road West, Guelph, Ontario N1G 3Z2, Canada
| | - Shen Guo
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | | | - Elizabeth A Edwards
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
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21
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Effects of the Feeding Solution Composition on a Reductive/Oxidative Sequential Bioelectrochemical Process for Perchloroethylene Removal. Processes (Basel) 2021. [DOI: 10.3390/pr9030405] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Chlorinated aliphatic hydrocarbons (CAHs) are common groundwater contaminants due to their improper use in several industrial activities. Specialized microorganisms are able to perform the reductive dechlorination (RD) of high-chlorinated CAHs such as perchloroethylene (PCE), while the low-chlorinated ethenes such as vinyl chloride (VC) are more susceptible to oxidative mechanisms performed by aerobic dechlorinating microorganisms. Bioelectrochemical systems can be used as an effective strategy for the stimulation of both anaerobic and aerobic microbial dechlorination, i.e., a biocathode can be used as an electron donor to perform the RD, while a bioanode can provide the oxygen necessary for the aerobic dechlorination reaction. In this study, a sequential bioelectrochemical process constituted by two membrane-less microbial electrolysis cells connected in series has been, for the first time, operated with synthetic groundwater, also containing sulphate and nitrate, to simulate more realistic process conditions due to the possible establishment of competitive processes for the reducing power, with respect to previous research made with a PCE-contaminated mineral medium (with neither sulphate nor nitrate). The shift from mineral medium to synthetic groundwater showed the establishment of sulphate and nitrate reduction and caused the temporary decrease of the PCE removal efficiency from 100% to 85%. The analysis of the RD biomarkers (i.e., Dehalococcoides mccartyi 16S rRNA and tceA, bvcA, vcrA genes) confirmed the decrement of reductive dechlorination performances after the introduction of the synthetic groundwater, also characterized by a lower ionic strength and nutrients content. On the other hand, the system self-adapted the flowing current to the increased demand for the sulphate and nitrate reduction, so that reducing power was not in defect for the RD, although RD coulombic efficiency was less.
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22
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Wackett LP, Robinson SL. The ever-expanding limits of enzyme catalysis and biodegradation: polyaromatic, polychlorinated, polyfluorinated, and polymeric compounds. Biochem J 2020; 477:2875-2891. [PMID: 32797216 PMCID: PMC7428800 DOI: 10.1042/bcj20190720] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/29/2020] [Accepted: 07/31/2020] [Indexed: 11/17/2022]
Abstract
Biodegradation is simply the metabolism of anthropogenic, or otherwise unwanted, chemicals in our environment, typically by microorganisms. The metabolism of compounds commonly found in living things is limited to several thousand metabolites whereas ∼100 million chemical substances have been devised by chemical synthesis, and ∼100 000 are used commercially. Since most of those compounds are not natively found in living things, and some are toxic or carcinogenic, the question arises as to whether there is some organism somewhere with the enzymes that can biodegrade them. Repeatedly, anthropogenic chemicals have been denoted 'non-biodegradable,' only to find they are reactive with one or more enzyme(s). Enzyme reactivity has been organized into categories of functional group transformations. The discovery of new functional group transformations has continually expanded our knowledge of enzymes and biodegradation. This expansion of new-chemical biodegradation is driven by the evolution and spread of newly evolved enzymes. This review describes the biodegradation of widespread commercial chemicals with a focus on four classes: polyaromatic, polychlorinated, polyfluorinated, and polymeric compounds. Polyaromatic hydrocarbons include some of the most carcinogenic compounds known. Polychlorinated compounds include polychlorinated biphenyls (PCBs) and many pesticides of the twentieth century. Polyfluorinated compounds are a major focus of bioremediation efforts today. Polymers are clogging landfills, killing aquatic species in the oceans and increasingly found in our bodies. All of these classes of compounds, each thought at one time to be non-biodegradable, have been shown to react with natural enzymes. The known limits of enzyme catalysis, and hence biodegradation, are continuing to expand.
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Affiliation(s)
- Lawrence P. Wackett
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Twin Cities, Minneapolis, MN 55108, U.S.A
- Biotechnology Institute, University of Minnesota, Twin Cities, Minneapolis, MN 55108, U.S.A
- Program in Microbiology, Immunology and Cancer Biology, University of Minnesota, Twin Cities, Minneapolis, MN 55108, U.S.A
| | - Serina L. Robinson
- Biotechnology Institute, University of Minnesota, Twin Cities, Minneapolis, MN 55108, U.S.A
- Program in Microbiology, Immunology and Cancer Biology, University of Minnesota, Twin Cities, Minneapolis, MN 55108, U.S.A
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