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Tornabene BJ, Smalling KL, Hossack BR. Effects of Harmful Algal Blooms on Amphibians and Reptiles are Under-Reported and Under-Represented. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2024. [PMID: 38967263 DOI: 10.1002/etc.5941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 05/07/2024] [Accepted: 06/03/2024] [Indexed: 07/06/2024]
Abstract
Harmful algal blooms (HABs) are a persistent and increasing problem globally, yet we still have limited knowledge about how they affect wildlife. Although semi-aquatic and aquatic amphibians and reptiles have experienced large declines and occupy environments where HABs are increasingly problematic, their vulnerability to HABs remains unclear. To inform monitoring, management, and future research, we conducted a literature review, synthesized the studies, and report on the mortality events describing effects of cyanotoxins from HABs on freshwater herpetofauna. Our review identified 37 unique studies and 71 endpoints (no-observed-effect and lowest-observed-effect concentrations) involving 11 amphibian and 3 reptile species worldwide. Responses varied widely among studies, species, and exposure concentrations used in experiments. Concentrations causing lethal and sublethal effects in laboratory experiments were generally 1 to 100 µg/L, which contains the mean value of reported HAB events but is 70 times less than the maximum cyanotoxin concentrations reported in the environment. However, one species of amphibian was tolerant to concentrations of 10,000 µg/L, demonstrating potentially immense differences in sensitivities. Most studies focused on microcystin-LR (MC-LR), which can increase systemic inflammation and harm the digestive system, reproductive organs, liver, kidneys, and development. The few studies on other cyanotoxins illustrated that effects resembled those of MC-LR at similar concentrations, but more research is needed to describe effects of other cyanotoxins and mixtures of cyanotoxins that commonly occur in the environment. All experimental studies were on larval and adult amphibians; there were no such studies on reptiles. Experimental work with reptiles and adult amphibians is needed to clarify thresholds of tolerance. Only nine mortality events were reported, mostly for reptiles. Given that amphibians likely decay faster than reptiles, which have tissues that resist decomposition, mass amphibian mortality events from HABs have likely been under-reported. We propose that future efforts should be focused on seven major areas, to enhance our understanding of effects and monitoring of HABs on herpetofauna that fill important roles in freshwater and terrestrial environments. Environ Toxicol Chem 2024;00:1-14. Published 2024. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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Affiliation(s)
- Brian J Tornabene
- Northern Rocky Mountain Science Center, US Geological Survey, Missoula, Montana
| | - Kelly L Smalling
- New Jersey Water Science Center, US Geological Survey, Lawrenceville, New Jersey
| | - Blake R Hossack
- Northern Rocky Mountain Science Center, US Geological Survey, Missoula, Montana
- Wildlife Biology Program, W. A. Franke College of Forestry and Conservation, University of Montana, Missoula, Montana, USA
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Mugani R, El Khalloufi F, Redouane EM, Haida M, Aba RP, Essadki Y, El Amrani Zerrifi S, Hejjaj A, Ouazzani N, Campos A, Grossart HP, Mandi L, Vasconcelos V, Oudra B. Unlocking the potential of bacterioplankton-mediated microcystin degradation and removal: A bibliometric analysis of sustainable water treatment strategies. WATER RESEARCH 2024; 255:121497. [PMID: 38555787 DOI: 10.1016/j.watres.2024.121497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 01/31/2024] [Accepted: 03/19/2024] [Indexed: 04/02/2024]
Abstract
Microcystins (MCs) constitute a significant threat to human and environmental health, urging the development of effective removal methods for these toxins. In this review, we explore the potential of MC-degrading bacteria as a solution for the removal of MCs from water. The review insights into the mechanisms of action employed by these bacteria, elucidating their ability to degrade and thus remove MCs. After, the review points out the influence of the structural conformation of MCs on their removal, particularly their stability at different water depths within different water bodies. Then, we review the crucial role played by the production of MCs in ensuring the survival and safeguarding of the enzymatic activities of Microcystis cells. This justifies the need for developing effective and sustainable methods for removing MCs from aquatic ecosystems, given their critical ecological function and potential toxicity to humans and animals. Thereafter, challenges and limitations associated with using MC-degrading bacteria in water treatment are discussed, emphasizing the need for further research to optimize the selection of bacterial strains used for MCs biodegradation. The interaction of MCs-degrading bacteria with sediment particles is also crucial for their toxin removal potential and its efficiency. By presenting critical information, this review is a valuable resource for researchers, policymakers, and stakeholders involved in developing sustainable and practical approaches to remove MCs. Our review highlights the potential of various applications of MC-degrading bacteria, including multi-soil-layering (MSL) technologies. It emphasizes the need for ongoing research to optimize the utilization of MC-degrading bacteria in water treatment, ultimately ensuring the safety and quality of water sources. Moreover, this review highlights the value of bibliometric analyses in revealing research gaps and trends, providing detailed insights for further investigations. Specifically, we discuss the importance of employing advanced genomics, especially combining various OMICS approaches to identify and optimize the potential of MCs-degrading bacteria.
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Affiliation(s)
- Richard Mugani
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Av. Prince My Abdellah, P.O. Box 2390, Marrakech 40000, Morocco; National Center for Studies and Research on Water and Energy, Cadi Ayyad University, P.O. Box: 511, 40000 Marrakech, Morocco; Department of Plankton and Microbial Ecology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Zur alten Fischerhuette 2, 14775 Stechlin, Germany
| | - Fatima El Khalloufi
- Natural Resources Engineering and Environmental Impacts Team, Multidisciplinary Research and Innovation Laboratory, Polydisciplinary Faculty of Khouribga, Sultan Moulay Slimane University of Beni Mellal, B.P.: 145, 25000, Khouribga, Morocco
| | - El Mahdi Redouane
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Av. Prince My Abdellah, P.O. Box 2390, Marrakech 40000, Morocco
| | - Mohammed Haida
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Av. Prince My Abdellah, P.O. Box 2390, Marrakech 40000, Morocco
| | - Roseline Prisca Aba
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Av. Prince My Abdellah, P.O. Box 2390, Marrakech 40000, Morocco; National Center for Studies and Research on Water and Energy, Cadi Ayyad University, P.O. Box: 511, 40000 Marrakech, Morocco
| | - Yasser Essadki
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Av. Prince My Abdellah, P.O. Box 2390, Marrakech 40000, Morocco
| | - Soukaina El Amrani Zerrifi
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Av. Prince My Abdellah, P.O. Box 2390, Marrakech 40000, Morocco; Higher Institute of Nurses Professions and Health Techniques of Guelmim, Guelmim, Morocco
| | - Abdessamad Hejjaj
- National Center for Studies and Research on Water and Energy, Cadi Ayyad University, P.O. Box: 511, 40000 Marrakech, Morocco.
| | - Naaila Ouazzani
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Av. Prince My Abdellah, P.O. Box 2390, Marrakech 40000, Morocco; National Center for Studies and Research on Water and Energy, Cadi Ayyad University, P.O. Box: 511, 40000 Marrakech, Morocco
| | - Alexandre Campos
- CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, s/n, 4450-208 Porto, Portugal
| | - Hans-Peter Grossart
- Department of Plankton and Microbial Ecology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Zur alten Fischerhuette 2, 14775 Stechlin, Germany; Institute of Biochemistry and Biology, University of Potsdam, Maulbeeralle 2, 14469 Potsdam, Germany
| | - Laila Mandi
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Av. Prince My Abdellah, P.O. Box 2390, Marrakech 40000, Morocco; National Center for Studies and Research on Water and Energy, Cadi Ayyad University, P.O. Box: 511, 40000 Marrakech, Morocco
| | - Vitor Vasconcelos
- CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos, s/n, 4450-208 Porto, Portugal; Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
| | - Brahim Oudra
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Av. Prince My Abdellah, P.O. Box 2390, Marrakech 40000, Morocco
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Reignier O, Bormans M, Hervé F, Robert E, Savar V, Tanniou S, Amzil Z, Noël C, Briand E. Spatio-temporal connectivity of a toxic cyanobacterial community and its associated microbiome along a freshwater-marine continuum. HARMFUL ALGAE 2024; 134:102627. [PMID: 38705620 DOI: 10.1016/j.hal.2024.102627] [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: 01/26/2024] [Revised: 03/22/2024] [Accepted: 04/10/2024] [Indexed: 05/07/2024]
Abstract
Due to climate changes and eutrophication, blooms of predominantly toxic freshwater cyanobacteria are intensifying and are likely to colonize estuaries, thus impacting benthic organisms and shellfish farming representing a major ecological, health and economic risk. In the natural environment, Microcystis form large mucilaginous colonies that influence the development of both cyanobacterial and embedded bacterial communities. However, little is known about the fate of natural colonies of Microcystis by salinity increase. In this study, we monitored the fate of a Microcystis dominated bloom and its microbiome along a French freshwater-marine gradient at different phases of a bloom. We demonstrated changes in the cyanobacterial genotypic composition, in the production of specific metabolites (toxins and compatible solutes) and in the heterotrophic bacteria structure in response to the salinity increase. In particular M. aeruginosa and M. wesenbergii survived salinities up to 20. Based on microcystin gene abundance, the cyanobacteria became more toxic during their estuarine transfer but with no selection of specific microcystin variants. An increase in compatible solutes occurred along the continuum with extensive trehalose and betaine accumulations. Salinity structured most the heterotrophic bacteria community, with an increased in the richness and diversity along the continuum. A core microbiome in the mucilage-associated attached fraction was highly abundant suggesting a strong interaction between Microcystis and its microbiome and a likely protecting role of the mucilage against an osmotic shock. These results underline the need to better determine the interactions between the Microcystis colonies and their microbiome as a likely key to their widespread success and adaptation to various environmental conditions.
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Affiliation(s)
| | - Myriam Bormans
- UMR CNRS 6553 ECOBIO, University of Rennes 1, Rennes F-35042, France
| | - Fabienne Hervé
- IFREMER, PHYTOX, Laboratoire METALG, Nantes F-44000, France
| | - Elise Robert
- IFREMER, PHYTOX, Laboratoire GENALG, Nantes F-44000, France
| | | | - Simon Tanniou
- IFREMER, PHYTOX, Laboratoire METALG, Nantes F-44000, France
| | - Zouher Amzil
- IFREMER, PHYTOX, Laboratoire METALG, Nantes F-44000, France
| | - Cyril Noël
- IFREMER, IRSI - Service de Bioinformatique (SeBiMER), Plouzané, France
| | - Enora Briand
- IFREMER, PHYTOX, Laboratoire GENALG, Nantes F-44000, France.
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Zhou Y, Wang Q, Xiao G, Zhang Z. Effects of the catastrophic 2020 Yangtze River seasonal floods on microcystins and environmental conditions in Three Gorges Reservoir Area, China. Front Microbiol 2024; 15:1380668. [PMID: 38511001 PMCID: PMC10951095 DOI: 10.3389/fmicb.2024.1380668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 02/26/2024] [Indexed: 03/22/2024] Open
Abstract
Introduction During July and August 2020, Three Gorges Reservoir Area (TGRA) suffered from catastrophic seasonal floods. Floods changed environmental conditions and caused increase in concentration of microcystins (MCs) which is a common and potent cyanotoxin. However, the effects and seasonal variations of MCs, cyanobacteria, and environmental conditions in TGRA after the 2020 Yangtze River extreme seasonal floods remain largely unclear, and relevant studies are lacking in the literature. Methods A total of 12 representative sampling sites were selected to perform concentration measurement of relevant water quality objectives and MCs in the representative area of the TGRA. The sampling period was from July 2020 to October 2021, which included the flood period. Organic membrane filters were used to perform the DNA extraction and analyses of the 16S rRNA microbiome sequencing data. Results Results showed the seasonal floods result in significant increases in the mean values of microcystin-RR (MCRR), microcystin-YR (MCYR), and microcystin-LR (MCLR) concentration and some water quality objectives (i.e., turbidity) in the hinterland of TGRA compared with that in non-flood periods (p < 0.05). The mean values of some water quality objectives (i.e., total nitrogen (TN), total phosphorus (TP), total dissolved phosphorus (TDP), and turbidity), MC concentration (i.e., MCRR, MCYR, and MCLR), and cyanobacteria abundance (i.e., Cyanobium_PCC-6307 and Planktothrix_NIVA-CYA_15) displayed clear tendency of increasing in summer and autumn and decreasing in winter and spring in the hinterland of TGRA. Discussions The results suggest that seasonal floods lead to changes in MC concentration and environmental conditions in the hinterland of TGRA. Moreover, the increase in temperature leads to changes in water quality objectives, which may cause water eutrophication. In turn, water eutrophication results in the increase in cyanobacteria abundance and MC concentration. In particular, the increased MC concentration may further contribute to adverse effects on human health.
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Affiliation(s)
- Yuanhang Zhou
- Key Laboratory of the Three Gorges Reservoir Regions Eco-Environment of Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing, China
| | - Qilong Wang
- Engineering Technology Research Center of Characteristic Biological Resources in Northeast Chongqing, College of Biology and Food Engineering, Chongqing Three Gorges University, Wanzhou, Chongqing, China
| | - Guosheng Xiao
- Engineering Technology Research Center of Characteristic Biological Resources in Northeast Chongqing, College of Biology and Food Engineering, Chongqing Three Gorges University, Wanzhou, Chongqing, China
| | - Zhi Zhang
- Key Laboratory of the Three Gorges Reservoir Regions Eco-Environment of Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing, China
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Baylous HR, Gladfelter MF, Gardner MI, Foley M, Wilson AE, Steffen MM. Indole-3-acetic acid promotes growth in bloom-forming Microcystis via an antioxidant response. HARMFUL ALGAE 2024; 133:102575. [PMID: 38485434 DOI: 10.1016/j.hal.2024.102575] [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: 10/20/2023] [Revised: 01/05/2024] [Accepted: 01/05/2024] [Indexed: 03/19/2024]
Abstract
Interactions between bacteria and phytoplankton in the phycosphere facilitate and constrain biogeochemical cycling in aquatic ecosystems. Indole-3-acetic acid (IAA) is a bacterially produced chemical signal that promotes growth of phytoplankton and plants. Here, we explored the impact of IAA on bloom-forming cyanobacteria and their associated bacteria. Exposure to IAA and its precursor, tryptophan, resulted in a strong growth response in a bloom of the freshwater cyanobacterium, Microcystis. Metatranscriptome analysis revealed the induction of an antioxidant response in Microcystis upon exposure to IAA, potentially allowing populations to increase photosynthetic rate and overcome internally generated reactive oxygen. Our data reveal that co-occurring bacteria within the phycosphere microbiome exhibit a division of labor for supportive functions, such as nutrient mineralization and transport, vitamin synthesis, and reactive oxygen neutralization. These complex dynamics within the Microcystis phycosphere microbiome are an example of interactions within a microenvironment that can have ecosystem-scale consequences.
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Affiliation(s)
- Hunter R Baylous
- Department of Biology, James Madison University, Harrisonburg, VA 22801, USA
| | - Matthew F Gladfelter
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA
| | - Malia I Gardner
- Department of Biology, James Madison University, Harrisonburg, VA 22801, USA
| | - Madalynn Foley
- Department of Biology, James Madison University, Harrisonburg, VA 22801, USA
| | - Alan E Wilson
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA
| | - Morgan M Steffen
- Department of Biology, James Madison University, Harrisonburg, VA 22801, USA.
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Salter C, Westrick JA, Chaganti SR, Birbeck JA, Peraino NJ, Weisener CG. Elucidating microbial mechanisms of microcystin-LR degradation in Lake Erie beach sand through metabolomics and metatranscriptomics. WATER RESEARCH 2023; 247:120816. [PMID: 37952399 DOI: 10.1016/j.watres.2023.120816] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/11/2023] [Accepted: 10/29/2023] [Indexed: 11/14/2023]
Abstract
As one of five Laurentian Great Lakes, Lake Erie ranks among the top freshwater drinking sources and ecosystems globally. Historical and current agriculture mismanagement and climate change sustains the environmental landscape for late summer cyanobacterial harmful algal blooms, and consequently, cyanotoxins such as microcystin (MC). Microcystin microbial degradation is a promising mitigation strategy, however the mechanisms controlling the breakdown of MCs in Lake Erie are not well understood. Pelee Island, Ontario, Canada is located in the western basin of Lake Erie and the bacterial community in the sand has demonstrated the capacity of metabolizing the toxin. Through a multi-omic approach, the metabolic, functional and taxonomical signatures of the Pelee Island microbial community during MC-LR degradation was investigated over a 48-hour period to comprehensively study the degradation mechanism. Cleavage of bonds surrounding nitrogen atoms and the upregulation of nitrogen deamination (dadA, alanine dehydrogenase, leucine dehydrogenase) and assimilation genes (glnA, gltB) suggests a targeted isolation of nitrogen by the microbial community for energy production. Methylotrophic pathways RuMP and H4MPT control assimilation and dissimilation of carbon, respectively and differential abundance of Methylophilales indicates an interconnected role through electron exchange of denitrification and methylotrophic pathways. The detected metabolites did not resolve a clear breakdown pathway, but rather the diversity of products in combination with taxonomic and functional results supports that a variety of strategies are applied, such as epoxidation, hydroxylation, and aromatic degradation. Annual repeated exposure to the toxin may have allowed the community to adaptatively establish a novel pathway through functional plasticity and horizontal gene transfer. The culmination of these results reveals the complexity of the Pelee Island sand community and supports a dynamic and cooperative metabolism between microbial species to achieve MC degradation.
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Affiliation(s)
- Chelsea Salter
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON N9B 3P4, Canada.
| | - Judy A Westrick
- Lumigen Instrument Center, Department of Chemistry, Wayne State University, Detroit, MI 48202, United States
| | - Subba Rao Chaganti
- Cooperative Institute for Great Lakes Research, School for Environment and Sustainability, University of Michigan, 440 Church Street, Ann Arbor, MI 48109, United States
| | - Johnna A Birbeck
- Lumigen Instrument Center, Department of Chemistry, Wayne State University, Detroit, MI 48202, United States
| | - Nicholas J Peraino
- Lumigen Instrument Center, Department of Chemistry, Wayne State University, Detroit, MI 48202, United States
| | - Christopher G Weisener
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON N9B 3P4, Canada
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Zhang J, Wang N, Zhang Z, Gao Y, Dong J, Gao X, Yuan H, Li X. The Combined Effects of Toxic Microcystis aeruginosa and Thermal Stress on the Edible Clam ( Corbicula fluminea): Insights into Oxidative Stress Responses and Molecular Networks. Antioxidants (Basel) 2023; 12:1901. [PMID: 38001754 PMCID: PMC10669901 DOI: 10.3390/antiox12111901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 10/21/2023] [Accepted: 10/23/2023] [Indexed: 11/26/2023] Open
Abstract
Cyanobacterial blooms (CYBs) have become a global environmental issue, posing risks to edible bivalves. Toxic cyanobacteria and thermal stress represent the two key co-occurring stressors to bivalves experiencing CYBs. To investigate the combined effects of these stressors on the edible bivalve Corbicula fluminea, the responses to oxidative stress and the molecular mechanisms of physiological adaptations in C. fluminea were examined under co-exposure to toxic Microcystis aeruginosa and thermal stress. The activity of antioxidant enzymes, including GST, SOD, CAT, GPx and GR, was significantly influenced by the interaction between temperature and M. aeruginosa (p < 0.05). A positive correlation was observed between toxic M. aeruginosa exposure and elevated SOD and GPx activities at 30 °C, demonstrating that SOD and GPx may help C. fluminea defend effectively against MCs under thermal stress. Furthermore, significant interactive effects between toxic M. aeruginosa and temperature were also observed in ROS and MDA (p < 0.05). The results of the PCA and IBR index also evidenced the apparent influence of toxic M. aeruginosa and thermal stress on oxidative stress responses of C. fluminea. The eggNOG and GO annotations confirmed that a substantial portion of differentially expressed genes (DEGs) exhibited associations with responses to oxidative stress and transporter activity. Additionally, KEGG analysis revealed that abundant DEGs were involved in pathways related to inflammatory responses, immune functions and metabolic functions. These findings improve our understanding of the mechanism of the physiological adaptation in bivalves in response to cyanotoxins under thermal conditions, potentially enabling the evaluation of the viability of using bivalves as a bioremediation tool to manage CYBs in eutrophic waters.
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Affiliation(s)
- Jingxiao Zhang
- College of Fisheries, Henan Normal University, Xinxiang 453007, China
- Observation and Research Station on Water Ecosystem in Danjiangkou Reservoir of Henan Province, Nanyang 473000, China
| | - Ning Wang
- College of Fisheries, Henan Normal University, Xinxiang 453007, China
| | - Zehao Zhang
- College of Fisheries, Henan Normal University, Xinxiang 453007, China
| | - Yunni Gao
- College of Fisheries, Henan Normal University, Xinxiang 453007, China
| | - Jing Dong
- College of Fisheries, Henan Normal University, Xinxiang 453007, China
| | - Xiaofei Gao
- College of Fisheries, Henan Normal University, Xinxiang 453007, China
| | - Huatao Yuan
- College of Fisheries, Henan Normal University, Xinxiang 453007, China
| | - Xuejun Li
- College of Fisheries, Henan Normal University, Xinxiang 453007, China
- Observation and Research Station on Water Ecosystem in Danjiangkou Reservoir of Henan Province, Nanyang 473000, China
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Teng J, Song M, Xu Q, Zou Q, Zhang H, Yin C, Liu X, Liu Y, Yan H. Purification and Activity of the Second Recombinant Enzyme for Biodegrading Linearized Microcystins by Sphingopyxis sp. USTB-05. Toxins (Basel) 2023; 15:494. [PMID: 37624251 PMCID: PMC10467064 DOI: 10.3390/toxins15080494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/26/2023] [Accepted: 08/02/2023] [Indexed: 08/26/2023] Open
Abstract
Hepatotoxic microcystins (MCs) are produced and released by the harmful bloom-forming cyanobacteria, which severely threaten drinking water safety and human health due to their high toxicity, widespread distribution, and structural stability. The linearized microcystinase (MlrB) further hydrolyses the poisonous linearized MCs produced by the microcystinase-catalysed MCs to form tetrapeptides. Here, the purification and activity of MlrB were investigated. The results showed that the linearized products generated by 12.5 mg/L MC-LR and MC-RR were removed by purified recombinant MlrB at a protein concentration of 1 mg/L within 30 min. The high catalytic activity of MlrB can be obtained via heterologous expression and affinity purification, which lays the foundation for further studies on the properties and mechanism of MCs biodegradation enzymes.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Hai Yan
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China; (J.T.)
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9
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Microcystin-Detoxifying Recombinant Saccharomyces cerevisiae Expressing the mlrA Gene from Sphingosinicella microcystinivorans B9. Microorganisms 2023; 11:microorganisms11030575. [PMID: 36985150 PMCID: PMC10058252 DOI: 10.3390/microorganisms11030575] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/20/2023] [Accepted: 02/22/2023] [Indexed: 03/03/2023] Open
Abstract
Contamination of water by microcystins is a global problem. These potent hepatotoxins demand constant monitoring and control methods in potable water. Promising approaches to reduce contamination risks have focused on natural microcystin biodegradation led by enzymes encoded by the mlrABCD genes. The first enzyme of this system (mlrA) linearizes microcystin structure, reducing toxicity and stability. Heterologous expression of mlrA in different microorganisms may enhance its production and activity, promote additional knowledge on the enzyme, and support feasible applications. In this context, we intended to express the mlrA gene from Sphingosinicella microcystinivorans B9 in an industrial Saccharomyces cerevisiae strain as an innovative biological alternative to degrade microcystins. The mlrA gene was codon-optimized for expression in yeast, and either expressed from a plasmid or through chromosomal integration at the URA3 locus. Recombinant and wild yeasts were cultivated in medium contaminated with microcystins, and the toxin content was analyzed during growth. Whereas no difference in microcystins content was observed in cultivation with the chromosomally integrated strain, the yeast strain hosting the mlrA expression plasmid reduced 83% of toxins within 120 h of cultivation. Our results show microcystinase A expressed by industrial yeast strains as a viable option for practical applications in water treatment.
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Anam GB, Guda DR, Ahn YH. Impact of melatonin on the hydrogen peroxide treatment efficacy in Microcystis aeruginosa: Cell growth, oxidative stress response, and gene transcription. CHEMOSPHERE 2022; 307:136036. [PMID: 36007744 DOI: 10.1016/j.chemosphere.2022.136036] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 07/22/2022] [Accepted: 08/08/2022] [Indexed: 06/15/2023]
Abstract
A study was conducted to determine how melatonin (MLT), a growth regulator, affects Microcystis aeruginosa cell behaviour and how MLT exposed cells respond to hydrogen peroxide (H2O2) treatment. MLT promotes the growth, chl-a content, Fv/Fm values, and microcystins (MCs) production of M. aeruginosa at low concentrations of 1-2.5 μmol/L but suppresses the growth at high concentrations (5-10 μmol/L). The cellular and genetic responses of MLT pre-treated cells to H2O2 treatment were examined further. Further research found that the cells pre-treated with MLT were susceptible to a range of growth-promoting, inhibiting and lethal effects when exposed to higher levels of H2O2. A dose-dependent pattern was observed under conditions of 0.05-0.2 mmol/L H2O2 with 0.5-2.5 μmol/L MLT concentrations to different degrees. High doses of H2O2 (0.2 and 0.3 mmol/L) typically lead to cell lysis and release of MCs in 5.0 and 10 μmol/L MLT pre-treated cells. A decrease in SOD/CAT activities and an increase in MDA levels validated the growth reduction. Furthermore, higher cell lysis and release of intracellular MCs were observed when H2O2 was increased for 5-10 μmol/L MLT pre-treated cells. This led to a higher accumulation of extracellular MCs. The results provide insight into how MLT influences H2O2 damage and assist in identifying situations where H2O2 treatment of cyanobacterial blooms is most appropriate.
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Affiliation(s)
- Giridhar Babu Anam
- Department of Civil Engineering, Yeungnam University, Gyeongsan, 38541, Gyeongbuk, Republic of Korea
| | - Dinneswara Reddy Guda
- Korea Center for Artificial Photosynthesis and Center for Nanomaterial, Sogang University, Seoul, 121-742, Republic of Korea
| | - Young-Ho Ahn
- Department of Civil Engineering, Yeungnam University, Gyeongsan, 38541, Gyeongbuk, Republic of Korea.
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11
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Hu C, Zuo Y, Peng L, Gan N, Song L. Widespread Distribution and Adaptive Degradation of Microcystin Degrader ( mlr-Genotype) in Lake Taihu, China. Toxins (Basel) 2021; 13:toxins13120864. [PMID: 34941702 PMCID: PMC8705652 DOI: 10.3390/toxins13120864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 11/30/2021] [Accepted: 12/01/2021] [Indexed: 11/16/2022] Open
Abstract
Microbial degradation is an important route for removing environmental microcystins (MCs). Here, we investigated the ecological distribution of microcystin degraders (mlr-genotype), and the relationship between the substrate specificity of the microcystin degrader and the profile of microcystin congener production in the habitat. We showed that microcystin degraders were widely distributed and closely associated with Microcystis abundance in Lake Taihu, China. We characterized an indigenous degrader, Sphingopyxis N5 in the northern Lake Taihu, and it metabolized six microcystin congeners in increasing order (RR > LR > YR > LA > LF and LW). Such a substrate-specificity pattern was congruent to the order of the dominance levels of these congeners in northern Lake Taihu. Furthermore, a meta-analysis on global microcystin degraders revealed that the substrate-specificity patterns varied geographically, but generally matched the profiles of microcystin congener production in the degrader habitats, and the indigenous degrader typically metabolized well the dominant MC congeners, but not the rare congeners in the habitat. This highlighted the phenotypic congruence between microcystin production and degradation in natural environments. We theorize that such congruence resulted from the metabolic adaptation of the indigenous degrader to the local microcystin congeners. Under the nutrient microcystin selection, the degraders might have evolved to better exploit the locally dominant congeners. This study provided the novel insight into the ecological distribution and adaptive degradation of microcystin degraders.
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Affiliation(s)
- Chenlin Hu
- State Key Laboratory of Fresh Water Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; (C.H.); (Y.Z.); (L.P.)
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
- College of Pharmacy, University of Houston, Houston, TX 77204, USA
| | - Yanxia Zuo
- State Key Laboratory of Fresh Water Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; (C.H.); (Y.Z.); (L.P.)
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - Liang Peng
- State Key Laboratory of Fresh Water Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; (C.H.); (Y.Z.); (L.P.)
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
- Institute of Hydrobiology, Jinan University, Guangzhou 510632, China
| | - Nanqin Gan
- State Key Laboratory of Fresh Water Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; (C.H.); (Y.Z.); (L.P.)
- Correspondence: (N.G.); (L.S.)
| | - Lirong Song
- State Key Laboratory of Fresh Water Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; (C.H.); (Y.Z.); (L.P.)
- Correspondence: (N.G.); (L.S.)
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12
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Pound HL, Gann ER, Wilhelm SW. A comparative study of metatranscriptomic assessment methods to characterize Microcystis blooms. LIMNOLOGY AND OCEANOGRAPHY, METHODS 2021; 19:846-854. [PMID: 35528780 PMCID: PMC9075346 DOI: 10.1002/lom3.10465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/28/2021] [Accepted: 10/19/2021] [Indexed: 06/14/2023]
Abstract
Harmful algal blooms are increasing in duration and severity globally, resulting in increased research interest. The use of genetic sequencing technologies has provided a wealth of opportunity to advance knowledge, but also poses a risk to that knowledge if handled incorrectly. The vast numbers of sequence processing tools and protocols provide a method to test nearly every hypothesis, but each method has inherent strengths and weaknesses. Here, we tested six methods to classify and quantify metatranscriptomic activity from a harmful algal bloom dominated by Microcystis spp. Three online tools were evaluated (Kaiju, MG-RAST, and GhostKOALA) in addition to three local tools that included a command line BLASTx approach, recruitment of reads to individual Microcystis genomes, and recruitment to a combined Microcystis composite genome generated from sequenced isolates with complete, closed genomes. Based on the analysis of each tool presented in this study, two recommendations are made that are dependent on the hypothesis to be tested. For researchers only interested in the function and physiology of Microcystis spp., read recruitments to the composite genome, referred to as "Frankenstein's Microcystis", provided the highest total estimates of transcript expression. However, for researchers interested in the entire bloom microbiome, the online GhostKOALA annotation tool, followed by subsequent read recruitments, provided functional and taxonomic characterization, in addition to transcript expression estimates. This study highlights the critical need for careful evaluation of methods before data analysis.
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Affiliation(s)
- Helena L. Pound
- Department of MicrobiologyUniversity of TennesseeKnoxvilleTennesseeUSA
| | - Eric R. Gann
- Department of MicrobiologyUniversity of TennesseeKnoxvilleTennesseeUSA
| | - Steven W. Wilhelm
- Department of MicrobiologyUniversity of TennesseeKnoxvilleTennesseeUSA
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13
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Biodegradation of Nodularin by a Microcystin-Degrading Bacterium: Performance, Degradation Pathway, and Potential Application. Toxins (Basel) 2021; 13:toxins13110813. [PMID: 34822597 PMCID: PMC8618024 DOI: 10.3390/toxins13110813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/15/2021] [Accepted: 11/15/2021] [Indexed: 01/19/2023] Open
Abstract
Currently, studies worldwide have comprehensively recognized the importance of Sphingomonadaceae bacteria and the mlrCABD gene cluster in microcystin (MC) degradation. However, knowledge about their degradation of nodularin (NOD) is still unclear. In this study, the degradation mechanism of NOD by Sphingopyxis sp. m6, an efficient MC degrader isolated from Lake Taihu, was investigated in several aspects, including degradation ability, degradation products, and potential application. The strain degraded NOD of 0.50 mg/L with a zero-order rate constant of 0.1656 mg/L/d and a half-life of 36 h. The average degradation rate of NOD was significantly influenced by the temperature, pH, and initial toxin concentrations. Moreover, four different biodegradation products, linear NOD, tetrapeptide H-Glu-Mdhb-MeAsp-Arg-OH, tripeptide H-Mdhb-MeAsp-Arg-OH, and dipeptide H-MeAsp-Arg-OH, were identified, of which the latter two are the first reported. Furthermore, the four mlr genes were upregulated during NOD degradation. The microcystinase MlrA encoded by the mlrA gene hydrolyzes the Arg-Adda bond to generate linear NOD as the first step of NOD biodegradation. Notably, recombinant MlrA showed higher degradation activity and stronger environmental adaptability than the wild strain, suggesting future applications in NOD pollution remediation. This research proposes a relatively complete NOD microbial degradation pathway, which lays a foundation for exploring the mechanisms of NOD degradation by MC-degrading bacteria.
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14
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Kibuye FA, Zamyadi A, Wert EC. A critical review on operation and performance of source water control strategies for cyanobacterial blooms: Part II-mechanical and biological control methods. HARMFUL ALGAE 2021; 109:102119. [PMID: 34815024 DOI: 10.1016/j.hal.2021.102119] [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: 11/19/2020] [Revised: 09/27/2021] [Accepted: 09/29/2021] [Indexed: 06/13/2023]
Abstract
This review summarizes current knowledge on mechanical (artificial mixing, hypolimnetic aeration, dredging, and sonication) and biological (biomanipulation, macrophytes, and straws) methods for the management of cyanobacterial blooms in drinking water sources. Emphasis has been given to (i) the mechanism of cyanobacterial control, (ii) successful and unsuccessful case studies, and (iii) factors influencing successful implementation. Most mechanical and biological control strategies offer long-term control. However, their application can be cost-prohibitive and treatment efficacy is influenced by source water geometry and continual nutrient inputs from external sources. When artificial mixing and hypolimnetic oxygenation units are optimized based on source water characteristics, observed water quality benefits included increased dissolved oxygen contents, reduced internal loading of nutrients, and lower concentrations of reduced ions . Treatment efficacy during oxygenation and aeration was derailed by excessive sedimentation of organic matter and sediment characteristics such as low Fe/P ratios. Dredging is beneficial for contaminated sediment removal, but it is too costly to be a practical bloom control strategy for most systems. Sonication control methods have contradictory findings requiring further research to evaluate the efficacy and applicability for field-scale control of cyanobacteria. Biological control methods such as biomanipulation offer long-term treatment benefits; however, investigations on the mechanisms of field-scale cyanobacterial control are still limited, particularly with the use of macrophytes and straws. Each control method has site-specific strengths, limitations, and ecological impacts. Reduction of external nutrient inputs should still be a significant focus of restoration efforts as treatment benefits from mechanical and biological control were commonly offset by continued nutrient inputs.
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Affiliation(s)
- Faith A Kibuye
- Southern Nevada Water Authority (SNWA), P.O. Box 99954, Las Vegas, NV 89193, United States.
| | - Arash Zamyadi
- Walter and Eliza Hall Institute of Medical Research (WEHI), 1G, Royal Parade, Parkville VIC 3052, Australia; Water Research Australia (WaterRA) Melbourne Based Position Hosted by Melbourne Water, 990 La Trobe St, Docklands VIC 3008, Australia
| | - Eric C Wert
- Southern Nevada Water Authority (SNWA), P.O. Box 99954, Las Vegas, NV 89193, United States.
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15
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Chaffin JD, Bratton JF, Verhamme EM, Bair HB, Beecher AA, Binding CE, Birbeck JA, Bridgeman TB, Chang X, Crossman J, Currie WJS, Davis TW, Dick GJ, Drouillard KG, Errera RM, Frenken T, MacIsaac HJ, McClure A, McKay RM, Reitz LA, Domingo JWS, Stanislawczyk K, Stumpf RP, Swan ZD, Snyder BK, Westrick JA, Xue P, Yancey CE, Zastepa A, Zhou X. The Lake Erie HABs Grab: A binational collaboration to characterize the western basin cyanobacterial harmful algal blooms at an unprecedented high-resolution spatial scale. HARMFUL ALGAE 2021; 108:102080. [PMID: 34588116 PMCID: PMC8682807 DOI: 10.1016/j.hal.2021.102080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 06/29/2021] [Accepted: 06/30/2021] [Indexed: 05/12/2023]
Abstract
Monitoring of cyanobacterial bloom biomass in large lakes at high resolution is made possible by remote sensing. However, monitoring cyanobacterial toxins is only feasible with grab samples, which, with only sporadic sampling, results in uncertainties in the spatial distribution of toxins. To address this issue, we conducted two intensive "HABs Grabs" of microcystin (MC)-producing Microcystis blooms in the western basin of Lake Erie. These were one-day sampling events during August of 2018 and 2019 in which 100 and 172 grab samples were collected, respectively, within a six-hour window covering up to 2,270 km2 and analyzed using consistent methods to estimate the total mass of MC. The samples were analyzed for 57 parameters, including toxins, nutrients, chlorophyll, and genomics. There were an estimated 11,513 kg and 30,691 kg of MCs in the western basin during the 2018 and 2019 HABs Grabs, respectively. The bloom boundary poses substantial issues for spatial assessments because MC concentration varied by nearly two orders of magnitude over very short distances. The MC to chlorophyll ratio (MC:chl) varied by a factor up to 5.3 throughout the basin, which creates challenges for using MC:chl to predict MC concentrations. Many of the biomass metrics strongly correlated (r > 0.70) with each other except chlorophyll fluorescence and phycocyanin concentration. While MC and chlorophyll correlated well with total phosphorus and nitrogen concentrations, MC:chl correlated with dissolved inorganic nitrogen. More frequent MC data collection can overcome these issues, and models need to account for the MC:chl spatial heterogeneity when forecasting MCs.
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Affiliation(s)
- Justin D Chaffin
- F.T. Stone Laboratory and Ohio Sea Grant, The Ohio State University, 878 Bayview Ave. P.O. Box 119, Put-In-Bay, OH 43456, USA.
| | | | | | - Halli B Bair
- F.T. Stone Laboratory and Ohio Sea Grant, The Ohio State University, 878 Bayview Ave. P.O. Box 119, Put-In-Bay, OH 43456, USA
| | - Amber A Beecher
- Lake Erie Center, University of Toledo, 6200 Bayshore Rd., Oregon, OH 43616, USA
| | - Caren E Binding
- Environment and Climate Change Canada, Canada Centre for Inland Waters, 867 Lakeshore Road, Burlington, Ontario L7S1A1, Canada
| | - Johnna A Birbeck
- Lumigen Instrument Center, Wayne State University, 5101Cass Ave., Detroit, MI 48202, USA
| | - Thomas B Bridgeman
- Lake Erie Center, University of Toledo, 6200 Bayshore Rd., Oregon, OH 43616, USA
| | - Xuexiu Chang
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Ave., Windsor, Ontario N9B 3P4, Canada; School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, PR China
| | - Jill Crossman
- School of the Environment, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
| | - Warren J S Currie
- Fisheries and Oceans Canada, Canada Centre for Inland Waters, 867 Lakeshore Rd., Burlington, Ontario L7S 1A1, Canada
| | - Timothy W Davis
- Biological Sciences, Bowling Green State University, Life Sciences Building, Bowling Green, OH 43402, United States
| | - Gregory J Dick
- Department of Earth and Environmental Sciences, University of Michigan, 2534 North University Building, 1100 North University Avenue, Ann Arbor, MI 48109-1005, USA
| | - Kenneth G Drouillard
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Ave., Windsor, Ontario N9B 3P4, Canada
| | - Reagan M Errera
- Great Lakes Environmental Research Laboratory, National Oceanic and Atmospheric Administration, Ann Arbor, MI 48108, USA
| | - Thijs Frenken
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Ave., Windsor, Ontario N9B 3P4, Canada
| | - Hugh J MacIsaac
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Ave., Windsor, Ontario N9B 3P4, Canada
| | - Andrew McClure
- Division of Water Treatment, City of Toledo, Toledo, OH 43605, USA
| | - R Michael McKay
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Ave., Windsor, Ontario N9B 3P4, Canada
| | - Laura A Reitz
- Biological Sciences, Bowling Green State University, Life Sciences Building, Bowling Green, OH 43402, United States
| | | | - Keara Stanislawczyk
- F.T. Stone Laboratory and Ohio Sea Grant, The Ohio State University, 878 Bayview Ave. P.O. Box 119, Put-In-Bay, OH 43456, USA
| | - Richard P Stumpf
- National Ocean Service, National Oceanic and Atmospheric Administration, 1305 East West Highway, Silver Spring, MD 20910, USA
| | - Zachary D Swan
- Lake Erie Center, University of Toledo, 6200 Bayshore Rd., Oregon, OH 43616, USA
| | - Brenda K Snyder
- Lake Erie Center, University of Toledo, 6200 Bayshore Rd., Oregon, OH 43616, USA
| | - Judy A Westrick
- Lumigen Instrument Center, Wayne State University, 5101Cass Ave., Detroit, MI 48202, USA
| | - Pengfei Xue
- Civil and Environmental Engineering, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931, USA
| | - Colleen E Yancey
- Department of Earth and Environmental Sciences, University of Michigan, 2534 North University Building, 1100 North University Avenue, Ann Arbor, MI 48109-1005, USA
| | - Arthur Zastepa
- Environment and Climate Change Canada, Canada Centre for Inland Waters, 867 Lakeshore Road, Burlington, Ontario L7S1A1, Canada
| | - Xing Zhou
- Civil and Environmental Engineering, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931, USA
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16
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Salter C, VanMensel D, Reid T, Birbeck J, Westrick J, Mundle SOC, Weisener CG. Investigating the microbial dynamics of microcystin-LR degradation in Lake Erie sand. CHEMOSPHERE 2021; 272:129873. [PMID: 33592515 DOI: 10.1016/j.chemosphere.2021.129873] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 01/27/2021] [Accepted: 02/04/2021] [Indexed: 06/12/2023]
Abstract
Cyanobacterial blooms and the associated hepatotoxins produced (e.g., microcystins, MCs) create a significant human health risk in freshwater lakes around the world, including Lake Erie. Though various physical and chemical treatment options are utilized, these are costly and their effectiveness decreases when other organics are present. Laboratory studies have identified a remediation option based on a mlr gene operon that can systematically degrade this toxin; however, studies on Lake Erie have been unable to amplify mlr genes from MC-degrading bacteria. These results suggest that either existing primers may be inefficient for broad identification of the mlr genes or that MC degradation genes and/or pathways may vary among bacterial taxa. To investigate the dynamics of the Lake Erie microbial community involved in the degradation of microcystin-LR (MC-LR), a flow-through column experiment using collected beach sand was conducted over a period of six weeks. Increasing concentrations of lake water spiked with MC-LR were continuously delivered to both biotic and abiotic (sterilized) sand columns, with influent and effluent MC-LR concentrations measured by LC-MS/MS. Despite the toxin concentrations far exceeding natural conditions during a bloom event (maximum dosage = 15.4 μg/L), MC-LR was completely removed within 21 h of contact time in the biotic columns. Stimulation of community taxa during the degradation process included Burkholderiaceae, Illumatobacteraceae, Pseudomonadaceae, Rhodocyclaceae and Nitrosomonadaceae. The overall results suggest several critical species may be required for the most complete and effective degradation of MC-LR.
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Affiliation(s)
- Chelsea Salter
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
| | - Danielle VanMensel
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
| | - Thomas Reid
- Environment and Climate Change Canada, 867 Lakeshore Road, Burlington, ON, L7R 1A1, Canada
| | - Johnna Birbeck
- Lumigen Instrument Center, Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - Judy Westrick
- Lumigen Instrument Center, Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - Scott O C Mundle
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
| | - Christopher G Weisener
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada.
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17
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Zeng YH, Cheng KK, Cai ZH, Zhu JM, Du XP, Wang Y, Zhou J. Transcriptome analysis expands the potential roles of quorum sensing in biodegradation and physiological responses to microcystin. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 771:145437. [PMID: 33736182 DOI: 10.1016/j.scitotenv.2021.145437] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/08/2021] [Accepted: 01/22/2021] [Indexed: 06/12/2023]
Abstract
Bacterial degradation is one of the most efficient ways to remove microcystins (MCs), the most frequently detected toxin in cyanobacterial blooms. Using Novosphingobium sp. ERW19 as a representative strain, our laboratory previously demonstrated that quorum sensing (QS), the cell density-dependent gene regulation system, positively regulates biodegradation of MCs via transcriptional activation of mlr-pathway-associated genes. Increasing evidence indicates that QS is involved in a wide spectrum of regulatory circuits, but it remains unclear which physiological processes in MC degradation besides the expression of MC-degrading genes are also subject to QS-dependent regulation. This study used transcriptome analysis to identify QS-regulated genes during degradation of MCs. A large percentage (up to 32.6%) of the genome of the MC-degrading bacterial strain Novosphingobium sp. ERW19 was significantly differentially expressed in the corresponding QS mutants. Pathway enrichment analysis of QS-regulated genes revealed that QS mainly influenced metabolism-associated pathways, particularly those related to amino acid metabolism, carbohydrate metabolism, and biodegradation and metabolism of xenobiotics. In-depth functional interpretation of QS-regulated genes indicated a variety of pathways were potentially associated with bacterial degradation or physiological responses to MCs, including genes involved in cell motility, cytochrome P450-dependent metabolism of xenobiotics, glutathione S-transferase (GST), envelope stress response, and ribosomes. Furthermore, QS may be involved in regulating the initial and final steps of the catabolic pathway of phenylacetic acid, an intermediate product of MC degradation. Collectively, this global survey of QS-regulated genes in a MC-degrading bacterial strain facilitates a deeper understanding of QS-controlled processes that may be important for bacterial degradation of MCs or may contribute to the physiological responses of bacteria to MCs.
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Affiliation(s)
- Yan-Hua Zeng
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, PR China; Institute for Ocean Engineering, Tsinghua University, Beijing 100084, PR China
| | - Ke-Ke Cheng
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, PR China; Institute for Ocean Engineering, Tsinghua University, Beijing 100084, PR China
| | - Zhong-Hua Cai
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, PR China; Institute for Ocean Engineering, Tsinghua University, Beijing 100084, PR China
| | - Jian-Ming Zhu
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, PR China
| | - Xiao-Peng Du
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, PR China
| | - Yan Wang
- Shenzhen Polytechnic, Shenzhen 518055, PR China.
| | - Jin Zhou
- Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, PR China; Institute for Ocean Engineering, Tsinghua University, Beijing 100084, PR China.
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18
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Anam GB, Guda DR, Ahn YH. Hormones induce the metabolic growth and cytotoxin production of Microcystis aeruginosa under terpinolene stress. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 769:145083. [PMID: 33736237 DOI: 10.1016/j.scitotenv.2021.145083] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/23/2020] [Accepted: 01/05/2021] [Indexed: 06/12/2023]
Abstract
Several organic compounds released into the aquatic environment have a detrimental impact on humans and other organisms. There is a lack of knowledge about natural hormones and herbicides on non-target organisms, including cyanobacteria. In this study, the response of Microcystis aeruginosa to four phytohormones, indole-3-acetic acid (IAA; 10-5), zeatin (ZT; 10-5), abscisic acid (ABA; 10-7), and brassinolide (BRL; 10-9 mol/L), exposed to terpinolene (TPN; (0.44, 0.88, 1.17, or 1.62 mmol/L) at the cellular and genetic levels were investigated. The results showed that TPN could inhibit the growth and photosynthetic activities and stimulate microcystins (MCs) of M. aeruginosa at various levels through the co-occurrence of oxidative stress, antioxidant defense activities, and an imbalance of the antioxidative system. Hormones played critical roles in the growth promotion and photosynthetic activity by enhancing the antioxidant defense mechanisms and MCs production of M. aeruginosa under TPN stress in both hormone and TPN dose-dependent manner. The growth performance and photosynthetic activities of M. aeruginosa were significant with IAA (p < 0.01) and BSL (p < 0.05) compared to ZT and ABA, as TPN concentrations increased. Hormones stimulated the MCs production significantly BSL (p < 0.05) at various levels and protected the cells against TPN-induced oxidative stress and expression of mcyB and mcyD genes involve in MCs synthesis. Our results indicated that hormone contamination in eutrophic lakes might increase the risk of Microcystis aeruginosa bloom and microcystin production with the TPN association.
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Affiliation(s)
- Giridhar Babu Anam
- Department of Civil Engineering, Yeungnam University, Gyeongsan 38541, Gyeongbuk, Republic of Korea
| | - Dinneswara Reddy Guda
- Korea Center for Artificial Photosynthesis and Center for Nanomaterial, Sogang University, Seoul 121-742, Republic of Korea
| | - Young-Ho Ahn
- Department of Civil Engineering, Yeungnam University, Gyeongsan 38541, Gyeongbuk, Republic of Korea.
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19
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Dexter J, McCormick AJ, Fu P, Dziga D. Microcystinase - a review of the natural occurrence, heterologous expression, and biotechnological application of MlrA. WATER RESEARCH 2021; 189:116646. [PMID: 33246218 DOI: 10.1016/j.watres.2020.116646] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 11/01/2020] [Accepted: 11/14/2020] [Indexed: 06/11/2023]
Abstract
Microcystinase (MlrA) was first described in 1996. Since then MlrA peptidase activity has proven to be both the most efficient enzymatic process and the most specific catalyst of all known microcystins detoxification pathways. Furthermore, MlrA and the MlrABC degradation pathway are presently the only enzymatic processes with clear genetic and biochemical descriptions available for microcystins degradation, greatly facilitating modern applied genetics for any relevant technological development. Recently, there has been increasing interest in the potential of sustainable, biologically inspired alternatives to current industrial practice, with note that biological microcystins degradation is the primary detoxification process found in nature. While previous reviews have broadly discussed microbial biodegradation processes, here we present a review focused specifically on MlrA. Following a general overview, we briefly highlight the initial discovery and present understanding of the MlrABC degradation pathway, before discussing the genetic and biochemical aspects of MlrA. We then review the potential biotechnology applications of MlrA in the context of available literature with emphasis on the optimization of MlrA for in situ applications including (i) direct modulation of Mlr activity within naturally existing populations, (ii) bioaugmentation of systems with introduced biodegradative capacity via whole cell biocatalysts, and (iii) bioremediation via direct MlrA application.
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Affiliation(s)
- Jason Dexter
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 31-007 Kraków, Poland; Cyanoworks, LLC, 1771 Haskell Rd., Olean, NY 14760, USA.
| | - Alistair J McCormick
- SynthSys & Institute of Molecular Plant Sciences, School of Biological Sciences, King's Buildings, University of Edinburgh, EH9 3BF, UK.
| | - Pengcheng Fu
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, 58 Renmin Avenue, Meilan District, Haikou, Hainan Province, 570228 China.
| | - Dariusz Dziga
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 31-007 Kraków, Poland.
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