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Wei J, Luo J, Peng T, Zhou P, Zhang J, Yang F. Comparative genomic analysis and functional investigations for MCs catabolism mechanisms and evolutionary dynamics of MCs-degrading bacteria in ecology. ENVIRONMENTAL RESEARCH 2024; 248:118336. [PMID: 38295970 DOI: 10.1016/j.envres.2024.118336] [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: 08/21/2023] [Revised: 01/06/2024] [Accepted: 01/27/2024] [Indexed: 02/07/2024]
Abstract
Microcystins (MCs) significantly threaten the ecosystem and public health. Biodegradation has emerged as a promising technology for removing MCs. Many MCs-degrading bacteria have been identified, including an indigenous bacterium Sphingopyxis sp. YF1 that could degrade MC-LR and Adda completely. Herein, we gained insight into the MCs biodegradation mechanisms and evolutionary dynamics of MCs-degrading bacteria, and revealed the toxic risks of the MCs degradation products. The biochemical characteristics and genetic repertoires of strain YF1 were explored. A comparative genomic analysis was performed on strain YF1 and six other MCs-degrading bacteria to investigate their functions. The degradation products were investigated, and the toxicity of the intermediates was analyzed through rigorous theoretical calculation. Strain YF1 might be a novel species that exhibited versatile substrate utilization capabilities. Many common genes and metabolic pathways were identified, shedding light on shared functions and catabolism in the MCs-degrading bacteria. The crucial genes involved in MCs catabolism mechanisms, including mlr and paa gene clusters, were identified successfully. These functional genes might experience horizontal gene transfer events, suggesting the evolutionary dynamics of these MCs-degrading bacteria in ecology. Moreover, the degradation products for MCs and Adda were summarized, and we found most of the intermediates exhibited lower toxicity to different organisms than the parent compound. These findings systematically revealed the MCs catabolism mechanisms and evolutionary dynamics of MCs-degrading bacteria. Consequently, this research contributed to the advancement of green biodegradation technology in aquatic ecology, which might protect human health from MCs.
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Affiliation(s)
- Jia Wei
- Xiangya School of Public Health, Central South University, Changsha, Hunan, 410078, China
| | - Jiayou Luo
- Xiangya School of Public Health, Central South University, Changsha, Hunan, 410078, China.
| | - Tangjian Peng
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang, Hunan, 421001, China
| | - Pengji Zhou
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang, Hunan, 421001, China
| | - Jiajia Zhang
- Xiangya School of Public Health, Central South University, Changsha, Hunan, 410078, China
| | - Fei Yang
- Xiangya School of Public Health, Central South University, Changsha, Hunan, 410078, China; Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang, Hunan, 421001, China.
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2
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Yang S, Zuo J, Grossart HP, Dai G, Liu J, Song L, Gan N. Evaluating microcystinase A-based approach on microcystins degradation during harvested cyanobacterial blooms. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 348:123878. [PMID: 38548158 DOI: 10.1016/j.envpol.2024.123878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 03/21/2024] [Accepted: 03/25/2024] [Indexed: 04/07/2024]
Abstract
Addressing notorious and worldwide Microcystis blooms, mechanical algae harvesting is an effective emergency technology for bloom mitigation and removal of nutrient loads in waterbodies. However, the absence of effective methods for removal of cyanobacterial toxins, e.g., microcystins (MCs), poses a challenge to recycle the harvested Microcystis biomass. In this study, we therefore introduced a novel approach, the "captured biomass-MlrA enzymatic MC degradation", by enriching microcystinase A (MlrA) via fermentation and spraying it onto salvaged Microcystis slurry to degrade all MCs. After storing the harvested Microcystis slurry, a rapid release of extracellular MCs occurred within the initial 8 h, reaching a peak concentration of 5.33 μg/mL at 48 h during the composting process. Upon spraying the recombinant MlrA crude extract (about 3.36 U) onto the Microcystis slurry in a ratio of 0.1% (v/v), over 95% of total MCs were degraded within a 24-h period. Importantly, we evaluated the reliability and safety of using MlrA extracts to degrade MCs. Results showed that organic matter/nutrient contents, e.g. soluble proteins, polysaccharides, phycocyanin and carotenoids, were not significantly altered. Furthermore, the addition of MlrA extracts did not significantly change the bacterial community composition and diversity in the Microcystis slurry, indicating that the MlrA extracts did not increase the risk of pathogenic bacteria. Our study provides an effective and promising method for the pre-treatment of harvested Microcystis biomass, highlighting an ecologically sustainable framework for addressing Microcystis blooms.
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Affiliation(s)
- Siyu Yang
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China; University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Jun Zuo
- National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution, Zhejiang Provincial Key Lab for Water Environment and Marine Biological Resources Protection, Institute for Eco-Environmental Research of Sanyang Wetland, Wenzhou University, Wenzhou, 325035, China.
| | - Hans-Peter Grossart
- Department of Plankton and Microbial Ecology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries IGB, Stechlin, Germany; Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Guofei Dai
- Jiangxi Academy of Water Science and Engineering, Nanchang, 330029, China
| | - Jin Liu
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Lirong Song
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Nanqin Gan
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
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3
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Redouane EM, Núñez A, Achouak W, Barakat M, Alex A, Martins JC, Tazart Z, Mugani R, Zerrifi SEA, Haida M, García AM, Campos A, Lahrouni M, Oufdou K, Vasconcelos V, Oudra B. Microcystin influence on soil-plant microbiota: Unraveling microbiota modulations and assembly processes in the rhizosphere of Vicia faba. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170634. [PMID: 38325456 DOI: 10.1016/j.scitotenv.2024.170634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 02/09/2024]
Abstract
Microcystins (MCs) are frequently detected in cyanobacterial bloom-impacted waterbodies and introduced into agroecosystems via irrigation water. They are widely known as phytotoxic cyanotoxins, which impair the growth and physiological functions of crop plants. However, their impact on the plant-associated microbiota is scarcely tackled and poorly understood. Therefore, we aimed to investigate the effect of MCs on microbiota-inhabiting bulk soil (BS), root adhering soil (RAS), and root tissue (RT) of Vicia faba when exposed to 100 μg L-1 MCs in a greenhouse pot experiment. Under MC exposure, the structure, co-occurrence network, and assembly processes of the bacterial microbiota were modulated with the greatest impact on RT-inhabiting bacteria, followed by BS and, to a lesser extent, RAS. The analyses revealed a significant decrease in the abundances of several Actinobacteriota-related taxa within the RT microbiota, including the most abundant and known genus of Streptomyces. Furthermore, MCs significantly increased the abundance of methylotrophic bacteria (Methylobacillus, Methylotenera) and other Proteobacteria-affiliated genera (e.g., Paucibacter), which are supposed to degrade MCs. The co-occurrence network of the bacterial community in the presence of MCs was less complex than the control network. In MC-exposed RT, the turnover in community composition was more strongly driven by deterministic processes, as proven by the beta-nearest taxon index. Whereas in MC-treated BS and RAS, both deterministic and stochastic processes can influence community assembly to some extent, with a relative dominance of deterministic processes. Altogether, these results suggest that MCs may reshape the structure of the microbiota in the soil-plant system by reducing bacterial taxa with potential phytobeneficial traits and increasing other taxa with the potential capacity to degrade MCs.
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Affiliation(s)
- El Mahdi Redouane
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech 40000, Morocco; CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Terminal de Cruzeiros do Porto de Leixões, Matosinhos 4450-208, Portugal
| | - Andrés Núñez
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid (ETSII-UPM), Madrid 28006, Spain; Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Campus de Espinardo, Murcia 30100, Spain
| | - Wafa Achouak
- Aix Marseille University, CEA, CNRS, BIAM, Lab of Microbial Ecology of the Rhizosphere, (LEMiRE), Saint Paul Lez Durance 13115, France.
| | - Mohamed Barakat
- Aix Marseille University, CEA, CNRS, BIAM, Lab of Microbial Ecology of the Rhizosphere, (LEMiRE), Saint Paul Lez Durance 13115, France
| | - Anoop Alex
- CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Terminal de Cruzeiros do Porto de Leixões, Matosinhos 4450-208, Portugal; Department of Biology, Faculty of Sciences, University of Porto, Porto 4169-007, Portugal
| | - José Carlos Martins
- CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Terminal de Cruzeiros do Porto de Leixões, Matosinhos 4450-208, Portugal
| | - Zakaria Tazart
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech 40000, Morocco; AgroBioSciences, Plant Stress Physiology Laboratory, Mohammed VI Polytechnic University, Benguerir 43150, Morocco
| | - Richard Mugani
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech 40000, Morocco
| | - Soukaina El Amrani Zerrifi
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech 40000, Morocco; Higher Institute of Nurses Professions and Health Techniques of Guelmim, Guelmim 81000, Morocco
| | - Mohammed Haida
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech 40000, Morocco
| | - Ana M García
- Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid (ETSII-UPM), Madrid 28006, Spain
| | - Alexandre Campos
- CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Terminal de Cruzeiros do Porto de Leixões, Matosinhos 4450-208, Portugal
| | - Majida Lahrouni
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech 40000, Morocco
| | - Khalid Oufdou
- Laboratory of Microbial Biotechnologies, Agrosciences, and Environment (BioMAgE), Labeled Research Unit-CNRST N°4, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech 40000, Morocco
| | - Vitor Vasconcelos
- CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, Terminal de Cruzeiros do Porto de Leixões, Matosinhos 4450-208, Portugal; Department of Biology, Faculty of Sciences, University of Porto, Porto 4169-007, Portugal
| | - Brahim Oudra
- Water, Biodiversity and Climate Change Laboratory, Faculty of Sciences Semlalia, Cadi Ayyad University, Marrakech 40000, Morocco
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Kim W, Park Y, Jung J, Jeon CO, Toyofuku M, Lee J, Park W. Biological and Chemical Approaches for Controlling Harmful Microcystis Blooms. J Microbiol 2024; 62:249-260. [PMID: 38587591 DOI: 10.1007/s12275-024-00115-2] [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: 12/26/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 04/09/2024]
Abstract
The proliferation of harmful cyanobacterial blooms dominated by Microcystis aeruginosa has become an increasingly serious problem in freshwater ecosystems due to climate change and eutrophication. Microcystis-blooms in freshwater generate compounds with unpleasant odors, reduce the levels of dissolved O2, and excrete microcystins into aquatic ecosystems, potentially harming various organisms, including humans. Various chemical and biological approaches have thus been developed to mitigate the impact of the blooms, though issues such as secondary pollution and high economic costs have not been adequately addressed. Red clays and H2O2 are conventional treatment methods that have been employed worldwide for the mitigation of the blooms, while novel approaches, such as the use of plant or microbial metabolites and antagonistic bacteria, have also recently been proposed. Many of these methods rely on the generation of reactive oxygen species, the inhibition of photosynthesis, and/or the disruption of cellular membranes as their mechanisms of action, which may also negatively impact other freshwater microbiota. Nevertheless, the underlying molecular mechanisms of anticyanobacterial chemicals and antagonistic bacteria remain unclear. This review thus discusses both conventional and innovative approaches for the management of M. aeruginosa in freshwater bodies.
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Affiliation(s)
- Wonjae Kim
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Yerim Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Jaejoon Jung
- Department of Life Science, Chung-Ang University, Seoul, 02841, Republic of Korea
| | - Che Ok Jeon
- Department of Life Science, Chung-Ang University, Seoul, 02841, Republic of Korea
| | - Masanori Toyofuku
- Department of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-0006, Japan
| | - Jiyoung Lee
- Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, OH, 43210, USA
- Department of Food Science and Technology, The Ohio State University, Columbus, OH, 43210, USA
| | - Woojun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea.
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5
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Zhang L, Tang S, Jiang S. Immobilization of Microcystin by the Hydrogel-Biochar Composite to Enhance Biodegradation during Drinking Water Treatment. ACS ES&T WATER 2023; 3:3044-3056. [PMID: 37705994 PMCID: PMC10496130 DOI: 10.1021/acsestwater.3c00240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 08/17/2023] [Accepted: 08/18/2023] [Indexed: 09/15/2023]
Abstract
Microcystin-LR (MC-LR), the most common algal toxin in freshwater, poses an escalating threat to safe drinking water. This study aims to develop an engineered biofiltration system for water treatment, employing a composite of poly(diallyldimethylammonium chloride)-biochar (PDDA-BC) as a filtration medium. The objective is to capture MC-LR selectively and quickly from water, enabling subsequent biodegradation of toxin by bacteria embedded on the composite. The results showed that PDDA-BC exhibited a high selectivity in adsorbing MC-LR, even in the presence of competing natural organic matter and anions. The adsorption kinetics of MC-LR was faster, and capacity was greater compared to traditional adsorbents, achieving a capture rate of 98% for MC-LR (200 μg/L) within minutes to tens of minutes. Notably, the efficient adsorption of MC-LR was also observed in natural lake waters, underscoring the substantial potential of PDDA-BC for immobilizing MC-LR during biofiltration. Density functional theory calculations revealed that the synergetic effects of electrostatic interaction and π-π stacking predominantly contribute to the adsorption selectivity of MC-LR. Furthermore, experimental results validated that the combination of PDDA-BC with MC-degrading bacteria offered a promising and effective approach to achieve a sustainable removal of MC-LR through an "adsorption-biodegradation" process.
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Affiliation(s)
- Lixun Zhang
- Department of Civil and Environmental
Engineering, University of California, Irvine, California 92697, United States
| | - Shengyin Tang
- Department of Civil and Environmental
Engineering, University of California, Irvine, California 92697, United States
| | - Sunny Jiang
- Department of Civil and Environmental
Engineering, University of California, Irvine, California 92697, United States
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6
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Gu P, Wang Y, Wu H, Chen L, Zhang Z, Yang K, Zhang Z, Ren X, Miao H, Zheng Z. Efficient control of cyanobacterial blooms with calcium peroxide: Threshold and mechanism. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 882:163591. [PMID: 37087006 DOI: 10.1016/j.scitotenv.2023.163591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 04/10/2023] [Accepted: 04/15/2023] [Indexed: 05/03/2023]
Abstract
This study explored the feasibility and mechanism of cyanobacterial blooms control by calcium peroxide (CaO2). The obtained results demonstrated a strong inhibitory effect of CaO2 on cyanobacterial growth. The removal chlorophyll-a rate reached 31.4 %, while optimal/maximal quantum yield of PSII (Fv/Fm) decreased to 50 % after CaO2 treatment at a concentration of 100 mg L-1 for 96 h. Two main mechanisms were involved in the treatment of cyanobacterial bloom with CaO2, namely oxidative damage and cyanobacterial colony formation. It was found that CaO2 released reactive oxygen species (ROS), namely hydroxyl radicals (·OH), singlet oxygen (1O2), and superoxide radicals (·O2-), inhibiting the activity of antioxidant enzymes in cyanobacterial cells and resulting in intracellular oxidation imbalance. Cyanobacteria can resist oxidative damage by releasing extracellular polymeric substances (EPS). These EPS can combine with CaO2-derived Ca, forming large cyanobacterial aggregates and, consequently, accelerating cell sedimentation. In addition, CaO2 caused programmed cell death (PCD) of cyanobacteria and irreversible damage to the ultrastructure characteristic of the cyanobacterial cells. The apoptotic rate was greatly improved at 100 mg L-1 CaO2. On the other hand, the results obtained using qRT-PCR analysis confirmed the contribution of CaO2 to the down-regulation of photosynthesis-related genes (rbcL and psaB), the up-regulation of microcystins (mcyA and mcyD), the up-regulation of the oxidation system: peroxiredoxin (prx) through oxidative mechanisms. The present study proposes a novel treatment method for water-containing cyanobacterial blooms using CaO2.
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Affiliation(s)
- Peng Gu
- School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China; Taihu Water Environment Research Center, Changzhou 213169, PR China
| | - Yuting Wang
- School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China
| | - Hanqi Wu
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, PR China; Taihu Water Environment Research Center, Changzhou 213169, PR China
| | - Liqi Chen
- School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China
| | - Zhaochang Zhang
- School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China
| | - Kunlun Yang
- School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China
| | - Zengshuai Zhang
- School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China
| | - Xueli Ren
- School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China
| | - Hengfeng Miao
- School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China; Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment, Suzhou University of Science and Technology, Suzhou 215009, PR China.
| | - Zheng Zheng
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, PR China; Taihu Water Environment Research Center, Changzhou 213169, PR China
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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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Guo X, Li Z, Jiang Q, Cheng C, Feng Y, He Y, Zuo L, Rao L, Ding W, Feng L. Structural insight into the substrate-binding mode and catalytic mechanism for MlrC enzyme of Sphingomonas sp. ACM-3962 in linearized microcystin biodegradation. Front Microbiol 2023; 14:1057264. [PMID: 36876080 PMCID: PMC9982164 DOI: 10.3389/fmicb.2023.1057264] [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: 09/29/2022] [Accepted: 01/24/2023] [Indexed: 02/19/2023] Open
Abstract
Removing microcystins (MCs) safely and effectively has become an urgent global problem because of their extremely hazardous to the environment and public health. Microcystinases derived from indigenous microorganisms have received widespread attention due to their specific MC biodegradation function. However, linearized MCs are also very toxic and need to be removed from the water environment. How MlrC binds to linearized MCs and how it catalyzes the degradation process based on the actual three-dimensional structure have not been determined. In this study, the binding mode of MlrC with linearized MCs was explored using a combination of molecular docking and site-directed mutagenesis methods. A series of key substrate binding residues, including E70, W59, F67, F96, S392 and so on, were identified. Sodium dodecane sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to analyze samples of these variants. The activity of MlrC variants were measured using high performance liquid chromatography (HPLC). We used fluorescence spectroscopy experiments to research the relationship between MlrC enzyme (E), zinc ion (M), and substrate (S). The results showed that MlrC enzyme, zinc ion and substrate formed E-M-S intermediates during the catalytic process. The substrate-binding cavity was made up of N and C-terminal domains and the substrate-binding site mainly included N41, E70, D341, S392, Q468, S485, R492, W59, F67, and F96. The E70 residue involved in both substrate catalysis and substrate binding. In conclusion, a possible catalytic mechanism of the MlrC enzyme was further proposed based on the experimental results and a literature survey. These findings provided new insights into the molecular mechanisms of the MlrC enzyme to degrade linearized MCs, and laid a theoretical foundation for further biodegradation studies of MCs.
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Affiliation(s)
- Xiaoliang Guo
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, China
| | - Zengru Li
- The Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Qinqin Jiang
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, China
| | - Cai Cheng
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, China
| | - Yu Feng
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, China
| | - Yanlin He
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, China
| | - Lingzi Zuo
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, China
| | - Li Rao
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, China
| | - Wei Ding
- The Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Lingling Feng
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, China
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9
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Zou Q, Teng J, Wang K, Huang Y, Hu Q, Chen S, Xu Q, Zhang H, Fang D, Yan H. Purification and Mechanism of Microcystinase MlrC for Catalyzing Linearized Cyanobacterial Hepatotoxins Using Sphingopyxis sp. USTB-05. Toxins (Basel) 2022; 14:toxins14090602. [PMID: 36136540 PMCID: PMC9506587 DOI: 10.3390/toxins14090602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/11/2022] [Accepted: 08/16/2022] [Indexed: 11/16/2022] Open
Abstract
Cyanobacterial hepatotoxins, including microcystins (MCs) and nodularins (NODs), are widely produced, distributed and extremely hazardous to human beings and the environment. However, the catalytic mechanism of microcystinase for biodegrading cyanobacterial hepatotoxins is not completely understood yet. The first microcystinase (MlrA) catalyzes the ring opening of cyclic hepatotoxins, while being further hydrolyzed by the third microcystinase (MlrC). Based on the homology modeling, we postulated that MlrC of Sphingopyxis sp. USTB-05 was a Zn2+-dependent metalloprotease including five active sites: Glu56, His150, Asp184, His186 and His208. Here, the active recombinant MlrC and five site-directed mutants were successfully obtained with heterologous expression and then purified for investigating the activity. The results indicated that the purified recombinant MlrC had high activity to catalyze linearized hepatotoxins. Combined with the biodegradation of linearized NOD by MlrC and its mutants, a complete enzymatic mechanism for linearized hepatotoxin biodegradation by MlrC was revealed.
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Affiliation(s)
- Qianwen Zou
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Junhui Teng
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Kunyan Wang
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yiming Huang
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Qingbei Hu
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Sisi Chen
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Qianqian Xu
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Haiyang Zhang
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | | | - Hai Yan
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, China
- Correspondence:
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Liu HL, Cheng C, Zuo LZ, Yan MY, He YL, Huang S, Ke MJ, Guo XL, Feng Y, Qian HF, Feng LL. Strain-boosted hyperoxic graphene oxide efficiently loading and improving performances of microcystinase. iScience 2022; 25:104611. [PMID: 35789835 PMCID: PMC9250033 DOI: 10.1016/j.isci.2022.104611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/09/2022] [Accepted: 06/08/2022] [Indexed: 11/02/2022] Open
Abstract
Harmful Microcystis blooms (HMBs) and microcystins (MCs) that are produced by Microcystis seriously threaten water ecosystems and human health. This study demonstrates an eco-friendly strategy for simultaneous removal of MCs and HMBs by adopting unique hyperoxic graphene oxides (HGOs) as carrier and pure microcystinase A (PMlrA) as connecting bridge to form stable HGOs@MlrA composite. After oxidation, HGOs yield inherent structural strain effects for boosting the immobilization of MlrA by material characterization and density functional theory calculations. HGO5 exhibits higher loading capacities for crude MlrA (1,559 mg·g−1) and pure MlrA (1,659 mg·g−1). Moreover, the performances of HGO5@MlrA composite, including the capability of removing MCs and HMBs, the ecological and human safety compared to MlrA or HGO5 treatment alone, have been studied. These results indicate that HGO5 can be used as a promising candidate material to effectively improve the application potential of MlrA in the simultaneous removal of MCs and HMBs. Hyperoxic graphene oxide (HGO5) provides inherent strain effects HGO5 exhibits an impressive loading capacity for MlrA A new assembly mechanism for the HGO5@MlrA composite is proposed HGO5@MlrA composite shows excellent capability and ecological safety
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11
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Le VV, Ko SR, Kang M, Lee SA, Oh HM, Ahn CY. Algicide capacity of Paucibacter aquatile DH15 on Microcystis aeruginosa by attachment and non-attachment effects. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 302:119079. [PMID: 35245623 DOI: 10.1016/j.envpol.2022.119079] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 02/23/2022] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
The excessive proliferation of Microcystis aeruginosa can lead to ecological damage, economic losses, and threaten animal and human health. For controlling Microcystis blooms, microorganism-based methods have attracted much attention from researchers because of their eco-friendliness and species-specificity. Herein, we first found that a Paucibacter strain exhibits algicidal activity against M. aeruginosa and microcystin degradation capability. The algicidal activity of DH15 (2.1 × 104 CFU/ml) against M. aeruginosa (2 × 106 cells/ml) was 94.9% within 36 h of exposure. DH15 also degraded microcystin (1.6 mg/L) up to 62.5% after 72 h. We demonstrated that the algicidal activity of DH15 against M. aeruginosa can be mediated by physical attachment and indirect attack: (1) Both washed cells and cell-free supernatant could kill M. aeruginosa efficiently; (2) Treatment with DH15 cell-free supernatants caused oxidative stress, altered the fatty acid profile, and damaged photosynthetic system, carbohydrate, and protein metabolism in M. aeruginosa. The combination of direct and indirect attacks supported that strain DH15 exerts high algicidal activity against M. aeruginosa. The expression of most key genes responsible for photosynthesis, antioxidant activity, microcystin synthesis, and other metabolic pathways in M. aeruginosa was downregulated. Strain DH15, with its microcystin degradation capacity, can overcome the trade-off between controlling Microcystis blooms and increasing microcystin concentration. Our findings suggest that strain DH15 possesses great potential to control outbreaks of Microcystis blooms.
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Affiliation(s)
- Ve Van Le
- Cell Factory Research Centre, Korea Research Institute of Bioscience & Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea; Department of Environmental Biotechnology, KRIBB School of Biotechnology, University of Science and Technology, Daejeon, 34113, Republic of Korea
| | - So-Ra Ko
- Cell Factory Research Centre, Korea Research Institute of Bioscience & Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Mingyeong Kang
- Cell Factory Research Centre, Korea Research Institute of Bioscience & Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea; Department of Environmental Biotechnology, KRIBB School of Biotechnology, University of Science and Technology, Daejeon, 34113, Republic of Korea
| | - Sang-Ah Lee
- Cell Factory Research Centre, Korea Research Institute of Bioscience & Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea; Department of Environmental Biotechnology, KRIBB School of Biotechnology, University of Science and Technology, Daejeon, 34113, Republic of Korea
| | - Hee-Mock Oh
- Cell Factory Research Centre, Korea Research Institute of Bioscience & Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea; Department of Environmental Biotechnology, KRIBB School of Biotechnology, University of Science and Technology, Daejeon, 34113, Republic of Korea
| | - Chi-Yong Ahn
- Cell Factory Research Centre, Korea Research Institute of Bioscience & Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea; Department of Environmental Biotechnology, KRIBB School of Biotechnology, University of Science and Technology, Daejeon, 34113, Republic of Korea.
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12
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Genomic Analysis of Sphingopyxis sp. USTB-05 for Biodegrading Cyanobacterial Hepatotoxins. Toxins (Basel) 2022; 14:toxins14050333. [PMID: 35622580 PMCID: PMC9144602 DOI: 10.3390/toxins14050333] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 04/21/2022] [Accepted: 04/28/2022] [Indexed: 12/04/2022] Open
Abstract
Sphingopyxis sp. USTB-05, which we previously identified and examined, is a well-known bacterial strain for biodegrading cyanobacterial hepatotoxins of both nodularins (NODs) and microcystins (MCs). Although the pathways for biodegrading the different types of [D-Asp1] NOD, MC-YR, MC-LR and MC-RR by Sphingopyxis sp. USTB-05 were suggested, and several biodegradation genes were successfully cloned and expressed, the comprehensive genomic analysis of Sphingopyxis sp. USTB-05 was not reported. Here, based on second and third generation sequencing technology, we analyzed the whole genome of Sphingopyxis sp. USTB-05, which is 4,679,489 bp and contains 4,312 protein coding genes. There are 88 protein-coding genes related to the NODs and MCs biodegradation, of which 16 genes (bioA, hmgL, hypdh, speE, nspC, phy, spuC, murD, glsA, ansA, ocd, crnA, ald, gdhA, murC and murI) are unique. These genes for the transformation of phenylacetic acid CoA (PA-CoA) to CO2 were also found in Sphingopyxis sp. USTB-05. This study expands the understanding of the pathway for complete biodegradation of cyanobacterial hepatotoxins by Sphingopyxis sp. USTB-05.
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13
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Cai D, Wei J, Huang F, Feng H, Peng T, Luo J, Yang F. The detoxification activities and mechanisms of microcystinase towards MC-LR. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 236:113436. [PMID: 35367885 DOI: 10.1016/j.ecoenv.2022.113436] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/13/2022] [Accepted: 03/16/2022] [Indexed: 06/14/2023]
Abstract
Microcystins (MCs) are the most common and toxic cyanotoxins that are hazardous to human health and ecosystems. Microcystinase is the enzyme in charge of the initial step in the biodegradation of MCs. The characterization, application conditions, and detoxification mechanisms of microcystinase from an indigenous bacterium Sphingopyxis sp. YF1 towards MC-LR were investigated in the current study. The microcystinase gene of strain YF1 was most similar to Sphingomonas sp. USTB-05 and contained a CAAX-family conversed abortive Infection (ABI) domain. The microcystinase was successful obtained and purified by overexpression in Escherichia coli. The highest degradation rate of MC-LR was 1.0 μg/mL/min under the optimal condition of 30 ℃, pH 7, 20 μg/mL MC-LR, and 400 μg/mL microcystinase. The MC-degrading product was identified as linearized MC-LR, which possessed a much lower inhibitory activity against protein phosphatase 2A than MC-LR. Microcystinase interacted with MC-LR via amino acid residues involved in through the formation of conventional Hydrogen Bond, Pi-Pi T-shapes, Van der Waals force, and so on. The optimal MC-degrading condition of pure microcystinase and its detoxification mechanisms against MC-LR were revealed. The toxicity of purified linearized MC-LR was explored for the first time. These findings suggest that pure microcystinase may efficiently detoxify MCs and it is promising in the bioremediation of MC-polluted environments.
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Affiliation(s)
- Danping Cai
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang, China.
| | - Jia Wei
- Xiangya School of Public Health, Central South University, Changsha, China.
| | - Feiyu Huang
- The First People's Hospital of Jingzhou, Jingzhou, China.
| | - Hai Feng
- Xiangya School of Public Health, Central South University, Changsha, China.
| | - Tangjian Peng
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang, China.
| | - Jiayou Luo
- Xiangya School of Public Health, Central South University, Changsha, China.
| | - Fei Yang
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang, China; Xiangya School of Public Health, Central South University, Changsha, China.
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14
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Fionah A, Hackett C, Aljewari H, Brady L, Alqhtani F, Escobar IC, Thompson AK. Microcystin-LR Removal from Water via Enzymatic Linearization and Ultrafiltration. Toxins (Basel) 2022; 14:toxins14040231. [PMID: 35448840 PMCID: PMC9024530 DOI: 10.3390/toxins14040231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 03/14/2022] [Accepted: 03/18/2022] [Indexed: 02/05/2023] Open
Abstract
Microcystin-LR (MC-LR) is a toxin produced by cyanobacteria that can bloom in freshwater supplies. This study describes a new strategy for remediation of MC-LR that combines linearization of the toxin using microcystinase A, MlrA, enzyme with rejection of linearized byproducts using membrane filtration. The MlrA enzyme was expressed in Escherichia coli (E. coli) and purified via a His-tag with 95% purity. Additionally, composite membranes made of 95% polysulfone and 5% sulfonated polyether ether ketone (SPEEK) were fabricated and used to filter a solution containing cyclic and linearized MC-LR. Tests were also performed to measure the adsorption and desorption of MC-LR on polysulfone/SPEEK membranes. Liquid chromatography-mass spectrometry (LC-MS) was used to characterize the progress of linearization and removal of MC-LR. Results indicate that the MlrA was successful at linearizing MC-LR. Membrane filtration tests showed rejection of 97% of cyclic MC-LR and virtually all linearized MC-LR, with adsorption to the membranes being the main rejection mechanism. Adsorption/desorption tests indicated that methanol could be used to strip residual MC-LR from membranes to regenerate them. This study demonstrates a novel strategy of remediation of microcystin-tainted water, combining linearization of MC-LR to a low-toxicity byproduct along with removal by membrane filtration.
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Affiliation(s)
- Abelline Fionah
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA;
| | - Cannon Hackett
- Ralph E. Martin Department of Chemical Engineering, University of Arkansas, Fayetteville, AR 72701, USA; (C.H.); (H.A.); (F.A.)
| | - Hazim Aljewari
- Ralph E. Martin Department of Chemical Engineering, University of Arkansas, Fayetteville, AR 72701, USA; (C.H.); (H.A.); (F.A.)
| | - Laura Brady
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA; (L.B.); (I.C.E.)
| | - Faisal Alqhtani
- Ralph E. Martin Department of Chemical Engineering, University of Arkansas, Fayetteville, AR 72701, USA; (C.H.); (H.A.); (F.A.)
| | - Isabel C. Escobar
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA; (L.B.); (I.C.E.)
| | - Audie K. Thompson
- Ralph E. Martin Department of Chemical Engineering, University of Arkansas, Fayetteville, AR 72701, USA; (C.H.); (H.A.); (F.A.)
- Correspondence:
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15
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Ding Q, Song X, Yuan M, Sun R, Zhang J, Yin L, Pu Y. Multiple pathways for the anaerobic biodegradation of microcystin-LR in the enriched microbial communities from Lake Taihu. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 297:118787. [PMID: 34995687 DOI: 10.1016/j.envpol.2022.118787] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/28/2021] [Accepted: 12/31/2021] [Indexed: 06/14/2023]
Abstract
Anaerobic biodegradation is a non-negligible elimination approach for microcystin (MC) pollution and exhibits important bioremediation potential for environmental problems. However, the specific anaerobic MC-degrading mechanism remains unclear and few functional bacteria have been found. In this study, three microbial communities of sludges from different locations in Lake Taihu were collected and further enriched by microcystin-LR (MC-LR) under anaerobic conditions. MC-LR (1 mg/L) could be completely degraded by these enriched microbial communities under anaerobic conditions, but their degradation rates were significantly different. In addition, two different ring-opening sites of MC-LR in Ala-Leu and Arg-Adda were observed, and three new anaerobic degradation products were first identified, including two hexapeptides (MeAsp-Arg-Adda-Glu-Mdha-Ala and Adda-Glu-Mdha-Ala-Leu-MeAsp) and one end-product pentapeptide (Glu-Mdha-Ala-Leu-MeAsp). Based on the chemical structures and temporal trends of all detected degradation products, two novel anaerobic biodegradation pathways of MC-LR were proposed. Moreover, the MC-degrading genes mlrABC were not detected among all microbial communities, which suggested that some new MC-degrading mechanisms might exist under anaerobic conditions. Finally, through the comparison of microbial community structure, Gemmatimonas and Smithella were deduced as possible anaerobic MC-degrading bacteria. These findings strongly indicate that anaerobic biodegradation is an important method of self-repair in the natural environment and provides a potential removal strategy for MC pollution.
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Affiliation(s)
- Qin Ding
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, China
| | - Xiaolei Song
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, China
| | - Mengxuan Yuan
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, China
| | - Rongli Sun
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, China
| | - Juan Zhang
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, China
| | - Lihong Yin
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, China
| | - Yuepu Pu
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, China.
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16
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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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17
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Liu BL, Li YW, Tu XY, Yu PF, Xiang L, Zhao HM, Feng NX, Li H, Cai QY, Mo CH, Wong MH. Variant-Specific Adsorption, Desorption, and Dissipation of Microcystin Toxins in Surface Soil. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:11825-11834. [PMID: 34582220 DOI: 10.1021/acs.jafc.1c03918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Microcystins (MCs) are hepatotoxic heptapeptides identified in cyanobacterial bloom-impacted waters and soils. However, their environmental fate in soils is poorly understood, preventing reliable site assessment. This study aims to clarify the variant-specific adsorption, desorption, and dissipation of MC-LR and MC-RR in agricultural soils. Results revealed that their adsorption isotherms followed the Freundlich model (R2 ≥ 0.96), exhibiting a higher nonlinear trend and lower adsorption capacity for MC-LR than for MC-RR. The soils had low desorption rates of 8.14-21.06% and 3.06-34.04%, respectively, following a 24 h desorption cycle. Pairwise comparison indicated that soil pH and clay played key roles in MC-LR adsorption and desorption, while organic matter and cation exchange capacity played key roles in those of MC-RR. MC-LR dissipation half-lives in soils were 27.18-42.52 days, compared with 35.19-43.87 days for MC-RR. Specifically, an appreciable decrease in MC concentration in sterile soils suggested the significant role of abiotic degradation. This study demonstrates that the minor structural changes in MCs might have major effects on their environmental fates in agricultural soil and indicates that the toxic effects of MCs should be of high concern due to high adsorption, low desorption, and slow dissipation.
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Affiliation(s)
- Bai-Lin Liu
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Yan-Wen Li
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Xi-Ying Tu
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Peng-Fei Yu
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Lei Xiang
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Hai-Ming Zhao
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Nai-Xian Feng
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Hui Li
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Quan-Ying Cai
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Ce-Hui Mo
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Ming Hung Wong
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
- Consortium on Health, Environment, Education and Research (CHEER), Department of Science and Environmental Studies, The Education University of Hong Kong, Tai Po, Ting Kok 999077, Hong Kong, China
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18
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Santos AA, Soldatou S, de Magalhães VF, Azevedo SMFO, Camacho-Muñoz D, Lawton LA, Edwards C. Degradation of Multiple Peptides by Microcystin-Degrader Paucibacter toxinivorans (2C20). Toxins (Basel) 2021; 13:265. [PMID: 33917728 PMCID: PMC8068134 DOI: 10.3390/toxins13040265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/03/2021] [Accepted: 04/04/2021] [Indexed: 11/16/2022] Open
Abstract
Since conventional drinking water treatments applied in different countries are inefficient at eliminating potentially toxic cyanobacterial peptides, a number of bacteria have been studied as an alternative to biological filters for the removal of microcystins (MCs). Here, we evaluated the degradation of not only MCs variants (-LR/DM-LR/-RR/-LF/-YR), but also non-MCs peptides (anabaenopeptins A/B, aerucyclamides A/D) by Paucibactertoxinivorans over 7 days. We also evaluated the degradation rate of MC-LR in a peptide mix, with all peptides tested, and in the presence of M. aeruginosa crude extract. Furthermore, biodegradation was assessed for non-cyanobacterial peptides with different chemical structures, such as cyclosporin A, (Glu1)-fibrinopeptide-B, leucine-enkephalin, and oxytocin. When cyanopeptides were individually added, P. toxinivorans degraded them (99%) over 7 days, except for MC-LR and -RR, which decreased by about 85 and 90%, respectively. The degradation rate of MC-LR decreased in the peptide mix compared to an individual compound, however, in the presence of the Microcystis extract, it was degraded considerably faster (3 days). It was noted that biodegradation rates decreased in the mix for all MCs while non-MCs peptides were immediately degraded. UPLC-QTOF-MS/MS allowed us to identify two linear biodegradation products for MC-LR and MC-YR, and one for MC-LF. Furthermore, P. toxinivorans demonstrated complete degradation of non-cyanobacterial peptides, with the exception of oxytocin, where around 50% remained after 7 days. Thus, although P. toxinivorans was previously identified as a MC-degrader, it also degrades a wide range of peptides under a range of conditions, which could be optimized as a potential biological tool for water treatment.
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Affiliation(s)
- Allan A. Santos
- Biophysics Institute, Federal University of Rio de Janeiro, 373 Avenida Carlos Chagas Filho, Ilha do Fundão, Rio de Janeiro 21941-901, Brazil; (V.F.d.M.); (S.M.F.O.A.)
- School of Pharmacy and Life Sciences, Robert Gordon University, The Sir Ian Wood Building, Garthdee Road, Aberdeen AB10 7GJ, UK; (S.S.); (D.C.-M.); (L.A.L.); (C.E.)
| | - Sylvia Soldatou
- School of Pharmacy and Life Sciences, Robert Gordon University, The Sir Ian Wood Building, Garthdee Road, Aberdeen AB10 7GJ, UK; (S.S.); (D.C.-M.); (L.A.L.); (C.E.)
| | - Valeria Freitas de Magalhães
- Biophysics Institute, Federal University of Rio de Janeiro, 373 Avenida Carlos Chagas Filho, Ilha do Fundão, Rio de Janeiro 21941-901, Brazil; (V.F.d.M.); (S.M.F.O.A.)
| | - Sandra M. F. O. Azevedo
- Biophysics Institute, Federal University of Rio de Janeiro, 373 Avenida Carlos Chagas Filho, Ilha do Fundão, Rio de Janeiro 21941-901, Brazil; (V.F.d.M.); (S.M.F.O.A.)
| | - Dolores Camacho-Muñoz
- School of Pharmacy and Life Sciences, Robert Gordon University, The Sir Ian Wood Building, Garthdee Road, Aberdeen AB10 7GJ, UK; (S.S.); (D.C.-M.); (L.A.L.); (C.E.)
| | - Linda A. Lawton
- School of Pharmacy and Life Sciences, Robert Gordon University, The Sir Ian Wood Building, Garthdee Road, Aberdeen AB10 7GJ, UK; (S.S.); (D.C.-M.); (L.A.L.); (C.E.)
| | - Christine Edwards
- School of Pharmacy and Life Sciences, Robert Gordon University, The Sir Ian Wood Building, Garthdee Road, Aberdeen AB10 7GJ, UK; (S.S.); (D.C.-M.); (L.A.L.); (C.E.)
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19
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Wei J, Huang F, Feng H, Massey IY, Clara T, Long D, Cao Y, Luo J, Yang F. Characterization and Mechanism of Linearized-Microcystinase Involved in Bacterial Degradation of Microcystins. Front Microbiol 2021; 12:646084. [PMID: 33859631 PMCID: PMC8042282 DOI: 10.3389/fmicb.2021.646084] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Accepted: 02/22/2021] [Indexed: 01/17/2023] Open
Abstract
Microcystins (MCs) are extremely hazardous to the ecological environment and public health. How to control and remove MCs is an unsolved problem all over the world. Some microbes and their enzymes are thought to be effective in degrading MCs. Microcystinase can linearize microcystin-leucine-arginine (MC-LR) via a specific locus. However, linearized MC-LR is also very toxic and needs to be removed. How linearized MC-LR was metabolized by linearized-microcystinase, especially how linearized-microcystinase binds to linearized MC-LR, has not been defined. A combination of in vitro experiments and computer simulation was applied to explore the characterization and molecular mechanisms for linearized MC-LR degraded by linearized-microcystinase. The purified linearized-microcystinase was obtained by recombinant Escherichia coli overexpressing. The concentration of linearized MC-LR was detected by high-performance liquid chromatography, and linearized MC-LR degradation products were analyzed by the mass spectrometer. Homology modeling was used to predict the structure of the linearized-microcystinase. Molecular docking techniques on the computer were used to simulate the binding sites of linearized-microcystinase and linearized MC-LR. The purified linearized-microcystinase was obtained successfully. The linearized-microcystinase degraded linearized MC-LR to tetrapeptide efficiently. The second structure of linearized-microcystinase consisted of many alpha-helices, beta-strands, and colis. Linearized-microcystinase interacted the linearized MC-LR with hydrogen bond, hydrophobic interaction, electrostatic forces, and the Van der Waals force. This study firstly reveals the characterization and specific enzymatic mechanism of linearized-microcystinase for catalyzing linearized MC-LR. These findings encourage the application of MC-degrading engineering bacteria and build a great technique for MC-LR biodegradation in environmental engineering.
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Affiliation(s)
- Jia Wei
- Hunan Provincial Key Laboratory of Clinical Epidemiology, Xiangya School of Public Health, Central South University, Changsha, China
| | - Feiyu Huang
- Hunan Provincial Key Laboratory of Clinical Epidemiology, Xiangya School of Public Health, Central South University, Changsha, China
| | - Hai Feng
- Hunan Provincial Key Laboratory of Clinical Epidemiology, Xiangya School of Public Health, Central South University, Changsha, China
| | - Isaac Yaw Massey
- Hunan Provincial Key Laboratory of Clinical Epidemiology, Xiangya School of Public Health, Central South University, Changsha, China
| | - Tezi Clara
- Hunan Provincial Key Laboratory of Clinical Epidemiology, Xiangya School of Public Health, Central South University, Changsha, China
| | - Dingxin Long
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang, China
| | - Yi Cao
- Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang, China
| | - Jiayou Luo
- Hunan Provincial Key Laboratory of Clinical Epidemiology, Xiangya School of Public Health, Central South University, Changsha, China
| | - Fei Yang
- Hunan Provincial Key Laboratory of Clinical Epidemiology, Xiangya School of Public Health, Central South University, Changsha, China.,Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang, China.,Key Laboratory of Environmental Medicine Engineering, School of Public Health Southeast University, Ministry of Education, Nanjing, China
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