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Anjou C, Lotoux A, Morvan C, Martin-Verstraete I. From ubiquity to specificity: The diverse functions of bacterial thioredoxin systems. Environ Microbiol 2024; 26:e16668. [PMID: 38899743 DOI: 10.1111/1462-2920.16668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 05/24/2024] [Indexed: 06/21/2024]
Abstract
The thioredoxin (Trx) system, found universally, is responsible for the regeneration of reversibly oxidized protein thiols in living cells. This system is made up of a Trx and a Trx reductase, and it plays a central role in maintaining thiol-based redox homeostasis by reducing oxidized protein thiols, such as disulfide bonds in proteins. Some Trxs also possess a chaperone function that is independent of thiol-disulfide exchange, in addition to their thiol-disulfide reductase activity. These two activities of the Trx system are involved in numerous physiological processes in bacteria. This review describes the diverse physiological roles of the Trx system that have emerged throughout bacterial evolution. The Trx system is essential for responding to oxidative and nitrosative stress. Beyond this primary function, the Trx system also participates in redox regulation and signal transduction, and in controlling metabolism, motility, biofilm formation, and virulence. This range of functions has evolved alongside the diversity of bacterial lifestyles and their specific constraints. This evolution can be characterized by the multiplication of the systems and by the specialization of cofactors or targets to adapt to the constraints of atypical lifestyles, such as photosynthesis, insect endosymbiosis, or spore-forming bacteria.
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Affiliation(s)
- Cyril Anjou
- Institut Pasteur, Université Paris Cité, UMR CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, Paris, France
| | - Aurélie Lotoux
- Institut Pasteur, Université Paris Cité, UMR CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, Paris, France
| | - Claire Morvan
- Institut Pasteur, Université Paris Cité, UMR CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, Paris, France
| | - Isabelle Martin-Verstraete
- Institut Pasteur, Université Paris Cité, UMR CNRS 6047, Laboratoire Pathogenèse des Bactéries Anaérobies, Paris, France
- Institut Universitaire de France, Paris, France
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van Hoek ML, Marchesani A, Rawat M. Diverse roles of low-molecular weight thiol GSH in Francisella's virulence, location sensing and GSH-stealing from host. CURRENT RESEARCH IN MICROBIAL SCIENCES 2023; 6:100218. [PMID: 38303966 PMCID: PMC10831187 DOI: 10.1016/j.crmicr.2023.100218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024] Open
Abstract
Low-molecular weight (LMW) thiols, encompassing peptides and small proteins with active cysteine residue(s), are important to bacteria as they are involved in a wide range of redox reactions. They include the tripeptide glutathione (GSH) and the small redox proteins, thioredoxins and glutaredoxins. We review the low MW thiols and related molecules in Francisella species and what role they may play in growth and virulence. Genes for GSH biosynthesis, metabolism and thioredoxins are present in all strains of Francisella, including the fully human-virulent strains. GSH and cysteine (CSH) are the major LMW thiols in Francisella extracts. We explore the potential role of the LMW thiols to overcome the nutritional challenges of intracellular growth (high GSH conditions) as well as the nutritional challenges of planktonic growth (low GSH conditions), and their contribution to Francisella's sensing its environmental location. Francisella may also use GSH as a source of CSH, for which it is auxotrophic. "Glutathione stealing" from the host may be an important part of Francisella's success strategy as a facultative intracellular pathogen both to detect its location and obtain CSH. An understanding of GSH metabolism in Francisella provides insights into the interaction of this pathogen with its host and may reveal additional targets for therapeutic intervention for tularemia infections.
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Affiliation(s)
- Monique L. van Hoek
- School of Systems Biology, George Mason University, Manassas, VA, United States
| | | | - Mamta Rawat
- Biology Department, California State University, Fresno, CA, United States
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Veeraswamy D, Subramanian A, Mohan D, Ettiyagounder P, Selvaraj PS, Ramasamy SP, Veeramani V. Exploring the origins and cleanup of mercury contamination: a comprehensive review. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023:10.1007/s11356-023-30636-z. [PMID: 37964142 DOI: 10.1007/s11356-023-30636-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 10/19/2023] [Indexed: 11/16/2023]
Abstract
Mercury is a global pollutant that poses significant risks to human health and the environment. Natural sources of mercury include volcanic eruptions, while anthropogenic sources include industrial processes, artisanal and small-scale gold mining, and fossil fuel combustion. Contamination can arise through various pathways, such as atmospheric deposition, water and soil contamination, bioaccumulation, and biomagnification in food chains. Various remediation strategies, including phytoremediation, bioremediation, chemical oxidation/reduction, and adsorption, have been developed to address mercury pollution, including physical, chemical, and biological approaches. The effectiveness of remediation techniques depends on the nature and extent of contamination and site-specific conditions. This review discusses the challenges associated with mercury pollution and remediation, including the need for effective monitoring and management strategies. Overall, this review offers a comprehensive understanding of mercury contamination and the range of remediation techniques available to mitigate its adverse impacts.
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Affiliation(s)
- Davamani Veeraswamy
- Department of Environmental Sciences, Directorate of Natural Resource Management, Tamil Nadu Agricultural University, Coimbatore, 641 003, Tamil Nadu, India
- College of Engineering, Science and Environment, Global Centre for Environmental Remediation (GCER), ATC Building, The University of Newcastle, Callaghan Campus, Callaghan, NSW, 2308, Australia
| | - Arulmani Subramanian
- Department of Chemistry, Bannari Amman Institute of Technology, Sathyamangalam, 638 401, Tamil Nadu, India.
| | - Deepasri Mohan
- Division of Environmental Sciences, Sher-E-Kashmir University of Agricultural Sciences and Technology, Shalimar, 190025, Jammu and Kashmir Union Territory, India
| | - Parameswari Ettiyagounder
- Department of Environmental Sciences, Directorate of Natural Resource Management, Tamil Nadu Agricultural University, Coimbatore, 641 003, Tamil Nadu, India
| | - Paul Sebastian Selvaraj
- Department of Environmental Sciences, Directorate of Natural Resource Management, Tamil Nadu Agricultural University, Coimbatore, 641 003, Tamil Nadu, India
- College of Engineering, Science and Environment, Global Centre for Environmental Remediation (GCER), ATC Building, The University of Newcastle, Callaghan Campus, Callaghan, NSW, 2308, Australia
| | - Sangeetha Piriya Ramasamy
- Department of Environmental Sciences, Directorate of Natural Resource Management, Tamil Nadu Agricultural University, Coimbatore, 641 003, Tamil Nadu, India
- School of Water, Energy, and Environment, Cranfield University, Cranfield, MK43 0AL, UK
| | - Venkatesan Veeramani
- Department of Civil Engineering, University College of Engineering, Anna University, Ariyalur, 621 731, Tamil Nadu, India
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Huang M, Shen S, Meng Z, Si G, Wu X, Feng T, Liu C, Chen J, Duan C. Mechanisms involved in the sequestration and resistance of cadmium for a plant-associated Pseudomonas strain. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 266:115527. [PMID: 37806135 DOI: 10.1016/j.ecoenv.2023.115527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 09/07/2023] [Accepted: 09/24/2023] [Indexed: 10/10/2023]
Abstract
Understanding Cd-resistant bacterial cadmium (Cd) resistance systems is crucial for improving microremediation in Cd-contaminated environments. However, these mechanisms are not fully understood in plant-associated bacteria. In the present study, we investigated the mechanisms underlying Cd sequestration and resistance in the strain AN-B15. These results showed that extracellular Cd sequestration by complexation in strain AN-B15 was primarily responsible for the removal of Cd from the solution. Transcriptome analyses have shown that the mechanisms of Cd resistance at the transcriptional level involve collaborative processes involving multiple metabolic pathways. The AN-B15 strain upregulated the expression of genes related to exopolymeric substance synthesis, metal transport, Fe-S cluster biogenesis, iron recruitment, reactive oxygen species oxidative stress defense, and DNA and protein repair to resist Cd-induced stress. Furthermore, inoculation with AN-B15 alleviated Cd-induced toxicity and reduced Cd uptake in the shoots of wheat seedlings, indicating its potential for remediation. Overall, the results improve our understanding of the mechanisms involved in Cd resistance in bacteria and thus have important implications for improving microremediation.
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Affiliation(s)
- Mingyu Huang
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Shili Shen
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Zhuang Meng
- School of Agriculture, Yunnan University, Kunming 650091, China
| | - Guangzheng Si
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Xinni Wu
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Tingting Feng
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Chang'e Liu
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Jinquan Chen
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China.
| | - Changqun Duan
- Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China; School of Agriculture, Yunnan University, Kunming 650091, China.
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Harsonowati W, Rahayuningsih S, Yuniarti E, Susilowati DN, Manohara D, Sipriyadi, Widyaningsih S, Akhdiya A, Suryadi Y, Tentrem T. Bacterial Metal-Scavengers Newly Isolated from Indonesian Gold Mine-Impacted Area: Bacillus altitudinis MIM12 as Novel Tools for Bio-Transformation of Mercury. MICROBIAL ECOLOGY 2023; 86:1646-1660. [PMID: 36930295 DOI: 10.1007/s00248-023-02203-z] [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: 09/23/2022] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
Selikat river, located in the north part of Bengkulu Province, Indonesia, has critical environmental and ecological issues of contamination by mercury due to artisanal small-scale gold mining (ASGM) activities. The present study focused on the identification and bioremediation efficiency of the mercury-resistant bacteria (MRB) isolated from ASGM-impacted areas in Lebong Tambang village, Bengkulu Province, and analyzed their merA gene function in transforming Hg2+ to Hg0. Thirty-four MRB isolates were isolated, and four out of the 34 isolates exhibited not only the highest degree of resistance to Hg (up to 200 ppm) but also to cadmium (Cd), chromium (Cr), copper (Cu), and lead (Pb). Further analysis shows that all four selected isolates harbor a merA operon-encoded mercuric ion (Hg2+) reductase enzyme, with the Hg bioremediation efficiency varying from 71.60 to 91.30%. Additionally, the bioremediation efficiency for Cd, Cr, Cu, and Pb ranged from 54.36 to 98.37%. Among the 34, two isolates identified as Bacillus altitudinis possess effective and superior multi-metal degrading capacity up to 91.30% for Hg, 98.07% for Cu, and 54.36% for Cr. A pilot-scale study exhibited significant in situ bioremediation of Hg from gold mine tailings of 82.10 and 95.16% at 4- and 8-day intervals, respectively. Interestingly, translated nucleotide blast against bacteria and Bacilli merA sequence databases suggested that B. altitudinis harbor merA gene is the first case among Bacilli with the possibility exhibits a novel mechanism of bioremediation, considering our new finding. This study is the first to report the structural and functional Hg-resistant bacterial diversity of unexplored ASGM-impacted areas, emphasizing their biotechnological potential as novel tools for the biological transformation and adsorption of mercury and other toxic metals.
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Affiliation(s)
- Wiwiek Harsonowati
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia.
- Agrobiology and Bioresources Department, School of Agriculture, Utsunomiya University, 350 Mine-Machi, Utsunomiya, 321-8505, Tochigi, Japan.
| | - Sri Rahayuningsih
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Erny Yuniarti
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Dwi Ningsih Susilowati
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Dyah Manohara
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Sipriyadi
- Biology Department, Faculty of Mathematics and Natural Science, Universitas Bengkulu, Jalan W.R Supratman, Kandang Limun, Bengkulu, 38125, Indonesia
| | - Sri Widyaningsih
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Alina Akhdiya
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Yadi Suryadi
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Titi Tentrem
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
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Zhang S, Ke C, Jiang M, Li Y, Huang W, Dang Z, Guo C. S(-II) reactivates Cd 2+-stressed Shewanella oneidensis via promoting low-molecular-weight thiols synthesis and activating antioxidant defense. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 327:121516. [PMID: 36972810 DOI: 10.1016/j.envpol.2023.121516] [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: 11/28/2022] [Revised: 03/15/2023] [Accepted: 03/24/2023] [Indexed: 06/18/2023]
Abstract
Efficient remedies for living organisms including bacteria to counteract cadmium (Cd2+) toxicity are still highly needed. Plant toxicity studies have showed that exogenous S(-II) (including hydrogen sulfide and its ionic forms, i.e., H2S, HS-, and S2-) application can effectively alleviate adverse effects of Cd stress, but whether S(-II) could mitigate bacterial Cd toxicity remains unclear. In this study, S(-II) was applied exogenously to Cd-stressed Shewanella oneidensis MR-1 and the results showed that S(-II) can significantly reactivate impaired physiological processes including growth arrest and enzymatic ferric (Fe(III) reduction inhibition. The efficacy of S(-II) treatment is negatively correlated with the concentration and time length of Cd exposure. Energy-dispersive X-ray (EDX) analysis suggested the presence of cadmium sulfide inside cells treated with S(-II). Both compared proteomic analysis and RT-qPCR showed that enzymes associated with sulfate transport, sulfur assimilation, methionine, and glutathione biosynthesis were up-regulated in both mRNA and protein levels after the treatment, indicating S(-II) may induce the biosynthesis of functional low-molecular-weight (LMW) thiols to counteract Cd toxicity. Meanwhile, the antioxidant enzymes were positively modulated by S(-II) and thus the activity of intracellular reactive oxygen species was attenuated. The study demonstrated that exogenous S(-II) can effectively alleviate Cd stress for S. oneidensis likely through inducing intracellular trapping mechanisms and modulating cellular redox status. It suggested that S(-II) may be a highly effective remedy for bacteria such as S. oneidensis under Cd-polluted environments.
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Affiliation(s)
- Siyu Zhang
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
| | - Changdong Ke
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
| | - Mengge Jiang
- Guangzhou Metro Group Co., Ltd., Guangzhou, 510335, China
| | - Yuancheng Li
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
| | - Weilin Huang
- Department of Environmental Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA
| | - Zhi Dang
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
| | - Chuling Guo
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China.
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Chen Y, Liu G, Ali MR, Zhang M, Zhou G, Sun Q, Li M, Shirin J. Regulation of gut bacteria in silkworm (Bombyx mori) after exposure to endogenous cadmium-polluted mulberry leaves. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 256:114853. [PMID: 37023650 DOI: 10.1016/j.ecoenv.2023.114853] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 03/08/2023] [Accepted: 03/29/2023] [Indexed: 06/19/2023]
Abstract
Soil cadmium (Cd) pollution presents a severe pollution burden to flora and fauna due to its non-degradability and transferability. The Cd in the soil is stressing the silkworm (Bombyx mori) out through a soil-mulberry-silkworm system. The gut microbiota of B.mori are reported to shape host health. However, earlier research had not reported the effect of endogenous Cd-polluted mulberry leaves on the gut microbiota of B.mori. In the current research, we compared the phyllosphere bacteria of endogenous Cd-polluted mulberry leaves at different concentrations. The investigation of the gut bacteria of B.mori fed with the mulberry leaves was done to evaluate the impact of endogenous Cd- polluted mulberry leaves on the gut bacteria of the silkworm. The results revealed a dramatic change in the gut bacteria of B.mori whereas, the changes in the phyllosphere bacteria of mulberry leaves in response to an increased Cd concentration were insignificant. It also increased the α-diversity and altered the gut bacterial community structure of B. mori. A significant change in the abundance of dominant phyla of gut bacteria of B.mori was recorded. At the genus level, the abundance of Enterococcus, Brachybacterium and Brevibacterium group related to disease resistance, and the abundance of Sphingomonas, Glutamicibacter and Thermus related to metal detoxification was significantly increased after Cd exposure. Meanwhile, there was a significant decrease in the abundance of the pathogenic bacteria Serratia and Enterobacter. The results demonstrated that endogenous Cd-polluted mulberry leaves caused perturbations in the gut bacterial composition of B.mori, which may driven by Cd content rather than phyllosphere bacteria. A significant variation in the specific bacterial community indicated the adaptation of B. mori gut for its role in heavy metal detoxification and immune function regulation. The results of this study help to understand the bacterial community associated with endogenous Cd-polluted resistance in the gut of B.mori, which proves to be a novel addition in describing its response in activating the detoxification mechanism and promoting its growth and development. This research work will help to explore the other mechanisms and microbiota associated with the adaptations to mitigate the Cd pollution problems.
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Affiliation(s)
- Yongjing Chen
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, Anhui Province, China; Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, China; Anhui Province Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China
| | - Guijia Liu
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, Anhui Province, China; Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, China; Anhui Province Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China
| | - Maria Rafraf Ali
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, Anhui Province, China; Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, China; Anhui Province Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China
| | - Mingzhu Zhang
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, Anhui Province, China; Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, China; Anhui Province Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China
| | - Guowei Zhou
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, Anhui Province, China; Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, China; Anhui Province Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China
| | - Qingye Sun
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, Anhui Province, China; Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, China; Anhui Province Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China.
| | - Mingjun Li
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, Anhui Province, China; Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, China; Anhui Province Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China
| | - Jazbia Shirin
- School of Resources and Environmental Engineering, Anhui University, Hefei 230601, Anhui Province, China; Anhui Province Engineering Laboratory for Mine Ecological Remediation, Hefei, China; Anhui Province Key Laboratory of Wetland Ecological Protection and Restoration, Hefei, China
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Gutensohn M, Schaefer JK, Maas TJ, Skyllberg U, Björn E. Metabolic turnover of cysteine-related thiol compounds at environmentally relevant concentrations by Geobacter sulfurreducens. Front Microbiol 2023; 13:1085214. [PMID: 36713222 PMCID: PMC9874932 DOI: 10.3389/fmicb.2022.1085214] [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: 10/31/2022] [Accepted: 12/22/2022] [Indexed: 01/12/2023] Open
Abstract
Low-molecular-mass (LMM) thiol compounds are known to be important for many biological processes in various organisms but LMM thiols are understudied in anaerobic bacteria. In this work, we examined the production and turnover of nanomolar concentrations of LMM thiols with a chemical structure related to cysteine by the model iron-reducing bacterium Geobacter sulfurreducens. Our results show that G. sulfurreducens tightly controls the production, excretion and intracellular concentration of thiols depending on cellular growth state and external conditions. The production and cellular export of endogenous cysteine was coupled to the extracellular supply of Fe(II), suggesting that cysteine excretion may play a role in cellular trafficking to iron proteins. Addition of excess exogenous cysteine resulted in a rapid and extensive conversion of cysteine to penicillamine by the cells. Experiments with added isotopically labeled cysteine confirmed that penicillamine was formed by a dimethylation of the C-3 atom of cysteine and not via indirect metabolic responses to cysteine exposure. This is the first report of de novo metabolic synthesis of this compound. Penicillamine formation increased with external exposure to cysteine but the compound did not accumulate intracellularly, which may suggest that it is part of G. sulfurreducens' metabolic strategy to maintain cysteine homeostasis. Our findings highlight and expand on processes mediating homeostasis of cysteine-like LMM thiols in strict anaerobic bacteria. The formation of penicillamine is particularly noteworthy and this compound warrants more attention in microbial metabolism studies.
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Affiliation(s)
| | - Jeffra K. Schaefer
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, United States
| | - Torben J. Maas
- Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstraße, Münster, Germany
| | - Ulf Skyllberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, Umeå, Sweden,*Correspondence: Erik Björn, ✉
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Greeshma K, Kim HS, Ramanan R. The emerging potential of natural and synthetic algae-based microbiomes for heavy metal removal and recovery from wastewaters. ENVIRONMENTAL RESEARCH 2022; 215:114238. [PMID: 36108721 DOI: 10.1016/j.envres.2022.114238] [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: 04/13/2022] [Revised: 08/20/2022] [Accepted: 08/27/2022] [Indexed: 06/15/2023]
Abstract
Heavy Metal (HM) bioremoval by microbes is a successful, environment-friendly technique, particularly at low concentrations of HMs. Studies using algae, bacteria, and fungi reveal promising capabilities in isolation and when used in consortia. Yet, few reviews have emphasized individual and collective HM removal rates and the associated mechanisms in natural or synthetic microbiomes. Besides discussing the limitations of conventional and synthetic biology approaches, this review underscores the utility of indigenous microbial taxon, i.e., algae, fungi, and bacteria, in HM removal with adsorption capacities and their synergistic role in microbiome-led studies. The detoxification mechanisms studied for certain HMs indicate distinctive removal pathways in each taxon which points to an enhanced effect when used as a microbiome. The role and higher efficacies of the designer microbiomes with complementing and mutualistic taxa are also considered, followed by recovery options for a circular bioeconomy. The citation network analysis further validates the multi-metal removal ability of microbiomes and the restricted capabilities of the individual counterparts. In precis, the study reemphasizes increased metal removal efficiencies of inter-taxon microbiomes and the mechanisms for synergistic and improved removal, eventually drawing attention to the benefits of ecological engineering approaches compared to other alternatives.
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Affiliation(s)
- Kozhumal Greeshma
- Sustainable Resources Laboratory, Department of Environmental Science, Central University of Kerala, Tejaswini Hills, Periya, Kasaragod, Kerala, 671 316, India
| | - Hee-Sik Kim
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Yuseong-gu, Daejeon, 34141, Republic of Korea; Department of Environmental Biotechnology, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), 34113, Daejeon, Republic of Korea
| | - Rishiram Ramanan
- Sustainable Resources Laboratory, Department of Environmental Science, Central University of Kerala, Tejaswini Hills, Periya, Kasaragod, Kerala, 671 316, India; Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Yuseong-gu, Daejeon, 34141, Republic of Korea.
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10
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Singh S, Kumar V, Gupta P, Ray M. The trafficking of Hg II by alleviating its toxicity via Citrobacter sp. IITISM25 in batch and pilot-scale investigation. JOURNAL OF HAZARDOUS MATERIALS 2022; 433:128711. [PMID: 35395524 DOI: 10.1016/j.jhazmat.2022.128711] [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: 12/29/2021] [Revised: 03/10/2022] [Accepted: 03/13/2022] [Indexed: 06/14/2023]
Abstract
The study aims to see how effective the Citrobacter species strain is in removing HgII under stressful conditions. For this, a response surface methodology was chosen to optimized pH, temperature, and biomass for effective biotransformation of HgII. The optimized value for pH, temperature, and biomass were 6.5, 30 °C, and 2 mg/l with 89% HgII removal potential. TEM-EDX showed accumulated mercury onto the bacterial surface. Pot study was conducted to check the potentiality of this strain in alleviating the toxicity in Solanum lycopersicum L. under different concentrations of mercury. The enhancement in antioxidative enzymes, as well as mercury accumulation, was observed in test plants inoculated with IITISM25. Obtained result showed a greater accumulation of mercury in the root system than that of the shoot system due to poor translocation. Moreover, mercury reductase enzyme synthesis was also boosted by the addition of β-mercaptoethanol and L-cysteine. The optimized condition for maximum enzyme synthesis was at pH 7.5 and temperature 30 °C with Km = 48.07 μmol and Vmax = 9.75 μmol/min. Thus, we can say that Citrobacter species strain IITISM25 can be effectively applied in remediation of HgII stress condition as well as promotion of Solanum lycopersicum L growth under stress conditions as a promising host.
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Affiliation(s)
- Shalini Singh
- Laboratory of Applied Microbiology, Department of Environmental Science & Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad 826 004, Jharkhand, India
| | - Vipin Kumar
- Laboratory of Applied Microbiology, Department of Environmental Science & Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad 826 004, Jharkhand, India.
| | - Pratishtha Gupta
- Laboratory of Applied Microbiology, Department of Environmental Science & Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad 826 004, Jharkhand, India
| | - Madhurya Ray
- Laboratory of Applied Microbiology, Department of Environmental Science & Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad 826 004, Jharkhand, India
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11
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Organomercurial lyase (MerB)-mediated demethylation decreases bacterial methylmercury resistance in the absence of mercuric reductase (MerA). Appl Environ Microbiol 2022; 88:e0001022. [PMID: 35138926 DOI: 10.1128/aem.00010-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mer operon encodes enzymes that transform and detoxify methylmercury (MeHg) and/or inorganic mercury (Hg(II)). Organomercurial lyase (MerB) and mercuric reductase (MerA) can act sequentially to demethylate MeHg to Hg(II) and reduce Hg(II) to volatile elemental mercury (Hg0) that can escape from the cell, conferring resistance to MeHg and Hg(II). Most identified mer operons encode either MerA and MerB in tandem or MerA alone, however, microbial genomes were recently identified that encode only MerB. Yet, the effects of potentially producing intracellular Hg(II) via demethylation of MeHg by MerB, independent of a mechanism to further detoxify or sequester the metal is not well understood. Here, we investigate MeHg biotransformation in Escherichia coli strains engineered to express MerA and MerB, together or separately, and characterize cell viability and Hg detoxification kinetics when these strains are grown in the presence of MeHg. Strains expressing only MerB are capable of demethylating MeHg to Hg(II). Compared to strains that express both MerA and MerB, strains expressing only MerB exhibit a lower minimum inhibitory concentration with MeHg exposure, which parallels a redistribution of Hg from the cell-associated fraction to the culture medium, consistent with cell lysis occurring. The data support a model whereby intracellular production of Hg(II), in the absence of reduction or other forms of demobilization, results in a greater cytotoxicity compared to the parent MeHg compound. Collectively, these results suggest that in the context of MeHg detoxification, MerB must be accompanied by an additional mechanism(s) to reduce, sequester, or re-distribute generated Hg(II). Importance: Mercury is a globally distributed pollutant that poses a risk to wildlife and human health. The toxicity of mercury is influenced largely by microbially mediated biotransformation between its organic (methylmercury) and inorganic (Hg(II) and Hg0) forms. Here we show in a relevant cellular context that the organomercurial lyase (MerB) enzyme is capable of MeHg demethylation without subsequent mercuric reductase (MerA)-mediated reduction of Hg(II). Demethylation of MeHg without subsequent Hg(II) reduction results in a greater cytotoxicity and increased cell lysis. Microbes carrying MerB alone have recently been identified but have yet to be characterized. Our results demonstrate that mer operons encoding MerB but not MerA put the cell at a disadvantage in the context of MeHg exposure, unless subsequent mechanisms of reduction or Hg(II) sequestration exist. These findings may help uncover the existence of alternative mechanisms of Hg(II) detoxification in addition to revealing the drivers of mer operon evolution.
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Rani L, Srivastav AL, Kaushal J. Bioremediation: An effective approach of mercury removal from the aqueous solutions. CHEMOSPHERE 2021; 280:130654. [PMID: 34162069 DOI: 10.1016/j.chemosphere.2021.130654] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 04/03/2021] [Accepted: 04/21/2021] [Indexed: 06/13/2023]
Abstract
Mercury (Hg(II)) is the 16th rarest element present in the earth's crust. Due to rapid industrialization and urban expansions, the mercury concentration has been elevated in the environment. Hg(II) contamination in the aqueous environment has become a great challenge for human beings. The main source of Hg(II) in the aqueous phase is untreated effluent industries (such as the paper industry). Hg(II) is non-biodegradable in nature and even its trace amount in an aqueous environment can pose chronic threats among the humans (damage to the central nervous system, respiratory system, and cardiovascular system, mutation of DNA), animals, and aquatic creatures. Therefore, the removal of mercury from aqueous solutions is an urgent need of the modern era. The conventional techniques such as ion exchange, precipitation, membrane filtrations are costly and also generate byproducts in the environment. Bioremediation is a sustainable, environmentally sound, and cost-effective technique to remove Hg(II) from the aqueous solutions. In this process, naturally occurring microorganisms are utilized to remove the Hg(II) from the aqueous solutions. Lentinus edodes, U. lactuca, and Typha domingensis are found to have great potential to remove mercury from water ranged from ~100 mg g-1 to 337 mg g-1.
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Affiliation(s)
- Lata Rani
- Centre for Water Sciences, Chitkara University Institute of Engineering & Technology, Chitkara University, Punjab, 140 417, India; School of Basic Sciences, Chitkara University, Himachal Pradesh, 174 103, India
| | - Arun Lal Srivastav
- Chitkara University School of Engineering and Technology, Chitkara University, Himachal Pradesh, 174 103, India.
| | - Jyotsna Kaushal
- Centre for Water Sciences, Chitkara University Institute of Engineering & Technology, Chitkara University, Punjab, 140 417, India
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13
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Su Z, Zeng Y, Li X, Perumal AB, Zhu J, Lu X, Dai M, Liu X, Lin F. The Endophytic Fungus Piriformospora Indica-Assisted Alleviation of Cadmium in Tobacco. J Fungi (Basel) 2021; 7:jof7080675. [PMID: 34436214 PMCID: PMC8398633 DOI: 10.3390/jof7080675] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/15/2021] [Accepted: 08/18/2021] [Indexed: 01/14/2023] Open
Abstract
Increasing evidence suggests that the endophytic fungus Piriformospora indica helps plants overcome various abiotic stresses, especially heavy metals. However, the mechanism of heavy metal tolerance has not yet been elucidated. Here, the role of P. indica in alleviating cadmium (Cd) toxicities in tobacco was investigated. It was found that P. indica improved Cd tolerance to tobacco, increasing Cd accumulation in roots but decreasing Cd accumulation in leaves. The colonization of P. indica altered the subcellular repartition of Cd, increasing the Cd proportion in cell walls while reducing the Cd proportion in membrane/organelle and soluble fractions. During Cd stress, P. indica significantly enhanced the peroxidase (POD) activity and glutathione (GSH) content in tobacco. The spatial distribution of GSH was further visualized by Raman spectroscopy, showing that GSH was distributed in the cortex of P. indica-inoculated roots while in the epidermis of the control roots. A LC-MS/MS-based label-free quantitative technique evaluated the differential proteomics of P. indica treatment vs. control plants under Cd stress. The expressions of peroxidase, glutathione synthase, and photosynthesis-related proteins were significantly upregulated. This study provided extensive evidence for how P. indica enhances Cd tolerance in tobacco at physiological, cytological, and protein levels.
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Affiliation(s)
- Zhenzhu Su
- Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Z.S.); (Y.Z.); (J.Z.); (X.L.); (X.L.)
| | - Yulan Zeng
- Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Z.S.); (Y.Z.); (J.Z.); (X.L.); (X.L.)
| | - Xiaoli Li
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China; (X.L.); (A.B.P.)
| | - Anand Babu Perumal
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China; (X.L.); (A.B.P.)
| | - Jianan Zhu
- Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Z.S.); (Y.Z.); (J.Z.); (X.L.); (X.L.)
| | - Xuanjun Lu
- Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Z.S.); (Y.Z.); (J.Z.); (X.L.); (X.L.)
| | - Mengdi Dai
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China;
| | - Xiaohong Liu
- Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Z.S.); (Y.Z.); (J.Z.); (X.L.); (X.L.)
| | - Fucheng Lin
- Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China; (Z.S.); (Y.Z.); (J.Z.); (X.L.); (X.L.)
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-Products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China;
- Correspondence: ; Tel.: +86-571-8640-4007
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14
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Christakis CA, Barkay T, Boyd ES. Expanded Diversity and Phylogeny of mer Genes Broadens Mercury Resistance Paradigms and Reveals an Origin for MerA Among Thermophilic Archaea. Front Microbiol 2021; 12:682605. [PMID: 34248899 PMCID: PMC8261052 DOI: 10.3389/fmicb.2021.682605] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/28/2021] [Indexed: 11/13/2022] Open
Abstract
Mercury (Hg) is a highly toxic element due to its high affinity for protein sulfhydryl groups, which upon binding, can destabilize protein structure and decrease enzyme activity. Prokaryotes have evolved enzymatic mechanisms to detoxify inorganic Hg and organic Hg (e.g., MeHg) through the activities of mercuric reductase (MerA) and organomercury lyase (MerB), respectively. Here, the taxonomic distribution and evolution of MerAB was examined in 84,032 archaeal and bacterial genomes, metagenome assembled genomes, and single-cell genomes. Homologs of MerA and MerB were identified in 7.8 and 2.1% percent of genomes, respectively. MerA was identified in the genomes of 10 archaeal and 28 bacterial phyla previously unknown to code for this functionality. Likewise, MerB was identified in 2 archaeal and 11 bacterial phyla previously unknown to encode this functionality. Surprisingly, homologs of MerB were identified in a number of genomes (∼50% of all MerB-encoding genomes) that did not encode MerA, suggesting alternative mechanisms to detoxify Hg(II) once it is generated in the cytoplasm. Phylogenetic reconstruction of MerA place its origin in thermophilic Thermoprotei (Crenarchaeota), consistent with high levels of Hg(II) in geothermal environments, the natural habitat of this archaeal class. MerB appears to have been recruited to the mer operon relatively recently and likely among a mesophilic ancestor of Euryarchaeota and Thaumarchaeota. This is consistent with the functional dependence of MerB on MerA and the widespread distribution of mesophilic microorganisms that methylate Hg(II) at lower temperature. Collectively, these results expand the taxonomic and ecological distribution of mer-encoded functionalities, and suggest that selection for Hg(II) and MeHg detoxification is dependent not only on the availability and type of mercury compounds in the environment but also the physiological potential of the microbes who inhabit these environments. The expanded diversity and environmental distribution of MerAB identify new targets to prioritize for future research.
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Affiliation(s)
- Christos A. Christakis
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Tamar Barkay
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Eric S. Boyd
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
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15
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Chang J, Si G, Dong J, Yang Q, Shi Y, Chen Y, Zhou K, Chen J. Transcriptomic analyses reveal the pathways associated with the volatilization and resistance of mercury(II) in the fungus Lecythophora sp. DC-F1. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 752:142172. [PMID: 33207499 DOI: 10.1016/j.scitotenv.2020.142172] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 09/01/2020] [Accepted: 09/01/2020] [Indexed: 06/11/2023]
Abstract
The biotic enzymatic reduction of mercury II [Hg(II)] to elemental Hg [Hg(0)] is an important pathway for Hg detoxification in natural ecosystems. However, the mechanisms of Hg(II) volatilization and resistance in fungi have not been understood completely. In the present study, we investigated the mechanisms of Hg(II) volatilization and resistance in the fungus Lecythophora sp. DC-F1. Hg(II) volatilization occurred during the investigation via the reduction of Hg(II) to Hg(0) in DC-F1. Comparative transcriptome analyses of DC-F1 revealed 3439 differentially expressed genes under 10 mg/L Hg(II) stress, among which 2770 were up-regulated and 669 were down-regulated. Functional enrichment analyses of genes and pathways further suggested that the Hg(II) resistance of DC-F1 is a multisystem collaborative process with three important transcriptional responses to Hg(II) stress: a mer-mediated Hg detoxification system, a thiol compound metabolism, and a cell reactive oxygen species stress response system. The phylogenetic analysis of merA protein homologs suggests that the Hg(II) reduction by merA is widely distributed in fungi. Overall, this study provides evidence for the reduction of Hg(II) to Hg(0) in fungi via the mer-mediated Hg detoxification system and offers a comprehensive explanation for its role within Hg biogeochemical cycling. These findings offer a strong theoretical basis for the application of fungi in the bioremediation of Hg-contaminated envionments.
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Affiliation(s)
- Junjun Chang
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China; Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China; International Cooperative Center of Plateau Lake Ecological Restoration and Watershed Management of Yunnan Kunming, 650091, China
| | - Guangzheng Si
- Institute of International Rivers and Eco-security, Yunnan University, Kunming 650091, China
| | - Jia Dong
- International Cooperative Center of Plateau Lake Ecological Restoration and Watershed Management of Yunnan Kunming, 650091, China
| | - Qingchen Yang
- Institute of International Rivers and Eco-security, Yunnan University, Kunming 650091, China
| | - Yu Shi
- Institute of International Rivers and Eco-security, Yunnan University, Kunming 650091, China
| | - Yaling Chen
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Kexin Zhou
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China
| | - Jinquan Chen
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China; Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, School of Ecology and Environmental Science, Yunnan University, Kunming 650091, China; International Cooperative Center of Plateau Lake Ecological Restoration and Watershed Management of Yunnan Kunming, 650091, China.
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16
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Linzner N, Loi VV, Fritsch VN, Antelmann H. Thiol-based redox switches in the major pathogen Staphylococcus aureus. Biol Chem 2020; 402:333-361. [PMID: 33544504 DOI: 10.1515/hsz-2020-0272] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 11/05/2020] [Indexed: 12/15/2022]
Abstract
Staphylococcus aureus is a major human pathogen, which encounters reactive oxygen, nitrogen, chlorine, electrophile and sulfur species (ROS, RNS, RCS, RES and RSS) by the host immune system, during cellular metabolism or antibiotics treatments. To defend against redox active species and antibiotics, S. aureus is equipped with redox sensing regulators that often use thiol switches to control the expression of specific detoxification pathways. In addition, the maintenance of the redox balance is crucial for survival of S. aureus under redox stress during infections, which is accomplished by the low molecular weight (LMW) thiol bacillithiol (BSH) and the associated bacilliredoxin (Brx)/BSH/bacillithiol disulfide reductase (YpdA)/NADPH pathway. Here, we present an overview of thiol-based redox sensors, its associated enzymatic detoxification systems and BSH-related regulatory mechanisms in S. aureus, which are important for the defense under redox stress conditions. Application of the novel Brx-roGFP2 biosensor provides new insights on the impact of these systems on the BSH redox potential. These thiol switches of S. aureus function in protection against redox active desinfectants and antimicrobials, including HOCl, the AGXX® antimicrobial surface coating, allicin from garlic and the naphthoquinone lapachol. Thus, thiol switches could be novel drug targets for the development of alternative redox-based therapies to combat multi-drug resistant S. aureus isolates.
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Affiliation(s)
- Nico Linzner
- Freie Universität Berlin, Institute of Biology-Microbiology, Königin-Luise-Straße 12-16, D-14195Berlin, Germany
| | - Vu Van Loi
- Freie Universität Berlin, Institute of Biology-Microbiology, Königin-Luise-Straße 12-16, D-14195Berlin, Germany
| | - Verena Nadin Fritsch
- Freie Universität Berlin, Institute of Biology-Microbiology, Königin-Luise-Straße 12-16, D-14195Berlin, Germany
| | - Haike Antelmann
- Freie Universität Berlin, Institute of Biology-Microbiology, Königin-Luise-Straße 12-16, D-14195Berlin, Germany
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17
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Al-Tameemi H, Beavers WN, Norambuena J, Skaar EP, Boyd JM. Staphylococcus aureus lacking a functional MntABC manganese import system has increased resistance to copper. Mol Microbiol 2020; 115:554-573. [PMID: 33034093 DOI: 10.1111/mmi.14623] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/28/2020] [Accepted: 10/04/2020] [Indexed: 12/17/2022]
Abstract
S. aureus USA300 isolates utilize the copBL and copAZ gene products to prevent Cu intoxication. We created and examined a ΔcopAZ ΔcopBL mutant strain (cop-). The cop- strain was sensitive to Cu and accumulated intracellular Cu. We screened a transposon (Tn) mutant library in the cop- background and isolated strains with Tn insertions in the mntABC operon that permitted growth in the presence of Cu. The mutations were in mntA and they were recessive. Under the growth conditions utilized, MntABC functioned in manganese (Mn) import. When cultured with Cu, strains containing a mntA::Tn accumulated less Cu than the parent strain. Mn(II) supplementation improved growth when cop- was cultured with Cu and this phenotype was dependent upon the presence of MntR, which is a repressor of mntABC transcription. A ΔmntR strain had an increased Cu load and decreased growth in the presence of Cu, which was abrogated by the introduction of mntA::Tn. Over-expression of mntABC increased cellular Cu load and sensitivity to Cu. The presence of a mntA::Tn mutation protected iron-sulfur (FeS) enzymes from inactivation by Cu. The data presented are consistent with a model wherein defective MntABC results in decreased cellular Cu accumulation and protection to FeS enzymes from Cu poisoning.
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Affiliation(s)
- Hassan Al-Tameemi
- Department of Biochemistry and Microbiology, Rutgers, the State University of New Jersey, New Brunswick, NJ, USA
| | - William N Beavers
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Javiera Norambuena
- Department of Biochemistry and Microbiology, Rutgers, the State University of New Jersey, New Brunswick, NJ, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jeffrey M Boyd
- Department of Biochemistry and Microbiology, Rutgers, the State University of New Jersey, New Brunswick, NJ, USA
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18
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Chang J, Shi Y, Si G, Yang Q, Dong J, Chen J. The bioremediation potentials and mercury(II)-resistant mechanisms of a novel fungus Penicillium spp. DC-F11 isolated from contaminated soil. JOURNAL OF HAZARDOUS MATERIALS 2020; 396:122638. [PMID: 32361297 DOI: 10.1016/j.jhazmat.2020.122638] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 03/29/2020] [Accepted: 04/01/2020] [Indexed: 05/20/2023]
Abstract
Bioremediation of Hg-contaminated soil using microbe-based strategies is a promising and efficient method as it is inexpensive and not harmful to the environment. In this study, a novel Hg(II)-volatilizing fungus Penicillium spp., DC-F11 was isolated and showed bioremediation potential for reducing Hg(II) phytotoxicity, total Hg, and exchangeable Hg in Hg(II)-polluted soil. Subsequently, the mechanisms of Hg(II) volatilization and resistance involved were investigated using multiple complementary techniques. The fungal cells could detoxify Hg(II) by extracellular sequestration via adsorption and precipitation. Moreover, a comparative transcriptome analysis uncovered the primary intracellular adaptive responses of the DC-F11 to Hg(II) stress, including mer-mediated detoxification system, thiol compound metabolism, and oxidative stress defense and damage repair metabolism. These results showed that the resistance of DC-F11 to Hg(II) was generally a multisystem collaborative process. Here, we report, for the first time, that the mer-mediated detoxification system was responsible for Hg(II) volatilization in fungus. These findings provide a better understanding of the mechanisms involved in Hg(II) volatilization and resistance that occur in fungi and also provide a strong theoretical basis for the future application of fungi in the bioremediation of Hg-polluted environments.
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Affiliation(s)
- Junjun Chang
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, 650091, China; Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, Yunnan University, Kunming, 650091, China; International Cooperative Center of Plateau Lake Ecological Restoration and Watershed Management of Yunnan, Kunming, 650091, China
| | - Yu Shi
- Institute of International Rivers and Eco-security, Yunnan University, Kunming, 650091, China
| | - Guangzheng Si
- Institute of International Rivers and Eco-security, Yunnan University, Kunming, 650091, China
| | - Qingchen Yang
- Institute of International Rivers and Eco-security, Yunnan University, Kunming, 650091, China
| | - Jia Dong
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, 650091, China
| | - Jinquan Chen
- Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, 650091, China; Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, Yunnan University, Kunming, 650091, China; International Cooperative Center of Plateau Lake Ecological Restoration and Watershed Management of Yunnan, Kunming, 650091, China.
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19
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Effects of Mercury II on Cupriavidus metallidurans Strain MSR33 during Mercury Bioremediation under Aerobic and Anaerobic Conditions. Processes (Basel) 2020. [DOI: 10.3390/pr8080893] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Mercury is a toxic element that harms organisms and disturbs biogeochemical cycles. Mercury bioremediation is based on the reduction of Hg (II) to Hg (0) by mercury-resistant bacteria. Cupriavidus metallidurans MSR33 possesses a broad-spectrum mercury resistance. This study aims to establish the effects of mercury on growth, oxygen uptake, and mercury removal parameters by C. metallidurans MSR33 in aqueous solution during aerobic and anaerobic mercury bioremediation. A new culture medium (GBC) was designed. The effects of mercury (II) (20 ppm) on growth parameters, oxygen uptake, and mercury removal were evaluated in GBC medium in a bioreactor (3 L) under aerobiosis. The anaerobic kinetics of mercury removal was evaluated by nitrogen replacement during mercury bioremediation in a bioreactor. Strain MSR33 reached a growth rate of µ = 0.43 h−1 in the bioreactor. Mercury inhibited oxygen uptake and bacterial growth; however, this inhibition was reversed after 5 h. Strain MSR33 was able to reduce Hg (II) under aerobic and anaerobic conditions, reaching, at 24 h, a metal removal of 97% and 71%, respectively. Therefore, oxygen was crucial for efficient mercury removal by this bacterium. Strain MSR33 was capable of tolerating the toxic effects of mercury (II) during aerobic bioremediation and recovered its metabolic activity.
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20
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Recent developments in environmental mercury bioremediation and its toxicity: A review. ACTA ACUST UNITED AC 2020. [DOI: 10.1016/j.enmm.2020.100283] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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21
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Castro C, Urbieta MS, Plaza Cazón J, Donati ER. Metal biorecovery and bioremediation: Whether or not thermophilic are better than mesophilic microorganisms. BIORESOURCE TECHNOLOGY 2019; 279:317-326. [PMID: 30755320 DOI: 10.1016/j.biortech.2019.02.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 02/03/2019] [Accepted: 02/04/2019] [Indexed: 06/09/2023]
Abstract
Metal mobilization and immobilization catalyzed by microbial action are key processes in environmental biotechnology. Metal mobilization from ores, mining wastes, or solid residues can be used for recovering metals and/or remediating polluted environments; furthermore, immobilization reduces the migration of metals; cleans up effluents plus ground- and surface water; and, moreover, can help to concentrate and recover metals. Usually these processes provide certain advantages over traditional technologies such as more efficient economical and environmentally sustainable results. Since elevated temperatures typically increase chemical kinetics, it could be expected that bioprocesses should also be enhanced by replacing mesophiles with thermophiles or hyperthermophiles. Nevertheless, other issues like process stability, flexibility, and thermophile-versus-mesophile resistance to acidity and/or metal toxicity should be carefully considered. This review critically analyzes and compares thermophilic and mesophilic microbial performances in recent and selected representative examples of metal bioremediation and biorecovery.
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Affiliation(s)
- C Castro
- CINDEFI (CONICET-CCT LA PLATA UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115, (1900), La Plata, Argentina
| | - M S Urbieta
- CINDEFI (CONICET-CCT LA PLATA UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115, (1900), La Plata, Argentina.
| | - J Plaza Cazón
- CINDEFI (CONICET-CCT LA PLATA UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115, (1900), La Plata, Argentina
| | - E R Donati
- CINDEFI (CONICET-CCT LA PLATA UNLP), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115, (1900), La Plata, Argentina
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Superoxide Dismutase and Pseudocatalase Increase Tolerance to Hg(II) in Thermus thermophilus HB27 by Maintaining the Reduced Bacillithiol Pool. mBio 2019; 10:mBio.00183-19. [PMID: 30940703 PMCID: PMC6445937 DOI: 10.1128/mbio.00183-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thermus thermophilus is a deep-branching thermophilic aerobe. It is a member of the Deinococcus-Thermus phylum that, together with the Aquificae, constitute the earliest branching aerobic bacterial lineages; therefore, this organism serves as a model for early diverged bacteria (R. K. Hartmann, J. Wolters, B. Kröger, S. Schultze, et al., Syst Appl Microbiol 11:243–249, 1989, https://doi.org/10.1016/S0723-2020(89)80020-7) whose natural heated habitat may contain mercury of geological origins (G. G. Geesey, T. Barkay, and S. King, Sci Total Environ 569-570:321–331, 2016, https://doi.org/10.1016/j.scitotenv.2016.06.080). T. thermophilus likely arose shortly after the oxidation of the biosphere 2.4 billion years ago. Studying T. thermophilus physiology provides clues about the origin and evolution of mechanisms for mercury and oxidative stress responses, the latter being critical for the survival and function of all extant aerobes. Mercury (Hg) is a widely distributed, toxic heavy metal with no known cellular role. Mercury toxicity has been linked to the production of reactive oxygen species (ROS), but Hg does not directly perform redox chemistry with oxygen. How exposure to the ionic form, Hg(II), generates ROS is unknown. Exposure of Thermus thermophilus to Hg(II) triggered ROS accumulation and increased transcription and activity of superoxide dismutase (Sod) and pseudocatalase (Pcat); however, Hg(II) inactivated Sod and Pcat. Strains lacking Sod or Pcat had increased oxidized bacillithiol (BSH) levels and were more sensitive to Hg(II) than the wild type. The ΔbshA Δsod and ΔbshA Δpcat double mutant strains were as sensitive to Hg(II) as the ΔbshA strain that lacks bacillithiol, suggesting that the increased sensitivity to Hg(II) in the Δsod and Δpcat mutant strains is due to a decrease of reduced BSH. Treatment of T. thermophilus with Hg(II) decreased aconitase activity and increased the intracellular concentration of free Fe, and these phenotypes were exacerbated in Δsod and Δpcat mutant strains. Treatment with Hg(II) also increased DNA damage. We conclude that sequestration of the redox buffering thiol BSH by Hg(II), in conjunction with direct inactivation of ROS-scavenging enzymes, impairs the ability of T. thermophilus to effectively metabolize ROS generated as a normal consequence of growth in aerobic environments.
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Physiological Studies of Chlorobiaceae Suggest that Bacillithiol Derivatives Are the Most Widespread Thiols in Bacteria. mBio 2018; 9:mBio.01603-18. [PMID: 30482829 PMCID: PMC6282198 DOI: 10.1128/mbio.01603-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Low-molecular-weight thiols are key metabolites that participate in many basic cellular processes: central metabolism, detoxification, and oxidative stress resistance. Here we describe a new thiol, N-methyl-bacillithiol, found in an anaerobic phototrophic bacterium and identify a gene that is responsible for its synthesis from bacillithiol, the main thiol metabolite in many Gram-positive bacteria. We show that the presence or absence of this gene in a sequenced genome accurately predicts thiol content in distantly related bacteria. On the basis of these results, we analyzed genome data and predict that bacillithiol and its derivatives are the most widely distributed thiol metabolites in biology. Low-molecular-weight (LMW) thiols mediate redox homeostasis and the detoxification of chemical stressors. Despite their essential functions, the distribution of LMW thiols across cellular life has not yet been defined. LMW thiols are also thought to play a central role in sulfur oxidation pathways in phototrophic bacteria, including the Chlorobiaceae. Here we show that Chlorobaculum tepidum synthesizes a novel LMW thiol with a mass of 412 ± 1 Da corresponding to a molecular formula of C14H24N2O10S, which suggests that the new LMW thiol is closely related to bacillithiol (BSH), the major LMW thiol of low-G+C Gram-positive bacteria. The Cba. tepidum LMW thiol structure was N-methyl-bacillithiol (N-Me-BSH), methylated on the cysteine nitrogen, the fourth instance of this modification in metabolism. Orthologs of bacillithiol biosynthetic genes in the Cba. tepidum genome and the CT1040 gene product, N-Me-BSH synthase, were required for N-Me-BSH synthesis. N-Me-BSH was found in all Chlorobiaceae examined as well as Polaribacter sp. strain MED152, a member of the Bacteroidetes. A comparative genomic analysis indicated that BSH/N-Me-BSH is synthesized not only by members of the Chlorobiaceae, Bacteroidetes, Deinococcus-Thermus, and Firmicutes but also by Acidobacteria, Chlamydiae, Gemmatimonadetes, and Proteobacteria. Thus, BSH and derivatives appear to be the most broadly distributed LMW thiols in biology.
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