1
|
Chen X, Hu J, Cao D, Yang W, Zhang Z, Zu Y, Chen F, Zhiling L, Aijie W. Construction of biochar-based organohalide-respiring bacterial agent for remediation of 2,4,6-trichlorophenol contaminated soil. JOURNAL OF HAZARDOUS MATERIALS 2024; 472:134438. [PMID: 38718504 DOI: 10.1016/j.jhazmat.2024.134438] [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: 12/07/2023] [Revised: 04/17/2024] [Accepted: 04/24/2024] [Indexed: 05/30/2024]
Abstract
Construction of an efficient bio-reductive dechlorination system remains challenging due to the narrow ecological niche and low-growth rate of organohalide-respiring bacteria during field remediation. In this study, a biochar-based organohalide-respiring bacterial agent was obtained, and its performance and effects on indigenous microbial composition, diversity, and inter-relationship in soil were investigated. A well-performing material, Triton X-100 modified biochar (BC600-TX100), was found to have the superior average pore size, specific surface area and hydrophicity, compared to other materials. Interestingly, Pseudomonas aeruginosa CP-1, which is capable of 2,4,6-TCP dechlorination, showed a 348 times higher colonization cell number on BC600-TX100 than that of BC600 after 7 d. Meanwhile, the dechlorination rate in soil showed the highest (0.732 d-1) in the BC600-TX100 bacterial agent than in the other agents. The long-term performance of the BC600-TX100 OHRB agent was also verified, with a stable dechlorination activity over six cycles. Soil microbial community analysis found the addition of the BC600-TX100 OHRB agent significantly increased the relative abundance of genus Pseudomonas from 1.53 % to 11.2 %, and Pseudomonas formed a close interaction relationship with indigenous microorganisms, creating a micro-ecological environment conducive to reductive dechlorination. This study provides a feasible bacterial agent for the in-situ bioremediation of soil contaminated organohalides. ENVIRONMENTAL IMPLICATION: Halogenated organic compounds are a type of toxic, refractory, and bio-accumulative persistent compounds widely existed in environment, widely detected in the air, water, and soil. In this study, we provide a feasible bacterial agent for the in-situ bioremediation of soil contaminated halogenated organic compounds. The application of biochar provides new insights for "Turning waste into treasure", which meets with the concept of green chemistry.
Collapse
Affiliation(s)
- Xueqi Chen
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Jiatian Hu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Di Cao
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Wenxin Yang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Zimeng Zhang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Yunxia Zu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Fan Chen
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China
| | - Li Zhiling
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China.
| | - Wang Aijie
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, PR China; School of Civil & Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, PR China
| |
Collapse
|
2
|
Cimmino L, Duarte AG, Ni D, Ekundayo BE, Pereira IAC, Stahlberg H, Holliger C, Maillard J. Structure of a membrane-bound menaquinol:organohalide oxidoreductase. Nat Commun 2023; 14:7038. [PMID: 37923808 PMCID: PMC10624902 DOI: 10.1038/s41467-023-42927-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 10/26/2023] [Indexed: 11/06/2023] Open
Abstract
Organohalide-respiring bacteria are key organisms for the bioremediation of soils and aquifers contaminated with halogenated organic compounds. The major players in this process are respiratory reductive dehalogenases, corrinoid enzymes that use organohalides as substrates and contribute to energy conservation. Here, we present the structure of a menaquinol:organohalide oxidoreductase obtained by cryo-EM. The membrane-bound protein was isolated from Desulfitobacterium hafniense strain TCE1 as a PceA2B2 complex catalysing the dechlorination of tetrachloroethene. Two catalytic PceA subunits are anchored to the membrane by two small integral membrane PceB subunits. The structure reveals two menaquinone molecules bound at the interface of the two different subunits, which are the starting point of a chain of redox cofactors for electron transfer to the active site. In this work, the structure elucidates how energy is conserved during organohalide respiration in menaquinone-dependent organohalide-respiring bacteria.
Collapse
Affiliation(s)
- Lorenzo Cimmino
- Laboratory for Environmental Biotechnology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Américo G Duarte
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Oeiras, Portugal
| | - Dongchun Ni
- Laboratory of Biological Electron Microscopy, Ecole Polytechnique Fédérale de Lausanne (EPFL), and Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Babatunde E Ekundayo
- Laboratory of Biological Electron Microscopy, Ecole Polytechnique Fédérale de Lausanne (EPFL), and Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Inês A C Pereira
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Oeiras, Portugal
| | - Henning Stahlberg
- Laboratory of Biological Electron Microscopy, Ecole Polytechnique Fédérale de Lausanne (EPFL), and Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
| | - Christof Holliger
- Laboratory for Environmental Biotechnology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - Julien Maillard
- Laboratory for Environmental Biotechnology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| |
Collapse
|
3
|
Kumari S, Das S. Bacterial enzymatic degradation of recalcitrant organic pollutants: catabolic pathways and genetic regulations. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:79676-79705. [PMID: 37330441 DOI: 10.1007/s11356-023-28130-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 06/01/2023] [Indexed: 06/19/2023]
Abstract
Contamination of soil and natural water bodies driven by increased organic pollutants remains a universal concern. Naturally, organic pollutants contain carcinogenic and toxic properties threatening all known life forms. The conventional physical and chemical methods employed to remove these organic pollutants ironically produce toxic and non-ecofriendly end-products. Whereas microbial-based degradation of organic pollutants provides an edge, they are usually cost-effective and take an eco-friendly approach towards remediation. Bacterial species, including Pseudomonas, Comamonas, Burkholderia, and Xanthomonas, have the unique genetic makeup to metabolically degrade toxic pollutants, conferring their survival in toxic environments. Several catabolic genes, such as alkB, xylE, catA, and nahAc, that encode enzymes and allow bacteria to degrade organic pollutants have been identified, characterized, and even engineered for better efficacy. Aerobic and anaerobic processes are followed by bacteria to metabolize aliphatic saturated and unsaturated hydrocarbons such as alkanes, cycloalkanes, aldehydes, and ethers. Bacteria use a variety of degrading pathways, including catechol, protocatechuate, gentisate, benzoate, and biphenyl, to remove aromatic organic contaminants such as polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and pesticides from the environment. A better understanding of the principle, mechanisms, and genetics would be beneficial for improving the metabolic efficacy of bacteria to such ends. With a focus on comprehending the mechanisms involved in various catabolic pathways and the genetics of the biotransformation of these xenobiotic compounds, the present review offers insight into the various sources and types of known organic pollutants and their toxic effects on health and the environment.
Collapse
Affiliation(s)
- Swetambari Kumari
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, 769008, Odisha, India
| | - Surajit Das
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, 769008, Odisha, India.
| |
Collapse
|
4
|
Reino C, Ding C, Adrian L. Continuous cultivation of Dehalococcoides mccartyi with brominated tyrosine avoids toxic byproducts and gives tight reactor control. WATER RESEARCH 2023; 229:119396. [PMID: 36463679 DOI: 10.1016/j.watres.2022.119396] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 11/18/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
Dehalococcoides mccartyi strain CBDB1 is a strictly anaerobic organohalide-respiring bacterium with strong application potential to remediate aquifers and soils contaminated with halogenated aromatics. To date, cultivation of strain CBDB1 has mostly been done in bottles or fed-batch reactors. Challenges with such systems include low biomass yield and difficulties in controlling the growth conditions. Here, we report the cultivation of planktonic D. mccartyi strain CBDB1 in a continuous stirring tank reactor (CSTR) that led to high cell densities (∼8 × 108 cells mL-1) and dominance of strain CBDB1. The reactor culture received acetate, hydrogen, and the brominated amino acid D- or L-3,5-dibromotyrosine as substrates. Both D- and L-3,5-dibromotyrosine were utilized as respiratory electron acceptors and are promising for biomass production due to their decent solubility in water and the formation of a non-toxic debromination product, tyrosine. By monitoring headspace pressure decrease which is indicative of hydrogen consumption, the organohalide respiration rate was followed in real time. Proteomics analyses revealed that the reductive dehalogenase CbdbA238 was highly expressed with both D- and L-3,5-dibromotyrosine, while other reductive dehalogenases including those that were previously suggested to be constitutively expressed, were repressed. Denaturing gradient gel electrophoresis (DGGE) of amplified 16S rRNA genes indicated that the majority of cells in the community belonged to the Dehalococcoides although the CSTR was operated under non-sterile conditions. Hence, tightly controlled CSTR cultivation of Dehalococcoides opens novel options to improve biomass production for bioaugmentation and for advanced biochemical studies.
Collapse
Affiliation(s)
- Clara Reino
- Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstraße 15, 04318, Leipzig, Germany
| | - Chang Ding
- Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstraße 15, 04318, Leipzig, Germany.
| | - Lorenz Adrian
- Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstraße 15, 04318, Leipzig, Germany; Chair of Geobiotechnology, Technische Universität Berlin, Ackerstraße 76, 13355, Berlin, Germany
| |
Collapse
|
5
|
Cimmino L, Schmid AW, Holliger C, Maillard J. Stoichiometry of the Gene Products From the Tetrachloroethene Reductive Dehalogenase Operon pceABCT. Front Microbiol 2022; 13:838026. [PMID: 35283847 PMCID: PMC8905343 DOI: 10.3389/fmicb.2022.838026] [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] [Received: 12/17/2021] [Accepted: 01/27/2022] [Indexed: 11/13/2022] Open
Abstract
Organohalide respiration (OHR) is a bacterial anaerobic process that uses halogenated compounds, e.g., tetrachloroethene (PCE), as terminal electron acceptors. Our model organisms are Dehalobacter restrictus strain PER-K23, an obligate OHR bacterium (OHRB), and Desulfitobacterium hafniense strain TCE1, a bacterium with a versatile metabolism. The key enzyme is the PCE reductive dehalogenase (PceA) that is encoded in the highly conserved gene cluster (pceABCT) in both above-mentioned strains, and in other Firmicutes OHRB. To date, the functions of PceA and PceT, a dedicated molecular chaperone for the maturation of PceA, are well defined. However, the role of PceB and PceC are still not elucidated. We present a multilevel study aiming at deciphering the stoichiometry of pceABCT individual gene products. The investigation was assessed at RNA level by reverse transcription and (quantitative) polymerase chain reaction, while at protein level, proteomic analyses based on parallel reaction monitoring were performed to quantify the Pce proteins in cell-free extracts as well as in soluble and membrane fractions of both strains using heavy-labeled reference peptides. At RNA level, our results confirmed the co-transcription of all pce genes, while the quantitative analysis revealed a relative stoichiometry of the gene transcripts of pceA, pceB, pceC, and pceT at ~ 1.0:3.0:0.1:0.1 in D. restrictus. This trend was not observed in D. hafniense strain TCE1, where no substantial difference was measured for the four genes. At proteomic level, an apparent 2:1 stoichiometry of PceA and PceB was obtained in the membrane fraction, and a low abundance of PceC in comparison to the other two proteins. In the soluble fraction, a 1:1 stoichiometry of PceA and PceT was identified. In summary, we show that the pce gene cluster is transcribed as an operon with, however, a level of transcription that differs for individual genes, an observation that could be explained by post-transcriptional events. Despite challenges in the quantification of integral membrane proteins such as PceB and PceC, the similar abundance of PceA and PceB invites to consider them as forming a membrane-bound PceA2B protein complex, which, in contrast to the proposed model, seems to be devoid of PceC.
Collapse
Affiliation(s)
- Lorenzo Cimmino
- Laboratory for Environmental Biotechnology, Institute for Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Adrien W Schmid
- Protein Core Facility, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Christof Holliger
- Laboratory for Environmental Biotechnology, Institute for Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Julien Maillard
- Laboratory for Environmental Biotechnology, Institute for Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| |
Collapse
|
6
|
An Intracellular Sensing and Signal Transduction System That Regulates the Metabolism of Polycyclic Aromatic Hydrocarbons in Bacteria. mSystems 2021; 6:e0063621. [PMID: 34609168 PMCID: PMC8547461 DOI: 10.1128/msystems.00636-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many bacteria utilize polycyclic aromatic hydrocarbon (PAH) as carbon and energy sources for growth. These bacteria play an important role in the amelioration of PAH pollution in various environments. However, it is unclear how bacteria sense PAHs and how PAH degradation pathways are regulated via signal transduction. Here, we investigated these mechanisms in Cycloclasticus, a ubiquitous PAH-degrading bacterium in marine environments. We identified the key genes involved in intracellular PAH sensing, signal transduction, and the differential regulation of degradation pathways for each PAH examined. Our results showed that PAHs bind specifically to a diguanylate cyclase PdgC, leading to the generation of cyclic dimeric GMP (c-di-GMP), which subsequently binds to two CRP/FNR family regulators, DPR-1 and DPR-2. c-di-GMP activates the transcription of DPR-1 and DPR-2 to positively regulate degradation pathways specific to pyrene and phenanthrene/naphthalene, respectively. This is the first report of an intracellular signal transduction pathway associated with PAH degradation in bacteria. Our results improve our understanding of the intracellular responses to PAHs. The existence of the identified genes in other bacteria indicates that the strategy described here is widely used by other PAH-degrading bacteria. IMPORTANCE Polycyclic aromatic hydrocarbons (PAHs) are widely distributed and have been found indoors, in the atmosphere, in terrestrial soils, in marine waters and sediments, and even in outer space. Bacteria degrade PAHs via degradation pathways. PAH signal sensing and transduction, as well as the regulation of PAH degradation pathways, are crucial for bacterial PAH biodegradation. However, prior to this study, these processes were poorly known. This study employed multiple molecular approaches to better understand the regulatory networks controlling PAH metabolism in bacteria. This report illustrates, for the first time, PAH-specific intracellular sensing, signal transduction, and metabolic regulatory pathways. Our results will help to increase our understanding of the hydrocarbon-metabolism regulatory network as well as the regulatory intricacies that control microbial biodegradation of organic matter. These key data should be considered to improve the rational design and efficiency of recombinant biodegradable, bacterial biosensors, and biocatalysts in modern green chemistry.
Collapse
|
7
|
Shen R, Yu L, Xu P, Liang Z, Lu Q, Liang D, He Z, Wang S. Water content as a primary parameter determines microbial reductive dechlorination activities in soil. CHEMOSPHERE 2021; 267:129152. [PMID: 33316619 DOI: 10.1016/j.chemosphere.2020.129152] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 11/25/2020] [Accepted: 11/27/2020] [Indexed: 06/12/2023]
Abstract
Organohalide-respiring bacteria (OHRB) remove halogens from a variety of organohalides, which have been utilized for in situ remediation of different contaminated sites, e.g., groundwater, sediment and soil. Nonetheless, dehalogenation activities of OHRB and consequent remediation efficiencies can be synergistically affected by water content, soil type and inoculated/indigenous OHRB, which need to be disentangled to identify the key driving parameter and to elucidate the underlying mechanism. In this study, we investigated the impacts of water content (0-100%), soil type (laterite, brown soil and black soil) and inoculated OHRB (Dehalococcoides mccartyi CG1 and a river sediment culture) on reductive dechlorination of perchloroethene (PCE) and polychlorinated biphenyls (PCBs), as well as on associated microbial communities. Results suggested that the water content as a primary rate-limiting parameter governed dechlorination activities in environmental matrices, particularly in the soil, possibly through mediation of cell-to-organohalide mobility of OHRB. By contrast, interestingly, organohalide-dechlorinating microbial communities were predominantly clustered based on soil types, rather than water contents or inoculated OHRB. This study provided knowledge on the impacts of major parameters on OHRB-mediated reductive dechlorination in groundwater, sediment and soil for future optimization of in situ bioremediation of organohalides.
Collapse
Affiliation(s)
- Rui Shen
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, 510006, China
| | - Ling Yu
- Analysis and Test Center, Guangdong University of Technology, Guangzhou, 510006, China
| | - Pan Xu
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, 510006, China
| | - Zhiwei Liang
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, 510006, China
| | - Qihong Lu
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, 510006, China
| | - Dawei Liang
- Beijing Key Laboratory of Bio-inspired Energy Materials and Devices, School of Space & Environment, Beihang University, Beijing, 100191, China
| | - Zhili He
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, 510006, China
| | - Shanquan Wang
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, 510006, China.
| |
Collapse
|
8
|
Esken J, Goris T, Gadkari J, Bischler T, Förstner KU, Sharma CM, Diekert G, Schubert T. Tetrachloroethene respiration in Sulfurospirillum species is regulated by a two-component system as unraveled by comparative genomics, transcriptomics, and regulator binding studies. Microbiologyopen 2020; 9:e1138. [PMID: 33242236 PMCID: PMC7755780 DOI: 10.1002/mbo3.1138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 12/23/2022] Open
Abstract
Energy conservation via organohalide respiration (OHR) in dehalogenating Sulfurospirillum species is an inducible process. However, the gene products involved in tetrachloroethene (PCE) sensing and signal transduction have not been unambiguously identified. Here, genome sequencing of Sulfurospirillum strains defective in PCE respiration and comparative genomics, which included the PCE-respiring representatives of the genus, uncovered the genetic inactivation of a two-component system (TCS) in the OHR gene region of the natural mutants. The assumption that the TCS gene products serve as a PCE sensor that initiates gene transcription was supported by the constitutive low-level expression of the TCS operon in fumarate-adapted cells of Sulfurospirillum multivorans. Via RNA sequencing, eight transcriptional units were identified in the OHR gene region, which includes the TCS operon, the PCE reductive dehalogenase operon, the gene cluster for norcobamide biosynthesis, and putative accessory genes with unknown functions. The OmpR-family response regulator (RR) encoded in the TCS operon was functionally characterized by promoter-binding assays. The RR bound a cis-regulatory element that contained a consensus sequence of a direct repeat (CTATW) separated by 17 bp. Its location either overlapping the -35 box or 50 bp further upstream indicated different regulatory mechanisms. Sequence variations in the regulator binding sites identified in the OHR gene region were in accordance with differences in the transcript levels of the respective gene clusters forming the PCE regulon. The results indicate the presence of a fine-tuned regulatory network controlling PCE metabolism in dehalogenating Sulfurospirillum species, a group of metabolically versatile organohalide-respiring bacteria.
Collapse
Affiliation(s)
- Jens Esken
- Department of Applied and Ecological Microbiology, Institute of Microbiology, Friedrich Schiller University, Jena, Germany.,Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Tobias Goris
- Department of Applied and Ecological Microbiology, Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Jennifer Gadkari
- Department of Applied and Ecological Microbiology, Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Thorsten Bischler
- Core Unit Systems Medicine, University of Würzburg, Würzburg, Germany
| | - Konrad U Förstner
- ZB MED - Information Center for Life Sciences, Cologne, Germany.,TH Köln - University of Applied Sciences, Institute of Information Science, Cologne, Germany
| | - Cynthia M Sharma
- Core Unit Systems Medicine, University of Würzburg, Würzburg, Germany
| | - Gabriele Diekert
- Department of Applied and Ecological Microbiology, Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| | - Torsten Schubert
- Department of Applied and Ecological Microbiology, Institute of Microbiology, Friedrich Schiller University, Jena, Germany.,Research Group Anaerobic Microbiology, Institute of Microbiology, Friedrich Schiller University, Jena, Germany
| |
Collapse
|
9
|
Willemin MS, Vingerhoets M, Holliger C, Maillard J. Hybrid Transcriptional Regulators for the Screening of Target DNA Motifs in Organohalide-Respiring Bacteria. Front Microbiol 2020; 11:310. [PMID: 32194528 PMCID: PMC7062800 DOI: 10.3389/fmicb.2020.00310] [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: 12/02/2019] [Accepted: 02/12/2020] [Indexed: 11/13/2022] Open
Abstract
The bioremediation of persistent organohalide molecules under anoxic conditions mostly relies on the bacterial process called organohalide respiration (OHR). Organohalide-respiring bacteria (OHRB) are phylogenetically diverse anaerobic bacteria that share the capacity to use organohalides as terminal electron acceptors in an energy-conserving process. The reductive dehalogenase (rdh) gene clusters encode for proteins specialized in the respiration of one or a limited number of organohalides. One particular OHRB may harbor up to several dozens of rdh gene clusters suggesting a wide potential for bioremediation. To avoid wasting energy in producing unnecessary proteins, rdh gene clusters often include a transcriptional regulator. In organohalide-respiring Firmicutes, RdhK is a dedicated transcriptional regulator of OHR and represents a subfamily of proteins among the CRP/FNR superfamily of regulators. RdhK proteins are composed of an effector-binding domain (EBD) which recognizes a given organohalide and subsequently controls the interaction of its C-terminal DNA-binding domain (DBD) with a DNA motif (referred to as dehalobox, or DB) located in the promoter region of the target rdh genes. The two binding partners (i.e. an organohalide molecule and a DB sequence) of RdhK proteins are interdependent which impairs the exploration of OHR regulatory networks. Here, we propose a strategy relying on hybrid proteins to efficiently screen the DNA target of a single RdhK protein without prior knowledge on its effector. To demonstrate the potential of the method, two hybrids with alternative fusion points were designed based on RdhK6 EBD and RdhK1 DBD from Desulfitobacterium hafniense. Electrophoretic mobility shift assay was performed with purified hybrids along with the parental proteins and their binding properties were further tested in vivo through a β-galactosidase reporter assay. Along with revealing new RdhK6 features, we show that both hybrids resulted in active regulatory proteins with distinct binding patterns. While Hybrid A was less specific for the DNA motif, Hybrid B successfully mimicked the binding behavior of the parental proteins and thus represents a promising template for the design of new RdhK hybrids to screen yet uncharacterized RdhK proteins and also possibly other members of the CRP/FNR superfamily.
Collapse
Affiliation(s)
- Mathilde Stéphanie Willemin
- Laboratory for Environmental Biotechnology, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Marie Vingerhoets
- Laboratory for Environmental Biotechnology, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Christof Holliger
- Laboratory for Environmental Biotechnology, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Julien Maillard
- Laboratory for Environmental Biotechnology, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| |
Collapse
|