1
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Trotter VV, Shatsky M, Price MN, Juba TR, Zane GM, De León KB, Majumder ELW, Gui Q, Ali R, Wetmore KM, Kuehl JV, Arkin AP, Wall JD, Deutschbauer AM, Chandonia JM, Butland GP. Large-scale genetic characterization of the model sulfate-reducing bacterium, Desulfovibrio vulgaris Hildenborough. Front Microbiol 2023; 14:1095191. [PMID: 37065130 PMCID: PMC10102598 DOI: 10.3389/fmicb.2023.1095191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 03/10/2023] [Indexed: 04/03/2023] Open
Abstract
Sulfate-reducing bacteria (SRB) are obligate anaerobes that can couple their growth to the reduction of sulfate. Despite the importance of SRB to global nutrient cycles and their damage to the petroleum industry, our molecular understanding of their physiology remains limited. To systematically provide new insights into SRB biology, we generated a randomly barcoded transposon mutant library in the model SRB Desulfovibrio vulgaris Hildenborough (DvH) and used this genome-wide resource to assay the importance of its genes under a range of metabolic and stress conditions. In addition to defining the essential gene set of DvH, we identified a conditional phenotype for 1,137 non-essential genes. Through examination of these conditional phenotypes, we were able to make a number of novel insights into our molecular understanding of DvH, including how this bacterium synthesizes vitamins. For example, we identified DVU0867 as an atypical L-aspartate decarboxylase required for the synthesis of pantothenic acid, provided the first experimental evidence that biotin synthesis in DvH occurs via a specialized acyl carrier protein and without methyl esters, and demonstrated that the uncharacterized dehydrogenase DVU0826:DVU0827 is necessary for the synthesis of pyridoxal phosphate. In addition, we used the mutant fitness data to identify genes involved in the assimilation of diverse nitrogen sources and gained insights into the mechanism of inhibition of chlorate and molybdate. Our large-scale fitness dataset and RB-TnSeq mutant library are community-wide resources that can be used to generate further testable hypotheses into the gene functions of this environmentally and industrially important group of bacteria.
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Affiliation(s)
- Valentine V. Trotter
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Maxim Shatsky
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Morgan N. Price
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Thomas R. Juba
- Department of Biochemistry, University of Missouri, Columbia, MO, United States
| | - Grant M. Zane
- Department of Biochemistry, University of Missouri, Columbia, MO, United States
| | - Kara B. De León
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, United States
| | - Erica L.-W. Majumder
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, United States
| | - Qin Gui
- Department of Biochemistry, University of Missouri, Columbia, MO, United States
| | - Rida Ali
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Kelly M. Wetmore
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Jennifer V. Kuehl
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Adam P. Arkin
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, United States
| | - Judy D. Wall
- Department of Biochemistry, University of Missouri, Columbia, MO, United States
| | - Adam M. Deutschbauer
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
| | - John-Marc Chandonia
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Gareth P. Butland
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
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2
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Feng Y, Bui TPN, Stams AJM, Boeren S, Sánchez-Andrea I, de Vos WM. Comparative genomics and proteomics of Eubacterium maltosivorans: functional identification of trimethylamine methyltransferases and bacterial microcompartments in a human intestinal bacterium with a versatile lifestyle. Environ Microbiol 2022; 24:517-534. [PMID: 34978130 PMCID: PMC9303578 DOI: 10.1111/1462-2920.15886] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 12/01/2021] [Accepted: 12/21/2021] [Indexed: 12/14/2022]
Abstract
Eubacterium maltosivorans YIT is a human intestinal isolate capable of acetogenic, propionogenic and butyrogenic growth. Its 4.3-Mb genome sequence contains coding sequences for 4227 proteins, including 41 different methyltransferases. Comparative proteomics of strain YIT showed the Wood-Ljungdahl pathway proteins to be actively produced during homoacetogenic growth on H2 and CO2 while butyrogenic growth on a mixture of lactate and acetate significantly upregulated the production of proteins encoded by the recently identified lctABCDEF cluster and accessory proteins. Growth on H2 and CO2 unexpectedly induced the production of two related trimethylamine methyltransferases. Moreover, a set of 16 different trimethylamine methyltransferases together with proteins for bacterial microcompartments were produced during growth and deamination of the quaternary amines, betaine, carnitine and choline. Growth of strain YIT on 1,2-propanediol generated propionate with propanol and induced the formation of bacterial microcompartments that were also prominently visible in betaine-grown cells. The present study demonstrates that E. maltosivorans is highly versatile in converting low-energy fermentation end-products in the human gut into butyrate and propionate whilst being capable of preventing the formation of the undesired trimethylamine by converting betaine and other quaternary amines in bacterial microcompartments into acetate and butyrate.
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Affiliation(s)
- Yuan Feng
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands
| | - Thi Phuong Nam Bui
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands.,Caelus Pharmaceuticals, Amsterdam, The Netherlands
| | - Alfons J M Stams
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands.,Centre of Biological Engineering, IBB - Institute for Biotechnology and Bioengineering, University of Minho, Campus de Gualtar, Braga, 4710-057, Portugal
| | - Sjef Boeren
- Laboratory of Biochemistry, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands
| | - Irene Sánchez-Andrea
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands
| | - Willem M de Vos
- Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, Wageningen, 6708 WE, The Netherlands.,Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00014, Finland
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3
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Burrichter AG, Dörr S, Bergmann P, Haiß S, Keller A, Fournier C, Franchini P, Isono E, Schleheck D. Bacterial microcompartments for isethionate desulfonation in the taurine-degrading human-gut bacterium Bilophila wadsworthia. BMC Microbiol 2021; 21:340. [PMID: 34903181 PMCID: PMC8667426 DOI: 10.1186/s12866-021-02386-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/08/2021] [Indexed: 11/15/2022] Open
Abstract
Background Bilophila wadsworthia, a strictly anaerobic, sulfite-reducing bacterium and common member of the human gut microbiota, has been associated with diseases such as appendicitis and colitis. It is specialized on organosulfonate respiration for energy conservation, i.e., utilization of dietary and host-derived organosulfonates, such as taurine (2-aminoethansulfonate), as sulfite donors for sulfite respiration, producing hydrogen sulfide (H2S), an important intestinal metabolite that may have beneficial as well as detrimental effects on the colonic environment. Its taurine desulfonation pathway involves the glycyl radical enzyme (GRE) isethionate sulfite-lyase (IslAB), which cleaves isethionate (2-hydroxyethanesulfonate) into acetaldehyde and sulfite. Results We demonstrate that taurine metabolism in B. wadsworthia 3.1.6 involves bacterial microcompartments (BMCs). First, we confirmed taurine-inducible production of BMCs by proteomic, transcriptomic and ultra-thin sectioning and electron-microscopical analyses. Then, we isolated BMCs from taurine-grown cells by density-gradient ultracentrifugation and analyzed their composition by proteomics as well as by enzyme assays, which suggested that the GRE IslAB and acetaldehyde dehydrogenase are located inside of the BMCs. Finally, we are discussing the recycling of cofactors in the IslAB-BMCs and a potential shuttling of electrons across the BMC shell by a potential iron-sulfur (FeS) cluster-containing shell protein identified by sequence analysis. Conclusions We characterized a novel subclass of BMCs and broadened the spectrum of reactions known to take place enclosed in BMCs, which is of biotechnological interest. We also provided more details on the energy metabolism of the opportunistic pathobiont B. wadsworthia and on microbial H2S production in the human gut. Supplementary Information The online version contains supplementary material available at 10.1186/s12866-021-02386-w.
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Affiliation(s)
- Anna G Burrichter
- Department of Biology, University of Konstanz, Konstanz, Germany. .,Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany. .,Max von Pettenkofer Institute of Hygiene and Medical Microbiology, Faculty of Medicine, LMU Munich, Munich, Germany.
| | - Stefanie Dörr
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Paavo Bergmann
- Electron Microscopy Centre, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Sebastian Haiß
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Anja Keller
- Department of Biology, University of Konstanz, Konstanz, Germany.,Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
| | | | - Paolo Franchini
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Erika Isono
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - David Schleheck
- Department of Biology, University of Konstanz, Konstanz, Germany. .,Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany.
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4
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Era Y, Dennis JA, Wallace S, Horsfall LE. Micellar catalysis of the Suzuki Miyaura reaction using biogenic Pd nanoparticles from Desulfovibrio alaskensis. GREEN CHEMISTRY : AN INTERNATIONAL JOURNAL AND GREEN CHEMISTRY RESOURCE : GC 2021; 23:8886-8890. [PMID: 34912180 PMCID: PMC8593813 DOI: 10.1039/d1gc02392f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/22/2021] [Indexed: 06/02/2023]
Abstract
Microorganisms produce metal nanoparticles (MNPs) upon exposure to toxic metal ions. However, the catalytic activity of biosynthesised MNPs remains underexplored, despite the potential of these biological processes to be used for the sustainable recovery of critical metals, including palladium. Herein we report that biogenic palladium nanoparticles generated by the sulfate-reducing bacterium Desulfovibrio alaskensis G20 catalyse the ligand-free Suzuki Miyaura reaction of abiotic substrates. The reaction is highly efficient (>99% yield, 0.5 mol% Pd), occurs under mild conditions (37 °C, aqueous media) and can be accelerated within biocompatible micelles at the cell membrane to yield products containing challenging biaryl bonds. This work highlights how native metabolic processes in anaerobic bacteria can be combined with green chemical technologies to produce highly efficient catalytic reactions for use in sustainable organic synthesis.
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Affiliation(s)
- Yuta Era
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh Roger Land Building Alexander Crum Brown Road King's Buildings Edinburgh EH9 3FF UK
| | - Jonathan A Dennis
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh Roger Land Building Alexander Crum Brown Road King's Buildings Edinburgh EH9 3FF UK
- School of Chemistry, University of Edinburgh Joseph Black Building David Brewster Road King's Buildings Edinburgh EH9 3F UK
| | - Stephen Wallace
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh Roger Land Building Alexander Crum Brown Road King's Buildings Edinburgh EH9 3FF UK
| | - Louise E Horsfall
- Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh Roger Land Building Alexander Crum Brown Road King's Buildings Edinburgh EH9 3FF UK
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5
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Wall JD, Zane GM, Juba TR, Kuehl JV, Ray J, Chhabra SR, Trotter VV, Shatsky M, De León KB, Keller KL, Bender KS, Butland G, Arkin AP, Deutschbauer AM. Deletion Mutants, Archived Transposon Library, and Tagged Protein Constructs of the Model Sulfate-Reducing Bacterium Desulfovibrio vulgaris Hildenborough. Microbiol Resour Announc 2021; 10:e00072-21. [PMID: 33737356 PMCID: PMC7975874 DOI: 10.1128/mra.00072-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 02/17/2021] [Indexed: 11/20/2022] Open
Abstract
The dissimilatory sulfate-reducing deltaproteobacterium Desulfovibrio vulgaris Hildenborough (ATCC 29579) was chosen by the research collaboration ENIGMA to explore tools and protocols for bringing this anaerobe to model status. Here, we describe a collection of genetic constructs generated by ENIGMA that are available to the research community.
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Affiliation(s)
- Judy D Wall
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Grant M Zane
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Thomas R Juba
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Jennifer V Kuehl
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Jayashree Ray
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Swapnil R Chhabra
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Valentine V Trotter
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Maxim Shatsky
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Kara B De León
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Kimberly L Keller
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Kelly S Bender
- Biochemistry Division, University of Missouri, Columbia, Missouri, USA
| | - Gareth Butland
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Adam P Arkin
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Adam M Deutschbauer
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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6
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Shao S, Wei L, Xia F, Zhang Y, Wang AQ. Defined Mutant Library Sequencing (DML-Seq) for Identification of Conditional Essential Genes. Bio Protoc 2021; 11:e3943. [PMID: 33796617 DOI: 10.21769/bioprotoc.3943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 01/12/2021] [Accepted: 01/16/2021] [Indexed: 11/02/2022] Open
Abstract
Transposon insertion sequencing (TIS) is an emerging technique which utilizes a massive transposon mutant library to screen specific phenotype and determine the conditional essential genetic requirements for bacterial fitness under distinct conditions combined with high-throughput parallel sequencing technology. Compared with a massive mutant library in traditional TIS, the defined mutant library sequencing (DML-Seq) has advantages as: 1) efficient mutagenesis; 2) low bottleneck effects; 3) avoid hotpots caused by screening; 4) can be directly used in the following experiments. Here, we described an optimized procedure of DML-Seq for fitness screen to supply classical TIS using the marine pathogenic bacterium Edwardsiella piscicida as an example.
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Affiliation(s)
- Shuai Shao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Lifan Wei
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.,Department of Endodontics and Operative Dentistry, Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Feng Xia
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yuanxing Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 130 Meilong Road, Shanghai 200237, China.,Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
| | - And Qiyao Wang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.,Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 130 Meilong Road, Shanghai 200237, China.,Shanghai Engineering Research Center of Maricultured Animal Vaccines, Shanghai 200237, China
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7
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Smith DA, Fike DA, Johnston DT, Bradley AS. Isotopic Fractionation Associated With Sulfate Import and Activation by Desulfovibrio vulgaris str. Hildenborough. Front Microbiol 2020; 11:529317. [PMID: 33072004 PMCID: PMC7531388 DOI: 10.3389/fmicb.2020.529317] [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: 01/23/2020] [Accepted: 08/14/2020] [Indexed: 11/13/2022] Open
Abstract
The use of stable isotopes to trace biogeochemical sulfur cycling relies on an understanding of how isotopic fractionation is imposed by metabolic networks. We investigated the effects of the first two enzymatic steps in the dissimilatory sulfate reduction (DSR) network - sulfate permease and sulfate adenylyl transferase (Sat) - on the sulfur and oxygen isotopic composition of residual sulfate. Mutant strains of Desulfovibrio vulgaris str. Hildenborough (DvH) with perturbed expression of these enzymes were grown in batch culture, with a subset grown in continuous culture, to examine the impact of these enzymatic steps on growth rate, cell specific sulfate reduction rate and isotopic fractionations in comparison to the wild type strain. Deletion of several permease genes resulted in only small (∼1‰) changes in sulfur isotope fractionation, a difference that approaches the uncertainties of the measurement. Mutants that perturb Sat expression show higher fractionations than the wild type strain. This increase probably relates to an increased material flux between sulfate and APS, allowing an increase in the expressed fractionation of rate-limiting APS reductase. This work illustrates that flux through the initial steps of the DSR pathway can affect the fractionation imposed by the overall pathway, even though these steps are themselves likely to impose only small fractionations.
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Affiliation(s)
- Derek A Smith
- Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO, United States
| | - David A Fike
- Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO, United States
| | - David T Johnston
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, United States
| | - Alexander S Bradley
- Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO, United States.,Division of Biology and Biomedical Sciences, Washington University in St. Louis, St. Louis, MO, United States
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8
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Anion transport as a target of adaption to perchlorate in sulfate-reducing communities. ISME JOURNAL 2019; 14:450-462. [PMID: 31659234 DOI: 10.1038/s41396-019-0540-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/04/2019] [Accepted: 09/12/2019] [Indexed: 11/09/2022]
Abstract
Inhibitors can be used to control the functionality of microbial communities by targeting specific metabolisms. The targeted inhibition of dissimilatory sulfate reduction limits the generation of toxic and corrosive hydrogen sulfide across several industrial systems. Sulfate-reducing microorganisms (SRM) are specifically inhibited by sulfate analogs, such as perchlorate. Previously, we showed pure culture SRM adaptation to perchlorate stress through mutation of the sulfate adenylyltransferase, a central enzyme in the sulfate reduction pathway. Here, we explored adaptation to perchlorate across unconstrained SRM on a community scale. We followed natural and bio-augmented sulfidogenic communities through serial transfers in increasing concentrations of perchlorate. Our results demonstrated that perchlorate stress altered community structure by initially selecting for innately more resistant strains. Isolation, whole-genome sequencing, and molecular biology techniques allowed us to define subsequent genetic mechanisms of adaptation that arose across the dominant adapting SRM. Changes in the regulation of divalent anion:sodium symporter family transporters led to increased intracellular sulfate to perchlorate ratios, allowing SRM to escape the effects of competitive inhibition. Thus, in contrast to pure-culture results, SRM in communities cope with perchlorate stress via changes in anion transport and its regulation. This highlights the value of probing evolutionary questions in an ecological framework, bridging the gap between ecology, evolution, genomics, and physiology.
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9
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Rajeev L, Luning EG, Zane GM, Juba TR, Kazakov AE, Novichkov PS, Wall JD, Mukhopadhyay A. LurR is a regulator of the central lactate oxidation pathway in sulfate-reducing Desulfovibrio species. PLoS One 2019; 14:e0214960. [PMID: 30964892 PMCID: PMC6456213 DOI: 10.1371/journal.pone.0214960] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 03/22/2019] [Indexed: 11/18/2022] Open
Abstract
The central carbon/lactate utilization pathway in the model sulfate-reducing bacterium, Desulfovibrio vulgaris Hildenborough, is encoded by the highly conserved operon DVU3025-3033. Our earlier in vitro genome-wide study had suggested a network of four two-component system regulators that target this large operon; however, how these four regulators control this operon was not known. Here, we probe the regulation of the lactate utilization operon with mutant strains and DNA-protein binding assays. We show that the LurR response regulator is required for optimal growth and complete lactate utilization, and that it activates the DVU3025-3033 lactate oxidation operon as well as DVU2451, a lactate permease gene, in the presence of lactate. We show by electrophoretic mobility shift assays that LurR binds to three sites in the upstream region of DVU3025, the first gene of the operon. NrfR, a response regulator that is activated under nitrite stress, and LurR share similar binding site motifs and bind the same sites upstream of DVU3025. The DVU3025 promoter also has a binding site motif (Pho box) that is bound by PhoB, a two-component response regulator activated under phosphate limitation. The lactate utilization operon, the regulator LurR, and LurR binding sites are conserved across the order Desulfovibrionales whereas possible modulation of the lactate utilization genes by additional regulators such as NrfR and PhoB appears to be limited to D. vulgaris.
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Affiliation(s)
- Lara Rajeev
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Eric G. Luning
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Grant M. Zane
- Department of Biochemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Thomas R. Juba
- Department of Biochemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Alexey E. Kazakov
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Pavel S. Novichkov
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Judy D. Wall
- Department of Biochemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Aindrila Mukhopadhyay
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- * E-mail:
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10
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Mehta‐Kolte MG, Stoeva MK, Mehra A, Redford SA, Youngblut MD, Zane G, Grégoire P, Carlson HK, Wall J, Coates JD. Adaptation ofDesulfovibrio alaskensisG20 to perchlorate, a specific inhibitor of sulfate reduction. Environ Microbiol 2019; 21:1395-1406. [DOI: 10.1111/1462-2920.14570] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/20/2019] [Accepted: 02/23/2019] [Indexed: 12/01/2022]
Affiliation(s)
| | - Magdalena K. Stoeva
- Energy Biosciences InstituteUniversity of California‐ Berkeley, Berkeley CA USA
- Department of Plant and Microbial BiologyUniversity of California‐ Berkeley Berkeley CA USA
| | - Anchal Mehra
- Energy Biosciences InstituteUniversity of California‐ Berkeley, Berkeley CA USA
- Department of Plant and Microbial BiologyUniversity of California‐ Berkeley Berkeley CA USA
| | - Steven A. Redford
- Energy Biosciences InstituteUniversity of California‐ Berkeley, Berkeley CA USA
| | | | - Grant Zane
- Departments of Biochemistry and Molecular Microbiology and ImmunologyUniversity of Missouri—Columbia Columbia MO USA
| | - Patrick Grégoire
- Energy Biosciences InstituteUniversity of California‐ Berkeley, Berkeley CA USA
| | - Hans K. Carlson
- Energy Biosciences InstituteUniversity of California‐ Berkeley, Berkeley CA USA
| | - Judy Wall
- Departments of Biochemistry and Molecular Microbiology and ImmunologyUniversity of Missouri—Columbia Columbia MO USA
| | - John D. Coates
- Energy Biosciences InstituteUniversity of California‐ Berkeley, Berkeley CA USA
- Department of Plant and Microbial BiologyUniversity of California‐ Berkeley Berkeley CA USA
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11
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A glycyl radical enzyme enables hydrogen sulfide production by the human intestinal bacterium Bilophila wadsworthia. Proc Natl Acad Sci U S A 2019; 116:3171-3176. [PMID: 30718429 PMCID: PMC6386719 DOI: 10.1073/pnas.1815661116] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
This paper describes a pathway for anaerobic bacterial metabolism of taurine (2-aminoethanesulfonate), an abundant substrate in the human intestinal microbiota, by the intestinal bacterium and opportunistic pathogen, Bilophila wadsworthia. This metabolism converts taurine to the toxic metabolite hydrogen sulfide (H2S), an activity associated with inflammatory bowel disease and colorectal cancer. A critical enzyme in this pathway is isethionate sulfite-lyase, a member of the glycyl radical enzyme family. This enzyme catalyzes a novel, radical-based C-S bond-cleavage reaction to convert isethionate (2-hydroxyethanesulfonate) to sulfite and acetaldehyde. This discovery improves our understanding of H2S production in the human body and may also offer new approaches for controlling intestinal H2S production and B. wadsworthia infections. Hydrogen sulfide (H2S) production in the intestinal microbiota has many contributions to human health and disease. An important source of H2S in the human gut is anaerobic respiration of sulfite released from the abundant dietary and host-derived organic sulfonate substrate in the gut, taurine (2-aminoethanesulfonate). However, the enzymes that allow intestinal bacteria to access sulfite from taurine have not yet been identified. Here we decipher the complete taurine desulfonation pathway in Bilophila wadsworthia 3.1.6 using differential proteomics, in vitro reconstruction with heterologously produced enzymes, and identification of critical intermediates. An initial deamination of taurine to sulfoacetaldehyde by a known taurine:pyruvate aminotransferase is followed, unexpectedly, by reduction of sulfoacetaldehyde to isethionate (2-hydroxyethanesulfonate) by an NADH-dependent reductase. Isethionate is then cleaved to sulfite and acetaldehyde by a previously uncharacterized glycyl radical enzyme (GRE), isethionate sulfite-lyase (IslA). The acetaldehyde produced is oxidized to acetyl-CoA by a dehydrogenase, and the sulfite is reduced to H2S by dissimilatory sulfite reductase. This unique GRE is also found in Desulfovibrio desulfuricans DSM642 and Desulfovibrio alaskensis G20, which use isethionate but not taurine; corresponding knockout mutants of D. alaskensis G20 did not grow with isethionate as the terminal electron acceptor. In conclusion, the novel radical-based C-S bond-cleavage reaction catalyzed by IslA diversifies the known repertoire of GRE superfamily enzymes and enables the energy metabolism of B. wadsworthia. This GRE is widely distributed in gut bacterial genomes and may represent a novel target for control of intestinal H2S production.
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12
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Rajeev L, Garber ME, Zane GM, Price MN, Dubchak I, Wall JD, Novichkov PS, Mukhopadhyay A, Kazakov AE. A new family of transcriptional regulators of tungstoenzymes and molybdate/tungstate transport. Environ Microbiol 2019; 21:784-799. [PMID: 30536693 DOI: 10.1111/1462-2920.14500] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 12/03/2018] [Accepted: 12/07/2018] [Indexed: 11/30/2022]
Abstract
Bacterial genes for molybdenum-containing and tungsten-containing enzymes are often differentially regulated depending on the metal availability in the environment. Here, we describe a new family of transcription factors with an unusual DNA-binding domain related to excisionases of bacteriophages. These transcription factors are associated with genes for various molybdate and tungstate-specific transporting systems as well as molybdo/tungsto-enzymes in a wide range of bacterial genomes. We used a combination of computational and experimental techniques to study a member of the TF family, named TaoR (for tungsten-containing aldehyde oxidoreductase regulator). In Desulfovibrio vulgaris Hildenborough, a model bacterium for sulfate reduction studies, TaoR activates expression of aldehyde oxidoreductase aor and represses tungsten-specific ABC-type transporter tupABC genes under tungsten-replete conditions. TaoR binding sites at aor promoter were identified by electrophoretic mobility shift assay and DNase I footprinting. We also reconstructed TaoR regulons in 45 Deltaproteobacteria by comparative genomics approach and predicted target genes for TaoR family members in other Proteobacteria and Firmicutes.
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Affiliation(s)
- L Rajeev
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - M E Garber
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Comparative Biochemistry, University of California, Berkeley, CA, 94720, USA
| | - G M Zane
- Biochemistry and Molecular Microbiology & Immunology Department, University of Missouri, Columbia, MO, 65211, USA
| | - M N Price
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - I Dubchak
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - J D Wall
- Biochemistry and Molecular Microbiology & Immunology Department, University of Missouri, Columbia, MO, 65211, USA
| | - P S Novichkov
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Energy, Knowledge Base, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - A Mukhopadhyay
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.,Department of Comparative Biochemistry, University of California, Berkeley, CA, 94720, USA.,Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - A E Kazakov
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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13
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Grilli DJ, Mansilla ME, Giménez MC, Sohaefer N, Ruiz MS, Terebiznik MR, Sosa M, Arenas GN. Pseudobutyrivibrio xylanivorans adhesion to epithelial cells. Anaerobe 2019; 56:1-7. [PMID: 30615946 DOI: 10.1016/j.anaerobe.2019.01.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/06/2018] [Accepted: 01/02/2019] [Indexed: 01/09/2023]
Abstract
The ruminal bacteria Pseudobutyrivibrio xylanivorans strain 2 (P. xylanivorans 2), that mediates the digestion of plant fiber, is considered an attractive candidate for probiotics. Adherence to the epithelium of the digestive tract of the host is one of the major requirements for probiotics. In this study, we assessed the adhesion of P. xylanivorans 2 to SW480 cells and characterized this process utilizing multiple microscopy approaches. Our results indicate that a multiplicity of infection of 200 CFU/cell allows the highest bacteria to cell binding ratio, with a lower percentage of auto-agglutination events. The comparison of the adherence capacity subjected heat-shock treatment (100 °C, 1 min), which produces the denaturalization of proteins at the bacterial surface, as opposed untreated P. xylanivorans, suggested that this bacteria may attach to SW480 cells utilizing a proteinaceous structure. Confocal microscopy analyses indicate that P. xylanivorans 2 attachment induces the formation of F-actin-enriched areas on the surface of SW480 cells. Transmission electron microscopy (TEM) revealed the formation of a structure similar to a pedestal in the area of the epithelial cell surface, where the bacterium rests. Finally, a casual finding of TEM analysis of transverse and longitudinal thin-sections of P. xylanivorans 2, revealed irregular intra-cytoplasmic structures compatibles with the so-called bacterial microcompartments. This is the first ultrastructural description of bacterial microcompartments-like structures in the genus Pseudobutyrivibrio.
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Affiliation(s)
- Diego Javier Grilli
- Facultad de Ciencias Veterinarias y Ambientales, Universidad Juan Agustín Maza, Av. Acceso Este Lateral Sur 2245, CP 5519, Mendoza, Argentina; Instituto de Histología y Embriología de Mendoza, Universidad Nacional de Cuyo, Casilla de Correo 56, CP 5500, Mendoza, Argentina; Área de Microbiología, Departamento de Patología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Casilla de Correo 56, CP 5500, Mendoza, Argentina.
| | - Maria Eugenia Mansilla
- Instituto de Histología y Embriología de Mendoza, Universidad Nacional de Cuyo, Casilla de Correo 56, CP 5500, Mendoza, Argentina; Facultad de Farmacia y Bioquímica, Universidad Juan Agustín Maza, Av. Acceso Este Lateral Sur 2245, CP 5519, Mendoza, Argentina
| | - María Cecilia Giménez
- Facultad de Ciencias Veterinarias y Ambientales, Universidad Juan Agustín Maza, Av. Acceso Este Lateral Sur 2245, CP 5519, Mendoza, Argentina; Instituto de Histología y Embriología de Mendoza, Universidad Nacional de Cuyo, Casilla de Correo 56, CP 5500, Mendoza, Argentina; Departments of Biological Sciences and Cell and Systems Biology, University of Toronto at Scarborough, Toronto, Ontario, Canada
| | - Noelia Sohaefer
- Facultad de Ciencias Veterinarias y Ambientales, Universidad Juan Agustín Maza, Av. Acceso Este Lateral Sur 2245, CP 5519, Mendoza, Argentina
| | - María Soledad Ruiz
- Facultad de Ciencias Veterinarias y Ambientales, Universidad Juan Agustín Maza, Av. Acceso Este Lateral Sur 2245, CP 5519, Mendoza, Argentina
| | - Mauricio R Terebiznik
- Departments of Biological Sciences and Cell and Systems Biology, University of Toronto at Scarborough, Toronto, Ontario, Canada
| | - Miguel Sosa
- Instituto de Histología y Embriología de Mendoza, Universidad Nacional de Cuyo, Casilla de Correo 56, CP 5500, Mendoza, Argentina
| | - Graciela Nora Arenas
- Facultad de Ciencias Veterinarias y Ambientales, Universidad Juan Agustín Maza, Av. Acceso Este Lateral Sur 2245, CP 5519, Mendoza, Argentina; Área de Microbiología, Departamento de Patología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Casilla de Correo 56, CP 5500, Mendoza, Argentina; Facultad de Farmacia y Bioquímica, Universidad Juan Agustín Maza, Av. Acceso Este Lateral Sur 2245, CP 5519, Mendoza, Argentina
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14
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Stoeva MK, Coates JD. Specific inhibitors of respiratory sulfate reduction: towards a mechanistic understanding. MICROBIOLOGY-SGM 2018; 165:254-269. [PMID: 30556806 DOI: 10.1099/mic.0.000750] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Microbial sulfate reduction (SR) by sulfate-reducing micro-organisms (SRM) is a primary environmental mechanism of anaerobic organic matter mineralization, and as such influences carbon and sulfur cycling in many natural and engineered environments. In industrial systems, SR results in the generation of hydrogen sulfide, a toxic, corrosive gas with adverse human health effects and significant economic and environmental consequences. Therefore, there has been considerable interest in developing strategies for mitigating hydrogen sulfide production, and several specific inhibitors of SRM have been identified and characterized. Specific inhibitors are compounds that disrupt the metabolism of one group of organisms, with little or no effect on the rest of the community. Putative specific inhibitors of SRM have been used to control sulfidogenesis in industrial and engineered systems. Despite the value of these inhibitors, mechanistic and quantitative studies into the molecular mechanisms of their inhibition have been sparse and unsystematic. The insight garnered by such studies is essential if we are to have a more complete understanding of SR, including the past and current selective pressures acting upon it. Furthermore, the ability to reliably control sulfidogenesis - and potentially assimilatory sulfate pathways - relies on a thorough molecular understanding of inhibition. The scope of this review is to summarize the current state of the field: how we measure and understand inhibition, the targets of specific SR inhibitors and how SRM acclimatize and/or adapt to these stressors.
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Affiliation(s)
- Magdalena K Stoeva
- 1Energy Biosciences Institute, University of California - Berkeley, Berkeley, CA, USA
- 2Department of Plant and Microbial Biology, University of California - Berkeley, Berkeley, CA, USA
| | - John D Coates
- 2Department of Plant and Microbial Biology, University of California - Berkeley, Berkeley, CA, USA
- 1Energy Biosciences Institute, University of California - Berkeley, Berkeley, CA, USA
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15
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Williamson AJ, Carlson HK, Kuehl JV, Huang LL, Iavarone AT, Deutschbauer A, Coates JD. Dissimilatory Sulfate Reduction Under High Pressure by Desulfovibrio alaskensis G20. Front Microbiol 2018; 9:1465. [PMID: 30050504 PMCID: PMC6052904 DOI: 10.3389/fmicb.2018.01465] [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] [Received: 04/09/2018] [Accepted: 06/12/2018] [Indexed: 11/17/2022] Open
Abstract
Biosouring results from production of H2S by sulfate-reducing microorganisms (SRMs) in oil reservoirs. H2S is toxic, corrosive, and explosive, and as such, represents a significant threat to personnel, production facilities, and transportation pipelines. Since typical oil reservoir pressures can range from 10 to 50 MPa, understanding the role that pressure plays in SRM metabolism is important to improving souring containment strategies. To explore the impact of pressure, we grew an oil-field SRM isolate, Desulfovibrio alaskensis G20, under a range of pressures (0.1–14 MPa) at 30°C. The observed microbial growth rate was an inverse function of pressure with an associated slight reduction in sulfate and lactate consumption rate. Competitive fitness experiments with randomly bar-coded transposon mutant library sequencing (RB-TnSeq) identified several genes associated with flagellar biosynthesis and assembly that were important at high pressure. The fitness impact of specific genes was confirmed using individual transposon mutants. Confocal microscopy revealed that enhanced cell aggregation occurs at later stages of growth under pressure. We also assessed the effect of pressure on SRM inhibitor potency. Dose-response experiments showed a twofold decrease in the sensitivity of D. alaskensis to the antibiotic chloramphenicol at 14 MPa. Fortuitously, pressure had no significant influence on the inhibitory potency of the common souring controlling agent nitrate, or the emerging SRM inhibitors perchlorate, monofluorophosphate, or zinc pyrithione. Our findings improve the conceptual model of microbial sulfate reduction in high-pressure environments and the influence of pressure on souring inhibitor efficacy.
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Affiliation(s)
- Adam J Williamson
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Hans K Carlson
- Energy Biosciences Institute, Berkeley, CA, United States
| | - Jennifer V Kuehl
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Leah L Huang
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Anthony T Iavarone
- QB3/Chemistry Mass Spectrometry Facility, University of California, Berkeley, Berkeley, CA, United States
| | - Adam Deutschbauer
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - John D Coates
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States.,Energy Biosciences Institute, Berkeley, CA, United States
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16
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Price MN, Wetmore KM, Waters RJ, Callaghan M, Ray J, Liu H, Kuehl JV, Melnyk RA, Lamson JS, Suh Y, Carlson HK, Esquivel Z, Sadeeshkumar H, Chakraborty R, Zane GM, Rubin BE, Wall JD, Visel A, Bristow J, Blow MJ, Arkin AP, Deutschbauer AM. Mutant phenotypes for thousands of bacterial genes of unknown function. Nature 2018; 557:503-509. [PMID: 29769716 DOI: 10.1038/s41586-018-0124-0] [Citation(s) in RCA: 301] [Impact Index Per Article: 50.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 04/09/2018] [Indexed: 01/25/2023]
Abstract
One-third of all protein-coding genes from bacterial genomes cannot be annotated with a function. Here, to investigate the functions of these genes, we present genome-wide mutant fitness data from 32 diverse bacteria across dozens of growth conditions. We identified mutant phenotypes for 11,779 protein-coding genes that had not been annotated with a specific function. Many genes could be associated with a specific condition because the gene affected fitness only in that condition, or with another gene in the same bacterium because they had similar mutant phenotypes. Of the poorly annotated genes, 2,316 had associations that have high confidence because they are conserved in other bacteria. By combining these conserved associations with comparative genomics, we identified putative DNA repair proteins; in addition, we propose specific functions for poorly annotated enzymes and transporters and for uncharacterized protein families. Our study demonstrates the scalability of microbial genetics and its utility for improving gene annotations.
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Affiliation(s)
- Morgan N Price
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kelly M Wetmore
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - R Jordan Waters
- Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Mark Callaghan
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jayashree Ray
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Hualan Liu
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jennifer V Kuehl
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Ryan A Melnyk
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Jacob S Lamson
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Yumi Suh
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Hans K Carlson
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Zuelma Esquivel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Harini Sadeeshkumar
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Romy Chakraborty
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Grant M Zane
- Department of Biochemistry, University of Missouri, Columbia, MO, USA
| | - Benjamin E Rubin
- Division of Biological Sciences, University of California, San Diego, CA, USA
| | - Judy D Wall
- Department of Biochemistry, University of Missouri, Columbia, MO, USA
| | - Axel Visel
- Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.,School of Natural Sciences, University of California, Merced, CA, USA
| | - James Bristow
- Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Matthew J Blow
- Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Adam P Arkin
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. .,Department of Bioengineering, University of California, Berkeley, CA, USA.
| | - Adam M Deutschbauer
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. .,Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA.
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17
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A Bacterial Microcompartment Is Used for Choline Fermentation by Escherichia coli 536. J Bacteriol 2018; 200:JB.00764-17. [PMID: 29507086 DOI: 10.1128/jb.00764-17] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 02/23/2018] [Indexed: 01/16/2023] Open
Abstract
Bacterial choline degradation in the human gut has been associated with cancer and heart disease. In addition, recent studies found that a bacterial microcompartment is involved in choline utilization by Proteus and Desulfovibrio species. However, many aspects of this process have not been fully defined. Here, we investigate choline degradation by the uropathogen Escherichia coli 536. Growth studies indicated E. coli 536 degrades choline primarily by fermentation. Electron microscopy indicated that a bacterial microcompartment was used for this process. Bioinformatic analyses suggested that the choline utilization (cut) gene cluster of E. coli 536 includes two operons, one containing three genes and a main operon of 13 genes. Regulatory studies indicate that the cutX gene encodes a positive transcriptional regulator required for induction of the main cut operon in response to choline supplementation. Each of the 16 genes in the cut cluster was individually deleted, and phenotypes were examined. The cutX, cutY, cutF, cutO, cutC, cutD, cutU, and cutV genes were required for choline degradation, but the remaining genes of the cut cluster were not essential under the conditions used. The reasons for these varied phenotypes are discussed.IMPORTANCE Here, we investigate choline degradation in E. coli 536. These studies provide a basis for understanding a new type of bacterial microcompartment and may provide deeper insight into the link between choline degradation in the human gut and cancer and heart disease. These are also the first studies of choline degradation in E. coli 536, an organism for which sophisticated genetic analysis methods are available. In addition, the cut gene cluster of E. coli 536 is located in pathogenicity island II (PAI-II536) and hence might contribute to pathogenesis.
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18
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The redox-sensing protein Rex modulates ethanol production in Thermoanaerobacterium saccharolyticum. PLoS One 2018; 13:e0195143. [PMID: 29621294 PMCID: PMC5886521 DOI: 10.1371/journal.pone.0195143] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 03/16/2018] [Indexed: 11/19/2022] Open
Abstract
Thermoanaerobacterium saccharolyticum is a thermophilic anaerobe that has been engineered to produce high amounts of ethanol, reaching ~90% theoretical yield at a titer of 70 g/L. Here we report the physiological changes that occur upon deleting the redox-sensing transcriptional regulator Rex in wild type T. saccharolyticum: a single deletion of rex resulted in a two-fold increase in ethanol yield (from 40% to 91% theoretical yield), but the resulting strains grew only about a third as fast as the wild type strain. Deletion of the rex gene also had the effect of increasing expression of alcohol dehydrogenase genes, adhE and adhA. After several serial transfers, the ethanol yield decreased from an average of 91% to 55%, and the growth rates had increased. We performed whole-genome resequencing to identify secondary mutations in the Δrex strains adapted for faster growth. In several cases, secondary mutations had appeared in the adhE gene. Furthermore, in these strains the NADH-linked alcohol dehydrogenase activity was greatly reduced. Complementation studies were done to reintroduce rex into the Δrex strains: reintroducing rex decreased ethanol yield to below wild type levels in the Δrex strain without adhE mutations, but did not change the ethanol yield in the Δrex strain where an adhE mutation occurred.
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19
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Flowers JJ, Richards MA, Baliga N, Meyer B, Stahl DA. Constraint-based modelling captures the metabolic versatility of Desulfovibrio vulgaris. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:190-201. [PMID: 29377633 DOI: 10.1111/1758-2229.12619] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 01/18/2018] [Indexed: 06/07/2023]
Abstract
A refined Desulfovibrio vulgaris Hildenborough flux balance analysis (FBA) model (iJF744) was developed, incorporating 1016 reactions that include 744 genes and 951 metabolites. A draft model was first developed through automatic model reconstruction using the ModelSeed Server and then curated based on existing literature. The curated model was further refined by incorporating three recently proposed redox reactions involving the Hdr-Flx and Qmo complexes and a lactate dehydrogenase (LdhAB, DVU 3027-3028) indicated by mutation and transcript analyses to serve electron transfer reactions central to syntrophic and respiratory growth. Eight different variations of this model were evaluated by comparing model predictions to experimental data determined for four different growth conditions - three for sulfate respiration (with lactate, pyruvate or H2 /CO2 -acetate) and one for fermentation in syntrophic coculture. The final general model supports (i) a role for Hdr-Flx in the oxidation of DsrC and ferredoxin, and reduction of NAD+ in a flavin-based electron confurcating reaction sequence, (ii) a function of the Qmo complex in receiving electrons from the menaquinone pool and potentially from ferredoxin to reduce APS and (iii) a reduction of the soluble DsrC by LdhAB and a function of DsrC in electron transfer reactions other than sulfite reduction.
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Affiliation(s)
- Jason J Flowers
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | | | | | - Birte Meyer
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | - David A Stahl
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
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20
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Skariyachan S, Manjunath M, Bachappanavar N. Screening of potential lead molecules against prioritised targets of multi-drug-resistant-Acinetobacter baumannii - insights from molecular docking, molecular dynamic simulations and in vitro assays. J Biomol Struct Dyn 2018. [PMID: 29529934 DOI: 10.1080/07391102.2018.1451387] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Acinetobacter baumannii, an opportunistic pathogen, has become multi-drug resistant (MDR) to major classes of antibacterial and poses grave threat to public health. The current study focused to screen novel phytotherapeutics against prioritised targets of Acinetobacter baumannii by computational investigation. Fourteen potential drug targets were screened based on their functional role in various biosynthetic pathways and the 3D structures of 9 targets were retrieved from Protein Data Bank and others were computationally predicted. By extensive literature survey, 104 molecules from 48 herbal sources were screened and subjected to virtual screening. Ten clinical isolates of A. baumannii were tested for antibiotic susceptibility towards clinafloxacin, imipenem and polymyxin-E. Computational screening suggested that Ajmalicine ((19α)-16, 17-didehydro-19-methyloxayohimban-16-carboxylic acid methyl ester from Rauwolfia serpentina), Strictamin (Akuammilan-17-oic acid methyl ester from Alstonia scholaris) and Limonin (7, 16-dioxo-7, 16-dideoxylimondiol from Citrus sps) exhibited promising binding towards multiple drug targets of A. baumannii in comparison with the binding between standard drugs and their targets. Limonin displayed promising binding potential (binding energy -9.8 kcal/mol) towards diaminopimelate epimerase (DapF) and UDP-N-acetylglucosamine 1-carboxyvinyltransferase (MurA). Ajmalicine and Strictamin demonstrated good binding potential (-9.5, -8.5 kcal/mol, respectively) towards MurA and shikimate dehydrogenase (-7.8 kcal/mol). Molecular dynamic simulations further validated the docking results. In vitro assay suggested that the tested isolates exhibited resistance to clinafloxacin, imipenem and polymyxin-E and the herbal preparations (crude extract) demonstrated a significant antibacterial potential (p ≤ .05). The study suggests that the aforementioned lead candidates and targets can be used for structure-based drug screening towards MDR A. baumannii.
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Affiliation(s)
- Sinosh Skariyachan
- a Department of Biotechnology Engineering , Dayananda Sagar Institutions , Bengaluru 560 078 , Karnataka , India.,b Visvesvaraya Technological University , Belagavi , India
| | - Meghna Manjunath
- a Department of Biotechnology Engineering , Dayananda Sagar Institutions , Bengaluru 560 078 , Karnataka , India.,b Visvesvaraya Technological University , Belagavi , India
| | - Nikhil Bachappanavar
- a Department of Biotechnology Engineering , Dayananda Sagar Institutions , Bengaluru 560 078 , Karnataka , India.,b Visvesvaraya Technological University , Belagavi , India
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21
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Price MN, Zane GM, Kuehl JV, Melnyk RA, Wall JD, Deutschbauer AM, Arkin AP. Filling gaps in bacterial amino acid biosynthesis pathways with high-throughput genetics. PLoS Genet 2018; 14:e1007147. [PMID: 29324779 PMCID: PMC5764234 DOI: 10.1371/journal.pgen.1007147] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 12/10/2017] [Indexed: 11/18/2022] Open
Abstract
For many bacteria with sequenced genomes, we do not understand how they synthesize some amino acids. This makes it challenging to reconstruct their metabolism, and has led to speculation that bacteria might be cross-feeding amino acids. We studied heterotrophic bacteria from 10 different genera that grow without added amino acids even though an automated tool predicts that the bacteria have gaps in their amino acid synthesis pathways. Across these bacteria, there were 11 gaps in their amino acid biosynthesis pathways that we could not fill using current knowledge. Using genome-wide mutant fitness data, we identified novel enzymes that fill 9 of the 11 gaps and hence explain the biosynthesis of methionine, threonine, serine, or histidine by bacteria from six genera. We also found that the sulfate-reducing bacterium Desulfovibrio vulgaris synthesizes homocysteine (which is a precursor to methionine) by using DUF39, NIL/ferredoxin, and COG2122 proteins, and that homoserine is not an intermediate in this pathway. Our results suggest that most free-living bacteria can likely make all 20 amino acids and illustrate how high-throughput genetics can uncover previously-unknown amino acid biosynthesis genes. For a few bacteria, it is well known how they can make all 20 of the standard amino acids (the building blocks of proteins). For many other bacteria, their genome sequence implies that there are gaps in these biosynthetic pathways, so that the bacteria cannot make all of the amino acids and would need to take up some of them from their environment instead. But many bacteria can grow in minimal media (without any amino acids) despite these apparent gaps. We studied 10 bacteria with predicted gaps in amino acid biosynthesis that nevertheless grow in minimal media. Most of these gaps were spurious, but 11 of the gaps were genuine and could not be explained by current knowledge. Using high-throughput genetics, we systematically identified genes that were required for growth in minimal media and identified the biosynthetic genes that fill 9 of the 11 gaps. We hope that this approach can be applied to many more bacteria and will eventually allow us to accurately predict the nutritional requirements of a bacterium from its genome sequence.
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Affiliation(s)
- Morgan N. Price
- Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- * E-mail: (MNP); (AMD); (APA)
| | - Grant M. Zane
- Department of Biochemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Jennifer V. Kuehl
- Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Ryan A. Melnyk
- Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Judy D. Wall
- Department of Biochemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Adam M. Deutschbauer
- Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- * E-mail: (MNP); (AMD); (APA)
| | - Adam P. Arkin
- Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- * E-mail: (MNP); (AMD); (APA)
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22
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De Y, Dong C, Cao Y, Wang X, Yang X, Wang N, Zhang C, Wang Z, Lyu Y, Wu Q. Genome-wide sequence transposon insertion sites and analyze the essential genes of Brucella melitensis. Microb Pathog 2017; 112:97-102. [PMID: 28888882 DOI: 10.1016/j.micpath.2017.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/03/2017] [Accepted: 09/05/2017] [Indexed: 12/29/2022]
Abstract
A transposon mutant library of B. melitensis NI including 32,640 transposon mutants was established. By sequencing the transposon insertion sites, 10,832 mutants were successfully defined for their insertion sites. Analysis of the mutants with defined transposon insertion sites (DTIS) indicated that the insertions were well spread through the two genomes. In addition, 948 genes with no detectable transposon insertions were taken as the candidate for identification of essential genes. In comparison with the Bacterial Database of Essential Genes and by using comparative genomics analysis, 183 potential essential genes of B. melitensis NI cultured in vitro were found and they were conserved in the common bacteria. This work was focused on screening of the essential genes of B. melitensis NI, which may provide a foundation for identification of the novel drug targets against brucellosis. Besides, the sequence-defined transposon library should serve as a resource for screening of different function genes of Brucella.
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Affiliation(s)
- Yanyan De
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Congyue Dong
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yanyang Cao
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xiaolei Wang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xiaowen Yang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Ning Wang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Cunrui Zhang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Zhen Wang
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yanli Lyu
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Qingmin Wu
- Key Laboratory of Animal Epidemiology and Zoonosis of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China.
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23
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Ruiz L, Bottacini F, Boinett CJ, Cain AK, O'Connell-Motherway M, Lawley TD, van Sinderen D. The essential genomic landscape of the commensal Bifidobacterium breve UCC2003. Sci Rep 2017; 7:5648. [PMID: 28717159 PMCID: PMC5514069 DOI: 10.1038/s41598-017-05795-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 06/02/2017] [Indexed: 01/15/2023] Open
Abstract
Bifidobacteria are common gut commensals with purported health-promoting effects. This has encouraged scientific research into bifidobacteria, though recalcitrance to genetic manipulation and scarcity of molecular tools has hampered our knowledge on the precise molecular determinants of their health-promoting attributes and gut adaptation. To overcome this problem and facilitate functional genomic analyses in bifidobacteria, we created a large Tn5 transposon mutant library of the commensal Bifidobacterium breve UCC2003 that was further characterized by means of a Transposon Directed Insertion Sequencing (TraDIS) approach. Statistical analysis of transposon insertion distribution revealed a set of 453 genes that are essential for or markedly contribute to growth of this strain under laboratory conditions. These essential genes encode functions involved in the so-called bifid-shunt, most enzymes related to nucleotide biosynthesis and a range of housekeeping functions. Comparison to the Bifidobacterium and B. breve core genomes highlights a high degree of conservation of essential genes at the species and genus level, while comparison to essential gene datasets from other gut bacteria identified essential genes that appear specific to bifidobacteria. This work establishes a useful molecular tool for scientific discovery of bifidobacteria and identifies targets for further studies aimed at characterizing essential functions not previously examined in bifidobacteria.
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Affiliation(s)
- Lorena Ruiz
- School of Microbiology and APC Microbiome Institute, National University of Ireland, Cork, Western Road, Ireland.,Department of Nutrition, Bromatology and Food Technology, Complutense University, Avda Puerta de Hierro s/n, 28040, Madrid, Spain
| | - Francesca Bottacini
- School of Microbiology and APC Microbiome Institute, National University of Ireland, Cork, Western Road, Ireland
| | | | - Amy K Cain
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Mary O'Connell-Motherway
- School of Microbiology and APC Microbiome Institute, National University of Ireland, Cork, Western Road, Ireland
| | | | - Douwe van Sinderen
- School of Microbiology and APC Microbiome Institute, National University of Ireland, Cork, Western Road, Ireland.
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24
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Carlson HK, Mullan MR, Mosqueda LA, Chen S, Arkin MR, Coates JD. High-Throughput Screening To Identify Potent and Specific Inhibitors of Microbial Sulfate Reduction. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:7278-7285. [PMID: 28492331 DOI: 10.1021/acs.est.7b00686] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The selective perturbation of complex microbial ecosystems to predictably influence outcomes in engineered and industrial environments remains a grand challenge for geomicrobiology. In some industrial ecosystems, such as oil reservoirs, sulfate reducing microorganisms (SRM) produce hydrogen sulfide which is toxic, explosive, and corrosive. Despite the economic cost of sulfidogenesis, there has been minimal exploration of the chemical space of possible inhibitory compounds, and very little work has quantitatively assessed the selectivity of putative souring treatments. We have developed a high-throughput screening strategy to identify potent and selective inhibitors of SRM, quantitatively ranked the selectivity and potency of hundreds of compounds and identified previously unrecognized SRM selective inhibitors and synergistic interactions between inhibitors. Zinc pyrithione is the most potent inhibitor of sulfidogenesis that we identified, and is several orders of magnitude more potent than commonly used industrial biocides. Both zinc and copper pyrithione are also moderately selective against SRM. The high-throughput (HT) approach we present can be readily adapted to target SRM in diverse environments and similar strategies could be used to quantify the potency and selectivity of inhibitors of a variety of microbial metabolisms. Our findings and approach are relevant to efforts to engineer environmental ecosystems and also to understand the role of natural gradients in shaping microbial niche space.
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Affiliation(s)
- Hans K Carlson
- Energy Biosciences Institute, University of California, Berkeley , Berkeley, California 94720, United States
- Physical Biosciences Division, Lawrence Berkeley National Lab , Berkeley, California 94720, United States
| | - Mark R Mullan
- Energy Biosciences Institute, University of California, Berkeley , Berkeley, California 94720, United States
| | - Lorraine A Mosqueda
- Energy Biosciences Institute, University of California, Berkeley , Berkeley, California 94720, United States
| | - Steven Chen
- Small Molecule Discovery Center, University of California, San Francisco , San Francisco, California 94143, United States
| | - Michelle R Arkin
- Small Molecule Discovery Center, University of California, San Francisco , San Francisco, California 94143, United States
| | - John D Coates
- Energy Biosciences Institute, University of California, Berkeley , Berkeley, California 94720, United States
- Earth Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
- Department of Plant and Microbial Biology, University of California, Berkeley , Berkeley, California 94720, United States
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25
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Mechanism of H 2S Oxidation by the Dissimilatory Perchlorate-Reducing Microorganism Azospira suillum PS. mBio 2017; 8:mBio.02023-16. [PMID: 28223460 PMCID: PMC5358917 DOI: 10.1128/mbio.02023-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The genetic and biochemical basis of perchlorate-dependent H2S oxidation (PSOX) was investigated in the dissimilatory perchlorate-reducing microorganism (DPRM) Azospira suillum PS (PS). Previously, it was shown that all known DPRMs innately oxidize H2S, producing elemental sulfur (So). Although the process involving PSOX is thermodynamically favorable (ΔG°' = -206 kJ ⋅ mol-1 H2S), the underlying biochemical and genetic mechanisms are currently unknown. Interestingly, H2S is preferentially utilized over physiological electron donors such as lactate or acetate although no growth benefit is obtained from the metabolism. Here, we determined that PSOX is due to a combination of enzymatic and abiotic interactions involving reactive intermediates of perchlorate respiration. Using various approaches, including barcode analysis by sequencing (Bar-seq), transcriptome sequencing (RNA-seq), and proteomics, along with targeted mutagenesis and biochemical characterization, we identified all facets of PSOX in PS. In support of our proposed model, deletion of identified upregulated PS genes traditionally known to be involved in sulfur redox cycling (e.g., Sox, sulfide:quinone reductase [SQR]) showed no defect in PSOX activity. Proteomic analysis revealed differential abundances of a variety of stress response metal efflux pumps and divalent heavy-metal transporter proteins, suggesting a general toxicity response. Furthermore, in vitro biochemical studies demonstrated direct PSOX mediated by purified perchlorate reductase (PcrAB) in the absence of other electron transfer proteins. The results of these studies support a model in which H2S oxidation is mediated by electron transport chain short-circuiting in the periplasmic space where the PcrAB directly oxidizes H2S to So The biogenically formed reactive intermediates (ClO2- and O2) subsequently react with additional H2S, producing polysulfide and So as end products.IMPORTANCE Inorganic sulfur compounds are widespread in nature, and microorganisms are central to their transformation, thereby playing a key role in the global sulfur cycle. Sulfur oxidation is mediated by a broad phylogenetic diversity of microorganisms, including anoxygenic phototrophs and either aerobic or anaerobic chemotrophs coupled to oxygen or nitrate respiration, respectively. Recently, perchlorate-respiring microorganisms were demonstrated to be innately capable of sulfur oxidation regardless of their phylogenetic affiliation. As recognition of the prevalence of these organisms intensifies, their role in global geochemical cycles is being queried. This is further highlighted by the recently recognized environmental pervasiveness of perchlorate not only across Earth but also throughout our solar system. The inferred importance of this metabolism not only is that it is a novel and previously unrecognized component of the global sulfur redox cycle but also is because of the recently demonstrated applicability of perchlorate respiration in the control of biogenic sulfide production in engineered environments such as oil reservoirs and wastewater treatment facilities, where excess H2S represents a significant environmental, process, and health risk, with associated costs approximating $90 billion annually.
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26
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Bosak T, Schubotz F, de Santiago-Torio A, Kuehl JV, Carlson HK, Watson N, Daye M, Summons RE, Arkin AP, Deutschbauer AM. System-Wide Adaptations of Desulfovibrio alaskensis G20 to Phosphate-Limited Conditions. PLoS One 2016; 11:e0168719. [PMID: 28030630 PMCID: PMC5193443 DOI: 10.1371/journal.pone.0168719] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 12/04/2016] [Indexed: 12/13/2022] Open
Abstract
The prevalence of lipids devoid of phosphorus suggests that the availability of phosphorus limits microbial growth and activity in many anoxic, stratified environments. To better understand the response of anaerobic bacteria to phosphate limitation and starvation, this study combines microscopic and lipid analyses with the measurements of fitness of pooled barcoded transposon mutants of the model sulfate reducing bacterium Desulfovibrio alaskensis G20. Phosphate-limited G20 has lower growth rates and replaces more than 90% of its membrane phospholipids by a mixture of monoglycosyl diacylglycerol (MGDG), glycuronic acid diacylglycerol (GADG) and ornithine lipids, lacks polyphosphate granules, and synthesizes other cellular inclusions. Analyses of pooled and individual mutants reveal the importance of the high-affinity phosphate transport system (the Pst system), PhoR, and glycolipid and ornithine lipid synthases during phosphate limitation. The phosphate-dependent synthesis of MGDG in G20 and the widespread occurrence of the MGDG/GADG synthase among sulfate reducing ∂-Proteobacteria implicate these microbes in the production of abundant MGDG in anaerobic environments where the concentrations of phosphate are lower than 10 μM. Numerous predicted changes in the composition of the cell envelope and systems involved in transport, maintenance of cytoplasmic redox potential, central metabolism and regulatory pathways also suggest an impact of phosphate limitation on the susceptibility of sulfate reducing bacteria to other anthropogenic or environmental stresses.
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Affiliation(s)
- Tanja Bosak
- Department of Earth and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | | | - Ana de Santiago-Torio
- Department of Earth and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Jennifer V Kuehl
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Hans K Carlson
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Nicki Watson
- W.M. Keck Microscopy Facility, The Whitehead Institute, Cambridge, Massachusetts, United States of America
| | - Mirna Daye
- Department of Earth and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Roger E Summons
- Department of Earth and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Adam P Arkin
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.,Department of Bioengineering, University of California, Berkeley, Berkeley, California, United States of America
| | - Adam M Deutschbauer
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
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27
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Perry BJ, Akter MS, Yost CK. The Use of Transposon Insertion Sequencing to Interrogate the Core Functional Genome of the Legume Symbiont Rhizobium leguminosarum. Front Microbiol 2016; 7:1873. [PMID: 27920770 PMCID: PMC5118466 DOI: 10.3389/fmicb.2016.01873] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 11/07/2016] [Indexed: 02/04/2023] Open
Abstract
The free-living legume symbiont Rhizobium leguminosarum is of significant economic value because of its ability to provide fixed nitrogen to globally important leguminous food crops, such as peas and lentils. Discovery based research into the genetics and physiology of R. leguminosarum provides the foundational knowledge necessary for understanding the bacterium's complex lifestyle, necessary for augmenting its use in an agricultural setting. Transposon insertion sequencing (INSeq) facilitates high-throughput forward genetic screening at a genomic scale to identify individual genes required for growth in a specific environment. In this study we applied INSeq to screen the genome of R. leguminosarum bv. viciae strain 3841 (RLV3841) for genes required for growth on minimal mannitol containing medium. Results from this study were contrasted with a prior INSeq experiment screened on peptide rich media to identify a common set of functional genes necessary for basic physiology. Contrasting the two growth conditions indicated that approximately 10% of the chromosome was required for growth, under both growth conditions. Specific genes that were essential to singular growth conditions were also identified. Data from INSeq screening on mannitol as a sole carbon source were used to reconstruct a metabolic map summarizing growth impaired phenotypes observed in the Embden-Meyerhof-Parnas pathway, Entner-Doudoroff pathway, pentose phosphate pathway, and tricarboxylic acid cycle. This revealed the presence of mannitol dependent and independent metabolic pathways required for growth, along with identifying metabolic steps with isozymes or possible carbon flux by-passes. Additionally, genes were identified on plasmids pRL11 and pRL12 that are likely to encode functional activities important to the central physiology of RLV3841.
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Affiliation(s)
| | - Mir S Akter
- Department of Biology, University of Regina Regina, SK, Canada
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28
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Chowdhury C, Chun S, Sawaya MR, Yeates TO, Bobik TA. The function of the PduJ microcompartment shell protein is determined by the genomic position of its encoding gene. Mol Microbiol 2016; 101:770-83. [PMID: 27561553 PMCID: PMC5003431 DOI: 10.1111/mmi.13423] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2016] [Indexed: 12/20/2022]
Abstract
Bacterial microcompartments (MCPs) are complex organelles that consist of metabolic enzymes encapsulated within a protein shell. In this study, we investigate the function of the PduJ MCP shell protein. PduJ is 80% identical in amino acid sequence to PduA and both are major shell proteins of the 1,2-propanediol (1,2-PD) utilization (Pdu) MCP of Salmonella. Prior studies showed that PduA mediates the transport of 1,2-PD (the substrate) into the Pdu MCP. Surprisingly, however, results presented here establish that PduJ has no role 1,2-PD transport. The crystal structure revealed that PduJ was nearly identical to that of PduA and, hence, offered no explanation for their differential functions. Interestingly, however, when a pduJ gene was placed at the pduA chromosomal locus, the PduJ protein acquired a new function, the ability to mediate 1,2-PD transport into the Pdu MCP. To our knowledge, these are the first studies to show that that gene location can determine the function of a MCP shell protein. We propose that gene location dictates protein-protein interactions essential to the function of the MCP shell.
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Affiliation(s)
- Chiranjit Chowdhury
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011
| | - Sunny Chun
- Department of Energy Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, CA 90095
| | - Michael R. Sawaya
- Department of Energy Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, CA 90095
| | - Todd O. Yeates
- Department of Energy Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, CA 90095
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Thomas A Bobik
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, 50011
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29
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Kosina SM, Danielewicz MA, Mohammed M, Ray J, Suh Y, Yilmaz S, Singh AK, Arkin AP, Deutschbauer AM, Northen TR. Exometabolomics Assisted Design and Validation of Synthetic Obligate Mutualism. ACS Synth Biol 2016; 5:569-76. [PMID: 26885935 DOI: 10.1021/acssynbio.5b00236] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Synthetic microbial ecology has the potential to enhance the productivity and resiliency of biotechnology processes compared to approaches using single isolates. Engineering microbial consortia is challenging; however, one approach that has attracted significant attention is the creation of synthetic obligate mutualism using auxotrophic mutants that depend on each other for exchange or cross-feeding of metabolites. Here, we describe the integration of mutant library fitness profiling with mass spectrometry based exometabolomics as a method for constructing synthetic mutualism based on cross-feeding. Two industrially important species lacking known ecological interactions, Zymomonas mobilis and Escherichia coli, were selected as the test species. Amino acid exometabolites identified in the spent medium of Z. mobilis were used to select three corresponding E. coli auxotrophs (proA, pheA and IlvA), as potential E. coli counterparts for the coculture. A pooled mutant fitness assay with a Z. mobilis transposon mutant library was used to identify mutants with improved growth in the presence of E. coli. An auxotroph mutant in a gene (ZMO0748) with sequence similarity to cysteine synthase A (cysK), was selected as the Z. mobilis counterpart for the coculture. Exometabolomic analysis of spent E. coli medium identified glutathione related metabolites as potentially available for rescue of the Z. mobilis cysteine synthase mutant. Three sets of cocultures between the Z. mobilis auxotroph and each of the three E. coli auxotrophs were monitored by optical density for growth and analyzed by flow cytometry to confirm high cell counts for each species. Taken together, our methods provide a technological framework for creating synthetic mutualisms combining existing screening based methods and exometabolomics for both the selection of obligate mutualism partners and elucidation of metabolites involved in auxotroph rescue.
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Affiliation(s)
- Suzanne M. Kosina
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Megan A. Danielewicz
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Mujahid Mohammed
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jayashree Ray
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Yumi Suh
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Suzan Yilmaz
- Sandia National Laboratory, Livermore, California 94550, United States
| | - Anup K. Singh
- Sandia National Laboratory, Livermore, California 94550, United States
| | - Adam P. Arkin
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- University of California Berkeley, Berkeley, California 94720, United States
| | - Adam M. Deutschbauer
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Trent R. Northen
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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30
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Leavitt WD, Flynn TM, Suess MK, Bradley AS. Transhydrogenase and Growth Substrate Influence Lipid Hydrogen Isotope Ratios in Desulfovibrio alaskensis G20. Front Microbiol 2016; 7:918. [PMID: 27445998 PMCID: PMC4916218 DOI: 10.3389/fmicb.2016.00918] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 05/27/2016] [Indexed: 11/19/2022] Open
Abstract
Microbial fatty acids preserve metabolic and environmental information in their hydrogen isotope ratios ((2)H/(1)H). This ratio is influenced by parameters that include the (2)H/(1)H of water in the microbial growth environment, and biosynthetic fractionations between water and lipid. In some microbes, this biosynthetic fractionation has been shown to vary systematically with central energy metabolism, and controls on fatty acid (2)H/(1)H may be linked to the intracellular production of NADPH. We examined the apparent fractionation between media water and the fatty acids produced by Desulfovibrio alaskensis G20. Growth was in batch culture with malate as an electron donor for sulfate respiration, and with pyruvate and fumarate as substrates for fermentation and for sulfate respiration. A larger fractionation was observed as a consequence of respiratory or fermentative growth on pyruvate than growth on fumarate or malate. This difference correlates with opposite apparent flows of electrons through the electron bifurcating/confurcating transhydrogenase NfnAB. When grown on malate or fumarate, mutant strains of D. alaskensis G20 containing transposon disruptions in a copy of nfnAB show different fractionations than the wild type strain. This phenotype is muted during fermentative growth on pyruvate, and it is absent when pyruvate is a substrate for sulfate reduction. All strains and conditions produced similar fatty acid profiles, and the (2)H/(1)H of individual lipids changed in concert with the mass-weighted average. Unsaturated fatty acids were generally depleted in (2)H relative to their saturated homologs, and anteiso-branched fatty acids were generally depleted in (2)H relative to straight-chain fatty acids. Fractionation correlated with growth rate, a pattern that has also been observed in the fractionation of sulfur isotopes during dissimilatory sulfate reduction by sulfate-reducing bacteria.
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Affiliation(s)
- William D. Leavitt
- Department of Earth and Planetary Sciences, Washington University in St. LouisSaint Louis, MO, USA
| | | | - Melanie K. Suess
- Department of Earth and Planetary Sciences, Washington University in St. LouisSaint Louis, MO, USA
| | - Alexander S. Bradley
- Department of Earth and Planetary Sciences, Washington University in St. LouisSaint Louis, MO, USA
- Division of Biology and Biomedical Sciences, Washington University in St. LouisSaint Louis, MO, USA
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31
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Jameson E, Fu T, Brown IR, Paszkiewicz K, Purdy KJ, Frank S, Chen Y. Anaerobic choline metabolism in microcompartments promotes growth and swarming of Proteus mirabilis. Environ Microbiol 2015; 18:2886-98. [PMID: 26404097 PMCID: PMC5026066 DOI: 10.1111/1462-2920.13059] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/14/2015] [Accepted: 09/15/2015] [Indexed: 12/16/2022]
Abstract
Gammaproteobacteria are important gut microbes but only persist at low levels in the healthy gut. The ecology of Gammaproteobacteria in the gut environment is poorly understood. Here, we demonstrate that choline is an important growth substrate for representatives of Gammaproteobacteria. Using Proteus mirabilis as a model, we investigate the role of choline metabolism and demonstrate that the cutC gene, encoding a choline‐trimethylamine lyase, is essential for choline degradation to trimethylamine by targeted mutagenesis of cutC and subsequent complementation experiments. Proteus mirabilis can rapidly utilize choline to enhance growth rate and cell yield in broth culture. Importantly, choline also enhances swarming‐associated colony expansion of P. mirabilis under anaerobic conditions on a solid surface. Comparative transcriptomics demonstrated that choline not only induces choline‐trimethylamine lyase but also genes encoding shell proteins for the formation of bacterial microcompartments. Subsequent analyses by transmission electron microscopy confirmed the presence of such novel microcompartments in cells cultivated in liquid broth and hyper‐flagellated swarmer cells from solid medium. Together, our study reveals choline metabolism as an adaptation strategy for P. mirabilis and contributes to better understand the ecology of this bacterium in health and disease.
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Affiliation(s)
- Eleanor Jameson
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Tiantian Fu
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Ian R Brown
- School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK
| | - Konrad Paszkiewicz
- College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4QD, UK
| | - Kevin J Purdy
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Stefanie Frank
- School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK.
| | - Yin Chen
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
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32
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Gray AN, Koo BM, Shiver AL, Peters JM, Osadnik H, Gross CA. High-throughput bacterial functional genomics in the sequencing era. Curr Opin Microbiol 2015; 27:86-95. [PMID: 26336012 DOI: 10.1016/j.mib.2015.07.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 07/23/2015] [Indexed: 01/17/2023]
Abstract
High-throughput functional genomic technologies are accelerating progress in understanding the diversity of bacterial life and in developing a systems-level understanding of model bacterial organisms. Here we highlight progress in deep-sequencing-based functional genomics, show how whole genome sequencing is enabling phenotyping in organisms recalcitrant to genetic approaches, recount the rapid proliferation of functional genomic approaches to non-growth phenotypes, and discuss how advances are enabling genome-scale resource libraries for many different bacteria.
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Affiliation(s)
- Andrew N Gray
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94158, USA
| | - Byoung-Mo Koo
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94158, USA
| | - Anthony L Shiver
- Graduate Group in Biophysics, University of California, San Francisco, CA 94158, USA
| | - Jason M Peters
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94158, USA
| | - Hendrik Osadnik
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94158, USA
| | - Carol A Gross
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94158, USA; Department of Cell and Tissue Biology, University of California, San Francisco, CA 94158, USA.
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A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes. Adv Microb Physiol 2015. [PMID: 26210106 DOI: 10.1016/bs.ampbs.2015.05.002] [Citation(s) in RCA: 174] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Dissimilatory sulphate reduction is the unifying and defining trait of sulphate-reducing prokaryotes (SRP). In their predominant habitats, sulphate-rich marine sediments, SRP have long been recognized to be major players in the carbon and sulphur cycles. Other, more recently appreciated, ecophysiological roles include activity in the deep biosphere, symbiotic relations, syntrophic associations, human microbiome/health and long-distance electron transfer. SRP include a high diversity of organisms, with large nutritional versatility and broad metabolic capacities, including anaerobic degradation of aromatic compounds and hydrocarbons. Elucidation of novel catabolic capacities as well as progress in the understanding of metabolic and regulatory networks, energy metabolism, evolutionary processes and adaptation to changing environmental conditions has greatly benefited from genomics, functional OMICS approaches and advances in genetic accessibility and biochemical studies. Important biotechnological roles of SRP range from (i) wastewater and off gas treatment, (ii) bioremediation of metals and hydrocarbons and (iii) bioelectrochemistry, to undesired impacts such as (iv) souring in oil reservoirs and other environments, and (v) corrosion of iron and concrete. Here we review recent advances in our understanding of SRPs focusing mainly on works published after 2000. The wealth of publications in this period, covering many diverse areas, is a testimony to the large environmental, biogeochemical and technological relevance of these organisms and how much the field has progressed in these years, although many important questions and applications remain to be explored.
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Rapid quantification of mutant fitness in diverse bacteria by sequencing randomly bar-coded transposons. mBio 2015; 6:e00306-15. [PMID: 25968644 PMCID: PMC4436071 DOI: 10.1128/mbio.00306-15] [Citation(s) in RCA: 261] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Transposon mutagenesis with next-generation sequencing (TnSeq) is a powerful approach to annotate gene function in bacteria, but existing protocols for TnSeq require laborious preparation of every sample before sequencing. Thus, the existing protocols are not amenable to the throughput necessary to identify phenotypes and functions for the majority of genes in diverse bacteria. Here, we present a method, random bar code transposon-site sequencing (RB-TnSeq), which increases the throughput of mutant fitness profiling by incorporating random DNA bar codes into Tn5 and mariner transposons and by using bar code sequencing (BarSeq) to assay mutant fitness. RB-TnSeq can be used with any transposon, and TnSeq is performed once per organism instead of once per sample. Each BarSeq assay requires only a simple PCR, and 48 to 96 samples can be sequenced on one lane of an Illumina HiSeq system. We demonstrate the reproducibility and biological significance of RB-TnSeq with Escherichia coli, Phaeobacter inhibens, Pseudomonas stutzeri, Shewanella amazonensis, and Shewanella oneidensis. To demonstrate the increased throughput of RB-TnSeq, we performed 387 successful genome-wide mutant fitness assays representing 130 different bacterium-carbon source combinations and identified 5,196 genes with significant phenotypes across the five bacteria. In P. inhibens, we used our mutant fitness data to identify genes important for the utilization of diverse carbon substrates, including a putative d-mannose isomerase that is required for mannitol catabolism. RB-TnSeq will enable the cost-effective functional annotation of diverse bacteria using mutant fitness profiling. A large challenge in microbiology is the functional assessment of the millions of uncharacterized genes identified by genome sequencing. Transposon mutagenesis coupled to next-generation sequencing (TnSeq) is a powerful approach to assign phenotypes and functions to genes. However, the current strategies for TnSeq are too laborious to be applied to hundreds of experimental conditions across multiple bacteria. Here, we describe an approach, random bar code transposon-site sequencing (RB-TnSeq), which greatly simplifies the measurement of gene fitness by using bar code sequencing (BarSeq) to monitor the abundance of mutants. We performed 387 genome-wide fitness assays across five bacteria and identified phenotypes for over 5,000 genes. RB-TnSeq can be applied to diverse bacteria and is a powerful tool to annotate uncharacterized genes using phenotype data.
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Characterization and detection of a widely distributed gene cluster that predicts anaerobic choline utilization by human gut bacteria. mBio 2015; 6:mBio.00042-15. [PMID: 25873372 PMCID: PMC4453576 DOI: 10.1128/mbio.00042-15] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Elucidation of the molecular mechanisms underlying the human gut microbiota’s effects on health and disease has been complicated by difficulties in linking metabolic functions associated with the gut community as a whole to individual microorganisms and activities. Anaerobic microbial choline metabolism, a disease-associated metabolic pathway, exemplifies this challenge, as the specific human gut microorganisms responsible for this transformation have not yet been clearly identified. In this study, we established the link between a bacterial gene cluster, the choline utilization (cut) cluster, and anaerobic choline metabolism in human gut isolates by combining transcriptional, biochemical, bioinformatic, and cultivation-based approaches. Quantitative reverse transcription-PCR analysis and in vitro biochemical characterization of two cut gene products linked the entire cluster to growth on choline and supported a model for this pathway. Analyses of sequenced bacterial genomes revealed that the cut cluster is present in many human gut bacteria, is predictive of choline utilization in sequenced isolates, and is widely but discontinuously distributed across multiple bacterial phyla. Given that bacterial phylogeny is a poor marker for choline utilization, we were prompted to develop a degenerate PCR-based method for detecting the key functional gene choline TMA-lyase (cutC) in genomic and metagenomic DNA. Using this tool, we found that new choline-metabolizing gut isolates universally possessed cutC. We also demonstrated that this gene is widespread in stool metagenomic data sets. Overall, this work represents a crucial step toward understanding anaerobic choline metabolism in the human gut microbiota and underscores the importance of examining this microbial community from a function-oriented perspective. Anaerobic choline utilization is a bacterial metabolic activity that occurs in the human gut and is linked to multiple diseases. While bacterial genes responsible for choline fermentation (the cut gene cluster) have been recently identified, there has been no characterization of these genes in human gut isolates and microbial communities. In this work, we use multiple approaches to demonstrate that the pathway encoded by the cut genes is present and functional in a diverse range of human gut bacteria and is also widespread in stool metagenomes. We also developed a PCR-based strategy to detect a key functional gene (cutC) involved in this pathway and applied it to characterize newly isolated choline-utilizing strains. Both our analyses of the cut gene cluster and this molecular tool will aid efforts to further understand the role of choline metabolism in the human gut microbiota and its link to disease.
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Carlson HK, Stoeva MK, Justice NB, Sczesnak A, Mullan MR, Mosqueda LA, Kuehl JV, Deutschbauer AM, Arkin AP, Coates JD. Monofluorophosphate is a selective inhibitor of respiratory sulfate-reducing microorganisms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:3727-3736. [PMID: 25698072 DOI: 10.1021/es505843z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Despite the environmental and economic cost of microbial sulfidogenesis in industrial operations, few compounds are known as selective inhibitors of respiratory sulfate reducing microorganisms (SRM), and no study has systematically and quantitatively evaluated the selectivity and potency of SRM inhibitors. Using general, high-throughput assays to quantitatively evaluate inhibitor potency and selectivity in a model sulfate-reducing microbial ecosystem as well as inhibitor specificity for the sulfate reduction pathway in a model SRM, we screened a panel of inorganic oxyanions. We identified several SRM selective inhibitors including selenate, selenite, tellurate, tellurite, nitrate, nitrite, perchlorate, chlorate, monofluorophosphate, vanadate, molydate, and tungstate. Monofluorophosphate (MFP) was not known previously as a selective SRM inhibitor, but has promising characteristics including low toxicity to eukaryotic organisms, high stability at circumneutral pH, utility as an abiotic corrosion inhibitor, and low cost. MFP remains a potent inhibitor of SRM growing by fermentation, and MFP is tolerated by nitrate and perchlorate reducing microorganisms. For SRM inhibition, MFP is synergistic with nitrite and chlorite, and could enhance the efficacy of nitrate or perchlorate treatments. Finally, MFP inhibition is multifaceted. Both inhibition of the central sulfate reduction pathway and release of cytoplasmic fluoride ion are implicated in the mechanism of MFP toxicity.
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Affiliation(s)
- Hans K Carlson
- †Energy Biosciences Institute, University of California-Berkeley, Berkeley, California 94720, United States
| | - Magdalena K Stoeva
- ∥Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, California 94720, United States
| | - Nicholas B Justice
- ‡Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
| | - Andrew Sczesnak
- ⊥Department of Bioengineering, University of California-Berkeley, Berkeley, California 94720, United States
| | - Mark R Mullan
- †Energy Biosciences Institute, University of California-Berkeley, Berkeley, California 94720, United States
| | - Lorraine A Mosqueda
- †Energy Biosciences Institute, University of California-Berkeley, Berkeley, California 94720, United States
| | - Jennifer V Kuehl
- ‡Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
| | - Adam M Deutschbauer
- ‡Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
| | - Adam P Arkin
- ‡Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
- ⊥Department of Bioengineering, University of California-Berkeley, Berkeley, California 94720, United States
| | - John D Coates
- †Energy Biosciences Institute, University of California-Berkeley, Berkeley, California 94720, United States
- §Earth Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
- ∥Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, California 94720, United States
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Bacterial microcompartments and the modular construction of microbial metabolism. Trends Microbiol 2015; 23:22-34. [DOI: 10.1016/j.tim.2014.10.003] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 10/07/2014] [Accepted: 10/08/2014] [Indexed: 01/22/2023]
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Carlson HK, Kuehl JV, Hazra AB, Justice NB, Stoeva MK, Sczesnak A, Mullan MR, Iavarone AT, Engelbrektson A, Price MN, Deutschbauer AM, Arkin AP, Coates JD. Mechanisms of direct inhibition of the respiratory sulfate-reduction pathway by (per)chlorate and nitrate. ISME JOURNAL 2014; 9:1295-305. [PMID: 25405978 DOI: 10.1038/ismej.2014.216] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 09/30/2014] [Accepted: 10/04/2014] [Indexed: 12/26/2022]
Abstract
We investigated perchlorate (ClO(4)(-)) and chlorate (ClO(3)(-)) (collectively (per)chlorate) in comparison with nitrate as potential inhibitors of sulfide (H(2)S) production by mesophilic sulfate-reducing microorganisms (SRMs). We demonstrate the specificity and potency of (per)chlorate as direct SRM inhibitors in both pure cultures and undefined sulfidogenic communities. We demonstrate that (per)chlorate and nitrate are antagonistic inhibitors and resistance is cross-inducible implying that these compounds share at least one common mechanism of resistance. Using tagged-transposon pools we identified genes responsible for sensitivity and resistance in Desulfovibrio alaskensis G20. We found that mutants in Dde_2702 (Rex), a repressor of the central sulfate-reduction pathway were resistant to both (per)chlorate and nitrate. In general, Rex derepresses its regulon in response to increasing intracellular NADH:NAD(+) ratios. In cells in which respiratory sulfate reduction is inhibited, NADH:NAD(+) ratios should increase leading to derepression of the sulfate-reduction pathway. In support of this, in (per)chlorate or nitrate-stressed wild-type G20 we observed higher NADH:NAD(+) ratios, increased transcripts and increased peptide counts for genes in the core Rex regulon. We conclude that one mode of (per)chlorate and nitrate toxicity is as direct inhibitors of the central sulfate-reduction pathway. Our results demonstrate that (per)chlorate are more potent inhibitors than nitrate in both pure cultures and communities, implying that they represent an attractive alternative for controlling sulfidogenesis in industrial ecosystems. Of these, perchlorate offers better application logistics because of its inhibitory potency, solubility, relative chemical stability, low affinity for mineral cations and high mobility in environmental systems.
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Affiliation(s)
- Hans K Carlson
- Energy Biosciences Institute, UC Berkeley, Berkeley, CA, USA
| | - Jennifer V Kuehl
- Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | - Amrita B Hazra
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
| | - Nicholas B Justice
- Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | - Magdalena K Stoeva
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
| | - Andrew Sczesnak
- Department of Bioengineering, UC Berkeley, Berkeley, CA, USA
| | - Mark R Mullan
- Energy Biosciences Institute, UC Berkeley, Berkeley, CA, USA
| | - Anthony T Iavarone
- QB3/Chemistry Mass Spectrometry Facility, UC Berkeley, Berkeley, CA, USA
| | - Anna Engelbrektson
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
| | - Morgan N Price
- Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | - Adam M Deutschbauer
- Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | - Adam P Arkin
- 1] Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA [2] Department of Bioengineering, UC Berkeley, Berkeley, CA, USA
| | - John D Coates
- 1] Energy Biosciences Institute, UC Berkeley, Berkeley, CA, USA [2] Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, USA
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Price MN, Ray J, Wetmore KM, Kuehl JV, Bauer S, Deutschbauer AM, Arkin AP. The genetic basis of energy conservation in the sulfate-reducing bacterium Desulfovibrio alaskensis G20. Front Microbiol 2014; 5:577. [PMID: 25400629 PMCID: PMC4215793 DOI: 10.3389/fmicb.2014.00577] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 10/13/2014] [Indexed: 11/13/2022] Open
Abstract
Sulfate-reducing bacteria play major roles in the global carbon and sulfur cycles, but it remains unclear how reducing sulfate yields energy. To determine the genetic basis of energy conservation, we measured the fitness of thousands of pooled mutants of Desulfovibrio alaskensis G20 during growth in 12 different combinations of electron donors and acceptors. We show that ion pumping by the ferredoxin:NADH oxidoreductase Rnf is required whenever substrate-level phosphorylation is not possible. The uncharacterized complex Hdr/flox-1 (Dde_1207:13) is sometimes important alongside Rnf and may perform an electron bifurcation to generate more reduced ferredoxin from NADH to allow further ion pumping. Similarly, during the oxidation of malate or fumarate, the electron-bifurcating transhydrogenase NfnAB-2 (Dde_1250:1) is important and may generate reduced ferredoxin to allow additional ion pumping by Rnf. During formate oxidation, the periplasmic [NiFeSe] hydrogenase HysAB is required, which suggests that hydrogen forms in the periplasm, diffuses to the cytoplasm, and is used to reduce ferredoxin, thus providing a substrate for Rnf. During hydrogen utilization, the transmembrane electron transport complex Tmc is important and may move electrons from the periplasm into the cytoplasmic sulfite reduction pathway. Finally, mutants of many other putative electron carriers have no clear phenotype, which suggests that they are not important under our growth conditions, although we cannot rule out genetic redundancy.
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Affiliation(s)
- Morgan N. Price
- Physical Biosciences Division, Lawrence Berkeley LabBerkeley, CA, USA
| | - Jayashree Ray
- Physical Biosciences Division, Lawrence Berkeley LabBerkeley, CA, USA
| | - Kelly M. Wetmore
- Physical Biosciences Division, Lawrence Berkeley LabBerkeley, CA, USA
| | - Jennifer V. Kuehl
- Physical Biosciences Division, Lawrence Berkeley LabBerkeley, CA, USA
| | - Stefan Bauer
- Energy Biosciences Institute, University of CaliforniaBerkeley, CA, USA
| | | | - Adam P. Arkin
- Physical Biosciences Division, Lawrence Berkeley LabBerkeley, CA, USA
- Energy Biosciences Institute, University of CaliforniaBerkeley, CA, USA
- Department of Bioengineering, University of CaliforniaBerkeley, CA, USA
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Rex (encoded by DVU_0916) in Desulfovibrio vulgaris Hildenborough is a repressor of sulfate adenylyl transferase and is regulated by NADH. J Bacteriol 2014; 197:29-39. [PMID: 25313388 DOI: 10.1128/jb.02083-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Although the enzymes for dissimilatory sulfate reduction by microbes have been studied, the mechanisms for transcriptional regulation of the encoding genes remain unknown. In a number of bacteria the transcriptional regulator Rex has been shown to play a key role as a repressor of genes producing proteins involved in energy conversion. In the model sulfate-reducing microbe Desulfovibrio vulgaris Hildenborough, the gene DVU_0916 was observed to resemble other known Rex proteins. Therefore, the DVU_0916 protein has been predicted to be a transcriptional repressor of genes encoding proteins that function in the process of sulfate reduction in D. vulgaris Hildenborough. Examination of the deduced DVU_0916 protein identified two domains, one a winged helix DNA-binding domain common for transcription factors, and the other a Rossman fold that could potentially interact with pyridine nucleotides. A deletion of the putative rex gene was made in D. vulgaris Hildenborough, and transcript expression studies of sat, encoding sulfate adenylyl transferase, showed increased levels in the D. vulgaris Hildenborough Rex (RexDvH) mutant relative to the parental strain. The RexDvH-binding site upstream of sat was identified, confirming RexDvH to be a repressor of sat. We established in vitro that the presence of elevated NADH disrupted the interaction between RexDvH and DNA. Examination of the 5' transcriptional start site for the sat mRNA revealed two unique start sites, one for respiring cells that correlated with the RexDvH-binding site and a second for fermenting cells. Collectively, these data support the role of RexDvH as a transcription repressor for sat that senses the redox status of the cell.
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