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Garber AI, Cohen AB, Nealson KH, Ramírez GA, Barco RA, Enzingmüller-Bleyl TC, Gehringer MM, Merino N. Metagenomic Insights Into the Microbial Iron Cycle of Subseafloor Habitats. Front Microbiol 2021; 12:667944. [PMID: 34539592 PMCID: PMC8446621 DOI: 10.3389/fmicb.2021.667944] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 07/30/2021] [Indexed: 11/13/2022] Open
Abstract
Microbial iron cycling influences the flux of major nutrients in the environment (e.g., through the adsorptive capacity of iron oxides) and includes biotically induced iron oxidation and reduction processes. The ecological extent of microbial iron cycling is not well understood, even with increased sequencing efforts, in part due to limitations in gene annotation pipelines and limitations in experimental studies linking phenotype to genotype. This is particularly true for the marine subseafloor, which remains undersampled, but represents the largest contiguous habitat on Earth. To address this limitation, we used FeGenie, a database and bioinformatics tool that identifies microbial iron cycling genes and enables the development of testable hypotheses on the biogeochemical cycling of iron. Herein, we survey the microbial iron cycle in diverse subseafloor habitats, including sediment-buried crustal aquifers, as well as surficial and deep sediments. We inferred the genetic potential for iron redox cycling in 32 of the 46 metagenomes included in our analysis, demonstrating the prevalence of these activities across underexplored subseafloor ecosystems. We show that while some processes (e.g., iron uptake and storage, siderophore transport potential, and iron gene regulation) are near-universal, others (e.g., iron reduction/oxidation, siderophore synthesis, and magnetosome formation) are dependent on local redox and nutrient status. Additionally, we detected niche-specific differences in strategies used for dissimilatory iron reduction, suggesting that geochemical constraints likely play an important role in dictating the dominant mechanisms for iron cycling. Overall, our survey advances the known distribution, magnitude, and potential ecological impact of microbe-mediated iron cycling and utilization in sub-benthic ecosystems.
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Affiliation(s)
- Arkadiy I Garber
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
| | - Ashley B Cohen
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, United States
| | - Kenneth H Nealson
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
| | - Gustavo A Ramírez
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel.,College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA, United States
| | - Roman A Barco
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
| | | | - Michelle M Gehringer
- Department of Microbiology, Technical University of Kaiserslautern, Kaiserslautern, Germany
| | - Nancy Merino
- Biosciences & Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
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2
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Jiang V, Khare SD, Banta S. Computational structure prediction provides a plausible mechanism for electron transfer by the outer membrane protein Cyc2 from Acidithiobacillus ferrooxidans. Protein Sci 2021; 30:1640-1652. [PMID: 33969560 DOI: 10.1002/pro.4106] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/30/2021] [Accepted: 05/03/2021] [Indexed: 12/14/2022]
Abstract
Cyc2 is the key protein in the outer membrane of Acidithiobacillus ferrooxidans that mediates electron transfer between extracellular inorganic iron and the intracellular central metabolism. This cytochrome c is specific for iron and interacts with periplasmic proteins to complete a reversible electron transport chain. A structure of Cyc2 has not yet been characterized experimentally. Here we describe a structural model of Cyc2, and associated proteins, to highlight a plausible mechanism for the ferrous iron electron transfer chain. A comparative modeling protocol specific for trans membrane beta barrel (TMBB) proteins in acidophilic conditions (pH ~ 2) was applied to the primary sequence of Cyc2. The proposed structure has three main regimes: Extracellular loops exposed to low-pH conditions, a TMBB, and an N-terminal cytochrome-like region within the periplasmic space. The Cyc2 model was further refined by identifying likely iron and heme docking sites. This represents the first computational model of Cyc2 that accounts for the membrane microenvironment and the acidity in the extracellular matrix. This approach can be used to model other TMBBs which can be critical for chemolithotrophic microbial growth.
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Affiliation(s)
- Virginia Jiang
- Department of Chemical Engineering, Columbia University in the City of New York, New York, New York, USA
| | - Sagar D Khare
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Scott Banta
- Department of Chemical Engineering, Columbia University in the City of New York, New York, New York, USA
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3
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Zhan Y, Yang M, Zhang S, Zhao D, Duan J, Wang W, Yan L. Iron and sulfur oxidation pathways of Acidithiobacillus ferrooxidans. World J Microbiol Biotechnol 2019; 35:60. [PMID: 30919119 DOI: 10.1007/s11274-019-2632-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 03/08/2019] [Indexed: 12/13/2022]
Abstract
Acidithiobacillus ferrooxidans is a gram-negative, autotrophic and rod-shaped bacterium. It can gain energy through the oxidation of Fe(II) and reduced inorganic sulfur compounds for bacterial growth when oxygen is sufficient. It can be used for bio-leaching and bio-oxidation and contributes to the geobiochemical circulation of metal elements and nutrients in acid mine drainage environments. The iron and sulfur oxidation pathways of A. ferrooxidans play key roles in bacterial growth and survival under extreme circumstances. Here, the electrons transported through the thermodynamically favourable pathway for the reduction to H2O (downhill pathway) and against the redox potential gradient reduce to NAD(P)(H) (uphill pathway) during the oxidation of Fe(II) were reviewed, mainly including the electron transport carrier, relevant operon and regulation of its expression. Similar to the electron transfer pathway, the sulfur oxidation pathway of A. ferrooxidans, related genes and operons, sulfur oxidation mechanism and sulfur oxidase system are systematically discussed.
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Affiliation(s)
- Yue Zhan
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China
| | - Mengran Yang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China
| | - Shuang Zhang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China
| | - Dan Zhao
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China
| | - Jiangong Duan
- School of Pharmacy, Lanzhou University, Donggang West Road No. 199, Lanzhou, 730020, Gansu Province, People's Republic of China
| | - Weidong Wang
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China
| | - Lei Yan
- Heilongjiang Provincial Key Laboratory of Environmental Microbiology and Recycling of Argo-Waste in Cold Region, College of Life Science and Biotechnology, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China. .,College of Food Science, Heilongjiang Bayi Agricultural University, 5 Xinfeng Road, Daqing, 163319, Heilongjiang Province, People's Republic of China.
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Ai C, Liang Y, Miao B, Chen M, Zeng W, Qiu G. Identification and Analysis of a Novel Gene Cluster Involves in Fe 2+ Oxidation in Acidithiobacillus ferrooxidans ATCC 23270, a Typical Biomining Acidophile. Curr Microbiol 2018; 75:818-826. [PMID: 29464360 DOI: 10.1007/s00284-018-1453-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 02/12/2018] [Indexed: 11/26/2022]
Abstract
Iron-oxidizing Acidithiobacillus spp. are applied worldwide in biomining industry to extract metals from sulfide minerals. They derive energy for survival through Fe2+ oxidation and generate Fe3+ for the dissolution of sulfide minerals. However, molecular mechanisms of their iron oxidation still remain elusive. A novel two-cytochrome-encoding gene cluster (named tce gene cluster) encoding a high-molecular-weight cytochrome c (AFE_1428) and a c4-type cytochrome c552 (AFE_1429) in A. ferrooxidans ATCC 23270 was first identified in this study. Bioinformatic analysis together with transcriptional study showed that AFE_1428 and AFE_1429 were the corresponding paralog of Cyc2 (AFE_3153) and Cyc1 (AFE_3152) which were encoded by the extensively studied rus operon and had been proven involving in ferrous iron oxidation. Both AFE_1428 and AFE_1429 contained signal peptide and the classic heme-binding motif(s) as their corresponding paralog. The modeled structure of AFE_1429 showed high resemblance to Cyc1. AFE_1428 and AFE_1429 were preferentially transcribed as their corresponding paralogs in the presence of ferrous iron as sole energy source as compared with sulfur. The tce gene cluster is highly conserved in the genomes of four phylogenetic-related A. ferrooxidans strains that were originally isolated from different sites separated with huge geographical distance, which further implies the importance of this gene cluster. Collectively, AFE_1428 and AFE_1429 involve in Fe2+ oxidation like their corresponding paralog by integrating with the metalloproteins encoded by rus operon. This study provides novel insights into the Fe2+ oxidation mechanism in Fe2+-oxidizing A. ferrooxidans ssp.
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Affiliation(s)
- Chenbing Ai
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, Hunan, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Yuting Liang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, Hunan, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Bo Miao
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, Hunan, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Miao Chen
- CSIRO Process Science and Engineering, Clayton, VIC, Australia
| | - Weimin Zeng
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, Hunan, China.
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China.
- CSIRO Process Science and Engineering, Clayton, VIC, Australia.
| | - Guanzhou Qiu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, Hunan, China.
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China.
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New Insight into Microbial Iron Oxidation as Revealed by the Proteomic Profile of an Obligate Iron-Oxidizing Chemolithoautotroph. Appl Environ Microbiol 2015; 81:5927-37. [PMID: 26092463 DOI: 10.1128/aem.01374-15] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 06/16/2015] [Indexed: 02/01/2023] Open
Abstract
Microaerophilic, neutrophilic, iron-oxidizing bacteria (FeOB) grow via the oxidation of reduced Fe(II) at or near neutral pH, in the presence of oxygen, making them relevant in numerous environments with elevated Fe(II) concentrations. However, the biochemical mechanisms for Fe(II) oxidation by these neutrophilic FeOB are unknown, and genetic markers for this process are unavailable. In the ocean, microaerophilic microorganisms in the genus Mariprofundus of the class Zetaproteobacteria are the only organisms known to chemolithoautotrophically oxidize Fe and concurrently biomineralize it in the form of twisted stalks of iron oxyhydroxides. The aim of this study was to identify highly expressed proteins associated with the electron transport chain of microaerophilic, neutrophilic FeOB. To this end, Mariprofundus ferrooxydans PV-1 was cultivated, and its proteins were extracted, assayed for redox activity, and analyzed via liquid chromatography-tandem mass spectrometry for identification of peptides. The results indicate that a cytochrome c4, cbb3-type cytochrome oxidase subunits, and an outer membrane cytochrome c were among the most highly expressed proteins and suggest an involvement in the process of aerobic, neutrophilic bacterial Fe oxidation. Proteins associated with alternative complex III, phosphate transport, carbon fixation, and biofilm formation were abundant, consistent with the lifestyle of Mariprofundus.
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Quatrini R, Appia-Ayme C, Denis Y, Jedlicki E, Holmes DS, Bonnefoy V. Extending the models for iron and sulfur oxidation in the extreme acidophile Acidithiobacillus ferrooxidans. BMC Genomics 2009; 10:394. [PMID: 19703284 PMCID: PMC2754497 DOI: 10.1186/1471-2164-10-394] [Citation(s) in RCA: 218] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2009] [Accepted: 08/24/2009] [Indexed: 11/10/2022] Open
Abstract
Background Acidithiobacillus ferrooxidans gains energy from the oxidation of ferrous iron and various reduced inorganic sulfur compounds at very acidic pH. Although an initial model for the electron pathways involved in iron oxidation has been developed, much less is known about the sulfur oxidation in this microorganism. In addition, what has been reported for both iron and sulfur oxidation has been derived from different A. ferrooxidans strains, some of which have not been phylogenetically characterized and some have been shown to be mixed cultures. It is necessary to provide models of iron and sulfur oxidation pathways within one strain of A. ferrooxidans in order to comprehend the full metabolic potential of the pangenome of the genus. Results Bioinformatic-based metabolic reconstruction supported by microarray transcript profiling and quantitative RT-PCR analysis predicts the involvement of a number of novel genes involved in iron and sulfur oxidation in A. ferrooxidans ATCC23270. These include for iron oxidation: cup (copper oxidase-like), ctaABT (heme biogenesis and insertion), nuoI and nuoK (NADH complex subunits), sdrA1 (a NADH complex accessory protein) and atpB and atpE (ATP synthetase F0 subunits). The following new genes are predicted to be involved in reduced inorganic sulfur compounds oxidation: a gene cluster (rhd, tusA, dsrE, hdrC, hdrB, hdrA, orf2, hdrC, hdrB) encoding three sulfurtransferases and a heterodisulfide reductase complex, sat potentially encoding an ATP sulfurylase and sdrA2 (an accessory NADH complex subunit). Two different regulatory components are predicted to be involved in the regulation of alternate electron transfer pathways: 1) a gene cluster (ctaRUS) that contains a predicted iron responsive regulator of the Rrf2 family that is hypothesized to regulate cytochrome aa3 oxidase biogenesis and 2) a two component sensor-regulator of the RegB-RegA family that may respond to the redox state of the quinone pool. Conclusion Bioinformatic analysis coupled with gene transcript profiling extends our understanding of the iron and reduced inorganic sulfur compounds oxidation pathways in A. ferrooxidans and suggests mechanisms for their regulation. The models provide unified and coherent descriptions of these processes within the type strain, eliminating previous ambiguity caused by models built from analyses of multiple and divergent strains of this microorganism.
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Affiliation(s)
- Raquel Quatrini
- Center for Bioinformatics and Genome Biology, MIFAB, Fundación Ciencia para la Vida and Depto. de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile.
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7
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Jiao Y, Newman DK. The pio operon is essential for phototrophic Fe(II) oxidation in Rhodopseudomonas palustris TIE-1. J Bacteriol 2007; 189:1765-73. [PMID: 17189359 PMCID: PMC1855732 DOI: 10.1128/jb.00776-06] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Accepted: 12/12/2006] [Indexed: 11/20/2022] Open
Abstract
Phototrophic Fe(II)-oxidizing bacteria couple the oxidation of ferrous iron [Fe(II)] to reductive CO(2) fixation by using light energy, but until recently, little has been understood about the molecular basis for this process. Here we report the discovery, with Rhodopseudomonas palustris TIE-1 as a model organism, of a three-gene operon, designated the pio operon (for phototrophic iron oxidation), that is necessary for phototrophic Fe(II) oxidation. The first gene in the operon, pioA, encodes a c-type cytochrome that is upregulated under Fe(II)-grown conditions. PioA contains a signal sequence and shares homology with MtrA, a decaheme c-type cytochrome from Shewanella oneidensis MR-1. The second gene, pioB, encodes a putative outer membrane beta-barrel protein. PioB is a homologue of MtrB from S. oneidensis MR-1. The third gene, pioC, encodes a putative high potential iron sulfur protein (HiPIP) with a twin-arginine translocation (Tat) signal sequence and is similar to the putative Fe(II) oxidoreductase (Iro) from Acidithiobacillus ferrooxidans. Like PioA, PioB and PioC appear to be secreted proteins. Deletion of the pio operon results in loss of Fe(II) oxidation activity and growth on Fe(II). Complementation studies confirm that the phenotype of this mutant is due to loss of the pio genes. Deletion of pioA alone results in loss of almost all Fe(II) oxidation activity; however, deletion of either pioB or pioC alone results in only partial loss of Fe(II) oxidation activity. Together, these results suggest that proteins encoded by the pio operon are essential and specific for phototrophic Fe(II) oxidation in R. palustris TIE-1.
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Affiliation(s)
- Yongqin Jiao
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
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Jiao Y, Kappler A, Croal LR, Newman DK. Isolation and characterization of a genetically tractable photoautotrophic Fe(II)-oxidizing bacterium, Rhodopseudomonas palustris strain TIE-1. Appl Environ Microbiol 2005; 71:4487-96. [PMID: 16085840 PMCID: PMC1183355 DOI: 10.1128/aem.71.8.4487-4496.2005] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2004] [Accepted: 03/11/2005] [Indexed: 11/20/2022] Open
Abstract
We report the isolation and characterization of a phototrophic ferrous iron [Fe(II)]-oxidizing bacterium named TIE-1 that differs from other Fe(II)-oxidizing phototrophs in that it is genetically tractable. Under anaerobic conditions, TIE-1 grows photoautotrophically with Fe(II), H2, or thiosulfate as the electron donor and photoheterotrophically with a variety of organic carbon sources. TIE-1 also grows chemoheterotrophically in the dark. This isolate appears to be a new strain of the purple nonsulfur bacterial species Rhodopseudomonas palustris, based on physiological and phylogenetic analysis. Fe(II) oxidation is optimal at pH 6.5 to 6.9. The mineral products of Fe(II) oxidation are pH dependent: below pH 7.0 goethite (alpha-FeOOH) forms, and above pH 7.2 magnetite (Fe3O4) forms. TIE-1 forms colonies on agar plates and is sensitive to a variety of antibiotics. A hyperactive mariner transposon is capable of random insertion into the chromosome with a transposition frequency of approximately 10(-5). To identify components involved in phototrophic Fe(II) oxidation, mutants of TIE-1 were generated by transposon mutagenesis and screened for defects in Fe(II) oxidation in a cell suspension assay. Among approximately 12,000 mutants screened, 6 were identified that are specifically impaired in Fe(II) oxidation. Five of these mutants have independent disruptions in a gene that is predicted to encode an integral membrane protein that appears to be part of an ABC transport system; the sixth mutant has an insertion in a gene that is a homolog of CobS, an enzyme involved in cobalamin (vitamin B12) biosynthesis.
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Affiliation(s)
- Yongqin Jiao
- California Institute of Technology, Division of Geological and Planetary Sciences, Mail Stop 100-23, Pasadena, CA 91125, USA
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Ohmura N, Sasaki K, Matsumoto N, Saiki H. Anaerobic respiration using Fe(3+), S(0), and H(2) in the chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans. J Bacteriol 2002; 184:2081-7. [PMID: 11914338 PMCID: PMC134942 DOI: 10.1128/jb.184.8.2081-2087.2002] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans has been known as an aerobe that respires on iron and sulfur. Here we show that the bacterium could chemolithoautotrophically grow not only on H(2)/O(2) under aerobic conditions but also on H(2)/Fe(3+), H(2)/S(0), or S(0)/Fe(3+) under anaerobic conditions. Anaerobic respiration using Fe(3+) or S(0) as an electron acceptor and H(2) or S(0) as an electron donor serves as a primary energy source of the bacterium. Anaerobic respiration based on reduction of Fe(3+) induced the bacterium to synthesize significant amounts of a c-type cytochrome that was purified as an acid-stable and soluble 28-kDa monomer. The purified cytochrome in the oxidized form was reduced in the presence of the crude extract, and the reduced cytochrome was reoxidized by Fe(3+). Respiration based on reduction of Fe(3+) coupled to oxidation of a c-type cytochrome may be involved in the primary mechanism of energy production in the bacterium on anaerobic iron respiration.
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Affiliation(s)
- Naoya Ohmura
- Department of Bio-Science, Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-City Chiba 270-1194, Japan.
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Yarzábal A, Brasseur G, Ratouchniak J, Lund K, Lemesle-Meunier D, DeMoss JA, Bonnefoy V. The high-molecular-weight cytochrome c Cyc2 of Acidithiobacillus ferrooxidans is an outer membrane protein. J Bacteriol 2002; 184:313-7. [PMID: 11741873 PMCID: PMC134758 DOI: 10.1128/jb.184.1.313-317.2002] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A high-molecular-weight c-type cytochrome, Cyc2, and a putative 22-kDa c-type cytochrome were detected in the membrane fraction released during spheroplast formation from Acidithiobacillus ferrooxidans. This fraction was enriched in outer membrane components and devoid of cytoplasmic membrane markers. The genetics, as well as the subcellular localization of Cyc2 at the outer membrane level, therefore make it a prime candidate for the initial electron acceptor in the respiratory pathway between ferrous iron and oxygen.
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Affiliation(s)
- Andrés Yarzábal
- Laboratoire de Chimie Bactérienne, CNRS, IBSM, Marseille, France
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Liu Z, Guiliani N, Appia-Ayme C, Borne F, Ratouchniak J, Bonnefoy V. Construction and characterization of a recA mutant of Thiobacillus ferrooxidans by marker exchange mutagenesis. J Bacteriol 2000; 182:2269-76. [PMID: 10735871 PMCID: PMC111277 DOI: 10.1128/jb.182.8.2269-2276.2000] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To construct Thiobacillus ferrooxidans mutants by marker exchange mutagenesis, a genetic transfer system is required. The transfer of broad-host-range plasmids belonging to the incompatibility groups IncQ (pKT240 and pJRD215), IncP (pJB3Km1), and IncW (pUFR034) from Escherichia coli to two private T. ferrooxidans strains (BRGM1 and Tf-49) and to two collection strains (ATCC 33020 and ATCC 19859) by conjugation was analyzed. To knock out the T. ferrooxidans recA gene, a mobilizable suicide plasmid carrying the ATCC 33020 recA gene disrupted by a kanamycin resistance gene was transferred from E. coli to T. ferrooxidans ATCC 33020 by conjugation under the best conditions determined. The two kanamycin-resistant clones, which have retained the kanamycin-resistant phenotype after growth for several generations in nonselective medium, were shown to have the kanamycin resistance gene inserted within the recA gene, indicating that the recA::Omega-Km mutated allele was transferred from the suicide plasmid to the chromosome by homologous recombination. These mutants exhibited a slightly reduced growth rate and an increased sensitivity to UV and gamma irradiation compared to the wild-type strain. However, the T. ferrooxidans recA mutants are less sensitive to these physical DNA-damaging agents than the recA mutants described in other bacterial species, suggesting that RecA plays a minor role in DNA repair in T. ferrooxidans.
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Affiliation(s)
- Z Liu
- Laboratoire de Chimie Bactérienne, Institut de Biologie Structurale et de Microbiologie, C.N.R.S., 13402 Marseille Cedex 20, France
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