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Hsu D, Flynn JR, Schuler CJ, Santelli CM, Toner BM, Bond DR, Gralnick JA. Isolation and genomic analysis of " Metallumcola ferriviriculae" MK1, a Gram-positive, Fe(III)-reducing bacterium from the Soudan Underground Mine, an iron-rich Martian analog site. Appl Environ Microbiol 2024; 90:e0004424. [PMID: 39007603 PMCID: PMC11337815 DOI: 10.1128/aem.00044-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 06/18/2024] [Indexed: 07/16/2024] Open
Abstract
The Soudan Underground Mine State Park, found in the Vermilion Iron Range in northern Minnesota, provides access to a ~ 2.7 billion-year-old banded iron formation. Exploratory boreholes drilled between 1958 and 1962 on the 27th level (713 m underground) of the mine intersect calcium and iron-rich brines that have recently been subject to metagenomic analysis and microbial enrichments. Using concentrated brine samples pumped from a borehole depth of up to 55 m, a novel Gram-positive bacterium was enriched under anaerobic, acetate-oxidizing, and Fe(III) citrate-reducing conditions. The isolated bacterium, designated strain MK1, is non-motile, rod-shaped, spore-forming, anaerobic, and mesophilic, with a growth range between 24°C and 30°C. The complete circular MK1 genome was found to be 3,720,236 bp and encodes 25 putative multiheme cytochromes, including homologs to inner membrane cytochromes in the Gram-negative bacterium Geobacter sulfurreducens and cytoplasmic membrane and periplasmic cytochromes in the Gram-positive bacterium Thermincola potens. However, MK1 does not encode homologs of the peptidoglycan (CwcA) and cell surface-associated (OcwA) multiheme cytochromes proposed to be required by T. potens to perform extracellular electron transfer. The 16S rRNA gene sequence of MK1 indicates that its closest related isolate is Desulfitibacter alkalitolerans strain sk.kt5 (91% sequence identity), which places MK1 in a novel genus within the Desulfitibacteraceae family and Moorellales order. Within the Moorellales order, only Calderihabitans maritimus strain KKC1 has been reported to reduce Fe(III), and only D. alkalitolerans can also grow in temperatures below 40°C. Thus, MK1 represents a novel species within a novel genus, for which we propose the name "Metallumcola ferriviriculae" strain MK1, and provides a unique opportunity to study a cytochrome-rich, mesophilic, Gram-positive, spore-forming Fe(III)-reducing bacterium.IMPORTANCEThe Soudan Underground Mine State Park gives access to understudied regions of the deep terrestrial subsurface that potentially predate the Great Oxidation Event. Studying organisms that have been relatively unperturbed by surface conditions for as long as 2.7 billion years may give us a window into ancient life before oxygen dominated the planet. Additionally, studying microbes from anoxic and iron-rich environments can help us better understand the requirements of life in analogous environments, such as on Mars. The isolation and characterization of "Metallumcola ferriviriculae" strain MK1 give us insights into a novel genus and species that is distinct both from its closest related isolates and from iron reducers characterized to date. "M. ferriviriculae" strain MK1 may also act as a model organism to study how the processes of sporulation and germination are affected by insoluble extracellular acceptors, as well as the impact of spores in the deep terrestrial biosphere.
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Affiliation(s)
- David Hsu
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Jack R. Flynn
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Christopher J. Schuler
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
| | - Cara M. Santelli
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
| | - Brandy M. Toner
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Earth and Environmental Sciences, University of Minnesota-Twin Cities, Minneapolis, Minnesota, USA
- Department of Soil, Water, and Climate, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Daniel R. Bond
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Jeffrey A. Gralnick
- BioTechnology Institute, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
- Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
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Yan X, Bu J, Chen X, Zhu MJ. Comparative genomic analysis reveals electron transfer pathways of Thermoanaerobacterium thermosaccharolyticum: Insights into thermophilic electroactive bacteria. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:167294. [PMID: 37741387 DOI: 10.1016/j.scitotenv.2023.167294] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 08/27/2023] [Accepted: 09/21/2023] [Indexed: 09/25/2023]
Abstract
Microbial extracellular respiration is an important energy metabolism on earth, which is significant for the elemental biogeochemical cycle. Herein, extracellular Fe(III) and electrode respiration were confirmed in Thermoanaerobacterium thermosaccharolyticum MJ2. The intra/extracellular electron transfer (IET/EET) mechanism of MJ2 was investigated by comparative genomic analysis for the first time. Morphological characterization and electrochemical properties of anode illustrated that MJ2 generated bio-electricity by forming a biofilm. The respiration chain inhibition and enzyme activity tests showed that hydrogenase with cytochrome c (Cyt-c) was involved in IET of MJ2. Noteworthily, the exogenous Cyt-c increased hydrogenase activity to promote bio-electricity generation by 92.84 %. The Cyt-c gene synteny between MJ2 and another well-known exoelectrogen (Thermincola potens JR) indicated that Cyt-c bound to the outer membrane mediated the formation of biofilm involved in EET of MJ2. This study broadened the understanding of microbial extracellular respiration diversity and provided new insights to explore the electron transfer pathways of exoelectrogens.
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Affiliation(s)
- Xing Yan
- School of Biology and Biological Engineering, Guangdong Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Panyu, Guangzhou 510006, People's Republic of China
| | - Jie Bu
- School of Biology and Biological Engineering, Guangdong Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Panyu, Guangzhou 510006, People's Republic of China
| | - Xiong Chen
- Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, Hubei, People's Republic of China
| | - Ming-Jun Zhu
- School of Biology and Biological Engineering, Guangdong Key Laboratory of Fermentation and Enzyme Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Panyu, Guangzhou 510006, People's Republic of China; Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, Hubei, People's Republic of China; The Key Laboratory of Biological Resources and Ecology of Pamirs Plateau in Xinjiang Uygur Autonomous Region, The Key Laboratory of Ecology and Biological Resources in Yarkand Oasis at Colleges & Universities under the Department of Education of Xinjiang Uygur Autonomous Region, College of Life and Geographic Sciences, Kashi University, Kashi, People's Republic of China.
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3
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Newberger DR, Minas IS, Manter DK, Vivanco JM. A Microbiological Approach to Alleviate Soil Replant Syndrome in Peaches. Microorganisms 2023; 11:1448. [PMID: 37374950 DOI: 10.3390/microorganisms11061448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
Replant syndrome (RS) is a global problem characterized by reduced growth, production life, and yields of tree fruit/nut orchards. RS etiology is unclear, but repeated monoculture plantings are thought to develop a pathogenic soil microbiome. This study aimed to evaluate a biological approach that could reduce RS in peach (Prunus persica) orchards by developing a healthy soil bacteriome. Soil disinfection via autoclave followed by cover cropping and cover crop incorporation was found to distinctly alter the peach soil bacteriome but did not affect the RS etiology of RS-susceptible 'Lovell' peach seedlings. In contrast, non-autoclaved soil followed by cover cropping and incorporation altered the soil bacteriome to a lesser degree than autoclaving but induced significant peach growth. Non-autoclaved and autoclaved soil bacteriomes were compared to highlight bacterial taxa promoted by soil disinfection prior to growing peaches. Differential abundance shows a loss of potentially beneficial bacteria due to soil disinfection. The treatment with the highest peach biomass was non-autoclaved soil with a cover crop history of alfalfa, corn, and tomato. Beneficial bacterial species that were cultivated exclusively in the peach rhizosphere of non-autoclaved soils with a cover crop history were Paenibacillus castaneae and Bellilinea caldifistulae. In summary, the non-autoclaved soils show continuous enhancement of beneficial bacteria at each cropping phase, culminating in an enriched rhizosphere which may help alleviate RS in peaches.
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Affiliation(s)
- Derek R Newberger
- Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, CO 80523, USA
| | - Ioannis S Minas
- Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, CO 80523, USA
| | - Daniel K Manter
- Agricultural Research Service, United States Department of Agriculture, Fort Collins, CO 80526, USA
| | - Jorge M Vivanco
- Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, CO 80523, USA
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Li J, Han H, Chang Y, Wang B. The material-microorganism interface in microbial hybrid electrocatalysis systems. NANOSCALE 2023; 15:6009-6024. [PMID: 36912348 DOI: 10.1039/d3nr00742a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
This review presents a comprehensive summary of the material-microorganism interface in microbial hybrid electrocatalysis systems. Microbial hybrid electrocatalysis has been developed to combine the advantages of inorganic electrocatalysis and microbial catalysis. However, electron transfer at the interfaces between microorganisms and materials is a very critical issue that affects the efficiency of the system. Therefore, this review focuses on the electron transfer at the material-microorganism interface and the strategies for building efficient microorganism and material interfaces. We begin with a brief introduction of the electron transfer mechanism in both the bioanode and biocathode of bioelectrochemical systems to understand the material-microorganism interface. Next, we summarise the strategies for constructing efficient material-microorganism interfaces including material design and modification and bacterial engineering. We also discuss emerging studies on the bio-inorganic hybrid electrocatalysis system. Understanding the interface between electrode/active materials and the microorganisms, especially the electron transfer processes, could help to drive the evolution of material-microorganism hybrid electrocatalysis systems towards maturity.
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Affiliation(s)
- Jiyao Li
- Department of Environmental Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), Beijing 100190, China.
| | - Hexing Han
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), Beijing 100190, China.
| | - Yanhong Chang
- Department of Environmental Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Bin Wang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology (NCNST), Beijing 100190, China.
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Verma M, Singh V, Mishra V. Moving towards the enhancement of extracellular electron transfer in electrogens. World J Microbiol Biotechnol 2023; 39:130. [PMID: 36959310 DOI: 10.1007/s11274-023-03582-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/15/2023] [Indexed: 03/25/2023]
Abstract
Electrogens are very common in nature and becoming a contemporary theme for research as they can be exploited for extracellular electron transfer. Extracellular electron transfer is the key mechanism behind bioelectricity generation and bioremediation of pollutants via microbes. Extracellular electron transfer mechanisms for electrogens other than Shewanella and Geobacter are less explored. An efficient extracellular electron transfer system is crucial for the sustainable future of bioelectrochemical systems. At present, the poor extracellular electron transfer efficiency remains a decisive factor in limiting the development of efficient bioelectrochemical systems. In this review article, the EET mechanisms in different electrogens (bacteria and yeast) have been focused. Apart from the well-known electron transfer mechanisms of Shewanella oneidensis and Geobacter metallireducens, a brief introduction of the EET pathway in Rhodopseudomonas palustris TIE-1, Sideroxydans lithotrophicus ES-1, Thermincola potens JR, Lysinibacillus varians GY32, Carboxydothermus ferrireducens, Enterococcus faecalis and Saccharomyces cerevisiae have been included. In addition to this, the article discusses the several approaches to anode modification and genetic engineering that may be used in order to increase the rate of extracellular electron transfer. In the side lines, this review includes the engagement of the electrogens for different applications followed by the future perspective of efficient extracellular electron transfer.
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Affiliation(s)
- Manisha Verma
- School of Biochemical Engineering, IIT (BHU), 221005, Varanasi, India
| | - Vishal Singh
- School of Biochemical Engineering, IIT (BHU), 221005, Varanasi, India
| | - Vishal Mishra
- School of Biochemical Engineering, IIT (BHU), 221005, Varanasi, India.
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6
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Aromokeye DA, Oni OE, Tebben J, Yin X, Richter-Heitmann T, Wendt J, Nimzyk R, Littmann S, Tienken D, Kulkarni AC, Henkel S, Hinrichs KU, Elvert M, Harder T, Kasten S, Friedrich MW. Crystalline iron oxides stimulate methanogenic benzoate degradation in marine sediment-derived enrichment cultures. THE ISME JOURNAL 2021; 15:965-980. [PMID: 33154547 PMCID: PMC8115662 DOI: 10.1038/s41396-020-00824-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 10/09/2020] [Accepted: 10/22/2020] [Indexed: 01/29/2023]
Abstract
Elevated dissolved iron concentrations in the methanic zone are typical geochemical signatures of rapidly accumulating marine sediments. These sediments are often characterized by co-burial of iron oxides with recalcitrant aromatic organic matter of terrigenous origin. Thus far, iron oxides are predicted to either impede organic matter degradation, aiding its preservation, or identified to enhance organic carbon oxidation via direct electron transfer. Here, we investigated the effect of various iron oxide phases with differing crystallinity (magnetite, hematite, and lepidocrocite) during microbial degradation of the aromatic model compound benzoate in methanic sediments. In slurry incubations with magnetite or hematite, concurrent iron reduction, and methanogenesis were stimulated during accelerated benzoate degradation with methanogenesis as the dominant electron sink. In contrast, with lepidocrocite, benzoate degradation, and methanogenesis were inhibited. These observations were reproducible in sediment-free enrichments, even after five successive transfers. Genes involved in the complete degradation of benzoate were identified in multiple metagenome assembled genomes. Four previously unknown benzoate degraders of the genera Thermincola (Peptococcaceae, Firmicutes), Dethiobacter (Syntrophomonadaceae, Firmicutes), Deltaproteobacteria bacteria SG8_13 (Desulfosarcinaceae, Deltaproteobacteria), and Melioribacter (Melioribacteraceae, Chlorobi) were identified from the marine sediment-derived enrichments. Scanning electron microscopy (SEM) and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) images showed the ability of microorganisms to colonize and concurrently reduce magnetite likely stimulated by the observed methanogenic benzoate degradation. These findings explain the possible contribution of organoclastic reduction of iron oxides to the elevated dissolved Fe2+ pool typically observed in methanic zones of rapidly accumulating coastal and continental margin sediments.
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Affiliation(s)
- David A. Aromokeye
- grid.7704.40000 0001 2297 4381Faculty of Biology/Chemistry, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Oluwatobi E. Oni
- grid.7704.40000 0001 2297 4381Faculty of Biology/Chemistry, University of Bremen, Bremen, Germany
| | - Jan Tebben
- grid.10894.340000 0001 1033 7684Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Xiuran Yin
- grid.7704.40000 0001 2297 4381Faculty of Biology/Chemistry, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Tim Richter-Heitmann
- grid.7704.40000 0001 2297 4381Faculty of Biology/Chemistry, University of Bremen, Bremen, Germany
| | - Jenny Wendt
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Rolf Nimzyk
- grid.7704.40000 0001 2297 4381Faculty of Biology/Chemistry, University of Bremen, Bremen, Germany
| | - Sten Littmann
- grid.419529.20000 0004 0491 3210Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Daniela Tienken
- grid.419529.20000 0004 0491 3210Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Ajinkya C. Kulkarni
- grid.7704.40000 0001 2297 4381Faculty of Biology/Chemistry, University of Bremen, Bremen, Germany
| | - Susann Henkel
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.10894.340000 0001 1033 7684Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Kai-Uwe Hinrichs
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Marcus Elvert
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Tilmann Harder
- grid.7704.40000 0001 2297 4381Faculty of Biology/Chemistry, University of Bremen, Bremen, Germany ,grid.10894.340000 0001 1033 7684Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Sabine Kasten
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.10894.340000 0001 1033 7684Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany ,grid.7704.40000 0001 2297 4381Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Michael W. Friedrich
- grid.7704.40000 0001 2297 4381Faculty of Biology/Chemistry, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
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7
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Faustino MM, Fonseca BM, Costa NL, Lousa D, Louro RO, Paquete CM. Crossing the Wall: Characterization of the Multiheme Cytochromes Involved in the Extracellular Electron Transfer Pathway of Thermincola ferriacetica. Microorganisms 2021; 9:microorganisms9020293. [PMID: 33572691 PMCID: PMC7911101 DOI: 10.3390/microorganisms9020293] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/25/2021] [Accepted: 01/27/2021] [Indexed: 12/13/2022] Open
Abstract
Bioelectrochemical systems (BES) are emerging as a suite of versatile sustainable technologies to produce electricity and added-value compounds from renewable and carbon-neutral sources using electroactive organisms. The incomplete knowledge on the molecular processes that allow electroactive organisms to exchange electrons with electrodes has prevented their real-world implementation. In this manuscript we investigate the extracellular electron transfer processes performed by the thermophilic Gram-positive bacteria belonging to the Thermincola genus, which were found to produce higher levels of current and tolerate higher temperatures in BES than mesophilic Gram-negative bacteria. In our study, three multiheme c-type cytochromes, Tfer_0070, Tfer_0075, and Tfer_1887, proposed to be involved in the extracellular electron transfer pathway of T. ferriacetica, were cloned and over-expressed in E. coli. Tfer_0070 (ImdcA) and Tfer_1887 (PdcA) were purified and biochemically characterized. The electrochemical characterization of these proteins supports a pathway of extracellular electron transfer via these two proteins. By contrast, Tfer_0075 (CwcA) could not be stabilized in solution, in agreement with its proposed insertion in the peptidoglycan wall. However, based on the homology with the outer-membrane cytochrome OmcS, a structural model for CwcA was developed, providing a molecular perspective into the mechanisms of electron transfer across the peptidoglycan layer in Thermincola.
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Omae K, Oguro T, Inoue M, Fukuyama Y, Yoshida T, Sako Y. Diversity analysis of thermophilic hydrogenogenic carboxydotrophs by carbon monoxide dehydrogenase amplicon sequencing using new primers. Extremophiles 2021; 25:61-76. [PMID: 33415441 PMCID: PMC7811984 DOI: 10.1007/s00792-020-01211-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/23/2020] [Indexed: 11/16/2022]
Abstract
The microbial H2-producing (hydrogenogenic) carbon monoxide (CO)-oxidizing activity by the membrane-associated CO dehydrogenase (CODH)/energy-converting hydrogenase (ECH) complex is an important metabolic process in the microbial community. However, the studies on hydrogenogenic carboxydotrophs had to rely on inherently cultivation and isolation methods due to their rare abundance, which was a bottleneck in ecological study. Here, we provided gene-targeted sequencing method for the diversity estimation of thermophilic hydrogenogenic carboxydotrophs. We designed six new degenerate primer pairs which effectively amplified the coding regions of CODH genes forming gene clusters with ECH genes (CODHech genes) in Firmicutes which includes major thermophilic hydrogenogenic carboxydotrophs in terrestrial thermal habitats. Amplicon sequencing by these primers using DNAs from terrestrial hydrothermal sediments and CO-gas-incubated samples specifically detected multiple CODH genes which were identical or phylogenetically related to the CODHech genes in Firmictes. Furthermore, we found that phylogenetically distinct CODHech genes were enriched in CO-gas-incubated samples, suggesting that our primers detected uncultured hydrogenogenic carboxydotrophs as well. The new CODH-targeted primers provided us with a fine-grained (~ 97.9% in nucleotide sequence identity) diversity analysis of thermophilic hydrogenogenic carboxydotrophs by amplicon sequencing and will bolster the ecological study of these microorganisms.
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Affiliation(s)
- Kimiho Omae
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Tatsuki Oguro
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Masao Inoue
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Yuto Fukuyama
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan.,Research Center for Bioscience and Nanoscience, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, Kanagawa, 237-0061, Japan
| | - Takashi Yoshida
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan.
| | - Yoshihiko Sako
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
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9
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Paquete CM. Electroactivity across the cell wall of Gram-positive bacteria. Comput Struct Biotechnol J 2020; 18:3796-3802. [PMID: 33335679 PMCID: PMC7720022 DOI: 10.1016/j.csbj.2020.11.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 02/07/2023] Open
Abstract
The growing interest on sustainable biotechnological processes for the production of energy and industrial relevant organic compounds have increased the discovery of electroactive organisms (i.e. organisms that are able to exchange electrons with an electrode) and the characterization of their extracellular electron transfer mechanisms. While most of the knowledge on extracellular electron transfer processes came from studies on Gram-negative bacteria, less is known about the processes performed by Gram-positive bacteria. In contrast to Gram-negative bacteria, Gram-positive bacteria lack an outer-membrane and contain a thick cell wall, which were thought to prevent extracellular electron transfer. However, in the last decade, an increased number of Gram-positive bacteria have been found to perform extracellular electron transfer, and exchange electrons with an electrode. In this mini-review the current knowledge on the extracellular electron transfer processes performed by Gram-positive bacteria is introduced, emphasising their electroactive role in bioelectrochemical systems. Also, the existent information of the molecular processes by which these bacteria exchange electrons with an electrode is highlighted. This understanding is fundamental to advance the implementation of these organisms in sustainable biotechnological processes, either through modification of the systems or through genetic engineering, where the organisms can be optimized to become better catalysts.
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Affiliation(s)
- Catarina M. Paquete
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Portugal
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10
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Yee MO, Deutzmann J, Spormann A, Rotaru AE. Cultivating electroactive microbes-from field to bench. NANOTECHNOLOGY 2020; 31:174003. [PMID: 31931483 DOI: 10.1088/1361-6528/ab6ab5] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electromicrobiology is an emerging field investigating and exploiting the interaction of microorganisms with insoluble electron donors or acceptors. Some of the most recently categorized electroactive microorganisms became of interest to sustainable bioengineering practices. However, laboratories worldwide typically maintain electroactive microorganisms on soluble substrates, which often leads to a decrease or loss of the ability to effectively exchange electrons with solid electrode surfaces. In order to develop future sustainable technologies, we cannot rely solely on existing lab-isolates. Therefore, we must develop isolation strategies for environmental strains with electroactive properties superior to strains in culture collections. In this article, we provide an overview of the studies that isolated or enriched electroactive microorganisms from the environment using an anode as the sole electron acceptor (electricity-generating microorganisms) or a cathode as the sole electron donor (electricity-consuming microorganisms). Next, we recommend a selective strategy for the isolation of electroactive microorganisms. Furthermore, we provide a practical guide for setting up electrochemical reactors and highlight crucial electrochemical techniques to determine electroactivity and the mode of electron transfer in novel organisms.
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Affiliation(s)
- Mon Oo Yee
- Nordcee, Department of Biology, University of Southern Denmark, Odense, DK-5230, Denmark
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Fukuyama Y, Inoue M, Omae K, Yoshida T, Sako Y. Anaerobic and hydrogenogenic carbon monoxide-oxidizing prokaryotes: Versatile microbial conversion of a toxic gas into an available energy. ADVANCES IN APPLIED MICROBIOLOGY 2020; 110:99-148. [PMID: 32386607 DOI: 10.1016/bs.aambs.2019.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Carbon monoxide (CO) is a gas that is toxic to various organisms including humans and even microbes; however, it has low redox potential, which can fuel certain microbes, namely, CO oxidizers. Hydrogenogenic CO oxidizers utilize an energy conservation system via a CO dehydrogenase/energy-converting hydrogenase complex to produce hydrogen gas, a zero emission fuel, by CO oxidation coupled with proton reduction. Biochemical and molecular biological studies using a few model organisms have revealed their enzymatic reactions and transcriptional response mechanisms using CO. Biotechnological studies for CO-dependent hydrogen production have also been carried out with these model organisms. In this chapter, we review recent advances in the studies of these microbes, which reveal their unique and versatile metabolic profiles and provides future perspectives on ecological roles and biotechnological applications. Over the past decade, the number of isolates has doubled (37 isolates in 5 phyla, 20 genera, and 32 species). Some of the recently isolated ones show broad specificity to electron acceptors. Moreover, accumulating genomic information predicts their unique physiologies and reveals their phylogenomic relationships with novel potential hydrogenogenic CO oxidizers. Combined with genomic database surveys, a molecular ecological study has unveiled the wide distribution and low abundance of these microbes. Finally, recent biotechnological applications of hydrogenogenic CO oxidizers have been achieved via diverse approaches (e.g., metabolic engineering and co-cultivation), and the identification of thermophilic facultative anaerobic CO oxidizers will promote industrial applications as oxygen-tolerant biocatalysts for efficient hydrogen production by genomic engineering.
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Affiliation(s)
- Yuto Fukuyama
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Masao Inoue
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Kimiho Omae
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Takashi Yoshida
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Yoshihiko Sako
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
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12
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Edwards MJ, Richardson DJ, Paquete CM, Clarke TA. Role of multiheme cytochromes involved in extracellular anaerobic respiration in bacteria. Protein Sci 2019; 29:830-842. [PMID: 31721352 PMCID: PMC7096707 DOI: 10.1002/pro.3787] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 11/05/2019] [Accepted: 11/05/2019] [Indexed: 01/08/2023]
Abstract
Heme containing proteins are involved in a broad range of cellular functions, from oxygen sensing and transport to catalyzing oxidoreductive reactions. The two major types of cytochrome (b-type and c-type) only differ in their mechanism of heme attachment, but this has major implications for their cellular roles in both localization and mechanism. The b-type cytochromes are commonly cytoplasmic, or are within the cytoplasmic membrane, while c-type cytochromes are always found outside of the cytoplasm. The mechanism of heme attachment allows for complex c-type multiheme complexes, having the capacity to hold multiple electrons, to be assembled. These are increasingly being identified as secreted into the extracellular environment. For organisms that respire using extracellular substrates, these large multiheme cytochromes allow for electron transfer networks from the cytoplasmic membrane to the cell exterior for the reduction of extracellular electron acceptors. In this review the structures and functions of these networks and the mechanisms by which electrons are transferred to extracellular substrates is described.
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Affiliation(s)
- Marcus J Edwards
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, UK
| | - David J Richardson
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, UK
| | - Catarina M Paquete
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Oeiras, Portugal
| | - Thomas A Clarke
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, UK
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13
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Omae K, Fukuyama Y, Yasuda H, Mise K, Yoshida T, Sako Y. Diversity and distribution of thermophilic hydrogenogenic carboxydotrophs revealed by microbial community analysis in sediments from multiple hydrothermal environments in Japan. Arch Microbiol 2019; 201:969-982. [PMID: 31030239 PMCID: PMC6687684 DOI: 10.1007/s00203-019-01661-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 03/15/2019] [Accepted: 04/15/2019] [Indexed: 12/18/2022]
Abstract
In hydrothermal environments, carbon monoxide (CO) utilisation by thermophilic hydrogenogenic carboxydotrophs may play an important role in microbial ecology by reducing toxic levels of CO and providing H2 for fuelling microbial communities. We evaluated thermophilic hydrogenogenic carboxydotrophs by microbial community analysis. First, we analysed the correlation between carbon monoxide dehydrogenase (CODH)–energy-converting hydrogenase (ECH) gene cluster and taxonomic affiliation by surveying an increasing genomic database. We identified 71 genome-encoded CODH–ECH gene clusters, including 46 whose owners were not reported as hydrogenogenic carboxydotrophs. We identified 13 phylotypes showing > 98.7% identity with these taxa as potential hydrogenogenic carboxydotrophs in hot springs. Of these, Firmicutes phylotypes such as Parageobacillus, Carboxydocella, Caldanaerobacter, and Carboxydothermus were found in different environmental conditions and distinct microbial communities. The relative abundance of the potential thermophilic hydrogenogenic carboxydotrophs was low. Most of them did not show any symbiotic networks with other microbes, implying that their metabolic activities might be low.
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Affiliation(s)
- Kimiho Omae
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8503, Japan
| | - Yuto Fukuyama
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8503, Japan
| | - Hisato Yasuda
- Center for Advanced Marine Core Research, Kochi University, B200 Monobe, Nankoku, Kochi, 783-8502, Japan
| | - Kenta Mise
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8503, Japan
| | - Takashi Yoshida
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8503, Japan
| | - Yoshihiko Sako
- Laboratory of Marine Microbiology, Graduate School of Agriculture, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8503, Japan.
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14
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Yuan HY, Ding LJ, Zama EF, Liu PP, Hozzein WN, Zhu YG. Biochar Modulates Methanogenesis through Electron Syntrophy of Microorganisms with Ethanol as a Substrate. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:12198-12207. [PMID: 30338987 DOI: 10.1021/acs.est.8b04121] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Biochar has the potential to influence methanogenesis which is a key component of global carbon cycling. However, the mechanisms governing biochar's influence on methanogenesis is not well understood, especially its effects on interspecies relationships between methanogens and anaerobic bacteria (e.g., Geobacteraceae). To understand how different types of biochar influence methanogenesis, biochars derived from rice straw (RB), wood chips (WB), and manure (MB) were added to the methanogenic enrichment culture system of a paddy soil. Compared to the nonbiochar control, RB and MB additions accelerated methanogenesis remarkably, showing 10.7 and 12.3-folds higher methane production rate, respectively; while WB had little effect on methanogenesis. Using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical methods, RB and MB also had higher redox-active properties or charging and discharging capacities than WB, and the functional groups, mainly quinones, on the biochar surface played an important role in facilitating methanogenesis. Quantitative polymerase chain reaction results demonstrated that electronic syntrophy did exist between methanogens and Geobacteraceae. RB and MB stimulate methanogenesis by facilitating direct interspecies electron transfer between methanogens and Geobacteraceae. Our findings contribute to a better understanding of the effects of biochars from different feedstocks on methanogenesis and provide new evidence to the mechanisms of stimulating methanogenesis via biochar.
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Affiliation(s)
- Hai-Yan Yuan
- State Key Lab of Urban and Regional Ecology , Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , People's Republic of China
- University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China
| | - Long-Jun Ding
- State Key Lab of Urban and Regional Ecology , Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , People's Republic of China
| | - Eric Fru Zama
- Key Lab of Urban Environment and Health , Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021 , People's Republic of China
| | - Pan-Pan Liu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment , Tsinghua University , Beijing 100084 , People's Republic of China
| | - Wael N Hozzein
- Bioproducts Research Chair, Zoology Department, College of Science , King Saud University , Riyadh 11451 , Kingdom of Saudi Arabia
| | - Yong-Guan Zhu
- State Key Lab of Urban and Regional Ecology , Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , People's Republic of China
- Key Lab of Urban Environment and Health , Institute of Urban Environment, Chinese Academy of Sciences , Xiamen 361021 , People's Republic of China
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15
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Costa NL, Clarke TA, Philipp LA, Gescher J, Louro RO, Paquete CM. Electron transfer process in microbial electrochemical technologies: The role of cell-surface exposed conductive proteins. BIORESOURCE TECHNOLOGY 2018; 255:308-317. [PMID: 29444758 DOI: 10.1016/j.biortech.2018.01.133] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/26/2018] [Accepted: 01/27/2018] [Indexed: 06/08/2023]
Abstract
Electroactive microorganisms have attracted significant interest for the development of novel biotechnological systems of low ecological footprint. These can be used for the sustainable production of energy, bioremediation of metal-contaminated environments and production of added-value products. Currently, almost 100 microorganisms from the Bacterial and Archaeal domains are considered electroactive, given their ability to efficiently interact with electrodes in microbial electrochemical technologies. Cell-surface exposed conductive proteins are key players in the electron transfer between cells and electrodes. Interestingly, it seems that among the electroactive organisms identified so far, these cell-surface proteins fall into one of four groups. In this review, the different types of cell-surface conductive proteins found in electroactive organisms will be overviewed, focusing on their structural and functional properties.
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Affiliation(s)
- Nazua L Costa
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Av. da República-EAN, 2780-157, Oeiras, Portugal
| | - Thomas A Clarke
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Laura-Alina Philipp
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (CS), Karlsruhe, Germany
| | - Johannes Gescher
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (CS), Karlsruhe, Germany; Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | - Ricardo O Louro
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Av. da República-EAN, 2780-157, Oeiras, Portugal
| | - Catarina M Paquete
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Av. da República-EAN, 2780-157, Oeiras, Portugal.
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16
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Diender M, Stams AJM, Sousa DZ. Pathways and Bioenergetics of Anaerobic Carbon Monoxide Fermentation. Front Microbiol 2015; 6:1275. [PMID: 26635746 PMCID: PMC4652020 DOI: 10.3389/fmicb.2015.01275] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 10/31/2015] [Indexed: 11/29/2022] Open
Abstract
Carbon monoxide can act as a substrate for different modes of fermentative anaerobic metabolism. The trait of utilizing CO is spread among a diverse group of microorganisms, including members of bacteria as well as archaea. Over the last decade this metabolism has gained interest due to the potential of converting CO-rich gas, such as synthesis gas, into bio-based products. Three main types of fermentative CO metabolism can be distinguished: hydrogenogenesis, methanogenesis, and acetogenesis, generating hydrogen, methane and acetate, respectively. Here, we review the current knowledge on these three variants of microbial CO metabolism with an emphasis on the potential enzymatic routes and bio-energetics involved.
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Affiliation(s)
- Martijn Diender
- Laboratory of Microbiology, Wageningen University Wageningen, Netherlands
| | - Alfons J M Stams
- Laboratory of Microbiology, Wageningen University Wageningen, Netherlands ; Centre of Biological Engineering, University of Minho Braga, Portugal
| | - Diana Z Sousa
- Laboratory of Microbiology, Wageningen University Wageningen, Netherlands
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17
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Dopson M, Ni G, Sleutels THJA. Possibilities for extremophilic microorganisms in microbial electrochemical systems. FEMS Microbiol Rev 2015; 40:164-81. [PMID: 26474966 PMCID: PMC4802824 DOI: 10.1093/femsre/fuv044] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2015] [Indexed: 11/12/2022] Open
Abstract
Microbial electrochemical systems exploit the metabolism of microorganisms to generate electrical energy or a useful product. In the past couple of decades, the application of microbial electrochemical systems has increased from the use of wastewaters to produce electricity to a versatile technology that can use numerous sources for the extraction of electrons on the one hand, while on the other hand these electrons can be used to serve an ever increasing number of functions. Extremophilic microorganisms grow in environments that are hostile to most forms of life and their utilization in microbial electrochemical systems has opened new possibilities to oxidize substrates in the anode and produce novel products in the cathode. For example, extremophiles can be used to oxidize sulfur compounds in acidic pH to remediate wastewaters, generate electrical energy from marine sediment microbial fuel cells at low temperatures, desalinate wastewaters and act as biosensors of low amounts of organic carbon. In this review, we will discuss the recent advances that have been made in using microbial catalysts under extreme conditions and show possible new routes that extremophilic microorganisms open for microbial electrochemical systems.
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Affiliation(s)
- Mark Dopson
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, SE-391 82 Kalmar, Sweden
| | - Gaofeng Ni
- Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, SE-391 82 Kalmar, Sweden
| | - Tom H J A Sleutels
- Wetsus, European Centre of Excellence for Sustainable Water Technology, 8911 MA Leeuwarden, The Netherlands
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18
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Draft Genome Sequence of the Gram-Positive Thermophilic Iron Reducer Thermincola ferriacetica Strain Z-0001T. GENOME ANNOUNCEMENTS 2015; 3:3/5/e01072-15. [PMID: 26404602 PMCID: PMC4582578 DOI: 10.1128/genomea.01072-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A 3.19-Mbp draft genome of the Gram-positive thermophilic iron-reducing Firmicutes isolate from the Peptococcaceae family, Thermincola ferriacetica Z-0001, was assembled at ~100× coverage from 100-bp paired-end Illumina reads. The draft genome contains 3,274 predicted genes (3,187 protein coding genes) and putative multiheme c-type cytochromes.
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19
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Brady AL, Sharp CE, Grasby SE, Dunfield PF. Anaerobic carboxydotrophic bacteria in geothermal springs identified using stable isotope probing. Front Microbiol 2015; 6:897. [PMID: 26388850 PMCID: PMC4555085 DOI: 10.3389/fmicb.2015.00897] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 08/17/2015] [Indexed: 12/25/2022] Open
Abstract
Carbon monoxide (CO) is a potential energy and carbon source for thermophilic bacteria in geothermal environments. Geothermal sites ranging in temperature from 45 to 65°C were investigated for the presence and activity of anaerobic CO-oxidizing bacteria. Anaerobic CO oxidation potentials were measured at up to 48.9 μmoles CO g−1 (wet weight) day−1 within five selected sites. Active anaerobic carboxydotrophic bacteria were identified using 13CO DNA stable isotope probing (SIP) combined with pyrosequencing of 16S rRNA genes amplified from labeled DNA. Bacterial communities identified in heavy DNA fractions were predominated by Firmicutes, which comprised up to 95% of all sequences in 13CO incubations. The predominant bacteria that assimilated 13C derived from CO were closely related (>98% 16S rRNA gene sequence identity) to genera of known carboxydotrophs including Thermincola, Desulfotomaculum, Thermolithobacter, and Carboxydocella, although a few species with lower similarity to known bacteria were also found that may represent previously unconfirmed CO-oxidizers. While the distribution was variable, many of the same OTUs were identified across sample sites from different temperature regimes. These results show that bacteria capable of using CO as a carbon source are common in geothermal springs, and that thermophilic carboxydotrophs are probably already quite well known from cultivation studies.
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Affiliation(s)
- Allyson L Brady
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada
| | - Christine E Sharp
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada
| | | | - Peter F Dunfield
- Department of Biological Sciences, University of Calgary Calgary, AB, Canada
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20
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Abstract
Formation of heat-resistant endospores is a specific property of the members of the phylum Firmicutes (low-G+C Gram-positive bacteria). It is found in representatives of four different classes of Firmicutes, Bacilli, Clostridia, Erysipelotrichia, and Negativicutes, which all encode similar sets of core sporulation proteins. Each of these classes also includes non-spore-forming organisms that sometimes belong to the same genus or even species as their spore-forming relatives. This chapter reviews the diversity of the members of phylum Firmicutes, its current taxonomy, and the status of genome-sequencing projects for various subgroups within the phylum. It also discusses the evolution of the Firmicutes from their apparently spore-forming common ancestor and the independent loss of sporulation genes in several different lineages (staphylococci, streptococci, listeria, lactobacilli, ruminococci) in the course of their adaptation to the saprophytic lifestyle in a nutrient-rich environment. It argues that the systematics of Firmicutes is a rapidly developing area of research that benefits from the evolutionary approaches to the ever-increasing amount of genomic and phenotypic data and allows arranging these data into a common framework.
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21
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Heterologous expression and purification of a multiheme cytochrome from a Gram-positive bacterium capable of performing extracellular respiration. Protein Expr Purif 2015; 111:48-52. [DOI: 10.1016/j.pep.2015.03.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/12/2015] [Accepted: 03/15/2015] [Indexed: 01/16/2023]
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22
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Rittmann SKM, Lee HS, Lim JK, Kim TW, Lee JH, Kang SG. One-carbon substrate-based biohydrogen production: Microbes, mechanism, and productivity. Biotechnol Adv 2015; 33:165-177. [DOI: 10.1016/j.biotechadv.2014.11.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 10/10/2014] [Accepted: 11/11/2014] [Indexed: 11/28/2022]
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23
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Nadalig T, Greule M, Bringel F, Keppler F, Vuilleumier S. Probing the diversity of chloromethane-degrading bacteria by comparative genomics and isotopic fractionation. Front Microbiol 2014; 5:523. [PMID: 25360131 PMCID: PMC4197683 DOI: 10.3389/fmicb.2014.00523] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 09/19/2014] [Indexed: 11/13/2022] Open
Abstract
Chloromethane (CH3Cl) is produced on earth by a variety of abiotic and biological processes. It is the most important halogenated trace gas in the atmosphere, where it contributes to ozone destruction. Current estimates of the global CH3Cl budget are uncertain and suggest that microorganisms might play a more important role in degrading atmospheric CH3Cl than previously thought. Its degradation by bacteria has been demonstrated in marine, terrestrial, and phyllospheric environments. Improving our knowledge of these degradation processes and their magnitude is thus highly relevant for a better understanding of the global budget of CH3Cl. The cmu pathway, for chloromethane utilisation, is the only microbial pathway for CH3Cl degradation elucidated so far, and was characterized in detail in aerobic methylotrophic Alphaproteobacteria. Here, we reveal the potential of using a two-pronged approach involving a combination of comparative genomics and isotopic fractionation during CH3Cl degradation to newly address the question of the diversity of chloromethane-degrading bacteria in the environment. Analysis of available bacterial genome sequences reveals that several bacteria not yet known to degrade CH3Cl contain part or all of the complement of cmu genes required for CH3Cl degradation. These organisms, unlike bacteria shown to grow with CH3Cl using the cmu pathway, are obligate anaerobes. On the other hand, analysis of the complete genome of the chloromethane-degrading bacterium Leisingera methylohalidivorans MB2 showed that this bacterium does not contain cmu genes. Isotope fractionation experiments with L. methylohalidivorans MB2 suggest that the unknown pathway used by this bacterium for growth with CH3Cl can be differentiated from the cmu pathway. This result opens the prospect that contributions from bacteria with the cmu and Leisingera-type pathways to the atmospheric CH3Cl budget may be teased apart in the future.
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Affiliation(s)
- Thierry Nadalig
- Université de Strasbourg, Equipe Adaptations et Interactions Microbiennes dans l'Environnement, Unitès Mixtes de Recherche 7156 Centre National de la Recherche Scientifique, Génétique Moléculaire, Génomique, Microbiologie Strasbourg, France
| | - Markus Greule
- Institute of Earth Sciences, Ruprecht Karls University Heidelberg Heidelberg, Germany
| | - Françoise Bringel
- Université de Strasbourg, Equipe Adaptations et Interactions Microbiennes dans l'Environnement, Unitès Mixtes de Recherche 7156 Centre National de la Recherche Scientifique, Génétique Moléculaire, Génomique, Microbiologie Strasbourg, France
| | - Frank Keppler
- Institute of Earth Sciences, Ruprecht Karls University Heidelberg Heidelberg, Germany
| | - Stéphane Vuilleumier
- Université de Strasbourg, Equipe Adaptations et Interactions Microbiennes dans l'Environnement, Unitès Mixtes de Recherche 7156 Centre National de la Recherche Scientifique, Génétique Moléculaire, Génomique, Microbiologie Strasbourg, France
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24
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The unique regulation of iron-sulfur cluster biogenesis in a Gram-positive bacterium. Proc Natl Acad Sci U S A 2014; 111:E2251-60. [PMID: 24847070 DOI: 10.1073/pnas.1322728111] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escherichia coli, the two existing iron-sulfur cluster assembly systems, iron-sulfur cluster (ISC) and sulfur assimilation (SUF) pathways, are closely interconnected. The ISC pathway regulator, IscR, is a transcription factor of the helix-turn-helix type that can coordinate a [2Fe-2S] cluster. Redox conditions and iron or sulfur availability modulate the ligation status of the labile IscR cluster, which in turn determines a switch in DNA sequence specificity of the regulator: cluster-containing IscR can bind to a family of gene promoters (type-1) whereas the clusterless form recognizes only a second group of sequences (type-2). However, iron-sulfur cluster biogenesis in Gram-positive bacteria is not so well characterized, and most organisms of this group display only one of the iron-sulfur cluster assembly systems. A notable exception is the unique Gram-positive dissimilatory metal reducing bacterium Thermincola potens, where genes from both systems could be identified, albeit with a diverging organization from that of Gram-negative bacteria. We demonstrated that one of these genes encodes a functional IscR homolog and is likely involved in the regulation of iron-sulfur cluster biogenesis in T. potens. Structural and biochemical characterization of T. potens and E. coli IscR revealed a strikingly similar architecture and unveiled an unforeseen conservation of the unique mechanism of sequence discrimination characteristic of this distinctive group of transcription regulators.
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25
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Torres CI. On the importance of identifying, characterizing, and predicting fundamental phenomena towards microbial electrochemistry applications. Curr Opin Biotechnol 2014; 27:107-14. [PMID: 24441074 DOI: 10.1016/j.copbio.2013.12.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 12/04/2013] [Accepted: 12/16/2013] [Indexed: 11/18/2022]
Abstract
The development of microbial electrochemistry research toward technological applications has increased significantly in the past years, leading to many process configurations. This short review focuses on the need to identify and characterize the fundamental phenomena that control the performance of microbial electrochemical cells (MXCs). Specifically, it discusses the importance of recent efforts to discover and characterize novel microorganisms for MXC applications, as well as recent developments to understand transport limitations in MXCs. As we increase our understanding of how MXCs operate, it is imperative to continue modeling efforts in order to effectively predict their performance, design efficient MXC technologies, and implement them commercially. Thus, the success of MXC technologies largely depends on the path of identifying, understanding, and predicting fundamental phenomena that determine MXC performance.
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Affiliation(s)
- César Iván Torres
- Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, 1001 S McAllister Avenue, Tempe, AZ 85287-5701, USA; School for Engineering of Matter Transport and Energy, Arizona State University, 501 E. Tyler Mall ECG 301, Tempe, AZ 85287, USA.
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26
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Parameswaran P, Bry T, Popat SC, Lusk BG, Rittmann BE, Torres CI. Kinetic, electrochemical, and microscopic characterization of the thermophilic, anode-respiring bacterium Thermincola ferriacetica. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:4934-4940. [PMID: 23544360 DOI: 10.1021/es400321c] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Thermincola ferriacetica is a recently isolated thermophilic, dissimilatory Fe(III)-reducing, Gram-positive bacterium with capability to generate electrical current via anode respiration. Our goals were to determine the maximum rates of anode respiration by T. ferriacetica and to perform a detailed microscopic and electrochemical characterization of the biofilm anode. T. ferriacetica DSM 14005 was grown at 60 °C on graphite-rod anodes poised at -0.06 V (vs) SHE in duplicate microbial electrolysis cells (MECs). The cultures grew rapidly until they achieved a sustained current density of 7-8 A m(-2) with only 10 mM bicarbonate buffer and an average Coulombic Efficiency (CE) of 93%. Cyclic voltammetry performed at maximum current density revealed a Nernst-Monod response with a half saturation potential (EKA) of -0.127 V (vs) SHE. Confocal microscopy images revealed a thick layer of actively respiring cells of T. ferriacetica (~38 μm), which is the first documentation for a gram positive anode respiring bacterium (ARB). Scanning electron microscopy showed a well-developed biofilm with a very dense network of extracellular appendages similar to Geobacter biofilms. The high current densities, a thick biofilm (~38 μm) with multiple layers of active cells, and Nernst-Monod behavior support extracellular electron transfer (EET) through a solid conductive matrix - the first such observation for Gram-positive bacteria. Operating with a controlled anode potential enabled us to grow T. ferriacetica that can use a solid conductive matrix resulting in high current densities that are promising for MXC applications.
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Affiliation(s)
- Prathap Parameswaran
- Swette Center for Environmental Biotechnology, The Biodesign Institute at Arizona State University, P.O. Box 875701, Tempe, Arizona 85287, USA.
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Abstract
Bacterial endospores are the most resistant cell type known to humans, as they are able to withstand extremes of temperature, pressure, chemical injury, and time. They are also of interest because the endospore is the infective particle in a variety of human and livestock diseases. Endosporulation is characterized by the morphogenesis of an endospore within a mother cell. Based on the genes known to be involved in endosporulation in the model organism Bacillus subtilis, a conserved core of about 100 genes was derived, representing the minimal machinery for endosporulation. The core was used to define a genomic signature of about 50 genes that are able to distinguish endospore-forming organisms, based on complete genome sequences, and we show this 50-gene signature is robust against phylogenetic proximity and other artifacts. This signature includes previously uncharacterized genes that we can now show are important for sporulation in B. subtilis and/or are under developmental control, thus further validating this genomic signature. We also predict that a series of polyextremophylic organisms, as well as several gut bacteria, are able to form endospores, and we identified 3 new loci essential for sporulation in B. subtilis: ytaF, ylmC, and ylzA. In all, the results support the view that endosporulation likely evolved once, at the base of the Firmicutes phylum, and is unrelated to other bacterial cell differentiation programs and that this involved the evolution of new genes and functions, as well as the cooption of ancestral, housekeeping functions.
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Letzel AC, Pidot SJ, Hertweck C. A genomic approach to the cryptic secondary metabolome of the anaerobic world. Nat Prod Rep 2012; 30:392-428. [PMID: 23263685 DOI: 10.1039/c2np20103h] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A total of 211 complete and published genomes from anaerobic bacteria are analysed for the presence of secondary metabolite biosynthesis gene clusters, in particular those tentatively coding for polyketide synthases (PKS) and non-ribosomal peptide synthetases (NRPS). We investigate the distribution of these gene clusters according to bacterial phylogeny and, if known, correlate these to the type of metabolic pathways they encode. The potential of anaerobes as secondary metabolite producers is highlighted.
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Affiliation(s)
- Anne-Catrin Letzel
- Leibniz Institute for Natural Product Research and Infection Biology HKI, Beutenbergstr. 11a, Jena, 07745, Germany
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Galperin MY, Mekhedov SL, Puigbo P, Smirnov S, Wolf YI, Rigden DJ. Genomic determinants of sporulation in Bacilli and Clostridia: towards the minimal set of sporulation-specific genes. Environ Microbiol 2012; 14:2870-90. [PMID: 22882546 PMCID: PMC3533761 DOI: 10.1111/j.1462-2920.2012.02841.x] [Citation(s) in RCA: 183] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Three classes of low-G+C Gram-positive bacteria (Firmicutes), Bacilli, Clostridia and Negativicutes, include numerous members that are capable of producing heat-resistant endospores. Spore-forming firmicutes include many environmentally important organisms, such as insect pathogens and cellulose-degrading industrial strains, as well as human pathogens responsible for such diseases as anthrax, botulism, gas gangrene and tetanus. In the best-studied model organism Bacillus subtilis, sporulation involves over 500 genes, many of which are conserved among other bacilli and clostridia. This work aimed to define the genomic requirements for sporulation through an analysis of the presence of sporulation genes in various firmicutes, including those with smaller genomes than B. subtilis. Cultivable spore-formers were found to have genomes larger than 2300 kb and encompass over 2150 protein-coding genes of which 60 are orthologues of genes that are apparently essential for sporulation in B. subtilis. Clostridial spore-formers lack, among others, spoIIB, sda, spoVID and safA genes and have non-orthologous displacements of spoIIQ and spoIVFA, suggesting substantial differences between bacilli and clostridia in the engulfment and spore coat formation steps. Many B. subtilis sporulation genes, particularly those encoding small acid-soluble spore proteins and spore coat proteins, were found only in the family Bacillaceae, or even in a subset of Bacillus spp. Phylogenetic profiles of sporulation genes, compiled in this work, confirm the presence of a common sporulation gene core, but also illuminate the diversity of the sporulation processes within various lineages. These profiles should help further experimental studies of uncharacterized widespread sporulation genes, which would ultimately allow delineation of the minimal set(s) of sporulation-specific genes in Bacilli and Clostridia.
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Affiliation(s)
- Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
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Surface multiheme c-type cytochromes from Thermincola potens and implications for respiratory metal reduction by Gram-positive bacteria. Proc Natl Acad Sci U S A 2012; 109:1702-7. [PMID: 22307634 DOI: 10.1073/pnas.1112905109] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they may be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or anthraquinone-2,6-disulfonate (AQDS), an analog of the redox active components of humic substances. The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin-shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS, and that several MHCs are localized to the cell wall or cell surface. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants, suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results provide unique direct evidence for cell wall-associated cytochromes and support MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium.
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Evidence for direct electron transfer by a gram-positive bacterium isolated from a microbial fuel cell. Appl Environ Microbiol 2011; 77:7633-9. [PMID: 21908627 DOI: 10.1128/aem.05365-11] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Despite their importance in iron redox cycles and bioenergy production, the underlying physiological, genetic, and biochemical mechanisms of extracellular electron transfer by Gram-positive bacteria remain insufficiently understood. In this work, we investigated respiration by Thermincola potens strain JR, a Gram-positive isolate obtained from the anode surface of a microbial fuel cell, using insoluble electron acceptors. We found no evidence that soluble redox-active components were secreted into the surrounding medium on the basis of physiological experiments and cyclic voltammetry measurements. Confocal microscopy revealed highly stratified biofilms in which cells contacting the electrode surface were disproportionately viable relative to the rest of the biofilm. Furthermore, there was no correlation between biofilm thickness and power production, suggesting that cells in contact with the electrode were primarily responsible for current generation. These data, along with cryo-electron microscopy experiments, support contact-dependent electron transfer by T. potens strain JR from the cell membrane across the 37-nm cell envelope to the cell surface. Furthermore, we present physiological and genomic evidence that c-type cytochromes play a role in charge transfer across the Gram-positive bacterial cell envelope during metal reduction.
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Techtmann SM, Colman AS, Murphy MB, Schackwitz WS, Goodwin LA, Robb FT. Regulation of multiple carbon monoxide consumption pathways in anaerobic bacteria. Front Microbiol 2011; 2:147. [PMID: 21808633 PMCID: PMC3135865 DOI: 10.3389/fmicb.2011.00147] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 06/22/2011] [Indexed: 11/13/2022] Open
Abstract
Carbon monoxide (CO), well known as a toxic gas, is increasingly recognized as a key metabolite and signaling molecule. Microbial utilization of CO is quite common, evidenced by the rapid escalation in description of new species of CO-utilizing bacteria and archaea. Carbon monoxide dehydrogenase (CODH), the protein complex that enables anaerobic CO-utilization, has been well-characterized from an increasing number of microorganisms, however the regulation of multiple CO-related gene clusters in single isolates remains unexplored. Many species are extraordinarily resistant to high CO concentrations, thriving under pure CO at more than one atmosphere. We hypothesized that, in strains that can grow exclusively on CO, both carbon acquisition via the CODH/acetyl CoA synthase complex and energy conservation via a CODH-linked hydrogenase must be differentially regulated in response to the availability of CO. The CO-sensing transcriptional activator, CooA is present in most CO-oxidizing bacteria. Here we present a genomic and phylogenetic survey of CODH operons and cooA genes found in CooA-containing bacteria. Two distinct groups of CooA homologs were found: one clade (CooA-1) is found in the majority of CooA-containing bacteria, whereas the other clade (CooA-2) is found only in genomes that encode multiple CODH clusters, suggesting that the CooA-2 might be important for cross-regulation of competing CODH operons. Recombinant CooA-1 and CooA-2 regulators from the prototypical CO-utilizing bacterium Carboxydothermus hydrogenoformans were purified, and promoter binding analyses revealed that CooA-1 specifically regulates the hydrogenase-linked CODH, whereas CooA-2 is able to regulate both the hydrogenase-linked CODH and the CODH/ACS operons. These studies point to the ability of dual CooA homologs to partition CO into divergent CO-utilizing pathways resulting in efficient consumption of a single limiting growth substrate available across a wide range of concentrations.
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Affiliation(s)
- Stephen M Techtmann
- Institute of Marine and Environmental Technology, University of Maryland Baltimore, MD, USA
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