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Flood BE, Louw DC, Van der Plas AK, Bailey JV. Giant sulfur bacteria (Beggiatoaceae) from sediments underlying the Benguela upwelling system host diverse microbiomes. PLoS One 2021; 16:e0258124. [PMID: 34818329 PMCID: PMC8612568 DOI: 10.1371/journal.pone.0258124] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 09/20/2021] [Indexed: 01/04/2023] Open
Abstract
Due to their lithotrophic metabolisms, morphological complexity and conspicuous appearance, members of the Beggiatoaceae have been extensively studied for more than 100 years. These bacteria are known to be primarily sulfur-oxidizing autotrophs that commonly occur in dense mats at redox interfaces. Their large size and the presence of a mucous sheath allows these cells to serve as sites of attachment for communities of other microorganisms. But little is known about their individual niche preferences and attached microbiomes, particularly in marine environments, due to a paucity of cultivars and their prevalence in habitats that are difficult to access and study. Therefore, in this study, we compare Beggiatoaceae strain composition, community composition, and geochemical profiles collected from sulfidic sediments at four marine stations off the coast of Namibia. To elucidate community members that were directly attached and enriched in both filamentous Beggiatoaceae, namely Ca. Marithioploca spp. and Ca. Maribeggiatoa spp., as well as non-filamentous Beggiatoaceae, Ca. Thiomargarita spp., the Beggiatoaceae were pooled by morphotype for community analysis. The Beggiatoaceae samples collected from a highly sulfidic site were enriched in strains of sulfur-oxidizing Campylobacterota, that may promote a more hospitable setting for the Beggiatoaceae, which are known to have a lower tolerance for high sulfide to oxygen ratios. We found just a few host-specific associations with the motile filamentous morphotypes. Conversely, we detected 123 host specific enrichments with non-motile chain forming Beggiatoaceae. Potential metabolisms of the enriched strains include fermentation of host sheath material, syntrophic exchange of H2 and acetate, inorganic sulfur metabolism, and nitrite oxidation. Surprisingly, we did not detect any enrichments of anaerobic ammonium oxidizing bacteria as previously suggested and postulate that less well-studied anaerobic ammonium oxidation pathways may be occurring instead.
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Affiliation(s)
- Beverly E. Flood
- Department of Earth and Environmental Sciences, University of Minnesota, Twin Cities, Minnesota, United States of America
- * E-mail:
| | - Deon C. Louw
- National Marine Information and Research Centre, Swakopmund, Namibia
| | | | - Jake V. Bailey
- Department of Earth and Environmental Sciences, University of Minnesota, Twin Cities, Minnesota, United States of America
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Paredes GF, Viehboeck T, Lee R, Palatinszky M, Mausz MA, Reipert S, Schintlmeister A, Maier A, Volland JM, Hirschfeld C, Wagner M, Berry D, Markert S, Bulgheresi S, König L. Anaerobic Sulfur Oxidation Underlies Adaptation of a Chemosynthetic Symbiont to Oxic-Anoxic Interfaces. mSystems 2021; 6:e0118620. [PMID: 34058098 PMCID: PMC8269255 DOI: 10.1128/msystems.01186-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 04/20/2021] [Indexed: 11/23/2022] Open
Abstract
Chemosynthetic symbioses occur worldwide in marine habitats, but comprehensive physiological studies of chemoautotrophic bacteria thriving on animals are scarce. Stilbonematinae are coated by thiotrophic Gammaproteobacteria. As these nematodes migrate through the redox zone, their ectosymbionts experience varying oxygen concentrations. However, nothing is known about how these variations affect their physiology. Here, by applying omics, Raman microspectroscopy, and stable isotope labeling, we investigated the effect of oxygen on "Candidatus Thiosymbion oneisti." Unexpectedly, sulfur oxidation genes were upregulated in anoxic relative to oxic conditions, but carbon fixation genes and incorporation of 13C-labeled bicarbonate were not. Instead, several genes involved in carbon fixation were upregulated under oxic conditions, together with genes involved in organic carbon assimilation, polyhydroxyalkanoate (PHA) biosynthesis, nitrogen fixation, and urea utilization. Furthermore, in the presence of oxygen, stress-related genes were upregulated together with vitamin biosynthesis genes likely necessary to withstand oxidative stress, and the symbiont appeared to proliferate less. Based on its physiological response to oxygen, we propose that "Ca. T. oneisti" may exploit anaerobic sulfur oxidation coupled to denitrification to proliferate in anoxic sand. However, the ectosymbiont would still profit from the oxygen available in superficial sand, as the energy-efficient aerobic respiration would facilitate carbon and nitrogen assimilation. IMPORTANCE Chemoautotrophic endosymbionts are famous for exploiting sulfur oxidization to feed marine organisms with fixed carbon. However, the physiology of thiotrophic bacteria thriving on the surface of animals (ectosymbionts) is less understood. One longstanding hypothesis posits that attachment to animals that migrate between reduced and oxic environments would boost sulfur oxidation, as the ectosymbionts would alternatively access sulfide and oxygen, the most favorable electron acceptor. Here, we investigated the effect of oxygen on the physiology of "Candidatus Thiosymbion oneisti," a gammaproteobacterium which lives attached to marine nematodes inhabiting shallow-water sand. Surprisingly, sulfur oxidation genes were upregulated under anoxic relative to oxic conditions. Furthermore, under anoxia, the ectosymbiont appeared to be less stressed and to proliferate more. We propose that animal-mediated access to oxygen, rather than enhancing sulfur oxidation, would facilitate assimilation of carbon and nitrogen by the ectosymbiont.
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Affiliation(s)
- Gabriela F. Paredes
- University of Vienna, Department of Functional and Evolutionary Ecology, Environmental Cell Biology Group, Vienna, Austria
| | - Tobias Viehboeck
- University of Vienna, Department of Functional and Evolutionary Ecology, Environmental Cell Biology Group, Vienna, Austria
- University of Vienna, Center for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
| | - Raymond Lee
- Washington State University, School of Biological Sciences, Pullman, Washington, USA
| | - Marton Palatinszky
- University of Vienna, Center for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
| | - Michaela A. Mausz
- University of Warwick, School of Life Sciences, Coventry, United Kingdom
| | - Siegfried Reipert
- University of Vienna, Core Facility Cell Imaging and Ultrastructure Research, Vienna, Austria
| | - Arno Schintlmeister
- University of Vienna, Center for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
- University of Vienna, Center for Microbiology and Environmental Systems Science, Large-Instrument Facility for Environmental and Isotope Mass Spectrometry, Vienna, Austria
| | - Andreas Maier
- University of Vienna, Faculty of Geosciences, Geography, and Astronomy, Department of Geography and Regional Research, Geoecology, Vienna, Austria
| | - Jean-Marie Volland
- University of Vienna, Department of Functional and Evolutionary Ecology, Environmental Cell Biology Group, Vienna, Austria
| | - Claudia Hirschfeld
- University of Greifswald, Institute of Pharmacy, Department of Pharmaceutical Biotechnology, Greifswald, Germany
| | - Michael Wagner
- University of Vienna, Center for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
- Aalborg University, Department of Chemistry and Bioscience, Aalborg, Denmark
| | - David Berry
- University of Vienna, Center for Microbiology and Environmental Systems Science, Division of Microbial Ecology, Vienna, Austria
- Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna, Vienna, Austria
| | - Stephanie Markert
- University of Greifswald, Institute of Pharmacy, Department of Pharmaceutical Biotechnology, Greifswald, Germany
| | - Silvia Bulgheresi
- University of Vienna, Department of Functional and Evolutionary Ecology, Environmental Cell Biology Group, Vienna, Austria
| | - Lena König
- University of Vienna, Department of Functional and Evolutionary Ecology, Environmental Cell Biology Group, Vienna, Austria
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Fonseca A, Ishoey T, Espinoza C, Pérez-Pantoja D, Manghisi A, Morabito M, Salas-Burgos A, Gallardo VA. Genomic features of "Candidatus Venteria ishoeyi", a new sulfur-oxidizing macrobacterium from the Humboldt Sulfuretum off Chile. PLoS One 2017; 12:e0188371. [PMID: 29236755 PMCID: PMC5728499 DOI: 10.1371/journal.pone.0188371] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Accepted: 11/06/2017] [Indexed: 12/13/2022] Open
Abstract
The Humboldt Sulfuretum (HS), in the productive Humboldt Eastern Boundary Current Upwelling Ecosystem, extends under the hypoxic waters of the Peru-Chile Undercurrent (ca. 6°S and ca. 36°S). Studies show that primeval sulfuretums held diverse prokaryotic life, and, while rare today, still sustain species-rich giant sulfur-oxidizing bacterial communities. We here present the genomic features of a new bacteria of the HS, "Candidatus Venteria ishoeyi" ("Ca. V. ishoeyi") in the family Thiotrichaceae.Three identical filaments were micro-manipulated from reduced sediments collected off central Chile; their DNA was extracted, amplified, and sequenced by a Roche 454 GS FLX platform. Using three sequenced libraries and through de novo genome assembly, a draft genome of 5.7 Mbp, 495 scaffolds, and a N50 of 70 kbp, was obtained. The 16S rRNA gene phylogenetic analysis showed that "Ca. V. ishoeyi" is related to non-vacuolate forms presently known as Beggiatoa or Beggiatoa-like forms. The complete set of genes involved in respiratory nitrate-reduction to dinitrogen was identified in "Ca. V. ishoeyi"; including genes likely leading to ammonification. As expected, the sulfur-oxidation pathway reported for other sulfur-oxidizing bacteria were deduced and also, key inorganic and organic carbon acquisition related genes were identified. Unexpectedly, the genome of "Ca. V. ishoeyi" contained numerous CRISPR repeats and an I-F CRISPR-Cas type system gene coding array. Findings further show that, as a member of an eons-old marine ecosystem, "Ca. V. ishoeyi" contains the needed metabolic plasticity for life in an increasingly oxygenated and variable ocean.
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Affiliation(s)
- Alexis Fonseca
- Department of Pharmacology, University of Concepcion, Concepcion, Chile
- Department of Oceanography, University of Concepcion, Concepcion, Chile
| | - Thomas Ishoey
- Independent consultant, Encinitas, California, United States of America
| | - Carola Espinoza
- Department of Oceanography, University of Concepcion, Concepcion, Chile
- College of Ocean Science and Resources, Institute Marine Affairs and Resource Management, National Taiwan Ocean University, Keelung, Taiwan
| | - Danilo Pérez-Pantoja
- Programa Institucional de Fomento a la Investigación, Desarrollo e Innovación, Universidad Tecnológica Metropolitana, San Joaquin, Santiago, Chile
| | - Antonio Manghisi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Marina Morabito
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | | | - Víctor A. Gallardo
- Department of Oceanography, University of Concepcion, Concepcion, Chile
- College of Ocean Science and Resources, Institute Marine Affairs and Resource Management, National Taiwan Ocean University, Keelung, Taiwan
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Impact of Seasonal Hypoxia on Activity and Community Structure of Chemolithoautotrophic Bacteria in a Coastal Sediment. Appl Environ Microbiol 2017; 83:AEM.03517-16. [PMID: 28314724 DOI: 10.1128/aem.03517-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 03/09/2017] [Indexed: 11/20/2022] Open
Abstract
Seasonal hypoxia in coastal systems drastically changes the availability of electron acceptors in bottom water, which alters the sedimentary reoxidation of reduced compounds. However, the effect of seasonal hypoxia on the chemolithoautotrophic community that catalyzes these reoxidation reactions is rarely studied. Here, we examine the changes in activity and structure of the sedimentary chemolithoautotrophic bacterial community of a seasonally hypoxic saline basin under oxic (spring) and hypoxic (summer) conditions. Combined 16S rRNA gene amplicon sequencing and analysis of phospholipid-derived fatty acids indicated a major temporal shift in community structure. Aerobic sulfur-oxidizing Gammaproteobacteria (Thiotrichales) and Epsilonproteobacteria (Campylobacterales) were prevalent during spring, whereas Deltaproteobacteria (Desulfobacterales) related to sulfate-reducing bacteria prevailed during summer hypoxia. Chemolithoautotrophy rates in the surface sediment were three times higher in spring than in summer. The depth distribution of chemolithoautotrophy was linked to the distinct sulfur oxidation mechanisms identified through microsensor profiling, i.e., canonical sulfur oxidation, electrogenic sulfur oxidation by cable bacteria, and sulfide oxidation coupled to nitrate reduction by Beggiatoaceae The metabolic diversity of the sulfur-oxidizing bacterial community suggests a complex niche partitioning within the sediment, probably driven by the availability of reduced sulfur compounds (H2S, S0, and S2O32-) and electron acceptors (O2 and NO3-) regulated by seasonal hypoxia.IMPORTANCE Chemolithoautotrophic microbes in the seafloor are dependent on electron acceptors, like oxygen and nitrate, that diffuse from the overlying water. Seasonal hypoxia, however, drastically changes the availability of these electron acceptors in the bottom water; hence, one expects a strong impact of seasonal hypoxia on sedimentary chemolithoautotrophy. A multidisciplinary investigation of the sediments in a seasonally hypoxic coastal basin confirms this hypothesis. Our data show that bacterial community structure and chemolithoautotrophic activity varied with the seasonal depletion of oxygen. Unexpectedly, the dark carbon fixation was also dependent on the dominant microbial pathway of sulfur oxidation occurring in the sediment (i.e., canonical sulfur oxidation, electrogenic sulfur oxidation by cable bacteria, and sulfide oxidation coupled to nitrate reduction by Beggiatoaceae). These results suggest that a complex niche partitioning within the sulfur-oxidizing bacterial community additionally affects the chemolithoautotrophic community of seasonally hypoxic sediments.
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Boschker HTS, Vasquez-Cardenas D, Bolhuis H, Moerdijk-Poortvliet TWC, Moodley L. Chemoautotrophic carbon fixation rates and active bacterial communities in intertidal marine sediments. PLoS One 2014; 9:e101443. [PMID: 25003508 PMCID: PMC4086895 DOI: 10.1371/journal.pone.0101443] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 06/06/2014] [Indexed: 11/18/2022] Open
Abstract
Chemoautotrophy has been little studied in typical coastal marine sediments, but may be an important component of carbon recycling as intense anaerobic mineralization processes in these sediments lead to accumulation of high amounts of reduced compounds, such as sulfides and ammonium. We studied chemoautotrophy by measuring dark-fixation of 13C-bicarbonate into phospholipid derived fatty acid (PLFA) biomarkers at two coastal sediment sites with contrasting sulfur chemistry in the Eastern Scheldt estuary, the Netherlands. At one site where free sulfide accumulated in the pore water right to the top of the sediment, PLFA labeling was restricted to compounds typically found in sulfur and ammonium oxidizing bacteria. At the other site, with no detectable free sulfide in the pore water, a very different PLFA labeling pattern was found with high amounts of label in branched i- and a-PLFA besides the typical compounds for sulfur and ammonium oxidizing bacteria. This suggests that other types of chemoautotrophic bacteria were also active, most likely Deltaproteobacteria related to sulfate reducers. Maximum rates of chemoautotrophy were detected in first 1 to 2 centimeters of both sediments and chemosynthetic biomass production was high ranging from 3 to 36 mmol C m−2 d−1. Average dark carbon fixation to sediment oxygen uptake ratios were 0.22±0.07 mol C (mol O2)−1, which is in the range of the maximum growth yields reported for sulfur oxidizing bacteria indicating highly efficient growth. Chemoautotrophic biomass production was similar to carbon mineralization rates in the top of the free sulfide site, suggesting that chemoautotrophic bacteria could play a crucial role in the microbial food web and labeling in eukaryotic poly-unsaturated PLFA was indeed detectable. Our study shows that dark carbon fixation by chemoautotrophic bacteria is a major process in the carbon cycle of coastal sediments, and should therefore receive more attention in future studies on sediment biogeochemistry and microbial ecology.
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Affiliation(s)
- Henricus T. S. Boschker
- Department of Marine Microbiology, Royal Netherlands Institute for Sea Research (NIOZ), Yerseke, The Netherlands
- * E-mail:
| | - Diana Vasquez-Cardenas
- Department of Marine Microbiology, Royal Netherlands Institute for Sea Research (NIOZ), Yerseke, The Netherlands
| | - Henk Bolhuis
- Department of Marine Microbiology, Royal Netherlands Institute for Sea Research (NIOZ), Yerseke, The Netherlands
| | | | - Leon Moodley
- Marine Environment Group, International Research Institute of Stavanger (IRIS), Randaberg, Norway
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Coyne KJ, Countway PD, Pilditch CA, Lee CK, Caron DA, Cary SC. Diversity and Distributional Patterns of Ciliates in Guaymas Basin Hydrothermal Vent Sediments. J Eukaryot Microbiol 2013; 60:433-47. [DOI: 10.1111/jeu.12051] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 03/18/2013] [Accepted: 03/18/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Kathryn J. Coyne
- College of Earth, Ocean, and Environment; University of Delaware; 700 Pilottown Road Lewes Delaware 19958 USA
| | - Peter D. Countway
- Department of Biological Sciences; University of Southern California; Los Angeles California 90089-0371 USA
| | - Conrad A. Pilditch
- Department of Biological Sciences; University of Waikato; Private Bag 3105 Hamilton 3240 New Zealand
| | - Charles K. Lee
- Department of Biological Sciences; University of Waikato; Private Bag 3105 Hamilton 3240 New Zealand
| | - David A. Caron
- Department of Biological Sciences; University of Southern California; Los Angeles California 90089-0371 USA
| | - Stephen C. Cary
- College of Earth, Ocean, and Environment; University of Delaware; 700 Pilottown Road Lewes Delaware 19958 USA
- Department of Biological Sciences; University of Waikato; Private Bag 3105 Hamilton 3240 New Zealand
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7
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McHatton SC, Barry JP, Jannasch HW, Nelson DC. High Nitrate Concentrations in Vacuolate, Autotrophic Marine Beggiatoa spp. Appl Environ Microbiol 2010; 62:954-8. [PMID: 16535282 PMCID: PMC1388807 DOI: 10.1128/aem.62.3.954-958.1996] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Massive accumulations of very large Beggiatoa spp. are found at a Monterey Canyon cold seep and at Guaymas Basin hydrothermal vents. Both environments are characterized by high sediment concentrations of soluble sulfide and low levels of dissolved oxygen in surrounding waters. These filamentous, sulfur-oxidizing bacteria accumulate nitrate intracellularly at concentrations of 130 to 160 mM, 3,000- to 4,000-fold higher than ambient levels. Average filament widths range from 24 to 122 (mu)m, and individual cells of all widths possess a central vacuole. These findings plus recent parallel discoveries for Thioploca spp. (H. Fossing, V. A. Gallardo, B. B. Jorgensen, M. Huttel, L. P. Nielsen, H. Schulz, D. E. Canfield, S. Forster, R. N. Glud, J. K. Gundersen, J. Kuver, N. B. Ramsing, A. Teske, B. Thamdrup, and O. Ulloa, Nature (London) 374:713-715, 1995) suggest that nitrate accumulation may be a universal property of vacuolate, filamentous sulfur bacteria. Ribulose bisphosphate carboxylase-oxygenase and 2-oxoglutarate dehydrogenase activities in the Beggiatoa sp. from Monterey Canyon suggest in situ autotrophic growth of these bacteria. Nitrate reductase activity is much higher in the Monterey Beggiatoa sp. than in narrow, laboratory-grown strains of Beggiatoa spp., and the activity is found primarily in the membrane fraction, suggesting that the vacuolate Beggiatoa sp. can reduce nitrate coupled to electron flow through an electron transport system. Nitrate-concentrating and respiration potentials of these chemolithoautotrophs suggest that the Beggiatoa spp. described here are an important link between the sulfur, nitrogen, and carbon cycles at the Monterey Canyon seeps and the Guaymas Basin hydrothermal vents where they are found.
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Ghosh W, Dam B. Biochemistry and molecular biology of lithotrophic sulfur oxidation by taxonomically and ecologically diverse bacteria and archaea. FEMS Microbiol Rev 2009; 33:999-1043. [PMID: 19645821 DOI: 10.1111/j.1574-6976.2009.00187.x] [Citation(s) in RCA: 288] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Lithotrophic sulfur oxidation is an ancient metabolic process. Ecologically and taxonomically diverged prokaryotes have differential abilities to utilize different reduced sulfur compounds as lithotrophic substrates. Different phototrophic or chemotrophic species use different enzymes, pathways and mechanisms of electron transport and energy conservation for the oxidation of any given substrate. While the mechanisms of sulfur oxidation in obligately chemolithotrophic bacteria, predominantly belonging to Beta- (e.g. Thiobacillus) and Gammaproteobacteria (e.g. Thiomicrospira), are not well established, the Sox system is the central pathway in the facultative bacteria from Alphaproteobacteria (e.g. Paracoccus). Interestingly, photolithotrophs such as Rhodovulum belonging to Alphaproteobacteria also use the Sox system, whereas those from Chromatiaceae and Chlorobi use a truncated Sox complex alongside reverse-acting sulfate-reducing systems. Certain chemotrophic magnetotactic Alphaproteobacteria allegedly utilize such a combined mechanism. Sulfur-chemolithotrophic metabolism in Archaea, largely restricted to Sulfolobales, is distinct from those in Bacteria. Phylogenetic and biomolecular fossil data suggest that the ubiquity of sox genes could be due to horizontal transfer, and coupled sulfate reduction/sulfide oxidation pathways, originating in planktonic ancestors of Chromatiaceae or Chlorobi, could be ancestral to all sulfur-lithotrophic processes. However, the possibility that chemolithotrophy, originating in deep sea, is the actual ancestral form of sulfur oxidation cannot be ruled out.
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Affiliation(s)
- Wriddhiman Ghosh
- Department of Microbiology, University of Burdwan, West Bengal, India.
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9
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Abstract
Two freshwater strains of the gammaproteobacterium Beggiatoa alba, B18LD and OH75-2a, are able to use methanol as a sole carbon and energy source under microoxic conditions. Genes encoding a methanol dehydrogenase large-subunit homolog and four enzymes of the tetrahydromethanopterin-dependent C(1) oxidation pathway were identified in B18LD. No evidence of methanotrophy was detected.
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Mußmann M, Hu FZ, Richter M, de Beer D, Preisler A, Jørgensen BB, Huntemann M, Glöckner FO, Amann R, Koopman WJH, Lasken RS, Janto B, Hogg J, Stoodley P, Boissy R, Ehrlich GD. Insights into the genome of large sulfur bacteria revealed by analysis of single filaments. PLoS Biol 2007; 5:e230. [PMID: 17760503 PMCID: PMC1951784 DOI: 10.1371/journal.pbio.0050230] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 06/26/2007] [Indexed: 11/19/2022] Open
Abstract
Marine sediments are frequently covered by mats of the filamentous Beggiatoa and other large nitrate-storing bacteria that oxidize hydrogen sulfide using either oxygen or nitrate, which they store in intracellular vacuoles. Despite their conspicuous metabolic properties and their biogeochemical importance, little is known about their genetic repertoire because of the lack of pure cultures. Here, we present a unique approach to access the genome of single filaments of Beggiatoa by combining whole genome amplification, pyrosequencing, and optical genome mapping. Sequence assemblies were incomplete and yielded average contig sizes of approximately 1 kb. Pathways for sulfur oxidation, nitrate and oxygen respiration, and CO2 fixation confirm the chemolithoautotrophic physiology of Beggiatoa. In addition, Beggiatoa potentially utilize inorganic sulfur compounds and dimethyl sulfoxide as electron acceptors. We propose a mechanism of vacuolar nitrate accumulation that is linked to proton translocation by vacuolar-type ATPases. Comparative genomics indicates substantial horizontal gene transfer of storage, metabolic, and gliding capabilities between Beggiatoa and cyanobacteria. These capabilities enable Beggiatoa to overcome non-overlapping availabilities of electron donors and acceptors while gliding between oxic and sulfidic zones. The first look into the genome of these filamentous sulfur-oxidizing bacteria substantially deepens the understanding of their evolution and their contribution to sulfur and nitrogen cycling in marine sediments.
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Affiliation(s)
- Marc Mußmann
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- * To whom correspondence should be addressed. E-mail: (MM); (FOG); (GDE)
| | - Fen Z Hu
- Center for Genomic Sciences, Allegheny General Hospital/Allegheny-Singer Research Institute, Pittsburgh, Pennsylvania, United States of America
| | - Michael Richter
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- School of Engineering and Sciences, Jacobs University Bremen, Bremen, Germany
| | - Dirk de Beer
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - André Preisler
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Bo B Jørgensen
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Marcel Huntemann
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- School of Engineering and Sciences, Jacobs University Bremen, Bremen, Germany
| | - Frank Oliver Glöckner
- Max Planck Institute for Marine Microbiology, Bremen, Germany
- School of Engineering and Sciences, Jacobs University Bremen, Bremen, Germany
- * To whom correspondence should be addressed. E-mail: (MM); (FOG); (GDE)
| | - Rudolf Amann
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Werner J. H Koopman
- Department of Membrane Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Roger S Lasken
- J. Craig Venter Institute, Rockville, Maryland, United States of America
| | - Benjamin Janto
- Center for Genomic Sciences, Allegheny General Hospital/Allegheny-Singer Research Institute, Pittsburgh, Pennsylvania, United States of America
| | - Justin Hogg
- Center for Genomic Sciences, Allegheny General Hospital/Allegheny-Singer Research Institute, Pittsburgh, Pennsylvania, United States of America
| | - Paul Stoodley
- Center for Genomic Sciences, Allegheny General Hospital/Allegheny-Singer Research Institute, Pittsburgh, Pennsylvania, United States of America
| | - Robert Boissy
- Center for Genomic Sciences, Allegheny General Hospital/Allegheny-Singer Research Institute, Pittsburgh, Pennsylvania, United States of America
| | - Garth D Ehrlich
- Center for Genomic Sciences, Allegheny General Hospital/Allegheny-Singer Research Institute, Pittsburgh, Pennsylvania, United States of America
- * To whom correspondence should be addressed. E-mail: (MM); (FOG); (GDE)
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Hinck S, Neu TR, Lavik G, Mussmann M, de Beer D, Jonkers HM. Physiological adaptation of a nitrate-storing Beggiatoa sp. to diel cycling in a phototrophic hypersaline mat. Appl Environ Microbiol 2007; 73:7013-22. [PMID: 17766448 PMCID: PMC2074952 DOI: 10.1128/aem.00548-07] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to investigate the supposed vertical diel migration and the accompanying physiology of Beggiatoa bacteria from hypersaline microbial mats. We combined microsensor, stable-isotope, and molecular techniques to clarify the phylogeny and physiology of the most dominant species inhabiting mats of the natural hypersaline Lake Chiprana, Spain. The most dominant morphotype had a filament diameter of 6 to 8 microm and a length varying from 1 to >10 mm. Phylogenetic analysis by 16S rRNA gene comparison revealed that this type appeared to be most closely related (91% sequence identity) to the narrow (4-microm diameter) nonvacuolated marine strain MS-81-6. Stable-isotope analysis showed that the Lake Chiprana species could store nitrate intracellularly to 40 mM. The presence of large intracellular vacuoles was confirmed by fluorescein isothiocyanate staining and subsequent confocal microscopy. In illuminated mats, their highest abundance was found at a depth of 8 mm, where oxygen and sulfide co-occurred. However, in the dark, the highest Beggiatoa densities occurred at 7 mm, and the whole population was present in the anoxic zone of the mat. Our findings suggest that hypersaline Beggiatoa bacteria oxidize sulfide with oxygen under light conditions and with internally stored nitrate under dark conditions. It was concluded that nitrate storage by Beggiatoa is an optimal strategy to both occupy the suboxic zones in sulfidic sediments and survive the dark periods in phototrophic mats.
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Affiliation(s)
- Susanne Hinck
- Max Planck Institute for Marine Microbiology, Celsiusstr. 1, D-28359 Bremen, Germany.
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12
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Stolyar S, Van Dien S, Hillesland KL, Pinel N, Lie TJ, Leigh JA, Stahl DA. Metabolic modeling of a mutualistic microbial community. Mol Syst Biol 2007; 3:92. [PMID: 17353934 PMCID: PMC1847946 DOI: 10.1038/msb4100131] [Citation(s) in RCA: 332] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Accepted: 12/21/2006] [Indexed: 11/24/2022] Open
Abstract
The rate of production of methane in many environments depends upon mutualistic interactions between sulfate-reducing bacteria and methanogens. To enhance our understanding of these relationships, we took advantage of the fully sequenced genomes of Desulfovibrio vulgaris and Methanococcus maripaludis to produce and analyze the first multispecies stoichiometric metabolic model. Model results were compared to data on growth of the co-culture on lactate in the absence of sulfate. The model accurately predicted several ecologically relevant characteristics, including the flux of metabolites and the ratio of D. vulgaris to M. maripaludis cells during growth. In addition, the model and our data suggested that it was possible to eliminate formate as an interspecies electron shuttle, but hydrogen transfer was essential for syntrophic growth. Our work demonstrated that reconstructed metabolic networks and stoichiometric models can serve not only to predict metabolic fluxes and growth phenotypes of single organisms, but also to capture growth parameters and community composition of simple bacterial communities.
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Affiliation(s)
- Sergey Stolyar
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
- Civil and Environmental Engineering, University of Washington, 478 Benjamin Hall Interdisciplinary Research Building, Box 355014, Seattle, WA 98195, USA. Tel.: +1 206 543 2094; Fax: +1 206 685 3836;
| | - Steve Van Dien
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
| | | | - Nicolas Pinel
- Department of Microbiology, University of Washington, Seattle WA, USA
| | - Thomas J Lie
- Department of Microbiology, University of Washington, Seattle WA, USA
| | - John A Leigh
- Department of Microbiology, University of Washington, Seattle WA, USA
| | - David A Stahl
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA
- Civil and Environmental Engineering, University of Washington, 302 More Hall, Seattle, WA, USA. Tel.: +1 206 685 3464; Fax: +1 206 685 3836;
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13
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Hubert C, Voordouw G. Oil field souring control by nitrate-reducing Sulfurospirillum spp. that outcompete sulfate-reducing bacteria for organic electron donors. Appl Environ Microbiol 2007; 73:2644-52. [PMID: 17308184 PMCID: PMC1855586 DOI: 10.1128/aem.02332-06] [Citation(s) in RCA: 230] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nitrate injection into oil reservoirs can prevent and remediate souring, the production of hydrogen sulfide by sulfate-reducing bacteria (SRB). Nitrate stimulates nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB) and heterotrophic nitrate-reducing bacteria (hNRB) that compete with SRB for degradable oil organics. Up-flow, packed-bed bioreactors inoculated with water produced from an oil field and injected with lactate, sulfate, and nitrate served as sources for isolating several NRB, including Sulfurospirillum and Thauera spp. The former coupled reduction of nitrate to nitrite and ammonia with oxidation of either lactate (hNRB activity) or sulfide (NR-SOB activity). Souring control in a bioreactor receiving 12.5 mM lactate and 6, 2, 0.75, or 0.013 mM sulfate always required injection of 10 mM nitrate, irrespective of the sulfate concentration. Community analysis revealed that at all but the lowest sulfate concentration (0.013 mM), significant SRB were present. At 0.013 mM sulfate, direct hNRB-mediated oxidation of lactate by nitrate appeared to be the dominant mechanism. The absence of significant SRB indicated that sulfur cycling does not occur at such low sulfate concentrations. The metabolically versatile Sulfurospirillum spp. were dominant when nitrate was present in the bioreactor. Analysis of cocultures of Desulfovibrio sp. strain Lac3, Lac6, or Lac15 and Sulfurospirillum sp. strain KW indicated its hNRB activity and ability to produce inhibitory concentrations of nitrite to be key factors for it to successfully outcompete oil field SRB.
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Affiliation(s)
- Casey Hubert
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
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Ju X, Field JA, Sierra-Alvarez R, Salazar M, Bentley H, Bentley R. Chemolithotrophic perchlorate reduction linked to the oxidation of elemental sulfur. Biotechnol Bioeng 2007; 96:1073-82. [PMID: 17009322 DOI: 10.1002/bit.21197] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Perchlorate (ClO(4)(-)) contamination of ground and surface water has been recently recognized as a widespread environmental problem. Biological methods offer promising perspectives of perchlorate remediation. Facultative anaerobic bacteria couple the oxidation of organic and inorganic electron-donating substrates to the reduction of perchlorate as a terminal electron acceptor, converting it completely to the benign end-product, chloride. Insoluble inorganic substrates are of interest for low maintenance bioreactor or permeable reactive barrier systems because they can provide a long-term supply of electron donor without generating organic residuals. The main objective of this research was to investigate the feasibility of utilizing elemental sulfur (S(0)) as an insoluble electron donor for the biological reduction of perchlorate. A chemolithotrophic enrichment culture derived from aerobic activated sludge was obtained which effectively coupled the oxidation of elemental sulfur to sulfate with the reduction of perchlorate to chloride and gained energy from the process for cell growth. The enrichment culture grew at a rate of 0.41 or 0.81 1/d in the absence and presence of added organic carbon for cell growth, respectively. The enrichment culture was also shown to carry out sulfur disproportionation to a limited extent as evidenced by the formation of sulfide and sulfate in the absence of added electron acceptor. When nitrate and perchlorate were added together, the two electron acceptors were removed simultaneously after an initial partial decrease in the nitrate concentration.
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Affiliation(s)
- Xiumin Ju
- Department of Chemical and Environmental Engineering, University of Arizona, PO Box 210011, Tucson, Arizona 85721-0011, USA
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15
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Ahmad A, Kalanetra KM, Nelson DC. Cultivated Beggiatoa spp. define the phylogenetic root of morphologically diverse, noncultured, vacuolate sulfur bacteria. Can J Microbiol 2006; 52:591-8. [PMID: 16788728 DOI: 10.1139/w05-154] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Within the last 10 years, numerous SSU rRNA sequences have been collected from natural populations of conspicuous, vacuolate, colorless sulfur bacteria, which form a phylogenetically cohesive cluster (large-vacuolate sulfur bacteria clade) in the gamma-Proteobacteria. Currently, this clade is composed of four named or de facto genera: all known Thioploca and Thiomargarita strains, all vacuolate Beggiatoa strains, and several strains of vacuolate, attached filaments, which bear a superficial similarity to Thiothrix. Some of these vacuolate bacteria accumulate nitrate for respiratory purposes. This clade encompasses the largest known prokaryotic cells (Thiomargarita namibiensis) and several strains that are important in the global marine sulfur cycle. Here, we report additional sequences from five pure culture strains of Beggiatoa spp., including the only two cultured marine strains (nonvacuolate), which firmly establish the root of this vacuolate clade. Each of several diverse metabolic motifs, including obligate and facultative chemolithoautotrophy, probable mixotrophy, and seemingly strict organoheterotrophy, is represented in at least one of the nonvacuolate strains that root the vacuolate clade. Because the genus designation Beggiatoa is interspersed throughout the vacuolate clade along with other recognized or de facto genera, the need for taxonomic revision is clear.
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Affiliation(s)
- Azeem Ahmad
- Section of Microbiology, University of California, Davis, 95616, USA
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16
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Zhang CL, Huang Z, Cantu J, Pancost RD, Brigmon RL, Lyons TW, Sassen R. Lipid biomarkers and carbon isotope signatures of a microbial (Beggiatoa) mat associated with gas hydrates in the gulf of Mexico. Appl Environ Microbiol 2005; 71:2106-12. [PMID: 15812044 PMCID: PMC1082508 DOI: 10.1128/aem.71.4.2106-2112.2005] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Accepted: 10/29/2004] [Indexed: 11/20/2022] Open
Abstract
White and orange mats are ubiquitous on surface sediments associated with gas hydrates and cold seeps in the Gulf of Mexico. The goal of this study was to determine the predominant pathways for carbon cycling within an orange mat in Green Canyon (GC) block GC 234 in the Gulf of Mexico. Our approach incorporated laser-scanning confocal microscopy, lipid biomarkers, stable carbon isotopes, and 16S rRNA gene sequencing. Confocal microscopy showed the predominance of filamentous microorganisms (4 to 5 mum in diameter) in the mat sample, which are characteristic of Beggiatoa. The phospholipid fatty acids extracted from the mat sample were dominated by 16:1omega7c/t (67%), 18:1omega7c (17%), and 16:0 (8%), which are consistent with lipid profiles of known sulfur-oxidizing bacteria, including Beggiatoa. These results are supported by the 16S rRNA gene analysis of the mat material, which yielded sequences that are all related to the vacuolated sulfur-oxidizing bacteria, including Beggiatoa, Thioploca, and Thiomargarita. The delta13C value of total biomass was -28.6 per thousand; those of individual fatty acids were -29.4 to -33.7 per thousand. These values suggested heterotrophic growth of Beggiatoa on organic substrates that may have delta13C values characteristic of crude oil or on their by-products from microbial degradation. This study demonstrated that integrating lipid biomarkers, stable isotopes, and molecular DNA could enhance our understanding of the metabolic functions of Beggiatoa mats in sulfide-rich marine sediments associated with gas hydrates in the Gulf of Mexico and other locations.
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Affiliation(s)
- Chuanlun L Zhang
- Department of Marine Sciences and Savannah River Ecology Laboratory, University of Georgia, Drawer E, Aiken, SC 29802, USA.
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Schulz HN, De Beer D. Uptake rates of oxygen and sulfide measured with individual Thiomargarita namibiensis cells by using microelectrodes. Appl Environ Microbiol 2002; 68:5746-9. [PMID: 12406774 PMCID: PMC129903 DOI: 10.1128/aem.68.11.5746-5749.2002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gradients of oxygen and sulfide measured towards individual cells of the large nitrate-storing sulfur bacterium Thiomargarita namibiensis showed that in addition to nitrate oxygen is used for oxidation of sulfide. Stable gradients around the cells were found only if acetate was added to the medium at low concentrations.
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Affiliation(s)
- Heide N Schulz
- Max Planck Institute for Marine Microbiology, D-28359 Bremen, Germany.
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18
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Grabovich MY, Patritskaya VY, Muntyan MS, Dubinina GA. Lithoautotrophic growth of the freshwater strain Beggiatoa D-402 and energy conservation in a homogeneous culture under microoxic conditions. FEMS Microbiol Lett 2001; 204:341-5. [PMID: 11731146 DOI: 10.1111/j.1574-6968.2001.tb10908.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The freshwater filamentous bacterium Beggiatoa D-402 was shown to grow lithoautotrophically in a homogeneous culture under microoxic conditions only, the growth yield being the highest at 0.1 mg O(2) l(-1). High activities of the Calvin cycle key enzymes and of the dissimilatory path thiosulfate oxidation enzymes were found in the bacterial cells. The rate of CO(2) fixation above 112 nmol min(-1) (mg protein)(-1), an about 90% increase in the protein carbon at the expense of CO(2) carbon and an increase in the molar yield up to 12 mg dry weight (mmol oxidized thiosulfate)(-1) indicate the bacterial growth was autotrophic. Thiosulfate was oxidized by the strain almost completely into sulfate. The metabolically useful energy was conserved by oxidative phosphorylation that was coupled to oxidation of sulfur compounds. The bacterial membranes were found to contain CO-binding cytochromes b and two cytochromes c with M(r) 23 and 26 kDa, the terminal part of the respiratory chain containing presumably a cbb(3)-type oxidase. A cytochrome c with M(r) 12 kDa was detected in the soluble fraction.
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Affiliation(s)
- M Y Grabovich
- Vorenezh State University, Department of Plant Biochemistry and Physiology, Voronezh, Russia
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Gray ND, Howarth R, Pickup RW, Jones JG, Head IM. Use of combined microautoradiography and fluorescence in situ hybridization to determine carbon metabolism in mixed natural communities of uncultured bacteria from the genus Achromatium. Appl Environ Microbiol 2000; 66:4518-22. [PMID: 11010908 PMCID: PMC92334 DOI: 10.1128/aem.66.10.4518-4522.2000] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Combined microautoradiography and fluorescence in situ hybridization (FISH) was used to investigate carbon metabolism in uncultured bacteria from the genus Achromatium. All of the Achromatium species identified in a freshwater sediment from Rydal Water, Cumbria, United Kingdom, which were distinguishable only by FISH, assimilated both [(14)C]bicarbonate and [(14)C]acetate. This extends previous findings that Achromatium spp. present at another location could only utilize organic carbon sources. Achromatium spp., therefore, probably exhibit a range of physiologies, i.e., facultative chemolithoautotrophy, mixotrophy, and chemoorganoheterotrophy, similar to other large sulfur bacteria (e.g., Beggiatoa spp.).
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Affiliation(s)
- N D Gray
- Fossil Fuels and Environmental Geochemistry Postgraduate Institute and Centre for Molecular Ecology, University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom
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21
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Gray ND, Howarth R, Pickup RW, Jones JG, Head IM. Substrate uptake by uncultured bacteria from the genus Achromatium determined by microautoradiography. Appl Environ Microbiol 1999; 65:5100-6. [PMID: 10543828 PMCID: PMC91686 DOI: 10.1128/aem.65.11.5100-5106.1999] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microautoradiography was used to investigate substrate uptake by natural communities of uncultured bacteria from the genus Achromatium. Studies of the uptake of (14)C-labelled substrates demonstrated that Achromatium cells from freshwater sediments were able to assimilate (14)C from bicarbonate, acetate, and protein hydrolysate; however, (14)C-labelled glucose was not assimilated. The pattern of substrate uptake by Achromatium spp. was therefore similar to those of a number of other freshwater and marine sulfur-oxidizing bacteria. Different patterns of radiolabelled bicarbonate uptake were noted for Achromatium communities from different geographical locations and indicated that one community (Rydal Water) possessed autotrophic potential, while the other (Hell Kettles) did not. Furthermore, the patterns of organic substrate uptake within a single population suggested that physiological diversity existed in natural communities of Achromatium. These observations are consistent with and may relate to the phylogenetic diversity observed in Achromatium communities. Incubation of Achromatium-bearing sediment cores from Rydal Water with (35)S-labelled sulfate in the presence and absence of sodium molybdate demonstrated that this bacterial population was capable of oxidizing sulfide to intracellular elemental sulfur. This finding supported the role of Achromatium in the oxidative component of a tightly coupled sulfur cycle in Rydal Water sediment. The oxidation of sulfide to sulfur and ultimately to sulfate by Achromatium cells from Rydal Water sediment is consistent with an ability to conserve energy from sulfide oxidation.
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Affiliation(s)
- N D Gray
- Fossil Fuels and Environmental Geochemistry Postgraduate Institute (NRG), University of Newcastle, Newcastle upon Tyne NE1 7RU
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Abstract
Filamentous sulfur bacteria of the genus Thioploca occur as dense mats on the continental shelf off the coast of Chile and Peru. Since little is known about their nitrogen, sulfur, and carbon metabolism, this study was undertaken to investigate their (eco)physiology. Thioploca is able to store internally high concentrations of sulfur globules and nitrate. It has been previously hypothesized that these large vacuolated bacteria can oxidize sulfide by reducing their internally stored nitrate. We examined this nitrate reduction by incubation experiments of washed Thioploca sheaths with trichomes in combination with 15N compounds and mass spectrometry and found that these Thioploca samples produce ammonium at a rate of 1 nmol min-1 mg of protein-1. Controls showed no significant activity. Sulfate was shown to be the end product of sulfide oxidation and was observed at a rate of 2 to 3 nmol min-1 mg of protein-1. The ammonium and sulfate production rates were not influenced by the addition of sulfide, suggesting that sulfide is first oxidized to elemental sulfur, and in a second independent step elemental sulfur is oxidized to sulfate. The average sulfide oxidation rate measured was 5 nmol min-1 mg of protein-1 and could be increased to 10.7 nmol min-1 mg of protein-1 after the trichomes were starved for 45 h. Incorporation of 14CO2 was at a rate of 0.4 to 0.8 nmol min-1 mg of protein-1, which is half the rate calculated from sulfide oxidation. [2-14C]acetate incorporation was 0.4 nmol min-1 mg of protein-1, which is equal to the CO2 fixation rate, and no 14CO2 production was detected. These results suggest that Thioploca species are facultative chemolithoautotrophs capable of mixotrophic growth. Microautoradiography confirmed that Thioploca cells assimilated the majority of the radiocarbon from [2-14C]acetate, with only a minor contribution by epibiontic bacteria present in the samples.
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Hagen KD, Nelson DC. Use of Reduced Sulfur Compounds by Beggiatoa spp.: Enzymology and Physiology of Marine and Freshwater Strains in Homogeneous and Gradient Cultures. Appl Environ Microbiol 1997; 63:3957-64. [PMID: 16535709 PMCID: PMC1389265 DOI: 10.1128/aem.63.10.3957-3964.1997] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The marine Beggiatoa strains MS-81-6 and MS-81-1c are filamentous, gliding, colorless sulfur bacteria. They have traditionally been cultured in very limited quantities in sulfide gradient media, where they grow as chemolithoautotrophs, forming a thin horizontal plate well below the air-agar interface. There, the facultatively chemolithoautotrophic strain MS-81-6 quantitatively harvests the flux of sulfide diffusing from below and oxidizes it to sulfate by using oxygen as the electron acceptor. Only recently have these strains been cultivated in bulk in defined liquid media (K. D. Hagen and D. C. Nelson, Appl. Environ. Microbiol. 62:947-953, 1996). In the current study, the obligately chemolithoautotrophic strain MS-81-1c was shown to have, despite much greater storage of elemental sulfur, an apparent Y(infH)(inf(inf2))(infS) twice that of MS-81-6 when the two strains were grown in identical sulfide-limited gradient media. While the basis of this difference in energy conservation has not been established, differences in sulfur oxidation enzymes were noted. Strain MS-81-1c appeared to be able to oxidize sulfite by using either the adenosine phosphosulfate (APS) pathway or a sulfite:acceptor oxidoreductase. APS pathway enzymes (ATP sulfurylase and APS reductase) were present at relatively high and constant levels regardless of growth conditions, while the sulfite:acceptor oxidoreductase activity varied at least eightfold, with the highest activity produced in sulfide gradient medium. By contrast, strain MS-81-6 showed no detectable activity of the APS pathway enzymes and possessed a sulfite:acceptor oxidoreductase activity just sufficient to account for its observed rate of growth in sulfide gradient medium. Freshwater strain OH-75-2a showed activity and regulation of sulfite:acceptor oxidoreductase consistent with lithotrophic energy conservation, a feature not yet proven for any freshwater Beggiatoa strain.
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