Project description:Microbial sulfur cycling and chemoautotrophy are focal points of research in cold seeps. However, limited culture-dependent and in-situ studies have described the biological features and ecological significance of chemoautotrophic sulfur-oxidizing bacteria. In this study, we isolated Guyparkeria hydrothermalis SP2, a thiosulfate/sulfide-oxidizing chemoautotrophic bacterium, from cold-seep sediment. Electron microscopy, Raman spectroscopy, and stoichiometry confirmed the efficient production of zero-valent sulfur (ZVS) by G. hydrothermalis SP2. Genomic, transcriptomic, and qRT-PCR analyses revealed its utilization of the Sox pathway for thiosulfate oxidation and the fccB gene for sulfide oxidation. Its chemoautotrophic capability mediated by the Calvin-Benson-Bassham (CBB) cycle was identified through isotopic and qRT-PCR analyses. In-situ studies demonstrated its ability to produce ZVS by oxidizing sulfide in cold seeps, with a preference for different genes compared to those under laboratory conditions. Metagenomic and metatranscriptomic analyses indicated the ubiquity of its sulfur oxidation-based chemoautotrophic pathway in cold seep sediments. Therefore, this strain holds significance for investigating sulfur oxidation-based chemoautotrophic pathways in cold seeps.
Project description:Wild type G. sulfurreducens DL1 strain (see Caccavo, F., Jr., D. J. Lonergan, D. R. Lovley, M. Davis, J. F. Stolz, and M. J. McInerney. 1994. Geobacter sulfurreducens sp. nov., a hydrogen- and acetate-oxidizing dissimilatory metal-reducing microorganism. Appl Environ Microbiol 60:3752-9. see also Coppi, M. V., C. Leang, S. J. Sandler, and D. R. Lovley. 2001. Development of a genetic system for Geobacter sulfurreducens. Appl Environ Microbiol 67:3180-7.) and DLCN16 mutant (.rpoS::Km) (see Nuñez, C., L. Adams, S. Childers, and D. R. Lovley. 2004. The RpoS sigma factor in the dissimilatory Fe(III)-reducing bacterium Geobacter sulfurreducens. J Bacteriol 186:5543-6.) were grown under anaerobic conditions at 30 °C in continuous culture with a 200 ml working volume as previously described (see Esteve-Nunez, A., M. Rothermich, M. Sharma, and D. Lovley. 2005. Growth of Geobacter sulfurreducens under nutrient-limiting conditions in continuous culture. Environ Microbiol 7:641-8.). Cells were cultured at a growth rate of 0.05 h-1, steady-state cell growth was obtained after 5 volume refills and was confirmed by a constant cell density and concentrations of fumarate and succinate. Acetate (5.5 mM) was the electron donor and the limiting substrate. The electron acceptor was fumarate (30mM). Three biological replicates of control and treatment cells were obtained to produce hybridizations for this experiment.
Project description:Wild type G. sulfurreducens DL1 strain (see Caccavo, F., Jr., D. J. Lonergan, D. R. Lovley, M. Davis, J. F. Stolz, and M. J. McInerney. 1994. Geobacter sulfurreducens sp. nov., a hydrogen- and acetate-oxidizing dissimilatory metal-reducing microorganism. Appl Environ Microbiol 60:3752-9. see also Coppi, M. V., C. Leang, S. J. Sandler, and D. R. Lovley. 2001. Development of a genetic system for Geobacter sulfurreducens. Appl Environ Microbiol 67:3180-7.) and DLCN16 mutant (.rpoS::Km) (see Nuñez, C., L. Adams, S. Childers, and D. R. Lovley. 2004. The RpoS sigma factor in the dissimilatory Fe(III)-reducing bacterium Geobacter sulfurreducens. J Bacteriol 186:5543-6.) were grown under anaerobic conditions at 30 °C in continuous culture with a 200 ml working volume as previously described (see Esteve-Nunez, A., M. Rothermich, M. Sharma, and D. Lovley. 2005. Growth of Geobacter sulfurreducens under nutrient-limiting conditions in continuous culture. Environ Microbiol 7:641-8.). Cells were cultured at a growth rate of 0.05 h-1, steady-state cell growth was obtained after 5 volume refills and was confirmed by a constant cell density and concentrations of Fe(II). Acetate (5.5 mM) was the electron donor and the limiting substrate. The electron acceptor was Fe(III)-citrate (60mM). Two biological replicates of control and treatment cells were obtained to produce hybridizations for this experiment.