title: Carbon source preference in chemosynthetic hot spring communities.
abstract: Rates of dissolved inorganic carbon (DIC), formate, and acetate mineralization and/or assimilation were determined in 13 high-temperature (>73 °C) hot springs in Yellowstone National Park (YNP), Wyoming, in order to evaluate the relative importance of these substrates in supporting microbial metabolism. While 9 of the hot spring communities exhibited rates of DIC assimilation that were greater than those of formate and acetate assimilation, 2 exhibited rates of formate and/or acetate assimilation that exceeded those of DIC assimilation. Overall rates of DIC, formate, and acetate mineralization and assimilation were positively correlated with spring pH but showed little correlation with temperature. Communities sampled from hot springs with similar geochemistries generally exhibited similar rates of substrate transformation, as well as similar community compositions, as revealed by 16S rRNA gene-tagged sequencing. Amendment of microcosms with small (micromolar) amounts of formate suppressed DIC assimilation in short-term (<45-min) incubations, despite the presence of native DIC concentrations that exceeded those of added formate by 2 to 3 orders of magnitude. The concentration of added formate required to suppress DIC assimilation was similar to the affinity constant (K(m)) for formate transformation, as determined by community kinetic assays. These results suggest that dominant chemoautotrophs in high-temperature communities are facultatively autotrophic or mixotrophic, are adapted to fluctuating nutrient availabilities, and are capable of taking advantage of energy-rich organic substrates when they become available.
authors.affiliation: Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, USA Thermal Biology Institute, Montana State University, Bozeman, Montana, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Urschel
authors.affiliation: NASA Ames Research Center, Mountain View, California, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Kubo
authors.affiliation: NASA Ames Research Center, Mountain View, California, USA.
authors.forename: Tori M
authors.initials: TM
authors.lastname: Hoehler
authors.affiliation: Thermal Biology Institute, Montana State University, Bozeman, Montana, USA Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA.
authors.forename: John W
authors.initials: JW
authors.lastname: Peters
authors.affiliation: Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, USA Thermal Biology Institute, Montana State University, Bozeman, Montana, USA eboyd@montana.edu.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Boyd
mesh_terms: D000085:Acetates / Q000378:metabolism*; D001105:Archaea / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D017554:Carbon Compounds, Inorganic / Q000378:metabolism*; D016000:Cluster Analysis; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005561:Formates / Q000378:metabolism*; D045482:Hot Springs / Q000382:microbiology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014959:Wyoming
chemical_list: D000085:Acetates; D017554:Carbon Compounds, Inorganic; D004275:DNA, Ribosomal; D005561:Formates; D012336:RNA, Ribosomal, 16S
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