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Title: Integration of metagenomic and stable carbon isotope evidence reveals the extent and mechanisms of carbon dioxide fixation in high-temperature microbial communities

Biological fixation of CO 2 is the primary mechanism of C reduction in natural systems, and provides a diverse suite of organic compounds utilized by chemoorganoheterotrophs. The extent and mechanisms of CO 2 fixation were evaluated across a comprehensive set of high-temperature, chemotrophic microbial communities in Yellowstone National Park by combining metagenomic and stable 13C isotope analyses. Fifteen geothermal sites representing three distinct habitat types (iron-oxide mats, anoxic sulfur sediments, and filamentous ‘streamer’ communities) were investigated. Genes of the 3-hydroxypropionate/4-hydroxybutyrate, dicarboxylate/4-hydroxybutyrate, and reverse tricarboxylic acid CO 2 fixation pathways were identified in assembled genome sequence corresponding to the predominant Crenarchaeota and Aquificales observed across this habitat range. Stable 13C analyses of dissolved inorganic and organic C (DIC, DOC), and possible landscape C sources were used to interpret the 13C content of microbial community samples. Isotope mixing models showed that the minimum amounts of autotrophic C in microbial biomass were > 50 % in the majority of communities analyzed, but were also dependent on the amounts of heterotrophy and/or accumulation of landscape C. Furthermore, the significance of CO 2 as a C source in these communities provides a foundation for understanding metabolic linkages among autotrophs and heterotrophs, community assembly and succession,more » and the likely coevolution of deeply-branching thermophiles.« less
 [1] ;  [2] ;  [3] ;  [1] ;  [2] ;  [3] ;  [2] ;  [3]
  1. Montana State Univ., Bozeman, MT (United States); Mercer Univ., Macon, GA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Montana State Univ., Bozeman, MT (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1664-302X; KP1601010
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Frontiers in Microbiology
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 1664-302X
Frontiers Research Foundation
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; autotrophy; CO2 fixation; stable C isotopes; geothermal; Aquificales; Crenarchaeota
OSTI Identifier: