The distribution, diversity and function of predominant Thermoproteales in high‐temperature environments of Yellowstone National Park

Abstract

Summary High‐temperature environments (> 70°C) contain diverse and abundant members of the crenarchaeal order Thermoproteales. However, a comprehensive study of the distribution and function of diverse members of this group across different habitat types has not been conducted. Consequently, the goals of this study were to determine the distribution of different Thermoproteales genera across geochemically distinct geothermal habitats of Yellowstone National Park, and to identify key functional attributes of major genera that correlate with environmental parameters. Curated sequence assemblies belonging to five genera were characterized in replicate samples of 11 high‐temperature communities ranging in pH from 3 to 9. Thermocladium , Vulcanisaeta and Caldivirga spp. were the primary Thermoproteales populations present in low pH (pH Thermoproteus populations were found in mildly‐acidic (pH 5–6) sulfur sediments, and Pyrobaculum populations were confined to higher pH (pH > 6) sulfur sediments and/or filamentous ‘streamer’ communities. Metabolic reconstruction and comparative genomics among assemblies show that these populations are primarily chemoorganotrophs that utilize different electron acceptors depending on geochemical conditions. The presence of potential CO 2 fixation pathways in some Thermoproteales populations appears to be linked with NiFe hydrogenases, which combined with high levels of H 2 in many sulfidic systems, may provide the energy required to fix inorganic C.

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