Verena B. Heuer
Denise M. Akob
Bernhard Viehweger
Marcus Elvert
Martina Herrmann
Kai-Uwe Hinrichs
Kirsten Küsel
Felix Beulig
2015
<p>Effects of extremely high carbon dioxide (CO<sub>2</sub>) concentrations on soil microbial communities and associated processes are largely unknown. We studied a wetland area affected by spots of subcrustal CO<sub>2</sub> degassing (mofettes) with focus on anaerobic autotrophic methanogenesis and acetogenesis because the pore gas phase was largely hypoxic. Compared with a reference soil, the mofette was more acidic (ΔpH ~0.8), strongly enriched in organic carbon (up to 10 times), and exhibited lower prokaryotic diversity. It was dominated by methanogens and subdivision 1Acidobacteria, which likely thrived under stable hypoxia and acidic pH. Anoxic incubations revealed enhanced formation of acetate and methane (CH<sub>4</sub>) from hydrogen (H<sub>2</sub>) and CO<sub>2</sub> consistent with elevated CH<sub>4</sub> and acetate levels in the mofette soil. <sup>13</sup>CO<sub>2</sub> mofette soil incubations showed high label incorporations with ~512<span class="mb"><span class="mb"> </span></span>ng<sup>13</sup>C<span class="mb"><span class="mb"> </span></span>g<span class="mb"><span class="mb"> </span></span>(dry weight (dw)) soil<sup>−1</sup><span class="mb"><span class="mb"> </span></span>d<sup>−1</sup> into the bulk soil and up to 10.7<span class="mb"><span class="mb"> </span></span>ng <sup>13</sup>C<span class="mb"><span class="mb"> </span></span>g<span class="mb"><span class="mb"> </span></span>(dw) soil<sup>−1</sup><span class="mb"><span class="mb"> </span></span>d<sup>−1</sup> into almost all analyzed bacterial lipids. Incorporation of CO<sub>2</sub>-derived carbon into archaeal lipids was much lower and restricted to the first 10<span class="mb"><span class="mb"> </span></span>cm of the soil. DNA-SIP analysis revealed that acidophilic methanogens affiliated withMethanoregulaceae and hitherto unknown acetogens appeared to be involved in the chemolithoautotrophic utilization of <sup>13</sup>CO<sub>2</sub>. Subdivision 1 Acidobacteriaceae assimilated <sup>13</sup>CO<sub>2</sub> likely via anaplerotic reactions because Acidobacteriaceae are not known to harbor enzymatic pathways for autotrophic CO<sub>2</sub> assimilation. We conclude that CO<sub>2</sub>-induced geochemical changes promoted anaerobic and acidophilic organisms and altered carbon turnover in affected soils.</p>
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10.1038/ismej.2014.148
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Nature Publishing Group
Carbon flow from volcanic CO<sub>2</sub> into soil microbial communities of a wetland mofette
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