Methanogenesis Facilitated by Geobiochemical Iron
Cycle in a Novel Syntrophic Methanogenic Microbial Community
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Abstract
Production
and emission of methane have been increasing concerns
due to its significant effect on global climate change and the carbon
cycle. Here we report facilitated methane production from acetate
by a novel community of methanogens and acetate oxidizing bacteria
in the presence of poorly crystalline akaganeite slurry. Comparative
analyses showed that methanogenesis was significantly enhanced by
added akaganeite and acetate was mostly stoichiometrically converted
to methane. Electrons produced from anaerobic acetate oxidation are
transferred to akaganeite nanorods that likely prompt the transformation
into goethite nanofibers through a series of biogeochemical processes
of soluble Fe(II) readsorption and Fe(III) reprecipitation. The methanogenic
archaea likely harness the biotransformation of akaganeite to goethite
by the Fe(III)–Fe(II) cycle to facilitate production of methane.
These results provide new insights into biogeochemistry of iron minerals
and methanogenesis in the environment, as well as the development
of sustainable methods for microbial methane production