AUTHOR=Fu Li , Song Tianze , Zhang Wei , Zhang Jie , Lu Yahai 

TITLE=Stimulatory Effect of Magnetite Nanoparticles on a Highly Enriched Butyrate-Oxidizing Consortium

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01480

DOI=10.3389/fmicb.2018.01480

ISSN=1664-302X

ABSTRACT=<p>Syntrophic oxidation of butyrate is catabolized by a few bacteria specialists in the presence of methanogens. In the present study, a highly enriched butyrate-oxidizing consortium was obtained from a wetland sediment in Tibetan Plateau. During continuous transfers of the enrichment, the addition of magnetite nanoparticles (nanoFe<sub>3</sub>O<sub>4</sub>) consistently enhanced butyrate oxidation and CH<sub>4</sub> production. Molecular analysis revealed that all bacterial sequences from the consortium belonged to <italic>Syntrophomonas</italic> with the closest relative of <italic>Syntrophomonas wolfei</italic> and 96% of the archaeal sequences were related to <italic>Methanobacteria</italic> with the remaining sequences to <italic>Methanocella</italic>. Addition of graphite and carbon nanotubes for a replacement of nanoFe<sub>3</sub>O<sub>4</sub> caused the similar stimulatory effect. Silica coating of nanoFe<sub>3</sub>O<sub>4</sub> surface, however, completely eliminated the stimulatory effect. The control experiment with axenic cultivation of a <italic>Syntrophomonas</italic> strain and two methanogen strains showed no effect by nanoFe<sub>3</sub>O<sub>4</sub>. Together, the results in the present study support that syntrophic oxidation of butyrate is likely facilitated by direct interspecies electron transfer in the presence of conductive nanomaterials.</p>