초록
<P><B>Abstract</B></P> <P>To provide insight into direct interspecies electron transfer via granular activated carbon (GAC), the effect of GAC supplementation on anaerobic digestion was evaluated. Compared to control samples, the GAC supplementation increased the total amount of methane production and its production rate by 31% and 72%, respectively. 16S rDNA sequencing analysis revealed a shift in the archaeal community composition; the <I>Methanosarcina</I> proportion decreased 17%, while the <I>Methanosaeta</I> proportion increased 5.6%. Metagenomic analyses based on shotgun sequencing demonstrated that the abundance of <I>pilA</I> and <I>omcS</I> genes belonging to <I>Geobacter</I> species decreased 69.4% and 29.4%, respectively. Furthermore, the analyses suggested a carbon dioxide reduction pathway rather than an acetate decarboxylation pathway for methane formation. Taken together, these results suggest that GAC improved methane production performance by shifting the microbial community and altering functional genes associated with direct interspecies electron transfer via conductive materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Serum bottles were supplemented with GAC to stimulate DIET. </LI> <LI> Methane production rate and yield improved 72% and 31%, respectively. </LI> <LI> Abundance of <I>pilA</I> and <I>omcS</I> genes decreased 69.4% and 29.4%, respectively. </LI> <LI> <I>Methanosaeta</I> species were selected over <I>Methanosarcina</I> species. </LI> <LI> The carbon dioxide reduction pathway was suggested for methane formation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>