초록
<P>Microbial electrosynthesis is the biocathode-driven production of chemicals from CO<SUB>2</SUB> and has the promise to be a sustainable, carbon-consuming technology. To date, microbial electrosynthesis of acetate, the first step in order to generate liquid fuels from CO<SUB>2</SUB>, has been characterized by low rates and yields. To improve performance, a previously established acetogenic biocathode was operated in semi-batch mode at a poised potential of −590 mV vs SHE for over 150 days beyond its initial development. Rates of acetate production reached a maximum of 17.25 mM day<SUP>–1</SUP> (1.04 g L<SUP>–1</SUP> d<SUP>–1</SUP>) with accumulation to 175 mM (10.5 g L<SUP>–1</SUP>) over 20 days. Hydrogen was also produced at high rates by the biocathode, reaching 100 mM d<SUP>–1</SUP> (0.2 g L<SUP>–1</SUP> d<SUP>–1</SUP>) and a total accumulation of 1164 mM (2.4 g L<SUP>–1</SUP>) over 20 days. Phylogenetic analysis of the active electrosynthetic microbiome revealed a similar community structure to what was observed during an earlier stage of development of the electroacetogenic microbiome. <I>Acetobacterium</I> spp. dominated the active microbial population on the cathodes. Also prevalent were <I>Sulfurospirillum</I> spp. and an unclassified Rhodobacteraceae. Taken together, these results demonstrate the stability, resilience, and improved performance of electrosynthetic biocathodes following long-term operation. Furthermore, sustained product formation at faster rates by a carbon-capturing microbiome is a key milestone addressed in this study that advances microbial electrosynthesis systems toward commercialization.</P><P><B>Graphic Abstract</B><BR><IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2013/esthag.2013.47.issue-11/es400341b/production/images/medium/es-2013-00341b_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es400341b'>ACS Electronic Supporting Info</A></P>