1J. Craig Venter Institute, Microbial & Environmental Genomics, 2Univ. Sourthern California, Dept. Earth Science
Microbial respiration via extracellular electron transfer (EET) is a ubiquitous reaction that occurs throughout anaerobic environments and is a driving force behind global biogeochemical cycling of metals. Here we identify specific EET-active microbes and associated microbial metabolic network in a diverse electrogenic biofilm using a novel stimulus-induced metatranscriptomic approach with genome-binning of dominant strains. In order to stimulate EET reaction in the community, EET rate was increased via electrode surface potential change, and both DNA and mRNA were co-extracted and sequenced. Metagenomic analyses enabled to associate high coverage draft genomes of eleven dominant microbes within the complex community. We find that the most significant gene expression responses to the applied EET-stimulus occurred in only two microbial groups, Desulfobulbaceae and Desulfuromonadaceae. Our stimulus-induced metatranscriptomic results also show known EET-associated genes that are coding multi-heme c-type cytochromes, several function-unknown EET-related genes, and metabolic competition in the two EET-responsive microbes. This new approach yields a comprehensive image of functional microbes and genes related to EET activity in a diverse community, representing the next step towards unravelling complex microbial roles within a community and how microbes adapt to specific stimuli.
keywords:Metatranscriptomics,Genome binning,Microbial fuel cell,Extracellular electron transport,Metabolic network