Summary
Biocathode microbial communities are proposed to catalyse a range of useful reactions. Unlike bioanodes, model biocathode organisms have not yet been successfully cultivated in isolation highlighting the need for culture‐independent approaches to characterization. Biocathode
MCL
(
Marinobacter
,
Chromatiaceae
,
Labrenzia
) is a microbial community proposed to couple
CO
2
fixation to extracellular electron transfer and O
2
reduction. Previous metagenomic analysis of a single
MCL
bioelectrochemical system (
BES
) resulted in resolution of 16 bin genomes. To further resolve bin genomes and compare community composition across replicate
MCL BES
, we performed shotgun metagenomic and 16S
rRNA
gene (16S) sequencing at steady‐state current. Clustering pooled reads from replicate
BES
increased the number of resolved bin genomes to 20, over half of which were > 90% complete. Direct comparison of unassembled metagenomic reads and 16S operational taxonomic units (
OTU
s) predicted higher community diversity than the assembled/clustered metagenome and the predicted relative abundances did not match. However, when 16S
OTU
s were mapped to bin genomes and genome abundance was scaled by 16S gene copy number, estimated relative abundance was more similar to metagenomic analysis. The relative abundance of the bin genome representing ‘
Ca
. Tenderia electrophaga’ was correlated with increasing current, further supporting the hypothesis that this organism is the electroautotroph.