Isolation of Fe(III)-reducing fermentative bacterium Bacteroides sp. W7 in the anode suspension of a microbial electrolysis cell (MEC)

The electron-donating strains in anode suspension of microbial electrolysis cell (MEC) have not been probed. This work for the first time isolated from the anode suspension in a double-chamber MEC a Fe(III)-reducing strain W7, which is a Gram-negative, short rod, polar flagellum, non-spore-forming bacterium. Physiological–biochemical characterization and 16S rRNA gene sequence analysis suggested that this strain is a typical fermentative bacterium and is designated to the strain Bacteroides sp. W7 (GeneBank accession no. FJ862827). The strain W7 could reduce Fe(III) to form 8.5 mmol L−1 of Fe(II) in 39 h cultivation. Moreover, this strain can transfer electrons to Fe(III) during its growth by adopting glucose, yeast extract and sodium lactate as carbon source. The presence of this Fe(III)-reducing fermentative bacterium suggests the possible contribution of suspended organisms to the efficiency of MEC.