AUTHOR=Wu Xiayuan , Ren Xiaoqian , Owens Gary , Brunetti Gianluca , Zhou Jun , Yong Xiaoyu , Wei Ping , Jia Honghua 

TITLE=A Facultative Electroactive Chromium(VI)-Reducing Bacterium Aerobically Isolated From a Biocathode Microbial Fuel Cell

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02883

DOI=10.3389/fmicb.2018.02883

ISSN=1664-302X

ABSTRACT=<p>A facultative electroactive bacterium, designated strain H, was aerobically isolated from the biocathode of a hexavalent chromium (Cr(VI))-reducing microbial fuel cell (MFC). Strain H is Gram-positive and rod shaped (1–3 μm length). 16S rRNA gene analysis suggested that this strain (accession number <ext-link ext-link-type="DDBJ/EMBL/GenBank" xlink:href="MH782060" xmlns:xlink="http://www.w3.org/1999/xlink">MH782060</ext-link>) belongs to the genus <italic>Bacillus</italic> and shows maximum similarity to <italic>Bacillus cereus</italic> whose electrochemical activity has never previously been reported. Moreover, this strain showed efficient Cr(VI)-reducing ability in both heterotrophic (aerobic LB broth) and autotrophic (anaerobic MFC cathode) environments. Cr(VI) removal reached 50.6 ± 1.8% after 20 h in LB broth supplemented with Cr(VI) (40 mg/L). The strain H biocathode significantly improved the performance of the Cr(VI)-reducing MFC, achieving a maximum power density of 31.80 ± 1.06 mW/m<sup>2</sup> and Cr(VI) removal rate of 2.56 ± 0.10 mg/L–h, which were 1.26 and 1.75 times higher than those of the MFC with the sterile control cathode, respectively. This study offers a novel Gram-positive <italic>Bacillus</italic> sp. strain for Cr(VI) removal in MFCs, and shows a facile aerobic isolation method could be used to screen facultative electroactive bacteria.</p>