Iron reducing sludge as a source of electroactive bacteria: assessing iron reduction in biofilm bacteria, planktonic cells and isolates from a microbial fuel cell.

In this study, bacteria from a microbial fuel cell (MFC) and isolates were evaluated on their Fe reduction capability at different concentrations of iron using acetate as the sole source of carbon. The results demonstrated that the planktonic cells can reach an iron reduction up to 60% at 27 mmol Fe. Azospira oryzae (µ 0.89 ± 0.27 d) and Cupriavidus metallidurans CH34 (µ 2.34 ± 0.81 d) presented 55 and 62% of Fe reduction, respectively, at 16 mmol l. Enterobacter bugandensis (µ 0.4 ± 0.01 d) 40% Fe at 27 mmol l, Citrobacter freundii ATCC 8090 (µ 0.23 ± 0.05 d) and Citrobacter murliniae CDC2970-59 (µ 0.34 ± 0.02 d) reduced Fe in ~ 50%, at 55 mmol l. This is the first report on these bacteria on a percentage of iron reduction. These results may be useful for anode design to contribute to a higher energy generation in MFCs.