Journal
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY
Volume 76, Issue 2, Pages 270-275Publisher
TAYLOR & FRANCIS LTD
DOI: 10.1271/bbb.110633
Keywords
biological energy conversion; microbial fuel cells; anode respiration; extracellular electron transfer
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Funding
- Japanese Science and Technology Agency (JST)
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In single-chamber microbial fuel cells (SC-MFCs), oxygen molecules diffuse through air cathodes into electrolytes and compete against anodes in accepting electrons. In this study, we constructed multiple gene-knockout mutants for terminal oxidases (SO4607, SO2364, and SO3286) in Shewanella oneidensis MR-1 and examined their abilities to generate electric currents in SC-MFCs. Although single-knockout mutants generated levels of current similar to that of the wild type (WT), an SO4607/SO2364 double-knockout mutant (DO) generated 50% higher current than WT. A triple-knockout mutant did not grow in SC-MFC. The Coulombic efficiencies in SC-MFC were, however, not substantially different between WT and DO. In aerobically grown DO cells, the transcription levels of the genes involved in extracellular electron transfer (mtrC and crp) were increased compared to those in WT cells. These results suggest that suppression of aerobic respiration activates the expression of genes related to the extracellular electron transfer and increases the electric output from SC-MFCs.
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