NADH dehydrogenases contribute to extracellular electron transfer by Shewanella oneidensis MR-1 in bioelectrochemical systems

Shewanella oneidensis MR-1 is quickly becoming a synthetic biology workhorse for bioelectrochemical technologies due to a high level of understanding of its interaction with electrodes. Transmembrane electron transfer via the Mtr pathway has been well characterized, however, the role of NADH dehydrogenases in feeding electrons to Mtr has been only minimally studied in S. oneidensis MR-1. Four NADH dehydrogenases are encoded in the genome, suggesting significant metabolic flexibility in oxidizing NADH under a variety of conditions. Strains containing in-frame deletions of each of these dehydrogenases were grown in anodic bioelectrochemical systems with N-acetylglucosamine or D,L-lactate as the carbon source to determine impact on extracellular electron transfer. A strain lacking the two dehydrogenases essential for aerobic growth exhibited a severe growth defect with an anode (+0.4 VSHE) or Fe(III)-NTA as the terminal electron acceptor. Our study reveals that the same NADH dehydrogenase complexes are utilized under oxic conditions or with a high potential anode. Understanding the role of NADH in extracellular electron transfer may help improve biosensors and give insight into other applications for bioelectrochemical systems.\n\nTOC Graphic\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=119 SRC=\"FIGDIR/small/657668v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (20K):\norg.highwire.dtl.DTLVardef@163db4org.highwire.dtl.DTLVardef@2cf477org.highwire.dtl.DTLVardef@165cb63org.highwire.dtl.DTLVardef@c0bc5_HPS_FORMAT_FIGEXP M_FIG C_FIG