title: The mechanism of neutral red-mediated microbial electrosynthesis in Escherichia coli: menaquinone reduction.
abstract: The aim of this work was to elucidate the mechanism of mediated microbial electrosynthesis via neutral red from an electrode to fermenting Escherichia coli cultures in a bioelectrochemical system. Chemical reduction of NAD(+) by reduced neutral red did not occur as predicted. Instead, neutral red was shown to reduce the menaquinone pool in the inner bacterial membrane. The reduced menaquinone pool altered fermentative metabolite production via the arcB redox-sensing cascade in the absence of terminal electron acceptors. When the acceptors DMSO, fumarate, or nitrate were provided, as many as 19% of the electrons trapped in the reduced acceptors were derived from the electrode. These results demonstrate the mechanism of neutral red-mediated microbial electrosynthesis during fermentation as well as how neutral red enables microbial electrosynthesis of reduced terminal electron acceptors.
authors.affiliation: The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Harrington
authors.affiliation: The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA.
authors.forename: Vi N
authors.initials: VN
authors.lastname: Tran
authors.affiliation: The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA.
authors.forename: Abdelrhman
authors.initials: A
authors.lastname: Mohamed
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Renslow
authors.affiliation: The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA.
authors.forename: Saeid
authors.initials: S
authors.lastname: Biria
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Orfe
authors.affiliation: Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, USA.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Call
authors.affiliation: The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA. Electronic address: beyenal@wsu.edu.
authors.forename: Haluk
authors.initials: H
authors.lastname: Beyenal
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D004558:Electric Stimulation / Q000295:instrumentation* / Q000379:methods; D004574:Electromagnetic Fields; D004867:Equipment Design; D004926:Escherichia coli / Q000378:metabolism* / Q000528:radiation effects; D009499:Neutral Red / Q000378:metabolism*; D010084:Oxidation-Reduction; D024482:Vitamin K 2 / Q000378:metabolism*
chemical_list: D024482:Vitamin K 2; D009499:Neutral Red
keywords: Bioelectrochemical system; Electron transfer; Menaquinone; Microbial electrosynthesis; Neutral red