Reversing an Extracellular Electron Transfer Pathway for Electrode-Driven Acetoin Reduction

• DOI: 10.1021/acssynbio.8b00498
• Publication Date: 2019-06-07T07:37:51Z
• Authors: Nicholas M. Tefft; Michaela A. TerAvest
• Keywords: Shewanella oneidensis; Acetoin; Electrosynthesis; Electron acceptor

Microbial electrosynthesis is an emerging technology with the potential to simultaneously store renewably generated energy, fix carbon dioxide, and produce high-value organic compounds. However, limited understanding of route electrons into cell remains obstacle developing a robust microbial platform. To address this challenge, we leveraged native extracellular electron transfer pathway in Shewanella oneidensis MR-1 connect electrode intracellular reduction reaction. The system uses Mtr proteins from inner membrane quinone pool. Subsequently, are transferred quinones NAD+ by NADH dehydrogenases. This reverse functioning dehydrogenases thermodynamically unfavorable; therefore, added light-driven proton pump (proteorhodopsin) generate proton-motive force drive activity. Finally, use acetoin 2,3-butanediol via heterologous butanediol dehydrogenase (Bdh) as sink. Bdh NADH-dependent enzyme; observation supports our hypothesis that cathodic NAD+. Multiple lines evidence indicate proper engineered system: flux cathode influenced both light availability, production highest when poised present. Using hydrogenase-deficient S. background strain resulted stronger correlation between production, suggesting hydrogen off-target sink wild-type background. represents promising step toward genetically platform will enable new focus on synthesis specific compounds using electrical energy.