Resting Escherichia coli as Chassis for Microbial Electrosynthesis: Production of Chiral Alcohols

Chiral alcohols constitute important building blocks that can be produced enantioselectively by using nicotinamide adenine dinucleotide (phosphate) [NAD(P)H]-dependent oxidoreductases. For NAD(P)H regeneration, electricity delivers the cheapest reduction equivalents. Enzymatic electrosynthesis suffers from cofactor and enzyme instability, whereas microbial electrosynthesis (MES) exploits whole cells. Here, we demonstrate MES by using resting Escherichia coli as biocatalytic chassis for a production platform towards fine chemicals through electric power. This chassis was exemplified for the synthesis of chiral alcohols by using a NADPH-dependent alcohol dehydrogenase from Lactobacillus brevis for synthesis of (R)-1-phenylethanol from acetophenone. The E. coli strain and growth conditions affected the performance. Maximum yields of (39.4±5.7) % at a coulombic efficiency of (50.5±6.0) % with enantiomeric excess >99 % was demonstrated at a rate of (83.5±13.9) μm h^-1 , confirming the potential of MES for synthesis of high-value compounds.