A Continuously Operated Bimembrane Reactor Process for the Biocatalytic Production of (2<i>R</i>,5<i>R</i>)-Hexanediol SchroerKirsten LützStephan 2009 Alcohol dehydrogenase-catalyzed reductions of prochiral ketones to chiral alcohols require the regeneration of consumed cofactors such as NADH or NADPH. In the substrate-coupled cofactor regeneration approach, where 2-propanol is oxidized to acetone, complete conversion is inhibited by a thermodynamic limitation. This can be overcome by applying methods of <i>in situ</i> product removal techniques such as pervaporation. Here we present a new reactor concept which enables a continuous biocatalytic ketone reduction process with concurrent <i>in situ</i> removal of the byproduct acetone. In such a bimembrane reactor system recombinant Escherichia coli cells expressing alcohol dehydrogenase from Lactobacillus brevis were applied for the continuous reduction of 2,5-hexanedione. The product (2<i>R</i>,5<i>R</i>)-hexanediol could be synthesized with exceedingly high space-time yield of >170 g/(L·d) and catalyst usage (17.9 g<sub>P</sub>/g<sub>wetcellweight</sub>).