An NADPH-dependent Lactobacillus composti short-chain dehydrogenase/reductase: characterization and application to ( R )-1-phenylethanol synthesis

A new anti-Prelog short-chain dehydrogenase/reductase (SDR) encoding gene lcsdr was cloned from Lactobacillus composti DSM 18527, and heterologously expressed in Escherichia coli. Lc SDR is nicotinamide adenine dinucleotide phosphate (NADPH)-dependent and has a molecular weight of approximately 30 kDa. The optimal pH and temperature were 6.5 and 30 °C, respectively. The maximal reaction rate V max was 133.9 U mg −1 ; the Michaelis–Menten constant K m of Lc SDR were 0.345 mM for acetophenone ( 1a ), and 0.085 mM for NADPH. Through introducing an Es GDH-catalyzed NADPH regeneration system, a biocatalytic process for ( R )-1-phenylethanol (( R )- 1b ) was developed with outstanding time–space yield. Under the optimized conditions, 50 g l −1 1a was converted to ( R )- 1b in 2 h with a yield of 93.8%, enantiomeric excess of product ( e.e . p ) above 99% and space–time yield of 562.8 g l −1 d −1 .