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. LcSDR 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 degrees C, respectively. The maximal reaction rate V-max was 133.9 U mg(-1); the Michaelis-Menten constant K-m of LcSDR were 0.345 mM for acetophenone (la), and 0.085 mM for NADPH. Through introducing an EsGDH-catalyzed NADPH regeneration system, a biocatalytic process for (R)-1-phenylethanol ((R)-lb) was developed with outstanding time-space yield. Under the optimized conditions, 50 g 1(-1) la was converted to (R)-lb 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 gl(-1) d(-1).