Enantioselective synthesis of (R)-phenylephrine by Serratia marcescens BCRC10948 cells that homologously express SM_SDR

A short-chain dehydrogenase/reductase from Serratia marcescens BCRC10948, SM_SDR, has been cloned and expressed in Escherichia coli for the bioconversion of 1-(3-hydroxyphenyl)-2-(methylamino) ethanone (HPMAE) to (R)-phenylephrine[(R)-PE]. However, only 5.11 mM (R)-PE was obtained from 10 mM HPMAE after a 9 h conversion in the previous report. To improve the biocatalytic efficiency, the homologous expression of the SM_SDR in S. marcescens BCRC10948 was achieved using the T5 promoter for expression. By using 2% glycerol as carbon source, we found that 8.00 +/- 0.15 mM of (R)-PE with more than 99% enantiomeric excess was produced from 10 mM HPMAE after 12 h conversion at 30 degrees C and pH 7.0. More importantly, by using 50 mM HPMAE as the substrate, 23.78 0.84 mM of (R)-PE was produced after a 12 h conversion with the productivity and the conversion yield of 1.98 mmol (R)-PE/1 h and 47.50%, respectively. The recombinant S. marcescens cells could be recycled 6 times for the production of (R)-PE, and the bioconversion efficiency remained at 85% when compared to that at the first cycle. Our data indicated that a high conversion efficiency of HPMAE to (R)-PE could be achieved using S. marcescens BCRC10948 cells that homologously express the SMSDR.