Streptomyces-catalyzed Carbonylaromatic Reduction And The Cloning And Expression Of Its Key Enzyme

Chiral aromatic alcohols are important intermediates of pharmaceuticals, pesticides and other industrial chemicals. Stereoselective reduction of carbonylaromatic compounds is the method for production of aromatic alcohols. At present, reduction of carbonylaromatic compounds by means of chemical methods encounters low yields, complicated processing, critical condition as well as environmental pollution. On the contrary, biocatalysis is of superior advantages because of high yield, easy operation, mild conditions and environmental friendliness. In this study, a Streptomyces strain with highly carbonylductive activity was isolated and its carbonylreductase in both native and recombinant forms were obtained, which may provide an alternative for carbonylreduction.The main findings of this work include:(1) A Streptomyces sp. strain, which can stereoselectively reduce carbonyl compounds, was obtained from Shanghai Branch of National Pesticide R&D South Center, and was named Streptomyces sp. DUT002. The culture condition of the strain is pH 6.5-7.5,30-37℃. It can stereoselectively reduce acetophenone with a yield of 85%and e.e. of 10%and reduce 3'-chloroacetophenone with a yield of 100%and e.e. of 83%. The optimal organic solvent for the reduction is DMSO and the co-substrate is glucose. Redox mediator AQDS can promote the reduction.(2) The gene adh encoding carbonylreductase was cloned and obtained from Streptomyces avermitilis MA-4680, which was then inserted into the expression vector pET43.1a(+). The resulting plasmid was transformed into the E. coli strain, BL21(DE3)plysS. The recombinant enzyme, adh, was expressed by the induction of IPTG and obtained by Ni-NTA Agarose affinity chromatograph. The recombinant enzyme exhibited reductive activity of acetophenone and 2-chloro-fluorenone.