Abstract
The biocatalysts for asymmetric reduction of aromatic ketones were successfully screened from soil samples polluted by substituted acetophenones. 12 strains could asymmetrically reduce acetophenone into phenethanol, while only strain YS62 possessed the best performance of reducing acetophenone into (S)-1-phenethanol. It was identified as Rhodotorula mucilaginosa based on phenotypic and genetics characteristics and it was used for further asymmetric reduction experiments of acetophenone as a new biocatalyst. R. mucilaginosa YS62 whole-cells could catalyze the asymmetric reduction of acetophenone (35 mM) into (S)-1-phenethanol (31.4 mM) with a conversion rate of 89.7% and enantiomeric excess (e.e.) of 99.9% under 60 g/L YS62 cell, pH 6.5 , 34°C for 30 h and 2% glucose as a co-substrate. These results have shown that R. mucilaginosa YS62 is a promising biocatalyst for the production of optically active phenylethanol derivatives. Key words: Asymmetric reduction, acetophenone, Rhodotorula mucilaginosa.
Highlights
Chiral phenylethanol derivatives are very important intermediates to introduce chiral centers into pharmaceuticals, spices, agricultural chemicals and special materials (Ni and Xu, 2011; Kurbanoglu et al, 2011)
It was identified as Rhodotorula mucilaginosa based on phenotypic and genetics characteristics and it was used for further asymmetric reduction experiments of acetophenone as a new biocatalyst
A new yeast strains with high activity and excellent enantioselectivity for the reduction of acetophenones has successfully been obtained from acetophenone-polluted soil
Summary
Chiral phenylethanol derivatives are very important intermediates to introduce chiral centers into pharmaceuticals, spices, agricultural chemicals and special materials (Ni and Xu, 2011; Kurbanoglu et al, 2011). Compared with conventional chemical processing, biocatalytic asymmetric reduction has recently become an important method to prepare enantiopure compounds because it has high enantioselectivity, environmentally benign processes and energy-effective operations (Ni and Xu, 2011). Lated enzymes and whole cells can be employed as biocatalysts in the asymmetric synthesis of chiral phenylethanol derivatives. The reaction of isolated enzymes needs the supply of external cofactors As they are very expensive, large-scale applications of such reaction are rather scarce despite considerable research efforts to develop in-vitro cofactor regeneration systems for re-establishing the biocatalyst reduction potential (Valadez-Blanco and Livingston, 2009). Much attention in biocatalytic asymmetric reduction has turned to developing the whole cell biocatalysts with desired activity (Shaw et al, 2003)
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