Stereoselective biotransformation of α-alkyl-β-keto esters by endophytic bacteria and yeast

Several strains of endophytic bacteria and yeast were isolated from Daucus carota, Erythrina crista-galli, Curcubita maxima and Fortunella margarita, and tested for the reduction of two model alpha-alkyl-beta-ketoesters. The yeast strains resulted better biocatalysts for the reduction of the tested substrates with the exception of Enterobacter agglomerans C8 strain, isolated from Erythrina crista-galli, that provided the best results for the preparation of syn (2R,3S)alpha-alkyl beta-hydroxyesters. Among the isolated yeast strains, the Pichia sp. strain isolated from D. carota, was the best biocatalyst for production of anti (2S,3S)alpha-alkyl beta-hydroxyesters. Our results show that the microbial endophytic community provides an interesting niche on the search for novel biocatalysts. (C) 2011 Elsevier B.V. All rights reserved.