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 α-alkyl-β-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) α-alkyl β-hydroxyesters. Among the isolated yeast strains, the Pichia sp. strain isolated from D. carota, was the best biocatalyst for production of anti (2S,3S) α-alkyl β-hydroxyesters. Our results show that the microbial endophytic community provides an interesting niche on the search for novel biocatalysts.

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► Endophytic microorganisms as a source for novel biocatalysts.
► β-keto esters were used to test their biocatalytic potential.
► Endophytic yeast showed the greatest potential as bioreducing agents.
► Pichia strain isolated from Daucus carota showed excellent yield and stereoselectivity.
► Enterobacter agglomerans from Erythrina crista-galli showed excellent yield and stereoselectivity.