Microorganisms’ mediated reduction of &#946-ketoesters

Several microorganism strains of genera Saccharomyces, Candida, Hansenula, Aspergillus and Lactobacillus were screened for their ability to perform the reduction of g-chloro-β-ketobutyric acid ethyl ester to g-chloro-β-hydroxybutyric acid ethyl ester. The optimal conditions for both stages of the bioprocess were established. Both stereoisomers of g-chloro-β-hydroxybutyric acid ethyl ester were obtained in different biotransformation conditions. While in aqueous medium the S isomer was obtained, in organic media the product had predominantly the R configuration