YEAST CATALYZED REDUCTION OF BETA-KETO-ESTERS .2. OPTIMIZATION OF THESTEREOSPECIFIC REDUCTION BY ZYGOSACCHAROMYCES-ROUXII

Zygosaccharomyces rouxii catalysed the reduction of ethyl 4-chloroacet oacetate (ethyl 4-chloro-3-oxobutanoate) to the corresponding (S)-hydr oxy ester (ethyl (S)-4-chloro-3-hydroxybutanoate) in high enantiomeric excess. The productivity of non-immobilised cells was compared to cel ls immobilised on a range of organic and inorganic supports. Cells imm obilised in calcium alginate displayed a catalytic activity significan tly higher than that of non-immobilised cells. A time dependent fall i n the enantiomeric purity of the product was observed with the use of this matrix. This phenomenon was not seen in the reduction catalysed b y non-immobilised cells.