R-(-)-MANDELIC ACID PRODUCTION FROM RACEMIC MANDELIC-ACIDS USING PSEUDOMONAS-POLYCOLOR IFO-3918 AND MICROCOCCUS-FREUDENREICHII FERM-P-13221

To develop a practical process for R-(-)-mandelic acid production from racemic mandelic acids, we investigated a two step microbial reaction which employs the asymmetric oxidation of S-(+)-mandelic acid by Pseu domonas polycolor IFO 3918 and the asymmetric reduction of oxidated S- (+)-mandelic acid by microorganisms. Microorganism screening was condu cted for the asymmetric reduction of benzoylformic acid. Among 800 cul ture strains tested, microorganisms belonging to Alcaligenes, Coryneba cterium, Enterococcus, Gluconobacter, Kurthia, Micrococcus and Strepto myces genera exhibited high reducing activity for benzoylformic acid d erived from S-(+)-mandelic acid. Micrococcus freudenreichii FERM-P 132 21 was determined to be the best, and therefore used as a biocatalyst for reducing benzoylformic acid. The optimum conditions for R-(-)-mand elic acid production were also determined. Under optimal conditions, w e attempted to convert racemic mandelic acid to R-(-)-mandelic acid us ing P. polycolor and M. freudenreichii, both simultaneously or consecu tively. For both types of reactions, the S-(+)-isomer in a racemic man delic acid (45 g/l) solution was completely oxidized, and 31.5 g/l of R-(-)-mandelic acid were produced in the reaction mixture.