R-(-)-MANDELIC ACID PRODUCTION FROM RACEMIC MANDELIC-ACIDS BY PSEUDOMONAS POLYCOLOR WITH ASYMMETRIC DEGRADING ACTIVITY

The microbial asymmetric degradation of S-(+)-mandelic acid was invest igated in order to develop a practical process for R-(-)-mandelic acid production from racemic mandelic acids. Among the 790 culture strains tested, microorganisms belonging to the Brevibacterium, Pseudomonas, Rhodococcus, Rhodotorula, Rhodosporidium, Spouobolomyces and Gibberell a genera exhibited high S-(+)-mandelic acid degrading activity, Pseudo monas polycolor IFO 3918 was determined to be the best strain and used as a biocatalyst for eliminating the S-(+)-isomer. The maximum rate o f S-(+)-isomer degradation was obtained at 30 degrees C and pH 7.0. Un der these optimal conditions, the S-(+)-isomer in a racemic mandelic a cid 45 g/l mixture was completely degraded within 24 h, with 20 g of R -(-)-mandelic acid per liter remaining in the reaction mixture, Crysta lline R-(-)-mandelic acid with a chemical purity greater than 99% and optical purity of 99.9% enantiomeric excess was obtained at a yield of 35% by acidification of the reaction mixture, extraction with ethyl a cetate and subsequent concentration.