Microbial Production of Optically Active β-Phenylalanine through Stereoselective Degradation of Racemic β-Phenylalanine

Abstract

The ability to produce (R)- or (S)-beta-phenylalanine from racemic beta-phenylalanine through stereoselective degradation was screened for. Variovorax sp. JH2 and Arthrobacter sp. the faculty of Agriculture, Kyoto University (AKU) 638 were found to be potential catalysts for (R)- and (S)-beta-phenylalanine production respectively. On 192 h cultivation of Variovorax sp. in medium containing 1.0% (w/v) racemic beta-phenylalanine, 0.46% (w/v) (R)-beta-phenylalanine with an enantiomeric purity of 99% e.e. was obtained. The initial step of the (S)-isomer degradation was stereoselective transamination. On 312 h cultivation of Arthrobacter sp. in medium containing 1.0% (w/v) racemic beta-phenylalanine, 0.51% (w/v) (R)-beta-phenylalanine with an enantiomeric purity of 90% e.e. was obtained. The initial step of the (R)-isomer degradation was supposed to be oxidative deamination. Resting cell reaction with vigorous shaking, with cells of Arthrobacter sp. as the catalyst, resulted in production of 0.49% (w/v) of (S)-beta-phenylalanine with an enantiomeric purity of 99% e.e. from 1.0% (w/v) racemic beta-phenylalanine in 45 h.