Phenylalanine methyl ester production from phenylpyruvate methyl ester by immobilized Nocardia opaca under high hydrogen pressure

Phenylalanine methyl ester was produced by immobilized cells of Nocardia opaca from phenylpyruvate methyl ester and NH₄Cl under high hydrogen pressure in a biphasic water-ethyl acetate mixture. The production rate (per dry cells) of phenylalanine methyl ester was 0.4 μmol g^-1 min^-1 under 100 bar hydrogen. When immobilized N. opaca were activated in the medium, the phenylalanine methyl ester production rate per gel increased from 12 to 20 nmol cm^-3 min^-1. Repeated batch production of phenylalanine methyl ester was carried out with periodic reactivation of immobilized cells. Immobilized cells retained about 70% of the initial activity after nine runs when they were activated in the medium and reacted in ethyl acetate-Tris-HCl buffer (80:20) system.