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Enhancement of enzyme activity and enantioselectivity via cultivation in nitrile metabolism by Rhodococcus sp. CGMCC 0497

Racemic 2‐phenylpropionitrile was resolved enantioselectively by nitrile‐converting enzymes in cells of Rhodococcus sp. CGMCC 0497 to S‐(+)‐2‐phenylpropionic acid and R‐(−)‐2‐phenylpropionamide. By optimization of the culture conditions, great enhancement of enzyme activity and enantioselectivity was achieved. Furthermore, the relationship between cell‐growth periodicity and enzyme accumulation was studied; the addition of inducer was delayed by 1 day and the reaction was further improved. This unusual strategy has almost never been reported with other nitrile‐converting strains. The resulting culture broth, containing methacrylamide as the inducer, beef extract as the nitrogen source and glucose as the carbon source, with methacrylamide added 24 h later, seemed to be most suitable. S‐(+)‐2‐Phenylpropionic acid and R‐(−)‐2‐phenylpropionamide were produced with yields of 48% (enantiomeric excess, 96%) and 42% (enantiomeric excess, 97%) respectively with no nitrile left after 3 h, or with yields of 52% and 39% (enantiomeric excess, 93% and 99%) respectively after 6 h.