Rhodococcus equi A4 cells containing a nitrile hydratase and an amidase converted (R, S)-2-(4-methoxyphenyl)-propionitrile into the corresponding (S)-acid (e.e. 87%) and (R)-nitrile (e.e. > 95%) in 49% yield. The same reaction using (R, S)-2-(4- chlorophenyl)-propionitrile gave the (S)-acid (e.e. > 95%) and (R)-nitrile (e.e. 52%) in 20 and 34% yield, respectively.