The bacterial strain Pseudomonas sp. BA2 did not develop L-aminoacylase activity in the absence of N-acetyl-DL-alanine, The maximum growth rate and enzyme production were obtained when the acetylated amino acid was used as the sole carbon and nitrogen source. A maximum biomass of A(660)=1.543, after 24 h of cultivation, was obtained. The L-aminoacylase activity reached the maximum value (5.6 U ml(-1) broth) in the stationary growth phase.