The growth and enzymatic production of Pseudomonas sp. BA2, a new L-aminoacylase-producing microorganism, were studied in a bench-top fermenter. Multiple fermentations were carried out in order to determine the optimal pH and temperature values. The influence of the substrate concentration on both growth and L-aminoacylase activity was also investigated. The maximum growth rate and the greatest yield of enzyme were obtained when the fermentation was carried out at pH 7 . 5, 25 degrees C and DOT greater than or equal to 50%. N-Acetyl-DL-alanine, at a concentration of 20 g dm(-3), was used as the sole carbon and nitrogen source. The fermentation process provided a maximum biomass concentration of 3 . 36 g dry weight dm(-3). The highest L-aminoacylase production (11429 U g(-1) dry weight) was obtained after 39 h of cultivation. The results were a significant improvement over those previously reported.