Arginine specific aminopeptidase from Lactobacillus brevis

ABSTRACT

The proteolytic system of lactic acid bacteria contribute to the development of flavor during the ripening of cheese through the generation of short peptides and free amino acids, which directly or indirectly act as flavor precursors. Newly isolated lactic acid bacteria (LAB) as well as those procured from culture collection centers were screened for the production of various substrate specific aminopeptidases. Among all the strains screened, L. brevis (NRRL B-1836) was found to produce quantifiable amount of intracellular arginine specific aminopeptidase (EC 3.4.11.6). The productivity of arginine aminopeptidase in 5 L fermentor was 36 IU/L/h. The Luedeking and Piret model was tested for intracellular production of aminopeptidase and the data seemed to fit well, as the correlation coefficient was 0.9964 for MRS. The αAP and βAP was 0.4865 and 0.0046, respectively in MRS medium indicating that the yield was predominantly depended on growth. The culture produced lactic acid and also tolerated pH 2.0-3.0 and 0.3-0.5 percent bile salts, the most important probiotic features.