IMMUNOLOGICAL AND ELECTROPHORETIC STUDY OF THE PROTEOLYTIC-ENZYMES FROM VARIOUS LACTOCOCCUS AND LACTOBACILLUS STRAINS

Cell extracts of various lactobacilli and two Lactococcus strains were investigated for their immunoresponse with monoclonal and polyclonal antibodies raised against various proteolytic enzymes from Lc. lactis. Except for Lactobacillus casei SBT 2233, none of the lactobacilli pro teins showed immunoresponse with the monoclonal antibodies. With polyc lonal antibodies raised against aminopeptidases N and C and endopeptid ase of Lc. lactis an immunoresponse was observed. However, the molecul ar masses of the reactive bands on the blot were considerably differen t from those of the corresponding lactococcal peptidases, except for t he band that reacted with polyclonal antibodies against aminopeptidase C. The polyclonal antibodies raised against X-prolyl-dipeptidyl amino peptidase and tripeptidase did not show any immunoreaction. As a contr ol, all antibodies reacted with the lactococcal proteins on the blot, with molecular masses corresponding to those reported for the proteina ses and peptidases. The results clearly showed that most of the proteo lytic enzymes of lactobacilli were immunologically different from thos e of lactococci. The proteolytic enzymes in the cell-free extracts wer e separated by nondenaturing PAGE and visualized by zymogram staining. The electrophoretic pattern of the proteolytic enzymes of lactobacill i was different from that of Lc. lactis. Both experiments indicate tha t the enzymes of the proteolytic system of lactobacilli are different from those of lactococci.