Immunological and electrophoretic study of the proteolytic enzymes from variousLactococcusandLactobacillusstrains

Abstract

SUMMARYCell extracts of various lactobacilli and twoLactococcusstrains were investigated for their immunoresponse with monoclonal and polyclonal antibodies raised against various proteolytic enzymes fromLc. lactis. Except forLactobacillus caseiSBT 2233, none of the lactobacilli proteins showed immunoresponse with the monoclonal antibodies. With polyclonal antibodies raised against aminopeptidases N and C and endopeptidase ofLc. lactisan immunoresponse was observed. However, the molecular masses of the reactive bands on the blot were considerably different from those of the corresponding lactococcal peptidases, except for the band that reacted with polyclonal antibodies against aminopeptidase C. The polyclonal antibodies raised against X-prolyl-dipeptidyl aminopeptidase and tripeptidase did not show any immunoreaction. As a control, all antibodies reacted with the lactococcal proteins on the blot, with molecular masses corresponding to those reported for the proteinases and peptidases. The results clearly showed that most of the proteolytic enzymes of lactobacilli were immunologically different from those of lactococci. The proteolytic enzymes in the cell-free extracts were separated by non-denaturing PAGE and visualized by zymogram staining. The electrophoretic pattern of the proteolytic enzymes of lactobacilli was different from that ofLc. lactis. Both experiments indicate that the enzymes of the proteolytic system of lactobacilli are different from those of lactococci.