Studies on Group Antigens of Lactobacillus casei

Abstract

Group antigens of Lactobacillus casei were analyzed by immunodiffusion in agar. Antigens were extracted with cold trichloroacetic acid (TCA) from whole cells or cell-wall preparations. Using cell wall extracts as antigens, group B strains were clearly distinguished from group C strains. The antigen specific for group B was designated as antigen 1, and for group C as antigen 2. Group B cells contained either antigen 4 or antigen 5, in addition to antigen 1, in their cell walls, and were divided into two subgroups. TCA extracts of the whole-cell preparations contained an antigen common to groups B and C. This antigen was called antigen 3. Antigen 3 was not found in the cell-wall extracts. All species of lactobacilli and some species of other genera were found to contain this antigen in their whole-cell extracts. Inhibition tests with various sugars showed that L-rhamnose was the most effective inhibitor for antigens 1 and 5, α-glucoside for antigen 4, β-glucoside for antigen 2, and hexosamines for antigen 3.