Immunological Relationships Among -Galactosidases in Members of the Genus Lactobacillus

Abstract

We prepared antisera against purified inducible β-galactosidases from Lactobacillus murinus ATCC 35020, Lactobacillus bulgaricus ATCC 11842T(T = type strain), and Lactobacillus helveticus ATCC 15009Tand used these antisera to measure the levels of immunological relatedness between the reference enzymes and β-galactosidases from various lactobacilli. Crude extracts from 11 species of lactobacilli, 7 wild-type strains isolated from Tafi cheese (Tucuman, Argentina), and 4 biotypes isolated from the guts of rats were tested against β-galactosidase antisera from L. murinus, L. bulgaricus and L. heveticus. Pairwise comparisons between cross-reacting crude extracts were done by using double-diffusion assays. These comparisons permitted the recognition of antigenic specificity groups based on the β-galactosidases of various nomenspecies of lactobacilli; some of the species gave bands of nonidentity. The results of microcomplement fixation experiments in which we used two of the three antisera supported the results obtained with the double-diffusion assays and provided quantitative estimations of the antigenic relationships within the various β-galactosidases. From the combined results obtained with the antisera, a composite phylogenetic map of the antigenic relationships among the β-galactosidases from lactobacilli was prepared. This map agreed with the maps for the following two other constitutive enzymes: fructose diphosphate aldolase (J. London and K. Kline, Bacteriol. Rev. 37:453-478, 1973) and D-(-)-lactic dehydrogenase (F. Gasser and C. Gasser J. Bacteriol. 106:113-125, 1971).