Characterization of two Bacillus probiotics

Abstract

Bacillus subtilis is currently used as an oral probiotic. We examined two commercial B. subtilis probiotic preparations, Enterogermina and Biosubtyl. Surprisingly, physiological and genetic characterization of the bacteria contained in each of these preparations has shown that neither contains B. subtilis.

FIG. 1

Growth of probiotic strains. Bacterial strains were grown at 37°C in LB medium (a), DSM (b), or medium at pH 10.1 (c). B. subtilis PY79 (●), Biosubtyl (○), Enterogermina (two isolates [□ and ■]) and ATCC 9799 (▵) were used. For growth in alkaline medium, sodium carbonate was used to adjust the pH to 10.1 in liquid and solid media as described by Horikoshi and Teruhiko (11). OD₅₉₅, optical density at 595 nm.

FIG. 2

Electron micrographs of mature spores. (A) B. subtilis PY79; (B) Biosubtyl; (C) Enterogermina. Bar, 0.2 μm. oc, outer coat; ex, exosporium.

FIG. 3

Phylogenetic relationship of Biosubtyl and Enterogermina. Phylogenetic relatedness of Biosubtyl and Enterogermina compared to representative Bacillus species. The branching pattern, rooted with Lactococcus casei as the outgroup, was generated by distance-matrix alignment (12) and neighbor joining (22) by using the PHYLIP suite of computer programs (9). Bootstrap values are given for each node having 70% or greater agreement. Group, subgroup, and assemblage associations are derived from sequence identity to the Ribosomal Database Project (13).