Antimicrobial substance from a human Lactobacillus strain

TLDR

Lactobacillus sp. The inhibitory substance had a low molecular weight (<1,000) and was soluble in acetone‑water (10:1). Strain GG isolated from human feces produced a heat‑stable, low‑pH (3–5) inhibitory substance that killed a broad spectrum of bacteria—including anaerobes, Enterobacteriaceae, Pseudomonas, Staphylococcus, and Streptococcus—at a 1:128 dilution against E.

Abstract

Lactobacillus sp. strain GG, which was isolated from the feces of a normal person, produced a substance with potent inhibitory activity against a wide range of bacterial species. It inhibited anaerobic bacteria (Clostridium spp., Bacteroides spp., Bifidobacterium spp. ), members of the family Enterobacteriaceae, Pseudomonas spp. Staphylococcus spp., and Streptococcus spp., as demonstrated by a microbiological assay; however, it did not inhibit other lactobacilli. The inhibitory activity occurred between pH 3 and 5 and was heat stable. Bactericidal activity against Escherichia coli was demonstrated at a dilution of 1:128. The inhibitory substance was distinct from lactic and acetic acids. It had a low molecular weight (less than 1,000) and was soluble in acetone-water (10:1). Because of these characteristics, the inhibitory material could not be considered a bacteriocin; it most closely resembled a microcin, which has been associated previously with members of the family Enterobacteriaceae.