Survival and adherence of antimicrobial peptide ST4SA, produced by Enterococcus mundtii, at conditions found in the human gastro-intestinal tract.

The probiotic strain Enterococcus mundtii ST4SA, isolated from soy beans, produces a broad-spectrum antimicrobial peptide. The aim of this study was to determine if peptide ST4SA could withstand conditions simulating those found in the gastro-intestinal tract (GIT). Antimicrobial activity of peptide ST4SA has been monitored by growth inhibition of Enterococcus faecium on plates and leakage of β-galactosidase from damaged cells.

Growth of Enterococcus mundtii ST15 in medium filtrate and purification of bacteriocin ST15 by cation-exchange chromatography.

Bacteriocin ST15 (bacST15), produced by Enterococcus mundtii ST15, inhibited the growth of a variety of bacteria, including exopolysaccharide (EPS)-producing strains isolated from biofilms in stainless steel pipes. Maximal production of bacST15 (51200 AU/ml) was recorded after 20 h of growth in MRS broth (Biolab), which was maintained throughout fermentation. Only 12800 AU/ml bacST15 has been recorded in MRS filtrate with components smaller than 8000 Da, suggesting that nutrients larger than 8000 Da are required for optimal bacST15 production.