Antimicrobial activity of a meat-borne Bacillus subtilis strain against food pathogens.

The aim of this study was to test the antibacterial activity of Bacillus subtilis TR50 isolated from a traditional cured sausage against ten food-borne pathogenic bacteria. Most of the pathogens were sensitive to cell-free concentrated supernatant from TR50. The inhibitory activity was retained at pH values between 4 and 8, up to80 _C for 30 min and after treatment with pepsin and trypsin, whereas it disappeared after chymotrypsin hydrolysis; lipase treatment abolished inhibitory activity only against one target strain. The ammonium sulphate precipitation of TR50 concentrated cell-free culture retained the most residual antibacterial activity unlike the ethyl acetate and acid fractions. All these results suggest that the antimicrobial compound(s) produced by TR50 could be of proteinaceous nature and require a lipid moiety for activity against the pathogens tested. This is the first report on the antimicrobial activity against food-borne pathogens of a B. subtilis strain occurring in a traditional sausage potentially useful for food safety improvement.