engleski

Bacteriocinogenic activity of probiotic strain L. helveticus M92

Besides biopreservative potential against undesirable bacterial species in food products, bacteriocin production is often proposed to be a beneficial property of probiotic bacteria. It may contribute to colonisation resistance of the host and to protection against gastrointestinal pathogens. Bacteriocinogenic activity of Lactobacillus helveticus M92 was induced by growth in coculture with Lactococcus lactis subsp. lactis LMG 9450. Neutralized cell free supernatant (NCFS) of L. helveticus M92 obtained after cocultivation with L. lactis subsp. lactis LMG 9450 showed enhanced inhibitory effect towards indicator lactic acid bacteria strains and towards Salmonella Typhimurium FP1 strain, in comparison to the inhibitory effect of NCFS from L. helveticus M92 monoculture. Presence of bacteriocin encoding hlv gene in L. helveticus M92 was confirmed by PCR analysis. Purification of bacteriocin by gel chromatography showed that the molecular weight of antibacterial substance is higher than 5000 Da. Bacteriocin of L. helveticus M92 was not sensitive to high temperature (100°C/30 min), but was sensitive to Proteinase K treatment. Active bacteriocin fraction retained the activity during 30 days of storage at 4°C and also after vacuum drying at 40°C, which was proved to be a suitable method for obtaining bacteriocin in concentrated form without losing its activity.

antimicrobial activity; bacteriocins; induction of biosynthesis of bacteriocins; probiotics

nije evidentirano