ANTIMICROBIAL ACTIVITY OF LACTOCOCCUS LACTIS SSP LACTIS 2 AGAINST ENTEROCOCCUS FAECALIS IN PARTIALLY PURIFIED BACTERIOCINS

STAGNITTA PV; MITJANS NM; CASTRO J; GAIDO N; BONOMI MR; REZZA IG

Mendoza

Congreso; XXVIII Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2010

Sociedad de biología de cuyo

The shelf-life of food can be increased by adding live microorganisms producing bacteriocins or their crude extracts as concentrates or partial purified peptides. The Lactococcus lactis ssp lactis 2 strain, has antimicrobial activity against pathogens such as Enterococcus faecalis. Previously it was reported that the crude extracts presented an inhibition zone of 6-8 mm The aim of this study was to obtain concentrates of culture supernatants of L. lactis and make a partial purification to determine later the fraction that produced the greatest inhibition of growth of E. faecalis. Three subcultures of the L. lactis strain were performed in MRS medium, the cell free supernatant was concentrated at level of 95%. The ammonium sulphate precipitation was carried out at 40%, 50% and 75% saturation. The dialysis was through 1000 Da membranes. Later the antimicrobial activity of concentrates and dialyzed fractions was determined. Molecular size of the antimicrobial substance was determined using SDS-PAGE. The results showed a higher inhibition by concentrated extracts (12 mm), the dialyzed showed 8- 11mm, the highest effect was observed in the 40% fraction. The SDS-PAGE showed a band of approximately 60 kDa in the 40% fraction. This study reveals the possibility of using L. lactis ssp lactis 2 strains as probiotic in the food preservation.