Heterologous expression of lacticin 3147 in Enterococcus faecalis: comparison of biological activity with cytolysin

Lacticin 3147 is a broad-spectrum, two-component, lanthionine-containing ba cteriocin produced by Lactococcus lactis DPC3147 which has widespread food and biomedical applications as a natural antimicrobial. Other two-component lantibiotics described to date include cytolysin and staphylococcin C55. I nterestingly, cytolysin, produced by Enterococcus faecalis, has an associat ed haemolytic activity. The objective of this study was to compare the biol ogical activity of lacticin 3147 with cytolysin. The lacticin 3147-encoding determinants were heterologously expressed in Ent. faecalis FA2-2, a plasm id-free strain, to generate Ent. faecalis pOM02, thereby facilitating a dir ect comparison with Ent. faecalis FA2-2.pAD1, a cytolysin producer. Both he terologously expressed lacticin 3147 and cytolysin exhibited a broad spectr um of activity against bacterial targets. Furthermore, enterococci expressi ng active lacticin 3147 did not exhibit a haemolytic activity against equin e blood cells. The results thus indicate that the lacticin 3147 biosyntheti c machinery can be heterologously expressed in an enterococcal background r esulting in the production of the bacteriocin with no detectable haemolytic activity.