Co-expression of Nisin Z and Leucocin C as a Basis for Effective Protection Against in Pasteurized Milk.

Nisin, an important bacteriocin from subsp., is primarily active against various Gram-positive bacteria. Leucocin C, produced by 4010, is a class IIa bacteriocin used to inhibit the growth of Because two bacteriocins have different modes of action, the combined use of them could be a potential strategy for effective inhibition of foodborne pathogens. In this study, N8-r-lecCI (N8 harboring gene) coexpressing nisin-leucocin C was constructed based on the food-grade carrier N8. Production of both bacteriocins was stably maintained. Antimicrobial measurements showed that the recombinant strain is effectively against and and moderately against serovar Enteritidis and because of its stronger antibacterial activity than the parental strain, this result first demonstrated that the co-expression of nisin and leucocin C results in highly efficient antimicrobial activity. The checkerboard assay showed that the antibacterial activity of N8-r-lecCI supernatant was enhanced in the presence of low concentration of EDTA. Analysis of the scanning electron microscope image showed the biggest cellular morphology change in treated with a mixture of EDTA and N8-r-lecCI supernatant. The practical effect was verified in pasteurized milk through time-kill assay. The N8-r-lecCI strain expressing both nisin and leucocin C has a promising application prospect in pasteurized milk processing and preservation because of its strong antibacterial activity.