Inhibition of Listeria and Staphylococcus aureus by Bovicin HC5 and Nisin Combination in Milk

The aim of this work was to evaluate the effect of the bacteriocins bovicin HC5 and nisin against Listeria and Staphylococcus aureus in synthetic media and in milk. Growth of Listeria monocytogenes, Listeria innocua and S. aureus was carried out at 37ºC in tryptic soy broth (TSB) and in ultra-high temperature whole milk containing bovicin HC5 and nisin added either individually or in combination. Concentrations above 100 AU ml-1 of bovicin HC5 or 50 AU ml-1 of nisin inhibited the growth of Listeria species in TSB. Bacteriocins at concentrations of at least 50 AU ml-1 clearly increased the lag phase, but did not prevent the growth of S. aureus. The combination of both bovicin HC5 and nisin in TSB inhibited the growth of Listeria and S. aureus Embrapa 4018 at lower concentrations than the bacteriocins added separately. Bactericidal effect against L. monocytogenes and S. aureus cells was observed when both bacteriocins were added together in milk in concentrations larger than 400 AU ml-1 of each one. The present results demonstrate that bovicin HC5 and nisin were effective against Listeria and S. aureus assessed in milk, especially when used in combination.