Protective effect of lysostaphin from Staphylococcus simulans against growth of Staphylococcus aureus in milk and some other food products

The effect of lysostaphin from Staphylococcus simulans expressed in Escherichia coli TOP10 strain on Staphylococcus aureus used for inoculation of milk, ground pork and mayonnaise salad was investigated. The populations of this pathogen in ultrahigh-temperature milk preserved at 4C by lysostaphin added up to concentrations of 1.5 or 3.0 μg/mL were reduced by 0.73 and 0.92 log(cfu/mL) in control samples without enzyme addition. The protective influence of lysostaphin was diminished in case of milk storage (20C) prolonged up to 24 h. Furthermore, a final reduction level by 0.92 log(cfu/mL) was achieved after 24 h of pork storage. The smaller and more dependent on enzyme concentration inactivation of S. aureus was observed in the case of the mayonnaise salad, and it led to the conclusion that some food components or proteolytic enzymes originating from other bacteria caused lysostaphin inactivation.