Potential for Growth of Enterotoxigenic Staphylococci in Cheddar Cheese Whey

Enterotoxigenic strains of Staphylococcus aureus were incubated in commercial and laboratory-prepared, heated and unheated Cheddar cheese wheys. Successive counts on Baird-Parker medium decreased. This loss of viability was confirmed by plating on Staphylococcus Medium-110, though the counts on Baird-Parker medium were consistently higher. Filtration removal or heat inactivation of the lactic acid bacteria diminished the inhibitory properties of the wheys for Staphylococcus aureus, which grew well in these processed neutralized wheys. Enterotoxin A was not detected by the capillary tube gel-diffusion method in heat-treated wheys with Baird-Parker counts in the magnitude of 1.7 106/ml whey. Heat-stable nuclease activity, on the other hand, was observed in these wheys.