A Simple Sensitive Method for Determining Staphylococcal Thermonuclease in Cheese

A simple quantitative method is described for the determination of staphylococcal thermostable nuclease in cheese. The method does not require concentration or purification of the nuclease prior to determination because of the increased sensitivity of the assay (0.5 ng/ml). Assay results of cheddar cheese made from pasteurized milk inoculated with enterotoxin-A producing Staphylococcus aureus strains demonstrated the sensitivity and reliability of the method for indicating the presence of Staph. aureus at concentrations of ≥ 1.4 × 10⁶/g of cheese.