Design and application of a Staphylococcus-specific single strand conformation polymorphism-PCR analysis to monitor Staphylococcus populations diversity and dynamics during production of raw milk cheese.

AIM Development of a nested-PCR single strand conformation polymorphism (SSCP) assay targeting the 16S rRNA genes of the Staphylococcus genus, to monitor staphylococci in cheese. METHODS AND RESULTS New primer sets to specifically amplify 16S rDNA of staphylococci were designed to be used in a nested-PCR SSCP assay. The method was efficient in discriminating the staphylococcal species most frequently found in cheese. It was validated by monitoring Staphylococcus populations in three productions of raw milk cheese. Analysis of milk samples revealed dominant SSCP peaks corresponding to Staphylococcus aureus, Staphylococcus equorum and Staphylococcus saprophyticus. After 12 h, the S. aureus peak became dominant. CONCLUSIONS The combination of specific Staphylococcus nested-PCR and SSCP allows rapid and direct monitoring of staphylococci diversity and dynamics in milk and cheese. In the core of the cheeses studied, S. aureus may have ecological advantages against other Staphylococcus populations. SIGNIFICANCE AND IMPACT OF THE STUDY This approach is a promising tool to study the ecology of staphylococci in cheeses and in other food samples.