Ecology and characterization by molecular methods of Staphylococcus species isolated from fresh sausages

Abstract

Staphylococcus spp. ecology in fresh sausages stored at 4 degrees C for a period of 10 days was investigated. Microbiological analyses to assess the quality and safety of the products studied were carried out, and strains on MSA agar were isolated. A total of 85 strains were identified, by traditional methods, as Staphylococcus spp. and a PCR-DGGE method, together with a S. xylosus-specific PCR, were used to determine the species of the strains isolated. Almost 50% of them were recognized as S. xylosus, but strains of S. pasteuri, S. warneri, S. equorum and S. succinus, were also found. Interesting population dynamics were observed, characterized by a succession of S. pasteuri and S. warneri at 0 day, with S. xylosus at 3 days and S. equorum at 6 and 10 days. Molecular characterization of S. xylosus strains and cluster analysis highlighted the presence of six main populations in the fresh sausages studied. However, the clusters were formed by strains isolated at different days of storage, implying a homogeneous distribution of the six subpopulations throughout the period in the products followed.