Identification by 16S-23S rDNA intergenic region amplification, genotypic and phenotypic clustering of Staphylococcus xylosus strains from dry sausages

Abstract

Aims: To ascertain the identi®cation and typing of the Gram-positive, coagulase-negative cocci present in `Salsiccia Sotto Sugna', an Italian artisanal sausage. Methods and Results: Fifty-one strains were isolated and genotypically identi®ed by ampli®cation of the 16S±23S rDNA intergenic region with universal primers. Most isolates were identi®ed as Staphylococcus xylosus and one strain as Staph. condimenti. Isolates were clustered by numerical analysis of both RAPD (Random Ampli®ed Polymorphic DNA) PCR pro®les and physiological characters. Genotypic clustering allowed the separation of strains showing nitrate reduction and amino acid decarboxylase activities. Phenotypic clustering distinguished strains isolated at diverse ripening stages. Conclusions: The predominance of Staph. xylosus in Italian dry sausages was con®rmed. Genotypic similarities related to the possession of single phenotypic traits. Signi®cance and Impact of the Study: In this study, a rapid method of Staphylococcus and Kocuria species distinction was proposed. The suitability of RAPD PCR to discriminate strains of Staph. xylosus with technologically relevant activities was reported