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

Aims: To ascertain the identification and typing of the Gram-positive, coag ulase-negative cocci present in 'Salsiccia Sotto Sugna', an Italian artisan al sausage. Methods and Results: Fifty-one strains were isolated and genotypically iden tified by amplification of the 16S-23S rDNA intergenic region with universa l primers. Most isolates were identified as Staphylococcus xylosus and one strain as Staph. condimenti. Isolates were clustered by numerical analysis of both RAPD (Random Amplified Polymorphic DNA) PCR profiles and physiologi cal characters. Genotypic clustering allowed the separation of strains show ing nitrate reduction and amino acid decarboxylase activities. Phenotypic c lustering distinguished strains isolated at diverse ripening stages. Conclusions: The predominance of Staph. xylosus in Italian dry sausages was confirmed. Genotypic similarities related to the possession of single phen otypic traits. Significance and Impact of the Study: In this study, a rapid method of Stap hylococcus and Kocuria species distinction was proposed. The suitability of RAPD PCR to discriminate strains of Staph. xylosus with technologically re levant activities was reported.