Staphylococcus condimenti sp. nov., from soy sauce mash, and Staphylococcus carnosus (Schleifer and Fischer 1982) subsp. utilis subsp. nov.

This study describes the taxonomic classification of Staphylococcus strains from fermented food products. Researchers analyzed 23S rRNA sequences and constructed species-specific oligonucleotide probes to investigate genetic heterogeneity among strains previously identified as Staphylococcus carnosus. Using DNA-DNA hybridization studies, physiological characterization, and phylogenetic analysis, they divided the strains into three distinct groups. Group F strains, originally isolated from soy sauce mash, showed only 51-58% DNA similarity to S. carnosus and S. piscifermentans, and exhibited unique physiological traits including urease and high lipolytic activity. The researchers propose these as a new species: Staphylococcus condimenti sp. nov. (type strain F-2T). The remaining S. carnosus strains were subdivided into groups A and B based on probe reactivity and physiological differences. Group B strains, lacking phosphatase activity and mannose/sorbitol fermentation, are designated as a new subspecies: Staphylococcus carnosus subsp. utilis (type strain SK 11T), while group A strains retain the name S. carnosus subsp. carnosus. These classifications are supported by DNA-DNA reassociation values exceeding 70% within subspecies and characteristic physiological profiles including amino acid decarboxylase activities.

Key findings

• S. condimenti sp. nov. from soy sauce mash represents a new Staphylococcus species distinct from S. carnosus, showing only 51-58% DNA relatedness and unique physiological characteristics including urease and high lipolytic activity.
• S. carnosus is taxonomically subdivided into two subspecies: subsp. carnosus (group A) with phosphatase activity and mannose/sorbitol fermentation, and subsp. utilis (group B) lacking these features.
• Species-specific oligonucleotide probes targeting 23S rRNA regions were successfully developed for rapid identification of S. condimenti, S. carnosus subspecies, S. piscifermentans, S. aureus, and S. epidermidis in fermented foods.
• Phylogenetic analysis using 16S and 23S rRNA sequences shows all three groups share >98.9% similarity in 16S rRNA but differ significantly in 23S rRNA (13-29 base changes), requiring DNA-DNA hybridization for accurate species definition.