Staphylococcus parequorum sp. nov. and Staphylococcus halotolerans sp. nov., isolated from traditional Korean soybean foods

Strains Mo2-6T, S9, KG4-3T, and 50Mo3-2, identified as coagulase-negative, Gram-stain-positive, halotolerant, non-motile coccoid bacteria, were isolated from traditional Korean soybean foods. Strains Mo2-6T and S9 were both catalase- and oxidase-negative, whereas KG4-3T and 50Mo3-2 were catalase-positive but oxidase-negative. The optimal growth conditions for Mo2-6T and S9 were 30°C, 2% NaCl, and pH 7.0, while KG4-3T and 50Mo3-2 grew best at 35°C, 2% NaCl, and pH 7.0. All strains contained menaquinone-7 as the predominant isoprenoid quinone, with anteiso-C15:0 and iso-C15:0 as the major cellular fatty acids (> 10%). Additionally, anteiso-C13:0 was a major fatty acid in strain KG4-3T. The DNA G + C contents of strains Mo2-6T, S9, KG4-3T, and 50Mo3-2 were 33.4%, 33.3%, 32.5%, and 32.7%, respectively. Phylogenetic analyses based on the 16S rRNA gene and whole-genome sequences revealed that strains Mo2-6T and S9, as well as KG4-3T and 50Mo3-2, formed distinct lineages within the genus Staphylococcus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses confirmed that strains Mo2-6T and S9, as well as KG4-3T and 50Mo3-2, belonged to the same species. Meanwhile, dDDH and ANI values between strains Mo2-6T and KG4-3T, as well as comparisons with other Staphylococcus type strains, were below the species delineation thresholds, indicating they represent novel species. Based on phenotypic, chemotaxonomic, and molecular data, we propose strain Mo2-6T as the type strain of Staphylococcus parequorum sp. nov. (=KACC 23685T =JCM 37038T) and strain KG4-3T as the type strain of Staphylococcus halotolerans sp. nov. (=KACC 23684T =JCM 37037T).