Salicibibacter cibarius sp. nov. and Salicibibacter cibi sp. nov., two novel species of the family Bacillaceae isolated from kimchi

To date, all species in the genus Salicibibacter have been isolated in Korean commercial kimchi. We aimed to describe the taxonomic characteristics of two strains, NKC5-3(T) and NKC21-4(T), isolated from commercial kimchi collected from various regions in the Republic of Korea. Cells of these strains were rod-shaped, Gram-positive, aerobic, oxidase- and catalase-positive, non-motile, halophilic, and alkalitolerant. Both strains, unlike other species of the genus Salicibibacter, could not grow without NaCl. Strains NKC5-3(T) and NKC21-4(T) could tolerate up to 25.0% (w/v) NaCl (optimum 10%) and grow at pH 7.0-10.0 (optimum 8.5) and 8.0-9.0 (optimum 8.5), respectively; they showed 97.1% 16S rRNA gene sequence similarity to each other and were most closely related to S. kimchii NKC1-1(T) (97.0% and 96.8% similarity, respectively). The genome of strain NKC5-3(T) was nearly 4.6 Mb in size, with 4,456 protein-coding sequences (CDSs), whereas NKC21-4(T) genome was nearly 3.9 Mb in size, with 3,717 CDSs. OrthoANI values between the novel strains and S. kimchii NKC1-1(T) were far lower than the species demarcation threshold. NKC5-3(T) and NKC21-4(T) clustered together to form branches that were distinct from the other Salicibibacter species. The major fatty acids in these strains were anteiso-C-15:0 and anteiso-C-17:0, and the predominant menaquinone was menaquinone-7. The polar lipids of NKC5-3(T) included diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), and five unidentified phospholipids (PL), and those of NKC21-4(T) included DPG, PG, seven unidentified PLs, and an unidentified lipid. Both isolates had DPG, which is the first case in the genus Salicibibacter. The genomic G + C content of strains NKC5-3(T) and NKC21-4(T) was 44.7 and 44.9 mol%, respectively. Based on phenotypic, genomic, phylogenetic, and chemotaxonomic analyses, strains NKC5-3(T) (= KACC 22040(T) = DSM 111417(T)) and NKC21-4(T) (= KACC 22041(T) = DSM 111418(T)) represent two novel species of the genus Salicibibacter, for which the names Salicibibacter cibarius sp. nov. and Salicibibacter cibi sp. nov. are proposed.