Granulicatella seriolae sp. nov., a Novel Facultative Anaerobe Isolated from Yellowtail Marine Fish

A bacterial strain, designated as S8^T, was isolated from the gut contents of Seriola quinqueradiata from the coastal sea area of Jeju Island, South Korea. The strain is a Gram-staining positive, non-motile, non-spore-forming, facultative anaerobic coccus. Optimal growth was observed at 30 °C, pH 8.0-9.0, and 0-0.5% w/v NaCl, under anaerobic conditions. The predominant fatty acids were C_18:1 ω9c, C_16:0, C_18:0, and C_16:1 ω9c, while quinone was not detected. The genome was 2,224,566 bp long, with a GC content of 38.2%. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain S8^T had 96.2% similarity with Granulicatella adiacens ATCC 49175^T, its closest known species according to nomenclature. The DNA-DNA hybridization (dDDH), average nucleotide identity, and average amino acid identity values between strain S8^T and G. adiacens ATCC 49175^T were 25.7%, 85.5%, and 77.2%, respectively, all of which fall below the recommended threshold for species differentiation. Based on genomic, phenotypic, and phylogenetic evidence, we propose that strain S8^T should be a novel species within the genus Granulicatella, for with the name Granulicatella seriolae sp. nov. is proposed. The type strain is S8^T (KCTC 43438^T = JCM 35604^T).