Phylogenetic characterization of Bifidobacterium kimbladii sp. nov., a novel species from the honey stomach of the honeybee Apis mellifera

Six novel Bifidobacterium strains H1HS16NT, Bin2N, Hma3N, H6bp22N, H1HS10N, and H6bp9N, were isolated from the honey stomach of Apis mellifera. Cells are Gram-positive, non-motile, non-sporulating, facultatively anaerobic, and fructose 6-phosphate phosphoketolase-positive. Optimal growth conditions occur at 37 degrees C in anaerobiosis in MRS medium added with 2 % fructose and 0.1 % L-cysteine. The 16S rRNA gene sequences analysis revealed clustering with Bifidobacterium species found in honeybees. Strains Hma3N, H6bp22N, and H1HS16NT showed significant similarity to Bifidobacterium polysaccharolyticum JCM 34588T, with an average similarity of 99.63 %. In contrast, strains Bin2N, H1HS10N, and H6bp9N were closely related to Bifidobacterium apousia JCM 34587T, with an average similarity of 99.22 %. Moreover, strains Hma3N and H6bp22N exhibited ANI values of 96.65 % and 96.53 % when compared to Bifidobacterium polysaccharolyticum JCM 34588T, while strains H1HS16NT, Bin2N, H6bp9N, and H1HS10N revealed ANI values of 94.18 %, 94.33 %, 94.22 %, and 95.50 % respectively when compared to B. apousia JCM 34587T. dDDH analysis confirmed that strains Hma3N and H6bp22N belong to B. polysaccharolyticum, whereas strains H1HS16NT, Bin2N, H6bp9N, and H1HS10N represent a novel species. The peptidoglycan of the novel species is of the A4 alpha type (L-Lys-D-Asp). The main cellular fatty acids of the type strain H1HS16NT are C16:0, C14:0, C19:0 cyclo omega 9c, and C18:1 omega 9c. The DNA G + C content of the type strain is 60.8 mol%. Genome analyses of the strains were also conducted to determine their biosynthesis-related gene clusters, probiotic features, and ecological distribution patterns. Phenotypic and genotypic characterization show that strain H1HS16NT is distinct from the type strains of other recognized Bifidobacterium species. Thus, Bifidobacterium kimbladii sp. nov. (H1HS16NT = DSM 115187T = CCUG 76695T) is proposed as a novel Bifidobacterium species.