Phenotypic and Genotypic Characterization of Bifidobacterium Isolates from Healthy Adult Koreans

A total of twenty-two strict anaerobic and Gram-positive Bifidobacteria, identified as B. adolescentis, B.pseudocatenulatum, or B. longum, were isolated from healthy adult Koreans. We here investigated the cellmorphology, antimicrobial resistance patterns to novel antibiotics and genotypic differentiation ofBifidobacteria assessing repetitive DNA element PCR (rep-PCR) fingerprinting using the BOXA1R primer atthe species level. All Bifidobacterium spp., except B. adolescentis SPM1005 and B. longum SPM1205,formed round and convex colonies. All B. adolescentis, B. pseudocatenulatum, and B. longum were opaquewhite glossy in colony color, and short, long, and irregular rods in morphological shape. In addition, all B.adolescentis, B. pseudocatenulatum, and B. longum formed a variety of shapes ranging from rods to Vshaped, Y-shaped, clubbed rods, or irregular. All Bifidobacterium spp., except B. adolescentisSPM0214, were sensitive to daptomycin (DAP), linezolid (LIN), and tigecycline (TIG). B. adolescentisSPM0214 was resistant to DAP. Genomic fingerprinting patterns of B. adolescentis, B. pseudocatenulatum,and B. longum were diverse and different from those of the KCTC strain. The band size of B. adolescentis, B.pseududocatenulatum, and B. longum varied from 3.0 kb to 300 bp, 2.0 kb to 200 bp, and 2.0 kb to 500 bp,respectively. In conclusion, twenty-two strains of B.adolescentis, B. pseudocatenulatum, and B. longumisolated from healthy adult Koreans were very diverse in both phenotype and genotype. Moreover, this diversity of phenotype and genotype may support that health promoting effects of individual strain ofBifidobacterium spp. human isolates could be differentand specific even within same species.