Molecular identification of predominant Bifidobacterium strains isolated from Korean feces

Abstract

In order to isolate and identify Bifidobacterium spp. that originated in Korea, feces were sampled from healthy Korean adults and children living in three villages, the first having a history of longevity and the other two where the diet did not include fermented milk or any pharmaceutical preparations. Through the use of Gram staining and microscopic examination for cell morphology, 23 bacterial strains presumed to be the Bifidobacterium genus were isolated from the feces of 13 out of a total of 59 Korean people. To identify the Bifidobacterium strains at the genus level, these bacteria were then analyzed by TLC and the fructose-6-phosphate phosphoketolase (F6PPK) test. The result showed that 22 of the isolated strains were confirmed to be members of the genus Bifidobacterium. All of these bifidobacteria were also identified as Bifidobacterium spp. by the fermentation test. Using a RFLP analysis, an attempt was made to identify the Bifidobacterium spp. that had been isolated from both Korean adults and children. In a genomic Southern blot analysis after digestion with two restriction enzymes (EcoRl, HindIII), all of the 14 randomly selected Korean isolates showed patterns identical to those of three different B. longum species. Another restriction enzyme, CfoI (4-bp recognition enzyme), was then used to identify the strain. Interestingly, all the Korean isolates were identified as B. longum ATCC 15708, indicating that a RFLP analysis was effective for identifying Bifidobacterium spp. at both the strain and species levels.