Screening of antioxidative activity ofBifidobacterium species isolated from Korean infant feces and their identification

Among 59 Korean isolated, 20 were confirmed as members of the genusBifidobacterium species based on gram staining, microscopic examination of cell morphology and the TLC method. The oxygen tolerance and antioxidative activities of these 20Bifidobacterium strains and 5 standardBifidobacterium strains were tested. All the strains demonstrated antioxidative activities as regards inhibiting linoleic acid peroxidation. The antioxidative activities of isolated and standard strains were found to range from 10.7–46.4% and from 10.7–22.2%, respectively. In addition, all tested strains exhibited a scavenging ability on DPPH free radicals, range from 15–41% for the isolated strains and 8.3–22% for the standard strain. Accordingly, the isolatedBifidobacterium strains demonstrated higher antioxidative activities than the 5 standardBifidobacterium strains. On the base of grades for each test, HJL 7511 was identified as the best strain, followed by HJL 7501. 2 strains were identified with Polymerase Chain Reaction (PCR) assay using group-specific primers designed from the nucleotide sequences of the 16S rRNA and internal transcribed spacer (ITS) regions of the Bifidobacteria. Based on the sequencing results, HJL 7511 and HJL 7501 were identified asBifidobacterium infantis.