Abstract: This study aimed to isolate and identify Bifidobacterium strains from the feces of Uygur infants and their mothers’ in Xinjiang. Using Wilkins-Chalgren anaerobic agar and BSM medium plates, Bifidobacterium strains were isolated and they were identified by repetitive extragenic palindromic-polymerase chain reaction (rep-PCR) fingerprinting and 16S rRNA gene analysis. High-yield expolysaccharides (EPS) producing strains were selected from these isolates and the antioxidant activities of the EPS produced by the selected strains as well as their tolerance and auto-adhesion ability were evaluated. The results showed that a total of 52 stains of Bifidobacterium were isolated from 20 feces samples and they belonged to B. pseudocatenulatum (14 strains), B. pseudolongum (8 strains), B. bifidum (9 strains), B. breve (7 strains), B. longum subsp. infantis (5 strains), B. animal subsp. lactis (6 strains) and B. longum (3 strains). respectively. Through phenotype screening and secondary screening using the phenol sulfuric acid method, we found 7 strains of Bifidobacterium with higher EPS yield. The yield of EPS produced by each of the 7 strains was more than 400 mg/L after 36 h fermentation at 37 ℃. The EPS had the ability to scavenge H2O2, superoxide anion, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Besides, strain BF66-16 had stronger tolerance to gastrointestinal juice and auto-adhesion ability than the other six strains. Thus, BF66-16 can be used as a potential antioxidant strain in the pharmaceutical and food industries.

Key words: Bifidobacterium, repetitive extragenic palindromic-polymerase chain reaction, exopolysaccharides, antioxidant activities