Abstract: The purpose of this study was to analyze the genetic and species heterogeneity of bifidobacterial strains isolated from the intestinal tract of Uygur infants in Kashi, Xinjiang, and, more broadly, to lay the foundation for exploiting intestinal probiotic bifidobacteria resources from ethnic minority infants. The inter-strain difference in genetic structure was analyzed according to the 16S rRNA gene sequence using rep-PCR fingerprint typing technology. According to the genetic fingerprints, some representative bifidobacteria were selected and tested for their antibacterial activities against 6 common pathogenic bacteria, and the strains with good antibacterial activity were further tested for acid and bile resistance, carbon source metabolism and antibiotic susceptibility. This study found that the 75 strains of Bifidobacterium were assigned to four species and two subspecies, B. bifidum, B. pseudocatenulatum, B. adolescentis, B. longum subsp. infantis and B. longum subsp. suis, respectively. The bacteriostatic tests showed that 16 of the 75 strains had broad-spectrum antibacterial properties. Drug sensitivity test showed that these strains were sensitive or moderately sensitive to all antibiotics except amikacin and vancomycin. The acid and bile salt tolerance tests showed that B. longum subsp. infantis f65-26 and B. pseudocatenulatum f115-8 were the most tolerant strains, which could have great potential for development and utilization.

Key words: infant intestine, Bifidobacteria, 16S rRNA gene sequence, fingerprints, probiotic characteristics, antibiotics resistance