Isolation and characterisation of an oxygen, acid and bile resistant Bifidobacterium animalis subsp. lactis Qq08

BACKGROUND: Currently, bifidobacteria are recognised as one of the most important bacteria used as probiotics, which promote human health. However, their commercial application has been limited by their anaerobic nature. The purpose of this study was to select an oxygen, acid and bile resistant strain of bifidobacterium for use as a new probiotic. RESULTS: A total of 10 strains of bifidobacteria from different sources were analysed for their relative bacterial growth ratio (RBGR) in different oxygen concentrations. Three strains with high RBGR values were selected and their survival rates in acid environment and bile salt conditions were investigated in vitro. One strain showed high tolerance to low pH, giving a survival rate of 84% at pH 2 after 4 h incubation, and high tolerance to bile, more than 90% after 4.5 h incubation at 0.01 g mL(-1) bile concentration. This strain was identified as Bifidobacterium animalis subsp. lactis strain Qq08 based on polyphasic taxonomy approaches, such as phenotype analysis and 16S rRNA and 16S to 23S internally transcribed spacer sequence analyses. CONCLUSION: We isolated an aerotolerant bifidobacterium and identified it as Bifidobacterium animalis subsp. lactis Qq08. This strain has characteristics more favourable than the commercial probiotic strain, Bifidobacterium lactis Bb12.