Abstract: In order to develop a rapid method for the detection of bifidobacteria in fermented milk products by real-time fluorescent quantitative PCR, the extraction efficiency of DNA in fermented milk products by different extraction methods, PCR amplification efficiency of four reference strains and enumeration of bifidobacteria according to different standard curves were compared. Results indicated that enzymatic hydrolysis with pronase E was the best extraction for total DNA with DNA OD260/280 ratio of 1.80. A significant difference between CT value of reference strain and the other strains was observed, and no significant difference between different standard curves was achieved. Therefore, real-time fluorescentn quantitative PCR technique is suitable for enumerating bifidobacteria that exist in commercial probiotic yoghurts.

Key words: fermented dairy products, bifidobacteria, real-time fluorescent quantitative polymerase chain reaction