In this study, real-time quantitative polymerase chain reaction (q-PCR) was used to compare and quantitatively analyze the predominant species Lactobacillus helveticus, Leuconostoc mesenteroides and Lactococcus lactis subsp. lactis isolated from 28 samples of traditional fermented dairy products（including 7 samples of fermented sheep milk, 8 samples of fermented goat milk and 13 samples of fermented cow milk）from Ordos in Inner Mongolia. The results showed that the order of the number of three predominant species in fermented goat milk and fermented cow milk was Leu.mesenteroides＞L.helveticus＞Lac. lactis subsp. lactis whereas that of fermented sheep milk was L.helveticus > Leu.mesenteroides > Lac. lactis subsp. lactis.

In this paper, we review metagenomic DNA analysis techniques which are widely used to detect the microbial diversity in traditional fermented dairy products with particular focus on molecular marker technologies based on 16S rRNA gene sequences, such as denaturinggradientgel electrophoresis(DGGE), restriction fragment length polymorphism (RFLP), terminal restriction fragment length polymorphism (T-RFLP) and single-stran dconformation polymorphism(SSCP). The recent progresses in the application of these methods are summarized in detail.