Identification of lactic acid bacteria in Taiwanese ropy fermented milk and evaluation of their microbial ecology in bovine and caprine milk

The purpose of this study was to identify species of lactic acid bacteria in Taiwanese ropy fermented milk and to study their microbial dynamics during the fermentation process through conventional microbiological cultivation and PCR-denaturing gradient gel electrophoresis. Identification results indicated that Lactococcus lactis ssp. cremoris and Leuconostoc mesenteroides ssp. mesenteroides were the major lactic acid bacteria in Taiwanese ropy fermented milk. Interestingly, 3 groups were identified as Lc. lactis ssp. cremoris using 16S rDNA sequencing, but they showed different denaturing gradient gel electrophoresis patterns and assimilation of carbohydrates. In addition, the microbial dynamics study in different fermentation stages demonstrated that Lc. lactis ssp. cremoris was the most dominant bacterial species in the samples, followed by Leu. mesenteroides ssp. mesenteroides with no differences among the fermentation stages. Finally, the microbial distribution profiles showed that the microbial ecology was different in bovine, caprine, and reconstituted milk, which might further affect the characteristics of the product.