PCR- DGGE analysis of lactic acid bacteria and fermentation characteristics of strains isolated from dairy fan

Traditional dairy products are rich in microbial resources. Isolation of specfic strains and exploration of their ability are the key steps to successfully use them in application. In this study,the polymerase chain reaction denaturing gradient gelelectrophoresis( PCR- DGGE) to confirm the miroflora in dairy fan was used. And using randomly amplified polymorphic DNA( RAPD) and traditional method,all strains detected by PCR- DGGE were successfully isolated.These inclued Streptococcus thermophilus S1 S2,Lactobacillus delbrueckii subsp.bulgaricus B14,Lactobacillus paracasei subsp paracasei LP9,Lactobacillus case LC6. The fermentation characteristics of 5strains of bacteria were evaluated. It was found that S1 and S2 had high acid production rate and low post acidification degree,B14 had excellent viscosity characteristics and S2 had an excellent ability to produce fragrant. Finally,S1,S2 and B14 were ascertained that they were potential strains with excellent fermentation properties.