Research And Application Of Microbial Source Tracking In Fermented Milk

There are a variety of contaminants in the production process of cheese, like other dairy products. The bacteria in cheese mainly contain fermentative lactic bacteria which basically originate from adding artificially and non-fermentative lactic bacteria whether which result from raw milk or environment, equipment, air is not clear. Generally speaking, microorganisms of cheese have has high homology with those in the environment. Thereby, research on microorganisms in the environment is very necessary.The microorganisms sampled from cheese, milk and production workshop were isolated, identified and analyzed by 16S rRNA of molecular methods and the physiological and biochemical experiment through which microbial distribution and phylogenetic tree were built. The results are as follow:(1) 4 Lactic acid bacteria were screened by 16S rRNA of molecular methods and the physiological and biochemical experiment combined with microbial characterization system. 1 Lactobacillus casei,1 Lactobacillus paracasei,1 Lactobacillus rhamnosus and 1 Enterococcus durans partial. They are defined as non-fermentative lactic bacteria except Lactobacillus casei internationally. The results showed that in mature stage of cheese NSLAB played a role in formation of flavor.4 Lactic acid bacteria were screened in the milk.(2)46 microorganisms were isolated and identified derived from different production of cheese:16 Staphylococcus sp., including 10 Staphylococcus epidermidis;11 Micrococcus luteus, including 5 Micrococcus sp,4 Micrococcus luteus,9 bacillus sp., including 2 Bacillus subtilis,,2 Bacillus subtilis,3 Bacillus cereus; 1 Kluyveromyces marxianus isolate,1 Lactococcus sp.,1 Sphingobacterium sp. and 1 Rhodococcus corynebacterides.Microorganisms in the environment had not high homology with Dominant bacteria NSLAB of cheese. Studies have shown that NSLAB of cheese had no correlation with environment and equipment. Moreover further research was needed.