The Construction Of Metagenomic Library From Traditional Fermented Dairy Products Of Dangxiong Region Of Tibet And Study On Biodiversity Of LAB

Metagenome can overcome the obstacles of which some bacteria were hard to be cultured, and can completely and objectively analyze microbiology diversity and molecular ecology in environment.The traditional fermented dairy products in China, which contains of great microbial resources, has a long history of drinking. The Lactic acid bacteria (LAB) in it which have valuable fermented characters were preserved through natural selection. Knowing and understanding the diversity of LAB in traditional fermented dairy has a great meaning in exploitation and utilization in industry. It's also has a theoretical directions in biology science.This paper was based on the advantage of metagenome.Total DNA of the samples were directly extracted using CTAB-SDS method without being cultured. After amplification 16S rDNA gene library was constructed, PCR-RFLP analysis was employed to choose the library, phylogenetic tree was constructed after sequencing and analyzing. In the pesent study,474 positive clones were constructed.Using three kinds of restriction endonuclease(Alu I,HaeIII and HindI), 64 OTUs were got.The representative clones were sequenced, and committed to NCBI to got the homology. Results revealed that 54 sequences had homologies with 13 strains at species level, they were Lactobacillus delbrueckii subsp. bulgaricus , Lactococcus lactis subsp. Lactis, Lactobacillus acidophilus, Lactobacillus helveticus, Streptococcus thermophilus, Leuconostoc mesenteroides subsp. Mesenteoides, Lactobacillus kefiri, Acetobacter malorum, Acetobacter fabarum, Acetobacter cerevisiae, Pseudomonas. and Chryseobacterium vrystaatense separately. Other 10 sequences had very high homologies with 16S rDNA gene of uncultured strains. These results indicated that an abundant LAB diversity in traditional fermented dairy products in this reign and may exist the new LAB resources.