Analysis Of The Population Distribution And Genetic Divergence Of Enterococcus Spp.Isolated From Fermented Dairy Products In Northern Xinjiang

Object: To reveal the distribution of population and the genetic structure difference of Enterococcus spp. isolated from fermented dairy products in the region of northern Xinjiang.To provide research theory basis for the further development of Enterococcus and metabolites as natural biological preservative, human medicine and animal feed.Methods: Using four types of culture medium to isolate Enterococcus(enterococci), using the genus and species specific primers amplification to identify to species level, determining the population distribution. The rep-PCR molecular fingerprint technology, 16 S r RNA genes,rpo A and phe S function gene sequence analysis and the corresponding phylogenetic tree were constructed to analyze the population genetic diversity of Enterococcus spp. Through the detection of vancomycin resistance genes further to analyze the structural differences.Conclusions: 1. 1016 enterococci strains isolated from 97 samples belonged to four genus, 406 strains were Enterococcus durans(39.9%), 431 strains were Enterococcus faecalis(42.3%),173 strains were Enterococcus faecium(17.2%), 4 strains were Enterococcus gilvus(0.4%)and 2 strains were Enterococcus hirae(0.2%). By rep-PCR fingerprint-clustering dividing into47 kinds of pattern type, 91 representative strains of enterococci selected were identified using 16 S r RNA gene sequencing technology. Choosing the 47 of representative strains to construct phylogenetic tree, cluster was divided into three groups, E. faecium and E. durans constituting the Group 1, E. faecalis and E. gilvus respectively constituting the Group 2 and Group 3. 16 S r RNA gene sequences analysis did not distinguish well E. faecium and E.durans.2. Amplifing rpo A and phe S genes respectively to construct phylogenetic tree, by comparing the phylogenetic trees constructed by rpo A genes, phe S gene sequences, and 16 S r DNA sequence, the ability of rpo A and phe S gene sequence to distinguish enterococci interspecific genetic differences was bigger than the 16 S r DNA sequence. Rpo A gene compared with phe S gene, phe S gene sequence analysis to distinguish the strains of interspecific ability was stronger.3. By multiple PCR to detect vancomycin resistance genes of 47 representative strains, 27 strains of enterococci tested showed positive, including four genotypes, 19 strains belonged to van C2/ C3 type, mostly were E. durans, 4 strains belonged to van C1 type, 2 strains of E.faecium was van B type, van A gene in 4 strains of E. faecium was detected, clear difference between species. E. durans JHEJ1-M-2 and E. faecium ALTMN1-R-2 were carrying two genes, JHEJ1-M-2 contained van C1 and van C2/C3, two genes of van A and van C2/C3 existed in ALTMN1-R-2, indicating its comparatively large difference with other strains in genetic structure.