Study On Lactobacillus Genetic Diversity And Probiotic Properties From Natural Fermented Dairy In Northern Regions In Xin Jiang

Object: Xin Jiang has vast land and lush pasture, in which a large number of ethnic minorities eat the fermented dairy as a diet to create a valuable resource for the unique Lactic Acid Bacteria in Xin Jiang. But nowadays the study of the Lactobacillus diversities and its extensive probiotic properties has not been documented in northern regions in Xin Jiang. In order to exploit and utilize the high quality LAB resources and the potential functional LAB, we collected samples and researched the diversity and probiotic properties to provide foundation for industrialized application of Lactobacillus.Methods: In this study, culture-dependent approaches were used to investigation and screening the LAB collected from the fermented dairy in northern regions in the Xin Jiang. Those isolated bacterias were screened out and physiology biochemistry experiments were also measured. The phylogenetic status of those Lactic acid bacteria were identified based on 16 S r RNA gene sequence.(GTG)5-PCR was used to preform the strains with highly homologous of 16 S r RNA were future investigated, combining with the species-species PCR to identify the Lactobacillus at specie level. We screened produced bacteriocins’ s strains of Lactobacillus by Oxford Cup Method, studyed growth characteristics and the resistance of bile and acid.Results: By using the five screening media, isolated 1520 persumptive LAB from the fermented dairy in different regions in the Xin Jiang, in which rhe rod-strains were accounted for most of LAB. The strains’ s phylogenetic tree analysis: isolated from the samples collected 1520 belonging to six genera: Lactobacillu,Carrobacterium, Weissella, Lactococcus, Enterococcus, Streptococcus, Lactobacillus is dominant flora.Using(GTG)5 primers REP-PCR molecular genetics technical study the different band forms of835 Lactobacillus strains biodiversity. Then species-species PCR was identified the Lactobacillus at specie level. The result of classification: L.plantarum(455strains), L.casei(241strains), L. sakei(25strains),L. helveticu(10 strains), L. rhamnosus(69 strains), L. acidophilus(6 strains), L. kefiri(1 strains), L.brevis(2 strains).Isolated and purified Lactobacillus in the above chapter as target bacteria, selected five Gram-positive bacteria, two Gram-negative bacteria, After exclusion of acid, over interference of the hydrogen peroxide and protein nature determination shows the 10 Lactobacillus will inhibit the growth of spoilage bacteria in varying degrees, As an important index for screening probiotic strains, the lactobacillus was able to grow in different bile salt concentration; When the p H was about 6, the growth of the strain was the best, and the strain could not grow at p H 2, which showed a certain tolerance when p H was 4.