Molecular Identification of Lactic Acid Bacteria Isolated from the Traditional Fermented Yak Yogurt in Western Sichuan Region

He 32 strains genetically stable and vigorous lactic acid bacteria isolated from fermented yak milk made by tibetans in Sichuan that were performered microscopic examination ,including 10 strains of Lactobacillus and 22 strains of Lactococcus after cultured, followed DNA extraction, PCR amplification. The sequencing results were submitted to NCBI database for sequence alignment (identities>97.5%). Showed there are 5 main spcies in the traditional fermented yak yogurt: Lactobacillus 5 strains (15.6%), Lactococcus 3 strains (9.4%), Leuconostoc 3 strains (9.4%), Bacillus 3 strains (9.4%), Enterococcus 16 strains (50.0%), with two strain identified unsuccessfully (No. 31 and 32, the preliminary result is Lactobacillus, identities is 95.0%). Then established the phylogenetic tree based on 16S rDNA sequence with MEGA5.05 software to analyze and provide theory reference for lactic acid bacteria genetic diversity in yak milk from the western Sichuan basin. Yak is a rare species mainly distributed in Tibet, Sichuan, Qinghai, Gansu and other regions. With the merits of withstanding cold weather and low temperature as well as tolerance to hypoxia, yak is praised as the "boat on the plateau" [1-3]. It feeds on grasses growing in high altitude areas, and produces milk, meat, fur and other animal products, among which the yak milk is known as "natural concentrated milk", containing abundant proteins, fats, lactose and minerals, rich in nutrients [4,5]. Yak yogurt, type IV fermented milk, is fermented from yak milk along with a variety of lactic acid bacteria and yeasts by traditional method. Due to rich ferment bacteria contents, yak yogurt is a treasure house of natural bacteria resources. Yak yogurt is high in lactic acid bacteria which has excellent fermentation properties [6] and probiotics beneficial to the health [6,7]. Collecting Tibetan yak yogurt fermented by traditional method to extract the bacteria inside and establish a bacteria resource library is of important significance to the development of traditional yak yogurt starter culture and the extraction of probiotics. Morphological observation as well as physiological and biochemical characteristics testing are the major traditional methods to identify the genera of lactic acid bacteria, but some lactic acid bacteria do not show obvious differences in morphology as well as physiological and biochemical characteristics, and it is difficult to understand genetic evolutionary status and relationship of lactic acid bacteria exactly. With the development of DNA sequencing technology, 16S rDNA sequencing has been increasingly applied in the identification of the genera of lactic acid bacteria and incorporated into international gene databases, using 16S rDNA as target sequence is convenient to analyze the structure of microbial community. In this study, we selected 32 strains of lactic acid bacteria isolated from traditional fermented yak milk produced in the western Sichuan as experimental materials, and extracted total DNA of lactic acid bacteria, polymerase chain reaction amplification, sequence determination and GeneBank retrieval methods were adopted and phylogenetic tree was constructed to determine the genera of lactic acid bacteria existing in yak milk. This study aimed to understand dominant lactic acid bacteria genera which were contained in yak yogurts produced in Western Sichuan, providing theoretical basis for the development of lactic acid bacteria resources as well as the standardized and industrialized production of yak yogurt. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). Copyright © 2017, the Authors. Published by Atlantis Press. 1248 Advances in Computer Science Research (ACSR), volume 76 7th International Conference on Education, Management, Information and Mechanical Engineering (EMIM 2017)