Diversity Analysis Of Yeast From Raw Milk And Cheese In Tacheng District Of Xinjiang

The unique geographical location and cultural environment of Xinjiang create favorable conditions for the production of traditional fermented dairy products for the local minority. This traditional production process makes the excellent microbial populations preserved after natural selection. Efforts in studies and preservation of these microbial resources have great significance for people to further recognize and make use of them. This study targets on the yeast contained in raw milk and cheese produced in the pastoral Tacheng area of Xinjiang, and works on the analysis and research for the yeast diversity in the sample by applying three methods, namely, combination of traditional culture and molecular biological technology, PCR-DGGE technique and High-throughput technique.(1)17 samples have been collected for the studies, including 10 cheese samples and 7 raw milk, from which 77 species of yeast are obtained via traditional culture method, including 44 from those cheese samples and 33 from raw milk samples. The 44 yeast varieties from cheese samples include 34 strains of P. Kudriavzevii(77%), 6 strains T. delbrueckii(14%), 2 strains K. lactis(5%), 1 strain K. marxianus(2%), 1 strain P. fermentans(2%); the 33 strains of raw milk, include: 20 strains of P. kudriavzevii(61%)were the dominant strains, 2 strains P. fermentans(6%), 3 strains M. pulcherrima(9%), 2 strain K. lactis(6%), 2 strain K. marxianus(6%), 2 strain R. mucilaginosa(6%), 1 strain H. uvarum(3%), 1 strain K. unispora(3%). Seeing from the predominant yeast strains in both cheese and raw milk is P. kudriavzevii while the remaining species take on a great different. And the yeast abundance looks more diversified in raw milk than that in cheese.(2)The yeast diversity in 17 samples was studied by PCR-DGGE. 11 bands of cheese were obtained from 10 samples by DGGE, respectively: G. candidum、Geotrichum sp.、Uncultured Galactomyces、K.unispora、D. hansenii、P. guilliermondii、K. marxianus、C. ramotenellum、C. parapsilosis、B. anomalus、P. kudriavzevii. 6 bands of raw milk were obtained from 7 samples by DGGE, respectively: Y. lipolytica、G.candidum、D. hansenii、P. guilliermondii、K. marxianus、P. kudriavzevii. The dominant yeast community was P. kudriavzevii, This result keeps compliant with that obtained from the traditional culture method. However, the yeast varieties in these two methods present great different in terms of varieties and quantity.(3)High-throughput technology is applied to conduct a sequential analysis on the samples and altogether 496953 reads, which belonged to 1237 OTUs, and Identified 4 Phylum 12 Class 22 Order 22 Family 30 Genus 33 Species. In the yeast communities of the samples, the predominant yeast phylums mainly include Ascomycota and Basidiomycota. While Saccharomycetes is the predominant phylums, Candida is the predominant genus. The major species in cheese samples is Candida xylopsoc. And that in whey and curd is also Candida xylopsoci. This method results in great difference comparing PCR-DGGE, making us have a general picture about the yeast community structure in the microbiology alive in the samples.Both methods of traditional culture and non-traditional culture can prove the yeast abundance diversity in cheese and raw milk. And the three methods of analysis present their advantage and disadvantage. Traditional culture would be active to the impact of yeast species characteristics, yet would gain pure culture strains for sequential probiotic test; PCR-DGGE directly and quickly reflects the composition of the bacteria community in the samples, including some non-cultivable strains; and High-throughput technology results in more yeast strains than DGGE technology can do and it reflects both the structure and abundance of the yeast community in the samples.