Studies On Species Diversity And Application Of Wild Yeast In Xinjiang

The resources of yeast species is a significant bio-resources and lays a solid substance foundation for maintaining bio-diversity and modifying industrial yeast .The abundance extent of species resources is the premise conditions for yeast identification , classification as well as phylogenetic study scientifically.Xinjiang,which is far from the sea and all surrounded by high mountains that lead to scarce water vapor, is located at the hinterland of Eurasian-Continent.It owns vast area, complex landform, sparse population and maintains relatively complete ecosystem. A lot of special animals, plants as well as microbiology species (or varieties) were created under the unique ecological environment. It is of certain theoretical and practical significance to explore the yeast resources of Xinjiang because of its unique and complexity of bio-diversity in China.198 yeast strains were isolated from 52 soil samples (mainly from grape orchards of 28 cities or counties) collected from Xinjiang, then parts of the strains were selected according to morphologic characteristics. Among them 29 species (or variety) belonging to 12 genera were identified based on the combination of morphology and 26S rDNA Dl/D2 domain sequence analysis. The dominant genera identified were Candida, Pichia and Cryptococcus. Galactomyces geotrichum and Issatchenkia orientalis were the most widely distributed species.Compared with yeast species published domestically,6 China new record species were discoverd there which were Cryptococcus uzbekistanensis from Kashi, Issatchenkia occidentalis from Hami, Issatchenkia terricola from Turpan,Shihezi and Bole, Pichia mexicana from Bole, Phichia galeiformis from Kuerle and Bole, Rhodosporidium kratochvilovae from Qitai,respectively.Based on the experimental results, the yeast species diversity in Kashi district was a little bit higher than that of Turpan district.25 yeast strains were chosen randomly to measure their capability of sugar fermentation, tolerance of glucose and NaCl, as well as growth temperature. The data indicated that the tested strains have a relatively good extreme growth ability on the whole.3 strains which were identified as Issatchenkia orientalis can grow at 46℃;One strain identified as Torulaspora delbrueckii can tolerate 14% NaCl. Therefore it makes sense to further study the four strains for their useful characteristics.Two strains producing fruity aroma, which are respectively XJB45 from Shihezi and XJA58 from Kashi, were identified as Galactomyces geotrichum based on morphology, physiology and 26S rDNA Dl/D2 domain sequence analysis. GC-MS analysis results show that both strains have strong esters-producing capability but a little difference, strain XJB45 can generate 15 kinds of esters compared with strain XJA58 with 16 kinds of ones. A great amounts ofβ-Phenethyl alcohol can also be produced by both strains. The two strains have a potential value of application because of their rapid growth ability, high ester-producing capability and short fermentation period.