Study On Identification And Diversity Of Wine-related Yeast From Xinjiang And Gansu

Biodiversity and microorganism has an important effect on wine sensory quality. The research of identification and biodiversity of wine yeasts is the basis and key to the isolation of excellent yeast. The climate of the northwest of China is arid with different grape plant areas having their own ecologic condition, which cause the diversities of yeasts in these areas. Manasi and Shanshan of Xinjiang and Mogao of Gansu are all excellent wine grape growing area in China, which become origins of high quality wine in recent years. Researches on the species and characteristics of wild yeast in these areas could discover yeast resources with region feature, and provide support for isolating and screening excellent wine yeast with region characteristics, which is valuable for the development of wine industry of China. Studies on isolation, identification and diversity of wild yeasts from three wine-producing regions in Xinjiang and Gansu were carried out by classic and molecular biology technology.Yeasts strains, which were isolated from Manasi and Shanshan of Xinjiang and MoGao of Gansu province, were classified by WL nutrient medium.Then the strains with different characteristics cultured feature on WL nutrient medium were selected and to be identified to the species by 26SrDNA D1/D2 domain sequence analysis and phylogenetic tree construction. The result showed that the selected yeast stains belonged to 18 species of 9 genera, Among them, 12 species of 7 genera were fond in Manasi of Xinjiang region, namely, Saccharomyces cerevisiae, Issatchenkia orientalis, Pichia kluyveri, Pichia membranefaciens, Hanseniaspora uvarum, Hanseniaspora opuntia, Hanseniaspora guilliermondii, Cryptococcus flavescens, Cryptococcus laurentii, Rhodotorula graminis Candida.zemplinin. 7 species of 5 genera were found in Shanshan of Xinjiang, namely Saccharomyces cerevisiae, Issatchenkia orientalis, Pichia kluyveri, Hanseniaspora uvarum, Hanseniaspora opuntiae, Hanseniaspora guilliermondii, Candida.zemplinin. 11 species of 8 genera were found in Gansu regions, namely, Saccharomyces cerevisiae, Hanseniaspora uvarum, Pichia fermentans, Pichia kluyveri, Issatchenkia orientalis, Metschnikowia pulcherrima, Metschnikowia aff fructicola, Rhodotorula mucilaqinosa, R.kratochvilovae, Cryptococcus magnus, Candida.albidus.Types of yeasts in the year of 2005 and 2006 were compared in this study. The result showed that there are 10 species of 7 genera in 2005 and 9 species of 7 genera in 2006. Among them, Saccharomyces cerevisiae, Issatchenkia orientalis, Pichia kluyveri, Hanseniaspora uvarum, Hanseniaspora guilliermondii and Candida zemplinin appeared the both two years. While Cryptococcus flavescens, Cryptococcus laurentii and Rhodotorula graminis only were found in 2005 and Pichia membranefaciens, Metschnikowia pulcherrima and Rhodosporidium mucilaginous only appeared in 2006. The reason of diversity maybe is the effect of different climate condition year and different isolation site.The yeasts appearing during wine spontaneous fermentation of Manasi were also identified to reveal the variation of yeast species between different fermentation phases in 2006. There were regular yeast growth and decline. There were 9 species of 7 genera in Manasi, Saccharomyces cerevisiae, Hanseniaspora uvarum, Hanseniaspora guilliermondii, Issatchenkia orientalis, Pichia kluyver, Pichia membranefaciens, Metschnikowia pulcherrima, Rhodosporidium mucilaginos, Candida zemplinina had appeared in the early phase of fermentation. Some of the strains, which were sensitive to alcohol, died out gradually, including Issatchenkia orientalis, Metschnikowia pulcherrima, Rhodosporidium mucilaginos, Candida zemplinina, but S.cerevisiae, which owns high alcohol tolerance, gradually gained priority and finished the fermentation to the end.