Diversity Of Culturable Yeast In The Snowpack From Different Glaciers On The Tibetan Plateau&Its Adjacent Regions

Mircoorganism originating from various atmospheric aerosol and dust entered the glacial ecosystem with atmospheric circulation through dry/wet deposition. Therefore, microorganism in glaciers and other environmental factors (particle concentration,major concentrations,etc.) were both influenced by the global climatic and environmental changes. Many investgations focused on microbial community structure and culturable bacterial diversity in different glacial ecosystem,the relationship between microorganisms with environmental factors. However, fewer were known about culturable yeasts diversity from glacier ecosystem. Studies on comparation on the differences between glacier snowpack influenced by different atmospheric circulations were limited. This study presents comparative culturable yeasts populations, diversity and influence of different temperature on growth in the the eight snowpack which were collected from glaciers along the north-south transect of the Tibetan Plateau and its adjacent regions, using culture-dependent combined with culture-independent techniques (identified by26S rRNA genesDl/D2and ITS sequences).This study aimed to compare the difference of culturable yeasts populations and diversity isolated from different glacier snowpack.The following major conclutions were obtained:Ⅰ.Changes of culturable yeast populations in different glacier snowpack.The concentrations of culturable yeast ranged1--463CFU ml-1in different snowpack. And the peak value of culturable yeast populations in each snowpack existed in coarse firn layers or ice layers. Snowpack from Tianshan No.1Glacier contained the highest abundant yeast(79±170CFU ml-1).However, snowpack at Baishui No.l Glacier was of the lowest yeast abundance(1±1CFU ml-1). Culturable yeast populations exhibited similar trend with Mg2+,Ca2+and particle concentrations. Generally, culturable yeast populations, Mg2+,Ca2+and particle concentrations were higher in northern snowpack than the southern ones.Ⅱ.Diversity of cold-adapted yeasts in eight snowpack.1.In all1916yeast strains were isolated from eight snowpack.Identified by26S rRNA gene D1/D2and ITS sequencing,these strains belonged to49ascomycetous and basidiomycetous species of16genera(Basidiomycota spp., Bensingtomia spp., Cryptococcus spp., Dioszegia spp., Filobasidium spp., Leucosporidium spp., Mrakia spp., Mrakiella spp., Rhodotorula spp., Sporobolomyces spp., Aureobasidium spp., Candida spp., Collophora spp., Conizyma spp., Lecythophora spp., Phaeococcomyces spp.).In agreement with other cold environments,Basidiomycetous yeasts strongly prevailed(95%),much higher than Ascomycetous.Among them, Cryptococcus spp.was dominant,accounting for53.1%of all strains. Rhodotorula spp.(22.9%) and Dioszegia spp.(12.0%) were frequently isolated genera.The other genera were observed more sporadically, accounting for less than10%.2. Culturable yeast diversity in northern snowpack were higher than southern ones. Morever,the dominant yeast genera and species were different among snowpack located in different regions. Diversity of culturable yeasts at northern snowpack were higher than that at middles and southerns. The dominant species were different in northern,middle and southern snowpack. In the northern snowpack(Musidao Glacier, Tianshan No.1Glacier,Laohugou No.12Glacier,Muztag Ata Glacier), Rhodotorula sp.1, Cryptococcus tephrensis, Basidiomycota sp.1,Dioszegia hungaric, Dioszegia fristingensis, Rhodotorula psychrophenolica were predominant. At middle snowpack(Guoqu Glacier,Zhadang Glacier),Cryptococcus victoriae, Cryptococcus adeliensis, Dioszegia sp.l, Rhodotorula minuta, Cryptococcus albidosimilis were dominant.However,only Cryptococcus victoriae(26CFU ml-1) was dominant in southern snowpack(Demula Glacier,Baishui No.l Glacier). Althogh there were common yeast genera in northern,middle and southern snowpack,such as Cryptococcus spp., Rhodotorula spp., Dioszegia spp..The proportion of each genus in every snowpack were different. Rhodotorula spp.was dominated in northern snowpack.However, Cryptococcus spp.was dominated in both middle and southern snowpack. Cultured yeast optimum growth temperature analysis showed that there were significant discipline among different snowpack.Generally, there were more cold-adapted yeasts in northern snowpack than middles and southerns.Ⅲ.Influence of temperature in suit on populations and diversity of culturable yeasts1.Comparing of two ZD snowpack with different temperature in suit,results showed that the concentrations of culturable yeast from ZD-1ranged1-463CFU ml-1,with mean value of85±41CFU ml-1.The populations of yeast in snowpack No.1of Zhadang Glacier was one order higher than that in snowpack No.2.This observation was accountting for the temperature of snowpack No.1was higher than0℃,and thus maybe there exsitted yeast propagation. Indicating that temperature in suit influenced yeast propagation in the snowpack.2.Culturable yeast diversity in ZD-1snowpack were higher than ZD-2.The result showed that there were both more yeast species and more genera in ZD-1snowpack than in ZD-2snowpack.8 species were obtained from ZD-1snowpack,belonging to4different genera. While only4species isolated from ZD-2snowpack.Morever,all these species belonged to1genu(Cryptococcus spp.) The CFU of two common species Cryptococcus adeliensis, Cryptococcus victoriae were two orders higher in ZD-1snowpack than ZD-2.This difference were mainly accounting for yeast propagation in suit because of the higher temperature.In summary,both yeast quantity and diversity were higher in northern snowpack than southerns on the Tibetan Plateau&its adjacent regions. Yeast quantities,Mg2+,Ca2+and particle concentrations were higher in northern snowpack than the southern ones.This observations were mainly due to the difference of local climate and atmospheric circulation privailled in different spatial glaciers.