Phylogeny and diversity of culturable yeasts in supraglacial cryoconite and subglacial sediments of the Glacier No.1 in Tianshan Mountains

Abstract:

[Objective] The objective of this study was to elucidate the phylogenetic group and diversity of structure composition of culturable yeasts isolated from supraglacial cryoconites and subglacial sediments of the Glacier No.1 in Tianshan Mountains and to analyze the physiological and biochemical characteristics of different low temperature yeasts.[Methods] Culturable yeasts were detected on rose Bengal agar (RB), clichloran 18% glycerol agar (DG18), malt extract yeast extract soytone agar (MYP) and yeast-malt extract agar (YMP) media. The phylogenetic position of yeasts was determined by internal transcribed spacer (ITS) gene sequence. The physiological and biochemical tests included optimal growth temperature, salinity tolerance and enzymatic activities.[Results] A total of 152 culturable yeasts were isolated from supraglacial cryoconites and subglacial sediments. The results of National Center of Biotechnology Information (NCBI) alignment of internal transcribed spacer (ITS) rRNA gene sequence and Rep-PCR fingerprinting showed that the yeast groups included Basidiomycota and Ascomycota, belonging to 14 genera and 26 species. Among them, 88 strains were Pucciniomycotina, 24 strains were Agariomycotina, and 40 strains were Ascomycota. Vishniacozyma victoriae was the dominant strain (21.84%). The optimum growth temperature for 17 yeasts was at 15℃, 2 strains at 10℃ and 6 strains at 20℃. The analysis of lipase, protease and amylase activity showed that 11 of the 25 low temperature yeasts produced lipase and 11 produced amylase and 5 produced protease, 6 strains did not produce any enzymes.[Conclusion] The results of this study provide valuable data for the research of community structure and physiological characteristics of cryogenic yeasts in glaciers.