Yeast diversity and distribution characteristics of activity strains producing extracellular enzyme in soil of Lhalu Wetland，Tibet

In this paper，we isolated yeasts from soil of Lhalu Wetland using the dilution method. In addition， we used 26S rDNA D1/D2 domain sequence analysis and traditional methods to identify isolates and screened extracelluar enzyme activity strains in petri dish. 83 yeast isolates were identified as belonging to 16 species of 5genera，including Cryptococcus，Candida，Protomyces，Rhodotorula and Cystofilobasidium. R. mucilaginosa was the most species in soil of the wetland，moreover，the relative abundance of Cryptococcus victoriae and Cryptococcus aspenensis was also high. Diversity indices showed that yeast isolates in the LhWS6 site were most abundant，however，that of the LhWS9 site were the lowest. The study showed that human activities had influences on spatial dynamics of yeast community in Lhalu Wetland. The test also manifested that the percentage of lipase activity strains was the highest at 25℃，however，the number of strains produced amylase most at 4℃，up to 49 isolates. Furthermore，the percentage of isolates producing amlyse，pectinase，cellulase and chitinase was higher in cold condition. Yeasts distributing in soil of Lhalu Wetland were abundant，but insingle site，the kind was few，which indicated that the wetland habitat or human activity could effect population distribution，and it was important to exploit low temperature-tolerant or exoenzyme activity microorganism in Qinghai-Tibet plateau.