[Diversity of cultivable yeast in Qilu Lake in winter].

Objective: To investigate yeasts diversity in Qilu Lake and analyze the influence of environmental factors on yeast diversity. Methods: Yeasts were isolated by in-situ cultivation and analyzed for the D1/D2 domain of large subunit (26S) ribosomal DNA and morphological characterization. We analyzed yeast species richness and species distribution in the Qilu Lake. Results: In total 321 isolated yeasts were identified to 14 genera and 27 species. Rhodosporidium kratochvilovae and Aureobasidium pullulans were the dominating species in the lake, representing 29.6% and 16.8% of the total strains, respectively. Principal component analysis (PCA) showed that the total phosphorus was an important environmental factor affecting the distribution of Rhodosporidium and the pH affected Cryptococcus yeasts distribution. Conclusion: There was a high diversity of yeasts community in the Qilu Lake. Keywords: Qilu Lake, yeast, diversity, environmental factors.

[Yeasts from Yangzonghai Lake in Yunnan (China): diversity and extracellular enzymes].

OBJECTIVE: The aims of this study were to investigate yeast diversity in Yangzonghai Lake, and to explore the value of these yeasts in such ecological environment, and at the same time, to analyze biological factors and abiotic factors on the influence of the yeast diversity. METHODS: Water was filtered through cellulose acetate membrane, serial dilutions of soil and sediment; The D1/D2 domain of 26S rRNA gene of all yeast strains have been sequenced and analyzed. The ability of the yeast strains to produce various enzymes was tested by enzyme screening plates. RESULTS: In total of 201 yeast strains were isolated,these strains were identified as 48 species in 15 genera, including 10 presumed new species or variety; 15.9% showed at least one extracellular enzymatic activity, mainly the lipases and amylases. CONCLUSION: The yeast community from Yangzonghai Lake showed high species richness, and anthropogenical influenced is an important factor for the yeast count and distribution, at same time, conductivity and turbidity are also important factors for yeast distribution; Some yeasts produced at least one extracellular enzymatic activity, which suggested that these microorganisms are participating in nature cycle and are metabolically active in the lake.