Extracellular enzymatic activities of yeasts isolated from Fuxian Lake and Xingyun Lake in Yunnan Plateau

Abstract:

[Background] Plateau lakes are a type of special environments due to the conditions of high altitude, low air pressure, high ultraviolet radiation and lower oxygen content; while microorganisms in the plateau lakes are important participants in substance circulation and energy flow of lake ecosystems, and the situations/performances of their extracellular enzymatic activities formulate their adaptation ways and abilities to the special environment. [Objective] To screen yeasts with extracellular enzymatic activities, which were isolated from Fuxian Lake and Xingyun Lake in Yunnan Plateau, and to obtain active yeasts with potential application values. [Methods] Yeasts exhibiting activities of extracellular proteinase, cellulase, amylase, lipase, chitinase, xylanase, phytase, inulase, laccase, manganese-dependent peroxidase and lignin peroxidase were detected by using screening plate method at 5 °C and 25 °C. [Results] All yeast strains exhibited at least one extracellular enzymatic activity, mainly exhibited activities of phytase, inulase and amylase, secondly exhibited activities of lipase, cellulase, xylanas and manganese-dependent peroxidase and lignin peroxidase. The number of strains exhibited activities of chitinase, proteinase and laccase activities were lower, and the yeast strains isolated from Xingyun Lake did not exhibited laccase activity. The number of yeast strains exhibited at least five extracellular enzymatic activities was higher at 5 °C than that at 25 °C. [Conclusion] The rich diversity of yeasts with extracellular enzymatic activities exists in the two lakes, and hence these yeasts might participate in the circulation of substances in the plateau lake ecosystems. For further exploitation and utilization of extracellular enzymes, these active yeasts can be used as the resources of extracellular enzymes, and it is worth to further explore their application potential.

Key words:Fuxian Lake, Xingyun Lake, Yeasts, Extracellular enzymatic activities