云南高原湖泊抚仙湖和星云湖的酵母菌胞外酶活性

【背景】高原湖泊因其海拔高、气压低、辐射强、氧气含量低,是一类特殊环境,而其中的微生物是高原湖泊生态系统物质循环与能量流动的重要参与者,其胞外酶活性的表现决定其适应这一特殊环境的方式与能力。【目的】对分离自云南高原湖泊抚仙湖和星云湖湖水的酵母菌进行产胞外酶活性的筛选,以期获得具有潜在应用价值的活性菌株。【方法】在5°C和25°C培养温度下,采用平板筛选法对两个湖泊酵母菌进行产胞外蛋白酶、纤维素酶、淀粉酶、脂肪酶、几丁质酶、木聚糖酶、植酸酶、菊粉酶、漆酶、锰依赖过氧化物酶和木质素过氧化物酶活性的筛选。【结果】抚仙湖和星云湖的所有测试酵母菌菌株至少都能产1种胞外酶,且主要产植酸酶、菊粉酶和淀粉酶;其次为脂肪酶、纤维素酶、木聚糖酶、锰依赖过氧化物酶和木质素过氧化物酶;产几丁质酶、蛋白酶和漆酶的酵母菌很少,星云湖酵母菌都不产漆酶。培养温度为5°C时,抚仙湖和星云湖的酵母菌产5种及5种以上胞外酶的活性菌株数均多于25°C。【结论】抚仙湖和星云湖的酵母菌产胞外酶菌株多样性丰富,胞外酶种类多样,产酶酵母菌可能参与高原湖泊生态系统的物质循环;筛选得到的产胞外酶菌株为开发与利用高原湖泊酶资源提供了良好的种质资源,具有进一步研究的价值。

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

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.