耐低温酵母Curvibasidium rogersii菌株在松萝样品中的首次分离鉴定及基于基因组分析的生物特性探究

First isolation and identification of cold adaptive yeast Curvibasidium rogersii from Usnea lichen and genome-based studies of its biological properties

摘要:

【目的】对西藏松萝地衣来源的两株非常规酵母进行分离鉴定，并通过基因组序列分析探究其生物学特性和应用潜力。【方法】从西藏来源的松萝地衣样品内部分离得到2株耐低温酵母菌株，通过26S D1/D2和ITS序列比对分析以及生理生化实验进行菌种鉴定；通过全基因组序列分析和验证探究菌株的生物特性。【结果】两株酵母菌株经鉴定均为Curvibasidium rogersii，可以在10℃低温良好生长，在20℃生长最佳，25℃及以上温度生长缓慢或不生长。对其进行基因组测序和基因组挖掘，测序结果发现，其基因组注释出功能的部分与产油脂的低温酵母白冬孢酵母Leucosporidium creatinivorum具有最高相似性，尼罗红染色发现两株酵母都能够生产油脂，另外在基因组序列中还发现了可能参与木糖代谢的相关蛋白编码基因，实验证明两个酵母菌株可以利用木糖生长。【结论】首次分离鉴定了来自西藏松萝的酵母C.rogersii，为充分开发利用松萝和其他地衣来源微生物，以及利用可代谢木糖的新资源酵母生产微生物油脂提供了基础。

Abstract:

[Objective] To isolate and identify two endophytic nonconventional yeast strains from Usnea lichen samples collected in Tibet, and investigate their biological characteristics and application potential through genome mining, which was further experimentally validated. [Methods] We isolated two cold-tolerant yeast strains from the Usnea samples under 15℃ culture condition. These two strains were further identified by physiological tests, biochemical tests, 26S D1/D2 sequence analysis, and ITS sequence analysis. Then we performed genome sequencing and analysis, and further tested lipid production capability by Nile red dye staining. [Results] We identified two strains of cold-tolerant yeast as Curvibasidium rogersii, which grow well at 10℃, and the optimum temperature for growth was determined to be 20℃. The growth was poor or not observed at 25℃ and the above temperature. Sequencing and analysis of the genome revealed that the genome is the most similar to that of Leucosporidium creatinivorum, which has been reported as a microbial lipid producer. We found that these two strains can accumulate lipid. Moreover, a putative xylose reductase protein encoded gene was also identified in the genome, and we also confirmed growth of the two strains using xylose. [Conclusion] We isolated two cold-adaptive C. rogersii strains which were identified for the first time from Usnea lichen. Our results provide a basis for further exploration of microbial resources from Usnea species and other lichens, as well as using novel xylose-utilizing yeast strains for single cell lipid production.