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

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.