Diversity and evaluation of carotenoids-producing of yeasts isolated from Xingyun Lake

Abstract:

[Background] Xingyun Lake is one of plateau lakes of Yunnan. The study of its diversity of yeasts and the screening of carotenoids-producing strains contribute to the development and utilization of the yeast resources of Xingyun Lake. [Objective] To study the diversity of community structure of yeasts in Xingyun Lake, and to screen the carotenoids-producing strains. [Methods] Yeast separation was carried to on the water samples of Xingyun Lake by membrane filtration flat culture. Identification was based on sequence analysis of D1/D2 domains of 26S rRNA gene, and to combinate with morphological characteristics and physiological and biochemical indicators, and the diversity of yeast was analyzed by software BIO-DAP. The carotenoids were extracted by acid-heating method, and the content of carotenoids were determined by ultraviolet spectrophotometer. [Results] A total of 797 strains were isolated from the water samples of Xingyun Lake, and identified as 18 genera and 37 species. The Rhodotorula mucilaginosa and Naganishia albida are the dominant species, accounting for 36.64% and 28.86% of the total strains, respectively. There were 28 strains of yeast carotenoids with a yield of more than 200 μg/g cell dry weight, and 4 strains of carotenoeds-producing were up to 300 μg/g cell dry weight: Rhodotorula glutinis (2 strains), Rhodotorula mucilaginosa (1 strain) and Rhodosporidiobolus fluviale (1 strain). [Conclusion] The yeasts of Xingyun Lake are rich in diversity, and the degree of lake nutrition and geographical difference affect the structure of yeast community. In Xingyun Lake, Rhodosporidiobolus and Rhodotorula are the major groups of carotenoids-producting, and carotenoids-producting were up to 300 μg/g of cell dry weight. It has the value of further development research.