Abstract:

In order to obtain pure exopolysaccharide from Tremella aurantialba through liquid fermentation, the yeast form strain EF145 of T. aurantialba was isolated by basidiospore ejection method and identified by ITS method, the antioxidant activity of its exopolysaccharide was studied. Orthogonal test was employed to optimize the medium formula for high yield exopolysaccharide. The result showed that the shape of EF145 was oval with a size of (2.5-4.0) μm×(2.0-4.0) μm, which proliferated by budding and its colonies were milky white, convex, smooth and moist. ITS sequence was consistent with the small band of T. aurantialba fruiting body, which was identified as T. aurantialba by BLAST analysis. The scavenging rates of hydroxyl radical, superoxide anion and DPPH radical of polysaccharide of T. aurantialba were 57.67%, 51.73% and 17.43%, respectively. The best carbon, nitrogen and inorganic salts of EF145 were sucrose, ammonium tartrate and potassium dihydrogen phosphate, respectively. The optimal medium formula for exopolysaccharide production was sucrose 40 g·L^-1, ammonium tartrate 7.5 g·L^-1, potassium dihydrogen phosphate 4 g·L^-1, potato powder 3 g·L^-1 and vitamin B₁ 0.2 g·L^-1.

Key words: Tremella aurantialba, yeast form strain, exopolysaccharide, medium optimization