Optimisation of the production of a selenium-enriched polysaccharide from and its structure and antioxidant activity.

The fermentation medium of a newly identified was optimized by response surface methodology, with the optimal medium containing sucrose (80 g/L), yeast powder (60 g/L), KHPO (5 g/L), MgSO·7HO (1 g/L) and NaSeO (0. 1 g/L). Under these conditions, the extracellular polysaccharide yield was 8.09 g/L. A novel selenium-enriched polysaccharide (PACI-1) was isolated from , purified and identified as a homofructose polysaccharide with a low average molecular weight of 9.95 × 10 Da. The fine structure of PACI-1 was analyzed using NMR, CD, and AFM. Additionally, the antioxidant results showed that the PACI-1 had stronger antioxidant capacity than natural polysaccharides. These results provided a candidate strain for producing selenium polysaccharide and a new polysaccharide from , which showed good antioxidant activity.