Optimisation of the production of a selenium-enriched polysaccharide from Cordyceps cicadae S1 and its structure and antioxidant activity
Wanwan Zhuansun, Jun Xu, Hengzhao Liu, Ying Zhao, Lulu Chen, Shufang Shan, Shiqin Song, Haoyu Zhang, Tingting Dong, Huawei Zeng, Qinxiang Xu
Abstract
The fermentation medium of a newly identified Cordyceps cicadae S1 was optimized by response surface methodology, with the optimal medium containing sucrose (80 g/L), yeast powder (60 g/L), KH 2 PO 4 (5 g/L), MgSO 4 ·7H 2 O (1 g/L) and Na 2 SeO 3 (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 Cordyceps cicadae , purified and identified as a homofructose polysaccharide with a low average molecular weight of 9.95 × 10 3 Da. The fine structure of PACI-1 was analyzed using NMR, CD, and AFM. Additionally, the in vitro 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 C. cicadae , which showed good antioxidant activity.