Abstract: The conditions of selenium enrichment in liquid fermentation of Ganoderma oregonense mycelium were optimized by orthogonal test.In addition to the study of the effects of different carbon sources,nitrogen sources and sodium selenite concentrations on mycelial biomass,selenium content,selenium enrichment rate and extracellular enzyme activity in culture medium,the antioxidant activity of selenosaccharide was also studied initially.The results showed that when the carbon source in the medium was 20% potato,the nitrogen source was 2% bran,and the concentration of Na₂SeO₃ was 5 mg/L,the mycelial biomass in the medium reached 3.86 g/L,and when the highest selenium content was 0.576 mg/g,the selenium enrichment rate also reached a maximum of 44.47%.The effect of Na₂SeO₃ on mycelial growth was greater than that of carbon and nitrogen sources.Na₂SeO₃ had the greatest effect on extracellular enzyme activity in the same way,and the optimal group of POD and PPO activities were active.The enzyme activity was higher than other groups,and the enzyme activity decreased gradually with the increase of Na₂SeO₃ concentration.The crude polysaccharides of selenium-enriched G. oregonense mycelium had strong antioxidant activity in vitro,and the resistance of crude polysaccharide was found by correlation analysis.Oxidation activity has a significant positive correlation with selenium content and selenium enrichment rate.It shows that selenium polysaccharide has good prospects for development and utilization in the fields of food and medicine.

Key words: Ganoderma oregonense mycelium, se-rich, selenium polysaccharide, antioxidant activity