Abstract: Sodium selenite was used as inorganic selenium source,in order to find the optimal fermentation condition of crude exopolysaccharides from selenium-enriched Lyophyllum decastes mycelium.It was carried out to investigate the effects of sterilizing condition,selenium adding amount,incubation time and pH on the yield of crude exopolysaccharides.Influence of different levels of the factors on exopolysaccharides of enriched selenium L.decastes mycelium were studied.The process parameters were optimized using single factor tests and response surface method.The optimal conditions were obtained as follows:sterilizing condition was 121 ℃,20 min,incubation time was 244 h,selenium adding amount was 2 μg/mL Na₂SeO₃,and pH was 7.0.Under these conditions,the extraction yield of exopolysaccharides of enriched selenium L.decastes mycelium was 0.760 g/100 mL,higher than sample without adding selenium in medium (0.218 g/100 mL) and before optimizing fermentation condition (0.755 g/100 mL).

Key words: Lyophyllum decastes, fluid fermentation, selenium-enriched, crude exopolysaccharides, response surface methodology