Abstract: The liquid-state fermentation conditions of selenium-enriched soybean by Ganoderma lucidum mycelium were studied. Before the fermentation, selenium-enriched soybean was soaked, milled, filtrate, boiled and inoculated. One-factor-at-a-time and orthogonal array design methods were used to optimize fermentation temperature, initial pH, shaking speed and soybean slurry concentration based on degree of hydrolysis. The optimal fermentation conditions were determined as follows: temperature 28 ℃, initial pH 5.8, shaking speed 160 r/min, soybean slurry concentration 5% and fermentation time 132 h. Under the optimized fermentation conditions, the degree of hydrolysis was 27.8% and the concentrations of soybean polypeptides, polysaccharides and ganoderic acid in the fermentation broth obtained was 7.0178, 1.75 mg/L and 0.66 mg/L, respectively.

Key words: Ganoderma lucidum mycelium, selenium-enriched soybean, fermentation, soybean polypeptide