Statistical optimization and kinetic modeling of submerged culture medium for exopolysaccharide production by Stropharia rugosoannulata

Stropharia rugosoannulata (S. rugosoannulata) is one of the most widely recognized edible mushrooms globally. However, knowledge of the fermentation process remains limited. In this study, a combination of statistical optimization techniques was employed to optimize the culture medium for exopolysaccharide (SREP) production during submerged fermentation. These methods included one-factor-at-a-time experiments, Plackett-Burman design, the steepest ascent method, and the Box-Behnken design. Maltose, pH and inoculum size were identified as the most significant factors affecting SREP production. The optimized conditions were determined to be: potato 150 g/L, maltose 26.8 g/L, yeast paste 1 g/L, KH₂PO₄ 0.5 g/L, MgSO₄ 0.5 g/L, vitamin C 0.02 g/L, temperature 28°C, rotational speed 150 r/min, inoculum size 7 %, liquid volume 200 mL, and initial pH 9. Compared to pre-optimization conditions, the yield of SREP increased from 1.06 g/L to 1.32 g/L following optimization. Additionally, cultivation kinetic models were established to study the relationships between mycelial cell growth, SREP production and substrate consumption throughout the fermentation process. These models provided practical guidance for the production of exopolysaccharides from S. rugosoannulata through liquid submerged fermentation.