Biological pretreatment of rice straw by fermenting with Dichomitus squalens

Rice straw was fermented by a wood-rot fungus Dichomitus squalens as a biological pretreatment, to increase the enzymatic digestibility of lignocellulose and promote cellulose hydrolysis. Response surface methodology was employed to optimize the fermentation medium of D. squalens for achieving the maximum volumetric activity of manganese peroxidase. The fermentation of rice straw by D. squalens for 15 days resulted in the enzymatic digestibility of 58.1% of theoretical glucose yield for the remaining glucan. In addition, a significant reduction in the crystallinity index and microstructural changes in the fermented rice straw were revealed. When the fungal-fermented rice straw was used as a substrate for ethanol production in simultaneous saccharification and fermentation, the ethanol production yield and productivity were 54.2% of the theoretical maximum and 0.39 g/L/hour, respectively, after 24 hours.