Continuous Pretreatments For Improving Saccharification Efficiency Of Corn Straw By White Rot Fungi Under Non-sterile Conditions

Production of ethanol by using corn straw can not only reduce the straw wastes, but also alleviates the pressure of the lacking of fossil fuel. The pretreatment of corn straw by white-rot fungus can improve the saccharification ratio of the production of fuel ethanol. A key technology of the biopretreatment is non-sterile conditions of the fermentation system.In this paper, two kinds of non-sterile fermentation systems have been excogitated by screening 8 staple basidiomycetes in the lab :1, The Pleurotus ostreatus system., which has growth superiority in corn straw. But the saccharification efficiency of this system is discontented.2,the Echinodontium taxodii 2538 system, which make against the growth of the fungi. But the saccharification efficiency of this system is the best.Based on the study of the relationship between fermentation conditions and saccharification efficiency, it is indicated that the influences of different factors differed a lot. Culture time is the most distinctive factor orthogonal experiment, inoculation volume is the second. Water content and pH value is indistinctive. Based on the orthogonal exprements , The optimized fermentation condition of the Pleurotus ostreatus system is: culture time 15 days, inoculation volume 38.5%, Water content 77.8%, pH value 7. The optimized fermentation condition of the Echinodontium taxodii 2538 system is: culture time 15 days, inoculation volume 42.9%, Water content 71.4%, pH value 3. Under the optimized fermentation condition, saccharification efficiency of the Pleurotus ostreatus system is 32.3%, which improved by 26.2%. saccharification efficiency of the Echinodontium taxodii 2538 system is 44.6%, which improved by 69.8%.Based on the study of the continuous pretreatments by white rot fungi under non-sterile conditions, it is indicated that Pleurotus ostreatus system can continue three times with steady saccharification efficiency, the Echinodontium taxodii 2538 system can continue 5 times at least. The key factor of the continuous pretreatments by white rot fungi under non-sterile conditions is the amount of the infectant microorganism.The study contrived the continuous pretreatments by white rot fungi under non-sterile conditions for the first time, and found out the relationship between fermentation conditions and saccharification efficiency. This paper provided important theoretic and practical significance for the ethanol production by using corn straw.