Research On Using Green Combination Technology To Improve Enzyme Production And Sugar Ethanol Conversion Rate Of Crop Straw

Crop straw provides an abundant biomass resource convertible for bioethanol and biochemicals.However,the natural lignocellulose recalcitrance could not only decide a high-cost and low-efficient biofuel conversion,but it may also cause secondary pollution to the environment.By performing integrative and green-like technology,this study optimized pretreatments with sugarcane bagasse and rice straw,followed with lignocellulose-induced fungi secretion of biomass-degradation enzymes and adaptivedomestication of engineered yeast strain for ethanol production.By integrating Trichoderma reesei-secreted enzymes with commercial mixed-cellulases,this study largely raised biomass enzymatic saccharification.Then,the biochar generated from pretreated lignocellulose was applied to remove potential inhibition compounds for high sugarbioethanol conversion.Finally,the domestication of engineered yeast strains was conducted to further enhance yeast fermentation capacity.Here are major results:1.By performing liquid hot water pretreatment(120℃,96 min)with crop straws,the pretreated lignocellulose substrates were incubated with Trichoderma reesei to secret biomass-degradation enzymes,and the secreted-enzymes were then mixed with commercial cellulases at proportion of 1.2:0.8 for enhancing biomass enzymatic saccharification.As a comparison with the control(without secreted-enzymes),the pretreated sugarcane bagasse(F134)and rice straw(NPB)showed their hexoses yields raised from enzymatic hydrolyses by 22% and 20%,respectively.2.While the biochar was generated from the lignocellulose residues remained from enzymatic hydrolyses,it was applied to adsorb any potential toxic compounds of enzymatic hydrates.As a comparison with the control(without biochar adsorption),the engineered yeast strain(E4)showed 3.71-fold-raised bioethanol yield by using all hexoses and pentoses from enzymatic hydrolysis.3.By conducting consistently-feeding and adaptive-domestication technologies for yeast fermentation along with biochar application,two engineered yeast strains(E4,SF7)were of significantly raised bioethanol production.As a result,the E4 strain showed the ethanol yield of 98.30 g/L and the sugar-ethanol conversion of 59.70%.As a comparison,the E4 and SF7 strains showed higher bioethanol yields than those of the control by 81.3%and 67.26%,respectively.In conclusion,this study has integrated three major technologies under green-like manner including pretreated-lignocellulose as inducing substrate for active fungi secretion of biomass-degradation,enzymes-undigested lignocellulose generated as biochar for toxic removal and adapted yeast strain for high fermentation.Therefore,the integrated technology has not only enhanced biomass enzymatic saccharification to large degree,but it should also provide a green-like strategy for full-chain utilization of biomass residues towards low-cost biofuels and high-value bioproducts.