Ethanol Production From Lignocellulose Using Irradiation Pretreatment And Simultaneous Saccharification And Fermentation Processes

Biofuels and biochemicals derived from renewable resources have becoming an urgent alternative due to the dilemma of fossil-based fuels and environmental deterioration in recent years. Lignocellulose is a natural rich resource. However, there are many challenges about new technology development and cost-effective process to make an industrial-scale production of lignocellulose ethanol because of its recalcitrant structure. Here, we report a novel proposal on ethanol production from lignocellulose through gamma-irradiation pretreatment combined with simultaneous saccharification and fermentation (SSF). Main research achievements are:(1) Using microcrystalline cellulose (MCC) as feedstock, five different pretreatment methods combined with SSF to produce ethanol are comprehensively compared. It is revealed that the effects of different pretreatment methods on ethanol production are significant, and decrease by the order of ILs?irradiation pretreatment>AA-ILs pretreatment>1% HC1 pretreatment>1% H2SO4 pretreatment. Irradiation pretreatment disrupts the stubborn structure of lignocellulose, leading to more efficient enzymatic hydrolysis and ethanol fermentation. On the optimistic cases (the appropriate irradiation dose was 891 kGy),99.6% of reducing sugars and 67% of ethanol yield are achieved(2) We develop a novel technology to produce ethanol from lignocellulose (using reed stover as an example) through irradiation pretreatment combined with SSF. Firstly, we elucidate the mechanism of lignocellulose stubborn structure disruption by irradiation through SEM and AFM analyses. Secondly, we optimize the enzyme cocktail ratio of cellulase, xylanase and ?-glucanase(1:2:2) by a 3 factors mixture design method. Under the optimistic condition,80% of glucose is achieved after enzymatic hydrolysis of irradiated reed stover. Thirdly, we analyze the irradiation-mediated inhibitors by GC/MS, and aromatic compounds are the major inhibitors. To eliminate the negative effects, four in situ detoxification strategies, H2O rinsing, H2O/ethyl acetate contacting, NaOH overliming and NaBH4 reduction, are conducted. It has been observed that NaBH4 reduction show the most detoxification effectiveness. Finally, we develop a novel technology to produce ethanol from lignocellulose (using reed stover as an example)through irradiation pretreatment combined with SSF. In the optimistic cases,70% of ethanol and 99.7% glucose bioconversion to ethanol are obtained.