Biotransformation of Bioethanol from Lignocellulose by High Yield Cellulase-Producing Aspergillus

Biotransformation of bioethanol was innovatively processed with crude enzyme to hydrolyse rice straw from a high-yield cellulase-producing Aspergillus W-10 and by simultaneous saccharification and fermentation (SSF) with Saccharomyces cerevisiae. Hydrolysis and saccharification of pretreated rice straw by crude enzyme with cellulase and cellobiase was measured at regular sampling of reducing sugar. Meanwhile, the impacts of substrate concentration, the amount of surfactant and synergism of cellobiase on hydrolysis process were studied. Then, the effects of fermentation temperature, fermentation time and initial pH value on the SSF were also explored on the bassis of the optimized hydrolysis conditions. The results show that when the concentration of substrate was 80 g/L, the concentration of surfactant Tween-80 was 5 g/L, and the amount of cellobiase was 166.67 nkat/g, the highest efficiency of hydrolysis of crude enzyme was observed. When the fermentation temperature was 35℃, the fermentation time was 4 d, and the initial pH value was 5, the concentration of ethanol in fermentation broth was the highest, reaching 0.43 g/g (dry weight of substrate). The optimization of the reaction conditions of high yield cellulase-producing Aspergillus W-10 can promote the bioconversion technology development of lignocellulosic ethanol, which is beneficial to the large-scale commercial production and application of bioethanol as a renewable clean energy.