Cellulase Production by Submerged Fermentation and Bioconversion of Poplar Wood to Ethanol

Growing tension with traditional fossil fuel supply, and will inevitably run out of fuel ethanol by more and more attention as one of the ideal alternative energy. Almost all fuel ethanol production from food raw materials, while supply is more abundant, cheaper lignocellulosic biomass could not be more widely available. Lignocellulosic biomass into ethanol, the key problem is the lack of a close connection with the cost of breaking down lignin and cellulose pretreatment technology, lack of the rapid cellulose and hemicellulose depolymerization release free sugar molecules technology, the lack of efficient use of the hexose and pentose fermentation process of the production of ethanol. This article is based optimization and compare lignocellulosic biomass biotransformation ethanol process for this purpose, Trichoderma reesei RUT C-30 liquid fermentation of cellulase experiment, poplar dilute acid pretreatment and simultaneous saccharification and fermentation experiments , poplar steam explosion pretreatment and simultaneous saccharification and co-fermentation ethanol experiment. The statistical software SPSS analysis of variance and LSD analysis shows that there are significant differences in the inoculum of Trichoderma reesei RUT C-30 cellulase production. Then, the use of experimental design software Design-Expert to find suitable bran and the ratio of microcrystalline cellulose to study bran Trichoderma reesei RUT C-30 cellulase production. The results show that the appropriate amount of wheat bran to promote the production of cellulase: binary quadratic orthogonal rotation combination design, determine the content of microcrystalline cellulose and bran content were 1.223% and 2.350% of the optimal enzyme production condition. Under these conditions, in 250 ml shake flasks filter paper activity reached 6.383 IU / ml, the yield coefficient 521.913FPIU / g microcrystalline cellulose; 7.5 L fermenter, filter paper activity and yield coefficients were 6.807IU / ml and 556.582 FPIU / g microcrystalline cellulose. Compared to before optimization, optimized shake flask experiments and fermentor experiment filter paper activity were increased by 14.247% and 17.403%, and the cellulase yield coefficient was 6.584% and 4.004% respectively. The try acidolysis poplar wood residue and steam explosion Yang wood pulp instead of microcrystalline cellulose as a carbon source, and ultimately get the highest filter paper activity for 1.953IU/ml and 1.745IU/ml. Obtained under the rapid climb the the optimal Young sawdust dilute sulfuric acid pretreatment conditions, i.e. 0.4% sulfuric acid was added 15% (w / v) Young sawdust, reaction of 75 minutes at 190 ℃. After dilute acid pretreatment, about 66% hemicellulose and 20% cellulose was dissolved in the acid hydrolyzate. Fermentation strains of E. coli KO11 enzyme loading amount 20FPIU / g acid hydrolysis residue simultaneous saccharification and fermentation process, 9.7g / l of ethanol production, the theoretical yield of about 63.3% of the (glucan count) . Acid hydrolyzate after Ca (OH) 2 detoxification, the initial amount of reducing sugar 47.2g / l, fermentation strains of E. coli KO11, the highest ethanol production to 12.4g / l, about the theoretical yield (as glucose) 56.9%. The steam bursting Yang wood pulp brown sludge moisture content of about 96.5%. Fermentation strains of E. coli KO11 in the amount of enzyme loaded 20 FPIU / g steam explosion residue simultaneous saccharification and co-fermentation process to obtain 3.6 g / l of ethanol production, accounting for the theoretical yield (to dextran) 51.4%. By scanning electron microscopy, infrared spectroscopy, X-ray diffraction analysis showed that dilute acid pretreatment and steam explosion process led to a series of changes in physical and chemical properties of the material of poplar, these changes increased cellulase on cellulose can and, thereby enhancing the enzymatic efficiency.