The Research On Mixture Enzymatic Hydrolysis From Poplar Wood And Multi-Strain Cofermentation For Fuel Ethanol Production

Using lignocellulose produce fuel ethanol gets more and more attention and support from our social. Ethanol produced from lignocellulose has already become an r important constituent in enewable energy. However, In the production process, the cellulase cost has accounted for a very great proportion, even has achieved half of the entire cost. Moreover theβ-glucosidase produced by trichoderma reesei has low activity. Utilization of cellulose is not very high. All of these affect the efficiency of ethanol production.This article based on the purpose which seeks the strain which producesβ-glucosidase with higher activity and reduces the cost of ethanol, executed these experiments which included the optimum of factors in which produced β-glucosidase with higher activity by eupenicillium javanicum ZN-205, mixed cellulase hydrolysised poplar and the different processes in which multi-strains co-fermentation produced bioethanol by steam explosion of poplar.The production technology ofβ-glycosidase by liquid fermentation was studied with Eupenicillium javanicum ZN-205 as experimental materials. Its optimal composition of culture medium for enzyme secretion by liquid fermentation was: microcrystalline cellulose 2.5%, peptone 0.75%, tween-800.05%, initial pH 6.0. The optimum cultivating condition was:100mL medium in 250mL flask, inoculating 5mL of 2.5 day of seed liquid, rotational speed 180 r/min, fermentation temperature 28℃, fermentation for 6 days. In this condition, the activity ofβ-glucosidase reaches 2.312 U/ml.7.5 L fermenter used to amplify test, the results showed that theβ-glucosidase activity by 5d fermentation reach to 2.201 U/ml.Dry poplar wood chips as feedstock were pretreated by steam explosion and hydrolyzed by mixture cellulase. The response surface methodology was applied to temperature of hydrolysis, pH value of hydrolysis and he ratio ofβ-glucosidase activity and filter paper activity. The study results showed that the optimum technological parameters for poplar hydrolyzed by mixture cellulase described as follows:temperature was 50.04℃, pH value was 4.99 and the ratio ofβ-glucosidase activity and filter paper activity was 1.39. In the optimum condition of 5% water-insoluble solids (WIS), the total reducing sugar concentration reached 25.54g/l and the 78.18% conversion of 5% WIS to reducing sugars were achieved, using mixture cellulase from Trichoderma reesei Rut C-30 and Eupenicillium javanicum ZN-205 (15 FPU/g substrate, the ratio ofβ-glucosidase activity and filter paper activity was 1.39), in 48 h.Two different process configurations, separate hydrolysis and fermentation and simultaneous saccharification and co-fermentation, regarding ethanol production from steam-pretreated polar wood. The enzymatic loading in these experiments were 15 FPU/g (The ratio ofβ-glucosidase activity and filter paper activity was 1.39) water-insoluble solids (WIS) and fermentations were both Escherichia coli K011 and Saccharomyces cerevisiae. In the condition of 5%,10%and 15%WIS, the total ethanol concentration in SHF reached 9.21g/l,14.29g/l and 15.20g/l, respectively, the total ethanol concentration in SSF reached 8.97g/l,13.98g/l and 16.86g/l, respectively.In the experiment, mixed cellulase increased the efficiency of cellulose hydrolysis. In addition, effectively reduced the cost of ethanol by using 15 FPU/g cellulase in fermentation process. What offered a possible choice to the industrialization of cellulosic ethanol.