Ultrasound-Assisted Enzymatic Hydrolysis Of Plant Fiber Resources

In the past twenty years, more and more studies have been carried out on the use of abundant plant resources in nature. In order to convert plant cellulosic substrate to monosaccharide, there are two steps, namely, pretreatment of materials and enzymatic hydrolysis of cellulose. At present the technology of pretreatment is not satisfying. There are many problems such as low rate of sugar conversion, process complication, low hydrolysis rate and large enzyme dosages. These factors limited the development of cellulose bioconversion. In this thesis corn stover is used as the substrate and study is carried out on the ultrasound-assisted pretreatment and enzymatic hydrolysis. The results are shown as follows.The hydrolysis rate of corn stover is improved with ultrasound pretreatment. The hydrolysis rates are 14.8%, 36.1%, 82.0% when ultrasound is combined with hot water, 1%dilute sulfuric acid or 1%dilute alkali. They are higher by 54.5%, 29.4%, 23.1% compared to the rates (9.58%, 29.4%, 66.6%) without ultrasound, respectively.Without substrate the filter-paper enzyme activity, theβ-glucosidase activity, and the CMCase activity decrease as the ultrasound power increases. The higher the power is, the more enzyme activity is lost. At the beginning, the filter-paper enzyme activity, theβ-glucosidase activity and the CMCase activity are 2.23FPIU/mL, 2.78IU/mL and 0.61IU/mL. When the power is 270W, the filter-paper enzyme activity is 0.34FPIU/mL, theβ-glucosidase activity is 0.32IU/mL, and the CMCase activity is 1.38IU/mL. The activities also fall with the treatment time. The longer the time is, the more obvious the effect is. When the power is 30W and the time is 30min, the filter-paper enzyme activity, theβ-glucosidase activity and the CMCase activity are 0.83 FPIU/mL, 0.13IU/mL, 1.25IU/mL, respectively.In the process of enzymatic hydrolysis, the hydrolysis rate is increased and the hydrolysis conversion is improved with ultrasound. Under the condition of 20kHz, 30w power and 30min operation time the optimal enzyme quantity is 20FPIU/g dry substrate. The optimal temperature...