A study on endogenous beta-glucosidases from termites and their applicability in biomass conversion

Worries regarding to the current crisis of climate change and depletion of fossil fuels make the utilization of bioethanol as an attractive option for combating both global warming and less dependence on fossil fuels. A further increase in bioethanol production may come from lignocellulosic biomass, such as agricultural residues and wood. Lignocellulose from waste products is abundant, inexpensive, and renewable. Cellulose, which is a homopolysaccharide composed of β-D-glucopyranose units linked by β-1,4 glycosidic bonds, comprises around 40-50 wt.% of plant biomass. One of the best known cellulose decomposers is termite, which is able to hydrolyze 74-99% of the cellulose ingested. Taking advantage of this high efficiency with which termites digest cellulose, and due to the essentiality of β-glucosidase catalyzing the hydrolysis of cellobiose or cello-oligomers into the fermentable sugar, glucose, in the process of cellulose degradation, the objective of this work is to heterologously express, purify, characterize, and compare three endogenous glycoside hydrolase family 1 (GH1) β-glucosidases from termites. Further comparison was done with the commercial β-glucosidase Novozym 188. In addition, the effect of addition of termite β-glucosidases or Novozym 188 to Celluclast 1.5 L on the degradation of Avicel was studied. This work might introduce alternative and efficient enzymes to the bioethanol production field.報告番号: 甲28064 ; 学位授与年月日: 2012-03-22 ; 学位の種別: 課程博士 ; 学位の種類: 博士(農学) ; 学位記番号: 博農第3780号 ; 研究科・専攻: 農学生命科学研究科応用生命工学専