Expression, characterization, and engineering of endoglucanase and mannanase from Clostridium thermocellum for degrading cellulose and biofuel production
Date Issued
2009
Date
2009
Author(s)
Jung, Wen-Jou
Abstract
Clostridium thermocellum endoglucanase CelT hydrolyzes internal β-1,4-glucosidic linkages along the cellulose chains to release shorter fragments. The CelT consists of a family-9 catalytic domain of the glycoside hydrolases, and a dockerin domain responsible for cellulosome assembly, but lacks a cellulose-binding domain, which is often found with family 9 catalytic domains. This study is focused on improving cellulolytic efficiency of CelT. The family-3 cellulose binding domain (CBD) from C. thermocellum cel9I was fused to the catalytic domain of CelT to generate CelT-CBD fusion protein. CelT-CBD is more active toward insoluble celluloses than the CelT (devoid of the region encoding the dockerin domain). The result indicates that the construction of a fusion protein using CBD from another thermophilic endoglucanase represents a possible strategy for obtaining higher activity toward insoluble cellulose substrates. In the case of the CelT-CBD catalyzed hydrolysis of phosphoric acid-swollen cellulose (PASC), the soluble sugars were released at a 4-fold higher rate to compared with wild type CelT.ue to the heterogeneity in the composition and the structure of the plant cell wall, a wide range of enzymes is required for the biodegradation of these polysaccharides. Previous studies also showed that cellulosomal enzymes work synergistically for efficient lignocelluloses degradation. To improve efficiently of plant cell wall degradation, the synergistic interactions of endoglucanse (CelT△doc) and β-mannanase (ManCthe0032△doc) were determined on the degradation of rice straw biomass. The results showed an increased rate of reducing sugar production by the addition of CelT△doc and ManCthe0032△doc when comparing to the sum of the individual activities of the corresponding enzymes.
Subjects
cellulase
bioethanol
enzyme
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