Biochemical characterization of [beta]-xylan acting glycoside hydrolases from the thermophilic bacterium Caldicellulosiruptor saccharolyticus.


Jin Cao

Date of Award


Degree Name

M.S. in Chemical Engineering


Department of Chemical and Materials Engineering


Advisor: Donald A. Comfort


Fossil fuels have been the dominant source for energy around the world since the industrial revolution, however, with the increasing demand for energy and decreasing fossil fuel reserves alternative energy sources must be exploited. Bio-ethanol is a promising prospect for an alternative energy source to petroleum, especially when plant biomass is used as the replacement carbon source. This gives greater benefit for implementation of bioethanol as a viable alternative transport fuel than food stocks such as starch from corn. The implementation of this next generation of bioethanol requires more robust and environmentally friendly methods for degrading cellulose and hemicellulose, the two major components of plant biomass. This work looks to understand the role and mechanism of xylan degradation by glycoside hydrolases from the thermophilic bacterium Caldicellulosiruptor saccharolyticus. The degradation of xylan is achieved through multiple glycoside hydrolase enzymes working synergistically. Among these genes is the β-xlyosidase from C. saccharolyticus, XynD (Csac_2409), which was characterized to determine the optimal temperature, pH value, kinetic properties, hydrolysis pattern of oligosaccharides, and effects of inhibition by xylose. This biochemical characterization of the enzyme provides insight into its role in hydrolyzing xylan oligosaccharides by C. saccharolyticus and also potential biotechnological applications of the enzyme for upstream processing of hemicellulose for bioenergy application.


Xylans Biodegradation, Cellulose Biodegradation, Hemicellulose Biodegradation, Thermophilic bacteria, Biomass energy, Biochemistry; Chemical Engineering; beta-xylosidase; bioethanol; thermophilic bacerium

Rights Statement

Copyright 2012, author