Monday, May 4, 2009
9-34
One Step Cellulosic Ethanol Production : modeling of enzymatic hydrolysis of cellulose by whole-cell biocatalyst
Seunghyun Ryu and M. Nazmul Karim. Chemical Engineering, Texas Tech University, 6th and Canton, MS: 43121, Lubbock, TX 79409
A whole-cell biocatalyst system was successfully developed in our research to directly produce ethanol from amorphous cellulose (Phosphoric Acid Swollen Cellulose, PASC) in a single step. It was also applied for ethanol production from diluted acid pretreated corn stover. For enzymatic hydrolysis of natural biomass, there are several factors determining hydrolysis rate e.g., crystallinity, degree of polymerization, particle size, pore volume, and accessible surface area. The enzymatic hydrolysis mainly occurs on the surface of cellulose. In order to understand the behavior of whole-cell biocatalyst on cellulose, we focus on the relationship between particle size in the sense of accessible surface area of cellulose and hydrolysis rate. The surface morphology of surface of cellulose exposed on the microorganism incorporating with cellulases is observed by SEM. In addition, a model of showing the correlations between the accessible surface area of pretreated corn stover and enzymatic hydrolysis rate is developed. Hence, the quantitative model and the experimental measurement can be applied to develop the hydrolytic capacity of whole-cell biocatalyst with the respect to a particle size of substrate and enzyme.