The new work explores the characteristics of heterogeneous cellulose, the complicated interaction between solid cellulose and soluble cellulase components, and the synergic/competitive relationship among various cellulase components that limit the understanding of the de-polymerization process. Work in this area lags the development of lignocellulose pretreatment and cellulase improvement, according to Zhang.

Cellulosic ethanol production involves three sequential steps: pretreatment/fractionation of lignocellulose—the plant material that includes cellulose, enzymatic cellulose hydrolysis, and ethanol fermentation. However, there is insufficient information on the characteristics of cellulose after pretreatment and how these characteristics impact cellulase enzyme activities.

—Y. H. P. Zhang

Zhang investigates hydrolysis of three types of cellulases that are produced by a cellulolytic filamentous fungus, Trichoderma reesei, which was discovered when it quickly degraded the cotton uniforms of marines fighting in the Pacific during the World War II.

(The Department of Energy Joint Genome Institute is funding research on T. reesei in light of its capacity to secrete large amounts of cellulases and hemicellulases. The DOE hopes to develop the fungus as a host to produce low-cost enzymes for the conversion of plant biomass materials into industrially useful bioproducts—such as ethanol.)

In his new research, in collaboration with Mike Himmel at the National Renewable Energy Laboratory and Jonathan Mielenz at ORNL, Zhang will develop a new nanoscale tool to determine cellulose accessibility to the digesting enzymes and measure the fraction and concentration of the enzymes on the cellulose surface.

The research will go on to quantitatively determine substrate characteristics and their impacts on the activities of the enzymes.

Resources:

• The Zhang Lab