Monday, April 19, 2010
2-07

Understanding biomass recalcitrance by single-molecule imaging of cellulases and chemical mapping of plant cell wall degradation

Yu-San Liu1, Yining Zeng1, Hui Wei1, Yonghua Luo1, Michael E. Himmel1, Qi Xu1, John O. Baker1, Steve Smith2, Brian G. Saar3, X. Sunney Xie3, and Shi-You Ding1. (1) Biosciences Center, National Renewable Energy Laboratory, 1617 Cole Blvd, Golden, CO 80401, (2) Nano-Science & Engineering PhD Program, South Dakota School of Mines and Technology, 501 East St. Joseph Street, Rapid City, SD 57701, (3) Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138

Current technology uses a combined chemical and biological process to convert plant biomass to biofuels.  The catalytic efficiency of the glycoside hydrolases utilized must be near theoretical values if the process is to be cost-effective and robust. This consideration is especially true of the cellulases, but little direct information is available concerning the actions of cellulases as catalysts in hydrolysis of the complex plant cell wall materials, largely due to the lack of techniques that are suitable for characterizing the complex system of plant cell walls and the enzymes that deconstruct them.  To this end, we focus on developing imaging techniques that combine optical and non-optical microscopy to elucidate the pretreatment and enzymatic-deconstruction processes of the plant cell wall at the molecular scale. These developing techniques include label-free chemical mapping (i.e., Coherent Raman Microscopy or CRM) and single molecule imaging (i.e., Total Internal Reflection Fluorescence or TIRF, and Atomic Force Microscopy or AFM) that allow us to characterize in real-time the processes of chemical pretreatment and enzymatic saccharification of plant cell walls, as well as to study the enzyme synergies by tracking single molecules simultaneously. We provide updates on our recent findings using these advanced imaging techniques, and particularly focus on mapping the major plant cell wall constitute (i.e., lignin and cellulose) distribution quantitatively during chemical pretreatment or in lignin-down-regulated plants, and on single-molecule, nanometer-scale tracking of the T. reesei cellobiohydrolase-I (CBH-I) or various carbohydrate-binding modules (CBMs) that catalyze the hydrolysis or disruption of crystalline cellulose.

See more of Poster Session One Sponsored by Genencor
See more of General Submissions

See more of The 32nd Symposium on Biotechnology for Fuels and Chemicals (April 19-22, 2010)