Improving Access to Cellulose in Biomass for Biofuel Production

The Science

The conversion of cellulosic biomass to fermentable sugars usually requires a costly and time-consuming pretreatment step to increase the material’s porosity, decrease its crystallinity and reduce the amount of structural lignin in the cell wall. Researchers at Oak Ridge National Laboratory have used small angle neutron scattering (SANS) to probe the morphological changes of switchgrass cell walls during dilute acid pretreatment. When the pretreatment temperature is in the vicinity of the glass transition temperature of lignin (the temperature at which lignin transforms from a liquid to a glass-like material), they find that the lignin rapidly redistributes on the surface of the cellulose as large aggregates that can be washed away with solvent. The underlying cellulose does not break down and is readily available for cellulose degradation by enzymatic hydrolysis (both desirable features) but appears to form a more crystalline structure (an undesirable feature). This work provides an alternative approach for efficient hemicellulose and lignin removal, improving the quantity and accessibility of cellulose but in a form (crystalline fibrils) that is not optimal for enzymatic hydrolysis. The research has just been published online in the journal Biomacromolecules. This work is sponsored by DOE’s Biological and Environmental Research program.


Pingali, V., V. S. Urban, W. T. Teller, J. McGaughey, H. O’Neill, M. Foston, D. A. Myles, A. J. Ragauskas, and B. R. Evans. 2010. “Breakdown of Cell Wall Nanostructure in Dilute Acid Pretreated Biomass,” Biomacromolecules. DOI:10.1021/bm100455h.