July 20, 2011

Los Alamos discovery makes biomass cellulose five times easier to attack which could unlock switchgrass biofuel

Los Alamos has found a potential key for unlocking the energy potential from non-edible biomass materials such as corn leaves and stalks, or switch grass. A potential pretreatment method that can make plant cellulose five times more digestible by enzymes that convert it into ethanol, a useful biofuel.



Journal of the American Chemical Society - Restructuring the Crystalline Cellulose Hydrogen Bond Network Enhances Its Depolymerization Rate

Conversion of lignocellulose to biofuels is partly inefficient due to the deleterious impact of cellulose crystallinity on enzymatic saccharification. We demonstrate how the synergistic activity of cellulases was enhanced by altering the hydrogen bond network within crystalline cellulose fibrils. We provide a molecular-scale explanation of these phenomena through molecular dynamics (MD) simulations and enzymatic assays. Ammonia transformed the naturally occurring crystalline allomorph Iβ to IIII, which led to a decrease in the number of cellulose intrasheet hydrogen bonds and an increase in the number of intersheet hydrogen bonds. This rearrangement of the hydrogen bond network within cellulose IIII, which increased the number of solvent-exposed glucan chain hydrogen bonds with water by 50%, was accompanied by enhanced saccharification rates by up to 5-fold (closest to amorphous cellulose) and 60–70% lower maximum surface-bound cellulase capacity. The enhancement in apparent cellulase activity was attributed to the “amorphous-like” nature of the cellulose IIII fibril surface that facilitated easier glucan chain extraction. Unrestricted substrate accessibility to active-site clefts of certain endocellulase families further accelerated deconstruction of cellulose IIII. Structural and dynamical features of cellulose IIII, revealed by MD simulations, gave additional insights into the role of cellulose crystal structure on fibril surface hydration that influences interfacial enzyme binding. Subtle alterations within the cellulose hydrogen bond network provide an attractive way to enhance its deconstruction and offer unique insight into the nature of cellulose recalcitrance. This approach can lead to unconventional pathways for development of novel pretreatments and engineered cellulases for cost-effective biofuels production.

13 pages of supplemental information

If you liked this article, please give it a quick review on ycombinator or StumbleUpon. Thanks

Congratulations! Now you can use SolidOpinion commenting system in all its magnificence! Click the link to get your password.

Форма для связи

Name

Email *

Message *