376361 Charge Engineering of Cellulases Improves Ionic Liquid Tolerance and Reduces Lignin Inhibition

Wednesday, November 19, 2014
Galleria Exhibit Hall (Hilton Atlanta)
Erik Nordwald1, Roman Brunecky2, Gregg T. Beckham2, Mike Himmel2 and Joel L. Kaar1, (1)Department of Chemical & Biological Engineering, University of Colorado, Boulder, CO, (2)National Renewable Energy Laboratory, Golden, CO

We report a novel approach to concurrently improve the tolerance to ionic liquids (ILs) as well as reduce lignin inhibition of Trichoderma reesei cellulase via engineering enzyme charge. Succinylation of the cellulase enzymes led to a nearly two-fold enhancement in cellulose conversion in 15% (v/v) 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]). The improvement in activity upon succinylation correlated with the apparent preferential exclusion of the [Cl] anion in fluorescence quenching assays. Additionally, modeling analysis of progress curves of Avicel hydrolysis in buffer indicated that succinylation had a negligible impact on the apparent KM of cellulase. As evidence of reducing lignin inhibition of T. reesei cellulase, succinylation resulted in a greater than two-fold increase in Avicel conversion after 170 h in buffer with 1 wt% lignin. The impact of succinylation on lignin inhibition of cellulase further led to the reduction in apparent KM of the enzyme cocktail for Avicel by 2.7-fold. These results provide evidence that naturally evolved cellulases with highly negative surface charge densities may similarly repel lignin, resulting in improved cellulase activity. Ultimately, these results underscore the potential of rational charge engineering as a means of enhancing cellulase function and thus conversion of whole biomass in ILs.

Extended Abstract: File Not Uploaded
See more of this Session: Poster Session: Bioengineering
See more of this Group/Topical: Food, Pharmaceutical & Bioengineering Division