RII Track-4: Elucidating Enzyme-Ionic Liquid Interactions to Enable Effective Lignin Valorization

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Shifting society's dependence on petroleum-based fuels and chemicals to biomass derived products is important not only to reduce our carbon usage but also to increase the robustness of our energy security and economic stability. To that end, the environmentally benign reuse or upgrading of materials considered byproducts of industrial and agricultural economies is one of the ultimate goals of sustainable practices. Lignin, as the most abundant aromatic polymers in nature, provides structural strength and protection against microbial/enzymatic degradation of plants. It is available in quantity of over 100 million dry tons as a waste stream from paper and pulping industry. Despite its great potential as a feedstock for making a wide range of chemicals, lignin is still an underutilized substrate. Under the current bio-refinery concept, lignin is commonly burned to generate steam and electricity. Converting lignin waste streams to high value-added chemicals and materials is critical for the economic viability and success of a bio-refinery industry. The successful demonstration of the proposed work will provide a novel biocatalysis route for valorizing lignin from relevant waste streams to high value commodity and specialty chemicals, greatly reducing barriers along the biofuels supply chain. This project will also integrate outreach and education activities for underprivileged groups from the Appalachian region in STEM fields.Two key challenges hindering effective lignin conversion are to improve the contact of the bulky poorly soluble lignin polymer to the catalyst and the selective/controlled breakdown of inter-unit linkages. Elucidating the interactions of lignolytic enzyme with ionic liquid (IL) will allow a more rational approach to synthesize better ILs and the ability to reengineer better enzymes to optimize their activities in aqueous IL solution. This EPSCoR Research Fellowship provides a unique opportunity for the PI to visit and collaborate with the Environmental Molecular Sciences Laboratory (EMSL) at the Department of Energy (DOE)'s Pacific Northwest National Laboratory. The overarching goal is to explore IL-enzyme interfaces through extended visits to EMSL by accessing the nation's premier scientific user facilities and build on efforts to develop innovative biocatalysis pathways to convert lignin to high value chemicals. The research will involve: 1) mechanistic understanding of lignin solubility, selective lignin depolymerization and enzyme compatibility with aqueous ILs; 2) exploration of new IL-lignolytic enzyme pairs via advanced EPR/NMR, bioimaging, spectrophotometry and computational chemistry capacities at EMSL to probe interfacial interactions between IL-enzyme-lignin. A better understanding of such interactions will guide our future research to design new biocompatible ILs, engineer better enzymes via directed evolution/modifying surface charges, or explore new membrane/catalyst interfaces, to further improve product yield and selectivity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.