(459g) Invited Presentation: Lignin Conversion By Biological Funneling and Chemical Catalysis

Lignin is an underutilized feedstock for producing renewable fuels and chemicals, where it is instead burned for process heat because its inherent heterogeneity and recalcitrance make it difficult to selectively valorize. Despite many decades of lignin depolymerization research, most catalytic strategies to break down lignin yield a highly heterogeneous slate of aromatic compounds. In Nature, some organisms have evolved metabolic pathways that enable the utilization of lignin-derived aromatic molecules as carbon sources. Aromatic catabolism typically occurs via upper pathways that act as a â??biological funnelâ? to convert heterogeneous substrates to central intermediates, such as protocatechuate or catechol, which undergo ring cleavage and are further converted via the β-ketoadipate pathway to central carbon metabolism. We are using a natural aromatic-catabolizing organism, Pseudomonas putida KT2440, to demonstrate that these metabolic pathways can be harnessed and engineered to convert both aromatic model compounds and heterogeneous, lignin-enriched streams into value-added compounds. To make this concept a reality will require tailoring the lignin chemistry of the feedstock to the catalytic deconstruction strategy and the biological pathways for upgrading. Overall, this work demonstrates that the use of microbial aromatic catabolism may one day enable an approach to valorize lignin by overcoming its inherent heterogeneity to produce fuels, chemicals, and materials.