Metabolic engineering for biological lignin valorization

Lignin accounts for 15-30% of terrestrial biomass but its utility as a feedstock for biological upgrading has been limited by the heterogeneity and toxicity of the aromatic molecules released upon its depolymerization. In spite of this, many microorganisms have evolved to utilize these energy-rich molecules as sources of carbon and energy using a “biological funneling” approach in which lignin monomers are converted to a few common intermediates for entry into the central metabolism. This presentation will provide an overview of our recent progress in developing the stress-tolerant, soil bacterium Pseudomonas putida as a biocatalyst for conversion of lignin-derived aromatic molecules to renewable, value-added products such as polyhydroxyalkanoates, lactate, and muconic acid. Metabolic engineering strategies for production of molecules derived from central metabolism and aromatic degradation pathways, as well as our efforts to expand the substrate utilization capabilities of P. putida, will be presented as a paradigm for biological lignin valorization.