Expanding the portfolio of products that can be made from lignin will be critical to enabling a viable bio-based economy. Here, we engineer Pseudomonas putida for high-yield production of the tricarboxylic acid cycle-derived building block chemical, itaconic acid, from model aromatic compounds and aromatics derived from lignin. We develop a nitrogen starvation-detecting biosensor for dynamic two-stage bioproduction in which itaconic acid is produced during a non-growth associated production phase. Through the use of two distinct itaconic acid production pathways, the tuning of TCA cycle gene expression, deletion of competing pathways, and dynamic regulation, we achieve an overall maximum yield of 56% (mol/mol) and titer of 1.3 g/L from p-coumarate, and 1.4 g/L titer from monomeric aromatic compounds produced from alkali-treated lignin.
Fig: Biological upgrading of lignin by funneling depolymerized lignin aromatics toward value added products up and downstream of central metabolism.
This work illustrates a proof-of-principle that using dynamic metabolic control to reroute carbon after it enters central metabolism enables production of valuable chemicals from lignin at high yields by relieving the burden of constitutively expressing toxic heterologous pathways.
Elmore, J.R., Dexter, G.N., Salvachúa, D. et al. Production of itaconic acid from alkali pretreated lignin by dynamic two stage bioconversion. Nat Commun 12, 2261 (2021). https://doi.org/10.1038/s41467-021-22556-8