Production of the Platform Chemical Muconic Acid in Plant Biomass

Muconic acid (MA) is used for the production of chemicals such as adipic acid, terephthalic acid, and caprolactam. Synthesis of these polymer precursors utilizes petroleum-derived chemicals, and the development of alternative strategies for bio-based production of MA has garnered significant interest. Plants represent advantageous hosts for engineered metabolic pathways towards the manufacturing of chemicals. We demonstrate that plants can be used for the bio-manufacturing of MA. In particular, co-expression of bacterial salicylate hydroxylase (NahG), catechol 1,2-dioxygenase (CatA), salicylate synthase (Irp9), and feedback-resistant 3-deoxy-D-arabino-heptulosonate synthase (AroG) resulted in the conversion of the shikimate-derived salicylic acid pool into MA. This value-added co-product was easily recovered after biomass pretreatment. The elucidation and implementation in bioenergy crops of MA biosynthetic routes that divert phenylpropanoid pathway intermediates away from lignin biosynthesis will be presented. These engineering strategies combine in plant biomass the production of value-added chemicals with low-recalcitrance traits towards sustainable development of biorefineries.