PNNL

Abstract

Muconic acid is a bioprivileged molecule that can be converted into direct replacement chemicals for incumbent petrochemicals and performance-advantaged bioproducts. In this study, Pseudomonas putida KT2440 was engineered to convert glucose and xylose, the primary carbohydrates in lignocellulosic hydrolysates, to muconic acid using a model-guided strategy to maximize the theoretical yield. Using adaptive laboratory evolution (ALE) and metabolic engineering in a strain engineered to express the D-xylose isomerase pathway, we demonstrated that mutations in the heterologous D-xylose:H+ symporter (XylE), increased expression of a major facilitator superfamily transporter (PP_2569), and overexpression of aroB encoding the native 3-dehydroquinate synthase, enabled efficient muconic acid production from glucose and xylose simultaneously. Using the rationally engineered strain, we produced 33.7 g/L muconate at 0.18 g/L/h and a 46% molar yield (92% of the maximum theoretical yield). This engineering strategy is exceptionally promising for the production of other shikimate pathway-derived compounds from lignocellulosic sugars.