Reprogramming of Saccharomyces cerevisiae for sustainable cis, cis-muconic acid production from lignocellulosic biomass

Abstract

Bio-based cis, cis-muconic acid (ccMA) is a versatile intermediate for the production of nylon and polyethylene terephthalate monomers, yet titers in yeast remain limited due to pathway inefficiencies and process constraints. In this study, we developed an efficient ccMA-producing strain of Saccharomyces cerevisiae through systematic selection of the host background and heterologous gene sources for ccMA biosynthesis. A heterologous ccMA pathway was constructed in an XUSEA strain, which is capable of co-fermenting glucose and xylose, using variants of 3-dehydroshikimate dehydratase (PaAroZ and KpAroZ), protocatechuate decarboxylase (ECL_01944 and KpAroY), and catechol 1,2-dioxygenase (CaHqd2). Among the engineered strains with different gene configurations, X-PEC strain expressing PaAroZ, ECL_01944, and CaHqd2 achieved the highest ccMA titer of 16.8 mg/L during glucose-xylose fermentation. High-inoculum-density fermentation combined with controlled catechol supplementation further increased ccMA production to 1.48 g/L, representing an 88-fold improvement over the unoptimized condition. Fermentation using lignocellulosic hydrolysate yielded 649 mg/L ccMA, demonstrating the feasibility of ccMA production from biomass-derived sugars. Overall, this work highlights how host strain selection, pathway gene configuration, inoculum strategy, and precursor supplementation synergistically enhance ccMA production in yeast, providing a foundation for scalable bio-based ccMA manufacturing.