Carbon catabolite de-repression enhances aromatic catabolism and muconate production in Pseudomonas putida KT2440

Most microbes have evolved mechanisms to selectively metabolize certain substrates over others in order to be more competitive in the environmental niches they occupy. Pseudomonas putida KT2440, for instance, prefers amino acids and organic acids over carbohydrates, which are preferred over aromatic molecules and hydrocarbons. While substrate preference undoubtedly lends greater fitness to microbes in their natural environment, such preferences may be detrimental to their performance as domesticated microbial cell factories that, ideally, should immediately and indiscriminately metabolize whatever substrate(s) they are provided in order to maximize productivity. The ramifications of such regulation are especially important to consider when conversion strategies involve substrate co-feeding or complex feedstocks containing a mixture of compounds. Here we describe means of overcoming carbon catabolite repression in P. putida KT2440 and demonstrate that doing so enhances the catabolism of lignin-derived, aromatic substrates and, subsequently, their conversion to muconate in strains co-fed glucose as a source of carbon and energy. These results illustrate the benefit of developing metabolically streamlined microbial hosts for biological transformations.