(576c) Production of Muconic Acid and Its Precursor Salicylic Acid By Extending the E. coli Shikimate Pathway
Due to the concerns on oil crisis and environment pollution, increasing attention has been paid to developing sustainable alternatives for the production of fuels and chemicals. Metabolic engineering has been proven to be a promising way to manufacture these molecules, which is generally considered renewable and environmental friendly. Muconic acid (MA) and salicylic acid (SA) are important organic acids having wide commercial applications. MA is a potential platform chemical for the production of nylon and plastics, while SA is mainly used for producing pharmaceuticals, such as aspirin, lamivudine and skincare products. At present, MA and SA are mainly produced by chemical synthesis from petro-derived aromatic chemicals, such as benzene, which is toxic and nonrenewable. Here, we report the design and optimization of a novel pathway for microbial production of MA and its precursor SA. First, a well-developed phenylalanine producing Escherichia coli strain was engineered into a SA overproducer by introducing isochorismate synthase and isochorismate pyruvate lyase. High-titer SA production was achieved using this recombinant stain from simple carbon sources. SA was further converted into MA by introducing another two enzymes salicylate 1-monoxygenase and catechol 1,2-dioxygenase. Finally, a de novo MA biosynthetic pathway was assembled. Modular optimization enabled the production of 1.5 g/L MA within 48 h in shake flask experiments, a result showing scale-up potential. This study not only established an efficient microbial platform for the production of MA and SA, but also provided a useful pathway design strategy for the biosynthesis of other important catabolic metabolites.