SUSTAINABLE PRODUCTION OF INDUSTRIALLY RELEVANT BIOMONOMERS: A PHOTOSYNTHETIC MICROBIAL CONSORTIA APPROACH

摘要

Engineering of synthetic microbial consortia has emerged as a new and powerful biotechnology platform. To date, most microbial consortia have focused on biofuel development, though they also have enormous potential in the production of biobased commodity chemicals. This proposal describes a tripartite system in which three microbes of differentiated specializations can convert sunlight, carbon dioxide, and atmospheric nitrogen into chemical precursors for bulk polymer production. This framework offers a novel opportunity for biobased plastic production without energetically or monetarily expensive nutrient inputs, subsequently providing an attractive, sustainable alternative to fossil fuel analogues. Specifically, Azotobacter vinelandii, a nitrogen-fixing bacterium that secretes ammonia, and Synechococcus elongatus, a photosynthetic cyanobacterium that secretes sucrose form a symbiotic chassis hypothesized to support a third producer strain. Escherichia coli and Corynebacterium glutamicum are two archetypal bacterial species previously modified to produce an enormous array of chemicals. Given that both species can naturally grow on ammonia and sucrose, this will facilitate a tailored tripartite system with drop-in target production. These microorganisms have demonstrated production of chemical biopolymers well beyond polyhydroxyalkanoates (PHAs) and polylactic acid (PLA), including varied titers of amino acids, which serve as biomonomers for downstream chemocatalytic bioplastic production. This work bridges a fundamental gap between commercial biofermentation and community engineering, potentially alleviating energetic and economic constraints barring market entry of industrial biopolymer development. The consortium will be studied and optimized for the production of industrially relevant biomonomers as illustrated in Figure 1. Firstly, a computational and experimental investigation will establish a viable tripartite system based on microbial growth. The baseline model will then be used with producer strains for fermentation of amino acid precursors such as L-glutamic acid and L-lysine. These precursors can be readily extracted for chemocatalytic or semisynthetic conversion to biopolymers. Results of this work will be interpreted through a life cycle assessment (LCA) followed by a techno-economic analysis (TEA), which weighs emissions against nonrenewable energy usage and estimates of overall cost at scale, respectively.