STTR Phase I: Low-Cost, High-Purity Biobased Glucaric Acid

The broader impact/commercial potential of this Small Business Technology Transfer(STTR) project is to develop a bio-based manufacturing process for glucaric acid and its intermediate, glucuronic acid. Microbial fermentation represents an attractive option for production of fuels and valuable chemicals from renewable resources, and glucaric acid can be produced from glucose, a renewable biomass-derived resource. The glucaric acid market was estimated at $550M in 2016, and has a plethora of uses ranging from detergents to food ingredients, corrosion inhibitors, and de-icing applications. The proposed project will engineer improved productivity of the microbe using C5/C6 sugars, thus accelerating the production of low-cost, high-purity glucaric acid. Achieving these bioprocess improvements will facilitate widespread adoption of bio-based glucaric acid in a variety of markets, broadening opportunity for US products. These applications include coatings, foams and foaming aids, electrolytes, gels, polymers, and polymer additives. This STTR Phase I project proposes to perform multi-omics studies to characterize the physiology of E. coli strains producing glucaric acid via fermentation, and develop strain engineering strategies to enable high yield and productivity. Most fermentation products are highly reduced compared to the starting sugar, and care must be taken to maintain cells in a reduced state, meaning high NADH/NAD ratio, to drive the NADH-consuming biosynthetic reactions. Products that are derived from sugar oxidation, in contrast, pose a much different challenge, and have been explored to a much lesser extent. Here, additional oxygen is needed to accept the excess electrons generated during glucose oxidation. It is well known that both S. cerevisiae and E. coli, two of the most common organisms for industrial application, are limited in their electron transport chain capacity, resulting in overflow products from high glucose uptake rates. Regardless of the oxygen transfer ability of the fermentation equipment, there is an inherent maximum production rate of these organisms. In this project, the plan is to develop E. coli strains with increased respiration capacity, thus increasing the maximum glucose oxidation rate. Glucaric acid, which can be produced from glucose via 3 enzymatic reaction steps, is an exemplary product. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.