Reducing the cost of scleroglucan production by use of a condensed corn solubles medium

To reduce costs for producing the microbial exopolysaccharide scleroglucan we replaced the defined medium by one based on a low-cost byproduct of corn ethanol production. We acclimated Sclerotium glucanicum to grow on a condensed corn solubles (CCS) based medium, then evaluated adding the minerals used in the defined medium. We optimized the carbon to nitrogen ratio in the CCS medium, and compared the defined medium to the CCS based medium in bioreactor trials. We achieved scleroglucan levels up to 26.5 g/L in the CCS medium, compared to 13.3 g/L in the defined medium. Even accounting for CCS particulates trapped in the scleroglucan (up to 5 g/L), scleroglucan yields on the CCS were at least equal to the highest yields reported in the literature. The cost of the production medium was lowered from $3.36/kg scleroglucan for the defined medium to $0.37/kg scleroglucan in the CCS medium.