Optimization of fermentation medium for succinic acid production using Basfia succiniciproducens

The development of cost-competitive bioprocesses is dependent on the formulation of low cost and efficient fermentation medium. Thus, optimization of nutrient composition in fermentation media combining efficient metabolic product formation with cost-competitiveness is needed. Within this context, the main novelty of this study was to optimize the nutrient composition of a fermentation medium used for bio-based succinic acid production by the wild-type bacterial strain Basfia succiniciproducens JF4016 combining low cost with high succinic acid production efficiency. Two Plackett-Burman Designs, a central composite design and constraint optimization were sequentially implemented to estimate the optimum and cost-competitive fermentation medium composition. The two Plackett-Burman Designs identified NaH 2PO4, Na2HPO4 and NaCl as the most important medium components. Central composite design identified the optimum concentrations of NaH 2PO4, Na2HPO4, NaCl, yeast extract and corn steep liquor leading to the highest productivity. Constraint optimization was employed to maximise productivity using constraints on the final succinic acid concentration, yield, by-products to succinic acid ratio and fermentation medium cost Validation of the model predictions was carried out in a bioreactor culture at ca. 30 g/L initial glucose concentration. The optimum fermentation medium containing 19.4 g/L CSL, 9.2 g/L yeast extract, 3 g/L NaCl and 4.32 g/L sodium phosphates led to the production of 19 g/L succinic acid concentration, 0.62 g/g yield and 1.9 g/(L ⋅ h) productivity.