Optimisation of 2,3-butanediol production by Enterobacter ludwigii using sugarcane molasses

•Fermentation medium optimisation for BDO production using sugarcane molasses.•Experimental design was employed to optimise medium composition.•BDO concentration reached 50.6 g/L with productivity of 2.66 g L−1 h−1.•The BDO minimum selling price is $3.82/kg at 10,000 t annual production capacity. Fermentation media optimisation for 2,3-butanediol (BDO) production from sugarcane molasses with Enterobacter ludwigii has been conducted. Plackett-Burman design, central composite design and constrained optimisation were combined to optimise nutrient composition leading to enhanced BDO production efficiency. (NH4)2SO4, yeast extract and KOH were the most significant media components affecting productivity. Constrained optimisation was applied to maximise productivity and maintain BDO concentration, yield and BDO to by-products ratio at desirable levels. Fed-batch fermentations carried out with sugarcane molasses at optimum pH (6.3) and temperature (33.9 °C) with the optimised media led to the production of BDO concentration, yield and productivity of 50.6 g/L, 0.31 g/g and 2.66 g L−1 h-1, respectively. The minimum selling price of BDO at 10,000 t and 50,000 t annual production capacity is $2.66 - $3.82/kg and $2.25 - $3.23/kg, respectively, when sugarcane molasses is used at a market price of $0.05 - $0.2/kg.