Succinic acid production from fruit and vegetable wastes hydrolyzed by on-site enzyme mixtures through solid state fermentation

In this study, a novel biorefinery concept of succinic acid (SA) production from fruit and vegetable wastes (FVWs) hydrolyzed by crude enzyme mixtures through solid state fermentation was designed. Enzyme complex solid mashes from various types of FVWs were on-site produced through solid-state fermentation by Aspergillus niger and Rhizopus oryzae. This solid was then added to FVW suspensions and undergo hydrolysis reaction to generate fermentable sugars and other essential nutrients for bacterial growth and product formation. The subsequent fungal hydrolysis produced 12.00 g/L glucose and 13.83 g/L fructose using 10% mass ratio (w/v) of FVW. Actinobacillus succinogenes used this FVW hydrolysate as the sole feedstock and produced 27.03 g/L of succinic acid with high yield and productivity of 1.18 g SA/g sugar and 1.28 gL⁻¹ h⁻¹, respectively. This work demonstrated that FVWs can be biotransformed to value added products which have considerable potential economics and environmental meaning.