Production of fumaric acid by immobilized Rhizopus arrhizus on net

► An immobilization device that filamentous fungi can cover with evenly was developed for fumaric acid fermentation. ► We optimized net size and spore concentration for the best performance of fermentation. ► We compared free-cell with immobilized-cell fermentation. ► The time of immobilization fermentation is 24 h while free-cell 144 h.