Optimization of fumaric acid production by Rhizopus delemar based on the morphology formation

► The Rhizopus oryzae (R. delemar) pellet can be formed in a simple medium. ► Temperature significantly affected the pellet formation. ► R. oryzae produce more fumaric acid in pellet than other morphology. ► The simple relationship between pellet sizes and fumaric acid yield can be applied in the fermentation process optimization.