Aspergillus niger morphology and citric acid production in submerged batch fermentation:: Effects of culture pH, phosphate and manganese levels

The effects of culture pH, phosphate and manganese levels on citric acid production and Aspergillus niger morphology were studied under various agitation conditions in submerged batch culture. These factors were found to play important roles in both morphological development and process productivities. In all cases morphology was closely related to productivity and, irrespective of the parameter studied, similar morphological types were obtained. Lower citric acid productivities resulted always from the form of loose clumps with small central cores and a diffuse mass of filaments around them.