CAMP concentration, morphological differentiation and citric acid production in Aspergillus niger

Abstract

The possibility that adenosine 3′,5′ monophosphate exerts an effect on citric acid production by Aspergillus niger by influencing pellet morphology has been investigated. The effect of pH and inoculum size on pellet formation, citric acid production, and intracellular and extracellular cAMP levels were studied. High levels of intracellular and extracellular cAMP in the later stages of the fermentation, the period of maximum citric acid formation, were associated with those treatments which gave pellets of intermediate size. The highest cAMP levels were associated with those treatments which gave the highest citric acid titre. It was concluded that high cAMP levels are principally associated with an optimum physiological state for citric acid production and that cAMP levels do not vary directly with pellet size.