Changes in carbohydrate composition and trehalase activity during conidiation of Aspergillus niger in continuous and batch culture

Abstract

In chemostat culture of Aspergillus niger under either glucose or citrate limitation there was an increase in glycogen and trehalose content when the dilution rate was lowered. There was a higher trehalose content under citrate limitation than under glucose limitation. Trehalase activity varied inversely with dilution rate under both citrate limitation and glucose limitation, but trehalase activity was much higher under citrate limitation where conidiation occurred. In synchronous batch culture there was an accumulation of glycogen and trehalose during early conidiophore development. After replacement into the citrate medium and coincident with the development of vesicles and phialides there was a rapid drop in the levels of glycogen and trehalose together with a sharp increase in the activity of trehalase. The results are interpreted in terms of catabolite repression, mycelial growth and conidiation.