The uptake of carbon sources by Aspergillus niger

Fungi have been used as food and in food fermentations long before written accounts were created and they have been used in folk medicine in ancient cultures. For centuries, species of the genus Aspergillus have been used for the preparation of traditional Asian foodstuffs or together with baker’s yeast in preparation of alcoholic beverages and have therefore been of great economical value. Later, Aspergillus niger has been used for large-scale production of organic acids, enzymes and other food-additives. Today, we aim to harness its saprophytic nature and extraordinary ability to degrade and utilize plant material that is naturally recalcitrant to degradation. To facilitate that ability, the range of sugar transporters employed by this fungus is large even among fungi. This makes it an excellent choice for the identification and characterization of a variety of proteins with different substrate specificities, with potential application in the design of newly engineered cell factories. This thesis was focused on the identification and characterization of previously unknown sugar uptake transporters. Aspergillus niger transporter proteins for the uptake of glucose, xylose, galacturonic acid and rhamnose were identified and characterized.