Secretion in spatially differentiated colonies of Aspergillus niger

Abstract

A wide variety of enzymes is commonly used in industrial applications, for instance in the food and feed industry. Because of its exceptionally high protein secretion capacity, one of the preferred hosts for the production of such enzymes is the filamentous fungus Aspergillus niger. The research described in this thesis focuses on the improvement of the A. niger secretory pathway to generate higher yields of industrially relevant enzymes. To this end, several aspects of the A. niger secretory pathway were manipulated: N-linked protein glycosylation, glycan- dependent quality control and endoplasmic reticulum- associated degradation. This resulted in altered secretion capacity in different zones of the fungal colony. To further investigate this spatial differentiation in A. niger colonies, laser microdissection coupled to mass spectrometry was used to specifically study hyphal tips from the colony periphery. These hyphal tips showed striking differences in protein composition compared to the total colony.