Deletion of the FlbA-regulated transcription factor msnB of Aspergillus niger affects protein secretion. Deletion of the FlbA-regulated transcription factor msnB of Aspergillus niger affects protein secretion

Colonies of Aspergillus niger secrete proteins throughout the colony except for the sporulating zone. Strains in which the sporulation gene flbA is deleted do not reproduce asexually and secrete proteins throughout the mycelium. Moreover, ΔflbA hyphae lyse and have thinner cell walls. This pleiotropic phenotype is associated with differential expression of 36 transcription factor genes, of which msnB was inactivated in this study. Whole genome expression analysis of wild-type and ΔmsnB colonies showed differential expression of genes encoding secreted proteins, genes involved in the oxidoreductive balance, and in (secondary) metabolism. Biomass formation, sporulation, and the secretome in the medium were not affected in strain ΔmsnB. In contrast, ΔmsnB secreted more protein when compared to wild type. Taken together, msnB affects protein secretion and is a potential lead for improving A. niger as a cell factory. Overall design: mRNA profiles from ΔrpnR and the control strain MA234.1 were generated by Illumina Hiseq using duplicate samples from liquid shaken cultures.