Deletion of Hydrophobin Genes in Aspergillus Niger

Abstract

Aspergillus niger is a saprophytic fungus that is widely used for the industrial production of enzymes and small molecules that find applications in food, feed, pharmaceutical and cosmetic industries. Optimization of industrial conditions requires understanding of the pellet formation process in liquid shaken culture. In this study, cell wall proteins called hydrophobins are studied regarding their role in pellet formation. Single knockouts were made of each of the eight hydrophobins of Aspergillus niger as well a triple knockout. Genes were removed using pairs of cas9 plasmids that were designed with sgRNA that targets regions upstream and downstream of the gene to be deleted. The knockout strains were assessed on solid and liquid shaken cultures for growth, spore dispersal and pellet formation. No major differences were found between the wildtype and the deletion strains for all properties. Functional redundancy is regarded as the most likely explanation for this outcome. Future studies should focus on creating a strain with a knockout of all eight hydrophobin genes to assess their function.