Aspergillus niger is an important industrial enzyme producer. Highly efficient production of enzymes mediated by modulating transcriptional regulation is meaningful. This thesis focuses on the... Show moreAspergillus niger is an important industrial enzyme producer. Highly efficient production of enzymes mediated by modulating transcriptional regulation is meaningful. This thesis focuses on the complex regulation of the expression of pectinolytic genes in A. niger. Chapter 1 gives an introduction of filamentous fungi with a focus on A. niger, and their industrial application. Chapter 2 describes a split marker approach in combination with NHEJ mutants for efficient targeted gene deletion. In Chapter 3, we constructed a set of isogenic auxotrophic strains by recycling pyrG marker. In Chapter 4, we selected five galacturonic acid (GA) induced genes to analyze the regulation of promoter activity of these genes in vivo by constructing promoter_amdS reporter strains. In Chapter 5, we identified the GA responsive transcription activator GaaR of A. niger by homology to BcGaaR of Botrytis cinerea. In Chapter 6 full genome sequencing of five mutants showing constitutive pectinolytic activity revealed allelic mutations in one particular gene gaaX. GaaX is likely to act as a transcription repressor which inhibits GaaR activity under non-inducing conditions. Chapter 7 summarizes and discusses the major conclusions of this thesis and proposes some future directions to study the regulatory mechanism of pectin degradation in A. niger. Show less
