Dissertation

Discovery and exploitation of the transcriptional regulatory system of pectinases in Aspergillus niger

Author: Alazi, E.
Date: 06 June 2018
Links: Thesis in Leiden Repository

Pectin is a plant cell wall polysaccharide made of mainly D-galacturonic acid (GA) subunits. The potency of the filamentous fungus Aspergillus niger to naturally secrete high amounts of pectinases to degrade pectin has been utilized for the industrial production of pectinases. Industrially produced pectinases by A. niger are subsequently used mainly in the food industry, and for the hydrolysis of plant biomass to produce renewable energy. In this thesis, the key players in the transcriptional regulatory system of pectinases in A. niger, such as the transcriptional activator GaaR, the repressor GaaX and the physiological inducer 2-keto-3-deoxy-L-galactonate, are discovered. Several approaches to exploit this system for increased or constitutive expression of the genes encoding pectinases are also presented, such as overexpression and constitutive activation of gaaR, accumulation of 2-keto-3-deoxy-L-galactonate, and deletion of gaaX or creA, the main transcriptional repressor involved in CCR