Diogo Robl*, Isabelle Benoit, Gabriel Padilla, Jose Geraldo da Cruz Pradella and Ronald P. de Vries Pages 10 - 18 ( 9 )
Background: Cultivation and media optimization is one way to improve hemicellulase production in Aspergillus niger, but bioprocess approaches have limitations due to the carbon catabolite repression (CCR) process.
Objective: This study aimed to improve hemicellulase production by genetic modifications at CCR levels in A. niger strain.
Method: Deletion of the creA gene to derepress the expression of the hemicellulolytic genes and introduction of a constitutively active version of xlnR were performed.
Results and Discussion: The deletion of creA resulted in a higher expression of some hemicellulolytic genes and a higher specific enzyme production. Introduction of the constitutively active xlnR in a ΔCreA strain increased fungal biomass production, but did not result in a higher expression/production of most hemicellulases on xylose, although it was possible to double the productivity of β-xylosidase.
Conclusions: A dominant effect of creA deletion on xlnR overexpression in the production of biomass degrading enzymes was present and indicated that a mechanism not totally elucidated is present and involves fungal growth and inductor.
Aspergillus niger, carbon catabolic repression, hemicellulases, enzyme production, biomass, plant cell wall degradation.
Institute of Biomedical Sciences, University of Sao Paulo - USP, Sao Paulo, Fungal Biodiversity Centre CBS-KNAW, Utrecht, Institute of Biomedical Sciences, University of Sao Paulo - USP, Sao Paulo, Brazilian Bioethanol Science and Technology Laboratory – CTBE, Campinas, Brazilian Bioethanol Science and Technology Laboratory – CTBE, Campinas