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Improved Hemicellulase Production by Genetic Modification of Carbon Catabolite Repression and Xylanolitic Activation in Aspergillus niger

[ Vol. 7 , Issue. 1 ]

Author(s):

Diogo Robl*, Isabelle Benoit, Gabriel Padilla, Jose Geraldo da Cruz Pradella and Ronald P. de Vries   Pages 10 - 18 ( 9 )

Abstract:


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.

Keywords:

Aspergillus niger, carbon catabolic repression, hemicellulases, enzyme production, biomass, plant cell wall degradation.

Affiliation:

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

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