Detailed analysis of the D-galactose catabolic pathways in Aspergillus niger reveals complexity at both metabolic and regulatory level

https://doi.org/10.1016/j.fgb.2022.103670Get rights and content
Under a Creative Commons license
open access

Highlights

  • XyrB, and not XyrA, seems to be involved in A. niger D-galactose catabolism.

  • GalX, AraR and XlnR co-regulate A. niger D-galactose and L-arabinose catabolism.

  • Leloir pathway is L-arabinose induced, mediated by AraR.

  • GalX does not control D-galactose release from oligo- and polysaccharides.

Abstract

The current impetus towards a sustainable bio-based economy has accelerated research to better understand the mechanisms through which filamentous fungi convert plant biomass, a valuable feedstock for biotechnological applications. Several transcription factors have been reported to control the polysaccharide degradation and metabolism of the resulting sugars in fungi. However, little is known about their individual contributions, interactions and crosstalk. D-galactose is a hexose sugar present mainly in hemicellulose and pectin in plant biomass. Here, we study D-galactose conversion by Aspergillus niger and describe the involvement of the arabinanolytic and xylanolytic activators AraR and XlnR, in addition to the D-galactose-responsive regulator GalX. Our results deepen the understanding of the complexity of the filamentous fungal regulatory network for plant biomass degradation and sugar catabolism, and facilitate the generation of more efficient plant biomass-degrading strains for biotechnological applications.

Keywords

D-galactose catabolism
Leloir pathway
Oxido-reductive D-galactose catabolic pathway
Pentose Catabolic Pathway (PCP)
Transcription factors
Aspergillus niger

Cited by (0)

1

Present address: Department of Food Biotechnology, Instituto de Agroquímica y Tecnología de Alimentos, Consejo Superior de Investigaciones Científicas, Paterna, Valencia, Spain.