PhD defence: Gene redundancy and metabolic flexibility in Aspergillus niger: Tools to enhance industrial biotechnology

This thesis explores primary carbon metabolism in Aspergillus niger, a fungus widely recognized for its metabolic versatility and high protein secretion, making it a promising candidate for industrial biotechnology.

Carbon metabolism, the process through which organisms break down and synthesize organic molecules, is key to the growth and energy balance of fungi and plays a crucial role in the conversion of biomass into valuable products. With advancements in genetic tools, like CRISPR/Cas9, our ability to manipulate fungal metabolic pathways has improved, but challenges remain in understanding the complexity and redundancy within carbon-metabolizing enzymes.

The thesis focus on key oxidoreductase enzyme families—PF00248, PF00106, and PF00107—that are central to A. niger's primary carbon metabolism, highlighting their roles in converting plant biomass into useful metabolites. The studies reveal that these enzyme families, though evolutionarily conserved, exhibit significant genetic diversity across fungi, providing adaptability and a broad metabolic toolkit.

Further studies in this thesis show specific enzyme functions, redundancy, and adaptations within the pentose catabolic pathway, crucial for metabolizing sugars from biomass. For instance, engineered A. niger strains show potential for increased xylitol production, a valuable bioproduct, by manipulating regulatory genes and enzyme expression.

Finally, this work highlights how deeper insights into fungal metabolic networks and enzyme diversity can drive the design of efficient fungal cell factories. Such advancements could significantly impact biofuel and biochemical production from renewable resources, aligning with circular bioeconomy principles.