Environmental Molecular Sciences Laboratory

A DOE Office of Science User Facility

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Dissecting the central metabolic network of Aspergillus niger during growth on plant biomass

Tuesday, November 26, 2019
Principal Investigator: 
Ronald de Vries
Lead Institution: 
Westerdijk Fungal Biodiversity Institute
Project ID: 

Sugar conversion through central carbon catabolism in filamentous fungi is a complex progress that involves many pathways. Using the high quality manually curated genome sequence of Aspergillus niger NRRL 3 and a large transcriptomic dataset on individual monomeric sugars, we have constructed a model for central carbon metabolism together with collaborators at DTU and Concordia University. More recently, we also validated this model experimentally using gene deletions for all genes of the pathways, in part in collaboration with EMSL staff. These studies enables us to identify steps in the pathways that, when blocked, fully inhibit growth of A. niger on the related sugar.
In this project we want to take our understanding of central carbon metabolism of A. niger to the next level by evaluating the relative contribution of each of these pathways during growth on two distinct plant biomass substrates, wheat bran and sugar beet pulp, and using the generated deletion strains that block specific pathways. By combining analysis of phenotype, metabolic activities, transcriptome, proteome and metabolome we will obtain an in-depth view in the effects of blocking a specific pathway on the overall physiology of A. niger. It will also reveal potential back-up genes and pathways that are not activated on pure sugars, but may be present during growth on plant biomass.
Metabolic engineering is receiving increasing interest for the biological production of valuable chemicals, such as xylitol. While the results are highly promising when the fungus is grown on defined sugars, this is not a sustainable approach for the production of the desired products due to the high costs of the pure substrate. A more sustainable approach would be the production of such compounds directly from plant biomass, but its more complex nature also results in a more complex metabolic response of the fungus. In depth understanding of how the different pathways interact and contribute to growth on plant biomass with diverse sugar composition is critical to develop metabolite cell factories that can use these substrates as a starting material.