How fungi choose from Nature's menu: Unravelling the molecular basis of substrate utilisation by Aspergillus niger
Ronald de Vries
Filamentous fungi play a crucial role in the global carbon cycle. They degrade and metabolise plant matter (mainly polysaccharides) and to this end produce diverse enzymatic mixtures. A complex regulatory network ensures the production of the most optimal mix of enzymes for the environment the fungus finds itself in. It is expected that the organism will consume preferred (metabolically most favourable) carbon sources first. However, the issue of dietary preference has not been addressed before for filamentous fungi. For instance, Aspergillus niger is one of the best studied fungi with respect to plant polysaccharide degradation. However, all these studies have been performed with pure mono- oligo- or polysaccharides.
This project is aimed at understanding the substrate preferences from A. niger during growth in a natural environment. It is known that some monosaccharides (e.g. D-glucose) are better carbon sources for A. niger than others (e.g. L-arabinose). Does this imply that polysaccharides with large amounts of D-glucose are preferentially degraded compared to polysaccharides with large amounts of L-arabinose?
The topic will be addressed by micro-array analysis to compare the transcriptional response during growth on natural and pure substrates, and by studying the temporal and spatial expression in the colony. Moreover, identification of the responsible transcriptional regulators and studying the interaction between them will result in a better understanding of the regulatory network involved in carbon consumption of this fungus.
The results of this project will significantly improve the understanding of the role of A. niger and other fungi in ecosystems. In addition, the results can be applied to improve growth of fungi in industrial fermentations and to increase utilisation of complex substrates in the process.