The chemotrophic behaviour of Aspergillus niger: mapping hyphal filaments during chemo-sensing; the first step towards directed materials formation

In the development of fungal based materials, including composites for applications in construction through to biomedical materials and fashion, understanding how to regulate and direct growth is key for gaining control over the form of the material generated. Here, we show how simple ‘chemical food’ cues can be used to manipulate the growth of fungal networks by taking Aspergillus niger as an exemplar species. Chemotrophic responses towards a range of nitrogen and carbon containing biomolecules including amino acids, sugars and sugar alcohols were quantified in terms of chemotrophic index (CI) for A. niger using a miniaturised assay under a range of basal media compositions (low and high concentrations of N and C sources). CI values varied according to the chemical composition of the basal medium for most nitrogen (N) or carbon (C) sources. Growth of filamentous networks was followed using fluorescence microscopy at single time points and during growth by an AI (artificial intelligence) analytical approach to explore the chemo sensing behaviour of the fungus when exposed to pairs (C-C, C-N, N-N) of biomolecules simultaneously. Data obtained suggest that the directive growth of A. niger can be controlled towards simple biomolecules with the CI values giving a good approximation for expected growth under a range of growth conditions. This is a first step towards identifying conditions for researcher-led directed growth of hyphae to make mycelial mats with tuneable morphological, physicochemical, and mechanical characteristics.