A minimal model of mycelium morphogenesis
Early results from modelling activities by partner KADK, at the Chair for Biohybrid Architecture. In this continuous PDE model we try to capture the microscopic dynamics of the fungi-substrate-environment system on a scale that can inform us about the resulting macroscopic material.
In the first trail we see the fungal metabolism in interaction with a simplified environment in an open container. The shoe last geometry defines an inert zone with no environmental exchange. Biomass is formed under respiratory conditions where digestive enzymes catabolize the substrate carbon source. As new oxygen diffuses into the substrate from the boundary the mycelial density increases locally compared to the interior anaerobic conditions. Although the simulation takes place in three-dimensional space the governing equations for the fungal behavior are one-dimensional. The inoculated biomass is assumed to be evenly distributed within the substrate and no transport takes place within the hyphal network
The second trial illustrates the effect of including internal transport. Carbon source and initial biomass are inoculated within a shoe-shaped mould. An age variable is included so that the directionality of the hyphae can be represented as a vector field. As the carbon source is converted into building material, it is transported within the existing network, and fixed at the periphery, thereby extending the colony - until it runs out of fuel.
With this simple model we can start interrogating the possibility of controlling the properties of the grown material by modulating the experimental conditions. The next steps will focus on making predictions and evaluating them with experiments, to improve our hypotheses about fungal behavior and our capability to model them.