The interactions between bacteria and fungi play important ecological roles, including the breakdown of organic materials, the degradation of pollutants, and the inhibition or facilitation of plant growth. “Fungal highway”, the fungi facilitated dispersal of bacteria can greatly expand the spatial range where bacteria can be active, but unlike inert pathways, the physical contacts between bacteria and fungal hyphae actively select the potential players, and provide the opportunity for direct nutrient exchanges and cross-chemical reactions among them. The “fungal highway” thereby sets up dynamic playgrounds for evolutionary games. Despite the fascinating variety of microbial interactions associated with the “fungal highway”, including helping, predator-prey, mutualism, antagonism, and exploitation, mathematical models that study the mechanisms of such interactions and make experimentally testable predictions are still missing.

As shown in the figure, we use both experiments and mathematical modelling to study whether the biotic interactions between bacteria and fungi may promote or hinder bacterial dispersal. To separate the effects of biotic interactions and the structural networks provided by the fungi on bacterial dispersal, we will build a simulation model of bacterial dispersal on fungal networks, considering the network structure alone. The simulation model will be configured and tested with bacterial dispersal experiments on glass fiber networks with controlled structures, until it can reproduce the bacterial dispersal pattern on the abiotic networks. We will then use the model to predict the bacterial dispersal patterns on abiotic networks which share the same structures as the fungal networks, but without biotic interactions. If the predicted bacterial dispersal patterns agree with experimental results, we can conclude that the effect of fungi on bacterial dispersal is mainly by providing the “highway” network structure, otherwise, the interactions between fungi and bacteria may play an important role. We expect the fungi to actively hinder bacterial dispersal in nutrient rich environments for reducing competition, but promote bacterial dispersal in nutrient poor environments in order to metabolically cooperate with bacteria or predate on them. We will also investigate the role of resources (e.g. different sharable/exclusive carbon or nitrogen sources) on the interactions between fungi and bacteria. Ultimately, we aim to develop strategies that can effectively control and manipulate the dispersal of bacteria through fungal hyphae networks.