Lipid rafts are tight assemblies of proteins and lipids in a biological membrane and are thought to be involved in many physiological processes such as immune signalling and host-pathogen interactions. However, due to their small sizes exceeding the resolution limit of conventional light microscopy, direct measurement and characterisation of lipid rafts in living membranes remains to be a challenge. Most studies on lipid rafts have been carried out on mammalian cells, but utilising lower eukaryotes is advantageous as the general properties of their plasma membrane organisation are similar to that of mammals while they are also easier to manipulate genetically. In this project, we aim to gain insight on the characteristics of lipid rafts in the model filamentous fungus Aspergillus nidulans, with a particular focus on the involvement of the SPFH protein, FloA. This protein was first tagged with GFP and observed as punctuated structures in the plasma membrane by Takeshita et al. (2011), but its functions are still unknown. Here, we show through use of a nanoluciferase fusion that FloA is highly expressed when A. nidulans is co-cultivated with the bacterium Streptomyces iranensis, which lives in soil as does the fungus. Interestingly, a mutant of the bacterium which is unable to produce secondary metabolites cannot induce the high expression of FloA, indicating that this upregulation is attributable to a secondary metabolite produced by S. iranensis. This finding could lead to the uncovering of the regulatory mechanisms as well as the biological functions of FloA and possibly its importance in organismic communication.