Tracing single-cell scale chemical signaling between interacting soil fungi

ongoing

Multiple species of fungi co-exist in soils and play an important role in biogeochemical cycles. To survive in a resource limited environment, they have developed the means for interspecific communication and warfare via an arsenal of secreted secondary metabolites. Specific ecological role of those metabolites and the extent to which they affect biogeochemical cycling during fungal interactions remains unknown. Because they are secreted and act at a single-cell scale, tracing them ‘then and there’ can aid in identifying potential triggers for their production and clarifying their function. Currently used methods have either insufficient resolution or are destructive, and are not suitable for such analyses. Here, I will use my expertise in spectroscopy techniques to (1) establish experimental protocols for the single-cell scale fungal secondary metabolite identification and characterization using surface-enhanced Raman scattering (SERS) microspectroscopy - a method that employs optical properties of gold nanoparticles for molecule specific sensing and that has been shown in biomedical research to have an extraordinary potential for studying microbial metabolic processes. I will combine it with microfluidics based soil chips, that provide visual access to and mimic real ecosystems via control over biotic and abiotic environment of soil microbes. Ultimately, my aim is to offer the community of soil fungal ecologists with a game-changing new tool to study ecosystem functions of secondary metabolites in more realistic settings. I will then use the approach to (2) determine how interspecific fungal interactions under varying nutrient conditions affect the composition of their secondary metabolome and its functions live and at single-cell scale. Additional transcriptome analysis will (3) reveal fungal genes involved in up- or downregulation of the metabolite biosynthesis, but also extracellular enzyme production for organic matter degradation and nutrient acquisition.