(125c) Engineered Habitats for Understanding Fungal Growth in Soil | AIChE

(125c) Engineered Habitats for Understanding Fungal Growth in Soil


Guo, Y. S. - Presenter, Oak Ridge National Lab
Bonito, G., Michigan State University
Retterer, S. T., Oak Ridge National Laboratory
Soil microbiomes play a crucial role in the development of the rhizosphere. The dynamic chemical exchange, growth, and migration of members of the soil microbiome and developing plants physically and chemically shapes local microenvironments within the rhizosphere, leading to potential improvements in soil hydrology, nutrient cycling, and general promotion of plant health. However, the specific organizational dynamics and physicochemical drivers of these complex interactions between bacteria, fungi, and the plant host, remain largely unidentified. In this study, we utilized the development of engineered habitats to visualize and quantify the impact of spatial confinement and network complexity on fungal growth. Briefly, such microfluidic environments were fabricated using photolithography and conventional soft lithography methods and assembled to glass slides. Microfluidic networks were designed to be a simplified 2D soil-mimicking media. Networks were generated using a Python script that creates a Voronoi-tessellation of grid points that can be randomly offset, “jiggled” to create geometries with systematically varied complexity. The resulting geometries consist of an array of pores (16 and 30 µm, respectively) connected by throats (10-µm wide). Two general designs were applied featuring (1) regular Cartesian porous media and (2) irregular soil-analog media to distinguish the fungal movements through complex networks. The responses of selected fungal strains isolated from soil (Linnemannia elongata, Podila minutissima, Fusarium falciforme, Laccaria bicolor, and Morchella sextalata) were recorded using time-lapse microscopy. Rates of hyphal penetration and expansion through well-defined cartesian and ‘soil’ networks were compared and revealed varied impacts on penetration and expansion rates commensurate with the hyphal size and branching frequency. Notably, pore size also had a significant impact on penetration rates for certain species. Our results demonstrate the utility of using microfluidics to systematically vary key spatial parameters to better understand fungal migration, and point towards the future utility in exploring the drivers of multi-kingdom interactions and rhizosphere microbiome assembly.