Collaborative Research: Mass Transport Mediated by Microbial Biosurfactants in Unsaturated Porous Media: Multiscale Experimental and Modeling Investigations

Many naturally occurring microorganisms can produce soap-like substances, called biosurfactants, that alter how fluids and other substances in the liquids move through porous spaces such as soils and biological tissues. However, scientists still do not know how far and how fast these biosurfactants spread or how they redirect substances ranging from nutrients and pollutants to disease-causing bacteria. Yet, these microbial agents play important roles in the health of soils, plant roots, and even human lungs. This project tackles this knowledge gap by using laboratory models that mimic real soils to observe the microbes and biosurfactants in action and quantify their influence on the transport of fluids and dissolved chemicals. Outcomes from the project could support improved soil remediation strategies, more sustainable agricultural practices, and new methods to manage the spread of harmful bacteria. The project also promotes national goals in science and education by training undergraduate and graduate students, supporting interdisciplinary collaboration, and conducting outreach activities to help K-12 students appreciate fluid mechanics and microbiology and their relevance to daily life. This project integrates multiscale experiments and physics-based modeling to investigate how biosurfactants and the microbes that secrete them alter mass transport in unsaturated porous media. The goals are to: (1) quantify how time-dependent biosurfactant production alters transport behavior in two-dimensional porous systems; (2) characterize feedback loops between biosurfactant-induced flow, solute transport, and bacterial migration; and (3) measure and model biosurfactant-driven transport processes in three-dimensional porous media. Innovative visualization experiments paired with advanced multiscale models will reveal the intertwined dynamics of bacteria, biosurfactants, and transported substances. Model-data comparisons will guide the development of predictive tools that can be applied to environmental systems ranging from contaminated soils to biological tissues. The findings will provide a mechanistic framework for understanding biosurfactant-mediated mass transport, improving our ability to forecast chemical and microbial movement in complex, unsaturated porous media. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.