Biofilms cost the U.S. billions of dollars every year due to human and animal infections, product contamination, and biofouling of membranes. Deep subsurface biofilms can be used for enhanced oil recovery and carbon sequestration in addition to bioremediation of contaminants in groundwater. Despite widespread implications of biofilms, the underlying hydrodynamics of bacterial aggregation that eventually leads to formation of biofilm streamers are currently unknown.
Intellectual Merit: Properties of bacteria-produced extracellular polymeric substances consisting of a filamentous network of macromolecules surrounded in a fluid play an important role in biofilm formation. In order to understand biofilm formation and growth, the dynamics of bacterial aggregation at ecologically relevant spatiotemporal scales in the presence of flow while interacting with extracellular polymeric substances must be studied. This is a challenge largely unanswered to date. The proposed research will employ state-of-the-art three-dimensional computational fluid dynamics and experimental techniques to transform our understanding of bacterial aggregation due to flow field, bacteria shape, bacteria motility and rheological properties of extracellular polymer. The literature shows that rigid particles ranging in sizes from microns to centimeters robustly aggregate in different flows of viscoelastic fluids. The proposed research investigates a hypothesis that motile microorganisms in viscoelastic fluids undergo strong hydrodynamic forces that result in their aggregation to the surfaces and/or each other. The fundamental knowledge about the aggregation of bacteria in the presence of flow in such complex fluids can transform our understanding of these microbial processes and advance the ability to control biofilm formation.
Broader Impact: The implications of this research extend to important biological, environmental, and oceanographic applications. Understanding of bacterial aggregation and formation of biofilms is crucial for human health and environmental control. Additionally, the ability to systematically investigate the interaction of bacteria using computational fluid dynamics, while capturing its detailed 3D response in complex fluids, is essential for correctly predicting the future state of the pathogen colonization in mucosal tissues and tracts. The proposed activity will significantly contribute to interdisciplinary training of the next generation of scientists and engineers. This grant will provide support for training of two graduate students fostering the development of state-of-the-art tools in the PI's laboratory. A new graduate course will be developed to integrate the research into graduate education. This interdisciplinary research will be used as a platform to attract diverse groups such as women and underrepresented minorities. The PI will lead an engineering education partnership with the Engineering and Technology Magnet Program for the South Bend (Indiana) Community School Corporation at Riley High School that focuses on restoring an aquatic ecosystem of a local creek by controlling Escherichia coli levels. The work will include hands-on experiments and projects for the students with the purpose of reinforcing basic principles of engineering analysis and design. By taking advantage of established articulation relationships, female and underrepresented minority undergraduate students from the all women's Saint Mary's and two Historically Black Colleges will be trained in experimental and mathematical aspects of the proposed research.
