The investigator develops differential equation models to study heterogeneous biofilms in fluid-saturated porous media. The underlying question is how biofilm interactions affect spatial heterogeneities in the biofilm. Of specific interest are causes of observed heterogeneities, whether heterogeneity is purely a hydrodynamic effect, whether cell-cell communication through chemical signaling can be responsible for some of the heterogeneity, and whether species competition can be a contributing factor in the observed roughness of the film. The mathematical approach involves one- and two-space-dimensional models, the development of analytical techniques, and computational studies. In the project the investigator collaborates with experimentalists at the Center for Biofilm Engineering and shares mentoring of students with members of the Center. Understanding the variations in biofilm form and structure will clarify the important issues of transport and chemistry within the biofilm. In the vernacular, a biofilm might be called slime or sludge. A biofilm is a film of microorganisms that accumulates on the surface of an object in a flowing fluid environment. The microorganisms secrete polymers outside their own body cells, which anchor the cells to each other and to the surfaces on which the film forms. Biofilms can clog pipes, foul the hulls of ships, corrode steel, sour oil fields, or cause infections by growing on host tissues or medical implants. Because of their pervasive effects on water quality, power generation, energy efficiency, and product quality, their negative effect is felt in most U.S. industries. Not all biofilm activity has negative results. They can also break down contaminants in water or soil and often are used for bioremediation. The potential of biofilm process control has yet been fully realized due in part to a lack of fundamental knowledge of biofilm form and structure. Recent experiments have shown that biofims are not so uniform in structure as once thought. In this project, the investigator develops mathematical models of biofilms to study heterogeneity in biofilms. Understanding the variations in biofilm structure will lead to understanding issues of chemistry and transport in the biofilm: how the biofilm grows and what it can do. He collaborates with experimentalists at the Center for Biofilm Engineering and shares mentoring of students with members of the Center.
