Elucidating the Onset of Bacterial Chemotaxis in Bioremediation

Abstract

Contamination of groundwater from industrial leakages and agricultural seepages presents a large problem for human health because almost half of the U.S. population relies on groundwater for their drinking water. Bioremediation, in which microorganisms are employed to degrade contaminants, is a promising method for cleaning up groundwater contaminants. Previous work suggests that chemotactic bacteria may be especially effective to use as they can actively sense, locate, and degrade the contaminants in situ. Chemotaxis, the phenomenon where bacteria can sense and respond to the concentration gradient of a chemical, can improve bioremediation strategies by driving the mass migration of chemotactic bacteria to contaminant sources for more efficient biodegradation. Effective application of bacteria for bioremediation requires an understanding of how they move through soil and other porous media. Researchers have already explored the advantage of chemotactic bacteria over non-chemotactic bacteria, but few researchers have considered how chemotactic response and the overall efficacy of bioremediation are affected by the spatial distribution of contaminants, initial bacterial density, and other factors. Such factors may determine whether bacteria will chemotactically respond since they affect the steepness of the concentration gradient, which chemotactic sensing depends on. To better understand the conditions that elicit a chemotactic response, we investigate the effect of changing bacteria properties, contaminant characteristics, and the spatial distribution of contaminant sources on bacteria distribution through simulations. Our work provides insight into how chemotactic bacteria may contribute to bioremediation at the pore scale and thereby may lead to more effective application of chemotactic bacteria in bioremediation strategies.