Harnessing diffusiophoresis to improve the bacterial motility toward toxic pollutants

In bioaugmentation, which requires delivering decomposer bacteria to contaminated soil micropores, chemotaxis has been identified as an advantageous strategy for directing the bacteria toward toxic pollutants. However, the complex microenvironment of the soil matrix often restricts bacterial movement, effectively hindering the remediation process. In this study, we investigate diffusiophoresis as a means to improve the chemotactic motility of soil bacteria toward the pollutant source. We examine the response of Pseudomonas putida F1, a flagellated soil bacterium, to salt (diffusiophoresis) and toluene (chemotaxis) gradients, and a combination of both. We observe that diffusiophoresis significantly influences bacterial run-and-tumble behavior, resulting in straighter trajectories during runs while tumbling less. Our results indicate that diffusiophoresis can improve the ability of P. putida to reach the chemoattractant in confined geometries, offering a promising strategy for bioremediation in contaminated soil environments.