(428c) Invited Speaker: Motility and Adhesion of Bacteria Near Oil Droplets

The interactions of bacteria with the oil/water interface of dispersed droplets plays an important role in numerous technological processes, including bioremediation of oil spills as well as droplet microfluidics for pathogen detection, antibiotic susceptibility, and biotechnological selection. Here, I will describe our recent studies in which we combine confocal microscopy and microfluidic emulsification to investigate interactions of bacteria with oil droplets suspended in water and stabilized by surfactants. We employ these techniques to probe the adhesion of both non-motile and motile bacteria on the droplet surface over time, examining the role of surfactant type and concentration as well as bacterial motility. Briefly, we find that adhesion is controlled by the interfacial tension, and the ability to swim enhances adhesion at the droplet interface. Interactions with a boundary can generate more complex behaviors. In this context, we show that motile bacteria can rotate oil droplets resting near a solid surface. This rotation is correlated both to cell adhesion to oil droplets and to cell motility. The methods applied here can be used to optimize and tune the interactions of other bacteria with interfaces in a variety of technologically relevant settings.