  Bacteria biodegradation of immiscible oil requires cell-droplet encounters,
surface attachment, and hydrocarbon metabolism. Chemical dispersants are
applied to oil spills to reduce the mean dispersed droplet size, thereby
increasing the available surface area for attachment, in attempts to facilitate
bacterial biodegradation. However, their effectiveness remains contentious as
studies have shown that dispersants can inhibit, enhance, or have no effect on
biodegradation. Therefore, questions remain on whether dispersants affect
surface attachment or cell viability. Here, using microfluidics and time-lapse
microscopy, we directly observe the attachment and growth of the marine
bacterium, \emph{Alcanivorax borkumensis}, on stationary crude oil droplets
($5$ \textmu m $< R < 150$ \textmu m) in the presence of Corexit 9500. We show
that the average colonization time, or the time comprised of encounters,
attachment, and growth, is dependent on droplet size and primarily driven by
diffusive encounters. Our results suggest that dispersants do not inhibit or
enhance these biophysical processes.
