Alcanivorax borkumensis are prominent actors in oil spill bioremediation; however, the interfacial dynamics of their biofilms and its role in oil degradation remain unclear. Longitudinal tracking of bacteria-covered oil droplets using microfluidics, reveals distinct biofilm phenotypes: thick and spherical versus thin and dendritic, with the latter having a faster consumption rate. We show experimentally that biofilm dendrites emerge from aster-like nematic defects in thin biofilms. We develop a theoretical model that elucidates the transition between phenotypes; this model links tubulation to decreased interfacial tension and increased cell hydrophobicity, which we verify experimentally. A. borkumensis manipulates its interfacial properties to utilize division to drive an increase in surface area, which could be the cause for its rapid blooming and dominance after oil spills.