(459f) Life at the Oil-Water Interface: Degradation of Crude Oil By Bacteria

The degradation of oil in the ocean is a process of immense societal and ecological importance, whose efficiency ultimately hinges on fundamental problems in colloidal and interface physics, because degradation occurs when individual bacteria attach to individual oil droplets. We present experimental and theoretical results on the effect of oil drop diameter on the attachment of marine bacteria to the oil-water interface. Using phase-contrast and fluorescence microscopy, we directly observed the dynamics of marine bacteria in the presence of oil droplets of varying diameter within microfluidic devices. We find that microbial growth and degradation become strongly limited for drops smaller than a critical diameter. A theoretical model of attachment supports this finding, suggesting that rendering oil droplets too small by the excessive addition of dispersants, as often done in oil spills, might be a counterproductive strategy, and that deeper understanding of the fundamental oil-microbe interactions should instead be pursued and guide oil spill management.