Bacterial adhesion and evolution at the oil–water
interface
are important for a broad range of applications such as food manufacturing
and microbial-enhanced oil recovery, etc. However, our understanding
on bacterial interfacial adhesion and evolution, particularly at the
single-cell level, is still far from complete. In this work, by employing Pseudomonas aeruginosa PAO1 at the dodecane–water
interface as a model system, we have studied the effects of different
factors on bacterial interfacial adhesion and the dynamic evolution
of bacterial interfacial behavior at the single-cell level. The results
show that PAO1 cells displayed a chemotactic behavior toward dodecane.
Among the tested factors, bacterial initial interfacial attachment
showed a negative correlation with the secreted cell-surface associated
lipopolysaccharide and Psl while a positive correlation with type
IV pili. Adding nonbiological surfactant Pluronic F-127, as expected,
greatly reduced the cell interfacial adhesion. More importantly, the
dynamics analysis of cell attachment/detachment at the dodecane–water
interface over a long-time scale revealed a reversible to irreversible
attachment transition of cells. This transition is accompanied with
the interface aging resulting from bacterial activities, which led
to an increase of the interfacial viscoelasticity with time and finally
the formation of the gel-like interface. Further analysis demonstrated
the important role of exopolysaccharides in the latter process. Our
findings provide more details of bacterial oil–water interfacial
behavior at the single-cell level and may shed light on developing
new strategies for controlling bacterial colonization at the oil–water
interface.