Scientific article: Bacteria, hydrophobicity, and oil

Bacteria are aqueous organisms, but many of them can feed on oils and can colonize oily interfaces. Is this an ability that relies on that bacteria are hydrophobic, i.e., their surfaces like oil better than water? Our investigation showed that while bacteria that have a more hydrophobic surface adsorb well to the interface between oil and water, also very hydrophilic bacteria that secrete surfactants to change the interface can be efficient biofilm formers.

Bacterial adsorption to interfaces is the initial step in biofilm formation. Until now, the mechanism of biofilm formation at liquid-liquid interfaces is not well understood. We studied the bacterial adsorption and biofilm formation of three different bacteria, P. aeruginosa, S. aureus, and S. epidermidis at the n-decane-water interface, with focus on the relationship between bacteria wettability, excretion of biosurfactants, and biofilm formation. The adhesion capacity of these bacteria to hydrocarbons was characterized using the bacterial adherence to hydrocarbons test. We monitored the interfacial rheology of bacterial adsorption and biofilm formation at the interface over time using a drop shape analyzer and imaged the formed biofilms by using fluorescence and scanning electron microscopy.


P. aeruginosa showed high adhesion capacity to hydrocarbons, while the adhesion capacity of both staphylococci was negligible. S. epidermidis, with a negligible hydrophobicity value, showed the most substantial reduction in interfacial tension and the formation of the most elastic biofilms at the oil-water interface, accomplished by the secretion of biosurfactants. S. aureus did not form biofilms at the n-decane-water interface, in contrast to P. aeruginosa and S. epidermidis.


This article is published in Colloids and Surfaces B: Biointerfaces