Mechanism of the biodemulsifier-enhanced biodegradation of phenanthrene by Achromobacter sp. LH-1

Biodemulsifiers are widely applied in petroleum processing, mining and petroleum pollution treatment. Polycyclic aromatic hydrocarbons (PAHs) are a common component in petroleum-polluted environments; however, little is known about the mechanism behind the effect of biodemulsifiers on promoting PAH biodegradation. To obtain clear mechanistic insights, the facilitating effects of biodemulsifiers on the bioavailability of phenanthrene (PHE), which is used as a model PAH, and the cell membrane properties of PHE-degrading bacteria Achromobacter sp. LH-1 were researched. The results showed that LH-1 achieved a 96.1 % degradation rate and a 60 % adsorption rate. Biodemulsifiers could encapsulate PHE within micelles to solubilize PHE and increase the cell surface hydrophobicity (CSH) of LH-1 to improve the association of LH-1 with PHE. Furthermore, biodemulsifier molecules can be embedded in the phospholipid bilayer of the LH-1 membrane to increase the permeability and the area of the LH-1 membrane, and they can increase the unsaturated fatty acid contents of the LH-1 membrane to loosen the arrangement of carbon chains, thus further facilitating the uptake of PHE by LH-1 for biodegradation. These results suggest that biodemulsifiers are powerful biological products for increasing the degradation potential of PHE-degrading bacteria in ecosystems, and their application will be important for the economical and efficient bioremediation of PHE-contaminated environments.