||Caption: Pseudomonas citronellolis - rod-shaped, motile, Gram-negative, petroleum / oil degrading bacterium (prokaryote). Pseudomonas species have the ability to degrade a wide range of organic pollutants, including polycyclic aromatic hydrocarbons, halogenated derivatives, and recalcitrant organic residues. A large number of Pseudomonas strains, capable of degrading polycyclic aromatic hydrocarbons, have been isolated from soil and aquifers. Pseudomonas citronellolis is one such hydrocarbon-degrading bacterium, which metabolizes citronellol (an isoprenoid) and can also degrade the toxic hydrocarbon constituents present in oily sludge. Citronellol, citronellal and citronellyl acetate are among the main constituent of the essential oils of several plants, like citrus, citronella grass, roses, and lemon eucalyptus. Oily sludge contains several toxic hydrocarbon constituents. It is a complex mixture of total petroleum hydrocarbon (TPH), water, and soil particles. TPH is primarily composed of alkane, aromatics, nitrogen-, sulfur-, and oxygen-containing compounds, and asphaltene fractions. P. citronellolis has the ability to degrade these types of aromatic hydrocarbons that are toxic to our environment.