**2. Bioremediation**

Polycyclic aromatic hydrocarbons (PAHs) are of particular concern because of their toxic, mutagenic and carcinogenic properties [51]. There is thus a chief interest in studying micro‐ organisms present in contaminated environments as a means for bioremediation. The fate of PAHs and other organic contaminants in the environment is associated with both abiotic and biotic processes, including volatilization, photooxidation, chemical oxidation, bioaccumula‐ tion and microbial transformation. Microbial activity has been deemed the most influential and significant cause of PAHs removal [3, 12]. PAHs may also be degraded by some micro‐ organisms in the soil [52]. The term bioremediation refers to the use of living organisms to degrade environmental pollutants [53]. Bioremediation is generally considered to include natural attenuation, biostimulation or bioaugmentation, the deliberate addition of natural or engineered microorganisms to accelerate the desired catalytic capabilities. According to the Environmental Protection Agency in the United States [54], natural attenuation processes may reduce contaminant mass (through destructive processes such as biodegradation and chemical transformations), reduce contaminant concentrations (through simple dilution or dispersion). Eventually, even the contaminants bound to the soil particles gets biodegraded by the bacterial species present in the environment.
