Biodegradation of polycyclic aromatic hydrocarbons (PAHs) in soil and groundwater:A review

Polycyclic aromatic hydrocarbons (PAHs) are known as toxic,mutagenic,carcinogenic and persistence organic contami-nants in the environment. Biodegradation is the main process to the fate of PAHs in soils and groundwater. Numerous genera of bac-teria and fungi with the ability to utilize low molecular weight PAHs as sole carbon and energy sources have been reported. Limited numbers of bacteria and white rot fungi are found be able to co-metabolize PAHs with four or more fused aromatic rings,provided that another carbon source is present. The focus of this review is on the sources of PAHs in the environment,the microorganisms that degrade PAHs,biodegradation mechanisms and the methods that are used to remedy PAHs-comtaminated soils and groundwater. In addition,the emphases of the biodegradation of PAHs will be focused on bioremediation of high molecular weight PAHs,applica-tions of gene engineering on PAHs biodegradation and the generation mechanism and application of biosurfactants on PAHs degra-dation.