Bioremediation of Polycyclic Aromatic Hydrocarbons (PAHs): Current Practices and Outlook

Polycyclic aromatic hydrocarbons (PAHs) are active members of the group of multi-aromatic organic compounds, considered to be the most ubiquitous environmental pollutants, mainly engendered from partial combustion of wood, coal, oil or other organic materials. Currently, more than 500 PAHs are prevalent in the atmosphere; reactions between PAHs and various chemicals such as ozone, sulfur dioxide and nitrogen oxides lead to the formation of more toxic chemicals such as diones, nitro- and dinitro-PAHs and sulfonic acids. Due to high global concern, studies are being carried out by researchers to remove PAHs in an eco-friendly and cost-effective manner. Biodegradation of PAHs is a widely used strategy in which diverse types of bacterial, fungal, algal, earthworms, protozoans, plant species and their derived compounds such as biocatalysts, and biosurfactants are being used. Though the microbial degradation of PAHs has been extensively explored, it is a quite progressive area with many research findings being added to the literature. This chapter focuses on a critical overview of current knowledge around the biodegradation of PAHs. It also discusses the recent advancement including ‘omics’ approaches in bioremediation techniques to illuminate fundamental challenges and future prospects.