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Corresponding Author: Arif, A., () Gene Expression Laboratory, Department of Biosciences, Jamia Millia Islamia, New Delhi-110025 Email: [email protected] P a te l e t a l. 2 0 1 4 J o u rn a l o f In n o v a ti v e B io lo g y hrysene is a colorless to white, crystalline solid. It is also known as benzo(a)phenanthrene. It is most often found as the gaseous by-product from the incomplete combustion of fossil fuel, wood, Coal Tar and Creosote. High environmental concerns due to its carcinogenic and mutagenic nature (Smith et al. 1989; Nwanna et al. 2006) compel us to look for innovative methodologies for its biodegradation. Chrysene oxidation occurs by incorporation of an oxygen molecule in an aromatic ring catalyzed by dioxygenases to a cis-dihydrodiol intermediate, which undergoes further catabolism results in complete mineralization (Hinchee et al. 1994). Dioxygeneses is thus a group of enzymes which play a key role in metabolism of PAHs i.e. catalysed the first ring opening step of aromatic hydrocarbon (including chrysene) and presence of catabolic genes encoding this enzyme in microbes is indicative of their role in biodegradation. The ubiquitous distribution of polycyclic aromatic hydrocarbons (PAHs) in aquatic environments has long been of great concern for their potential hazards to human health via tropic transfer in aquatic food chains. PAHs tend to be bio-accumulated and biomagnified due to their lipophilicity and chemical stability. A broad spectrum of microorganisms had been found capable of degrading PAHs, and bioremediation based on microbial processes has been considered as a promising alternative to conventional technologies to remove PAHs from contaminated soils and waters (Dean-Ross et al. 2002). However, PAHs can be photochemically decomposed under strong ultraviolet light or sunlight, and thus a fraction of PAHs is oxidized during atmospheric sampling. PAHs can also react with ozone, hydroxyl radicals, nitrogen and sulfur oxides, and nitric and sulfuric acids, which affect the environmental fate or conditions of PAHs. While physicochemical processes means to eliminate PAHs from the contaminated site but they degrade the quality of soil. The biological treatment of soil contaminated with PAHs is more environmental friendly, financially affordable and adaptable choice. It has the potential advantages such as the complete degradation of the pollutants, lower treatment cost, and greater safety and less soil disturbance (Habe and Omori, 2003).