الفهرس 
1. INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Biodegradation is a viable bioremediation technology for organic pollutants. It has long known that microorganisms degrade environmental pollutants in various matrices and environments. Biodegradation is a very broad field and involves uses
of a wide range of microorganisms to break chemical bonds (Jong-Su et al., 2009).The biodegradation of oil pollutants is not a new concept as it has beenintensively studied in controlled conditions and in open field experiments but it has acquired a new significance as an increasingly effective and potentially
inexpensive clean-up technology (Sugiura et al., 1997 ; Chaineau et al., 2003).In general, Polycyclic Aromatic Hydrocarbons (PAHs) are relatively stable and recalcitrant in soils and less easy to degrade than many other organic
compounds (Jong-Su et al., 2009).They are difficult to remove from ontaminated
soil using the treatments that have been used successfully to clean soils
contaminated with more degradable or volatile organic compounds such as alkanes (Pitter and Chudoba, 1990).
Naphthalene, the first member of PAH group and one of the 16 PAHs
classified as priority pollutants by Environmental Protection Agency (EPA) of
United States, is a frequent pollutant established in nature. This bicyclic aromatic hydrocarbon and its methylated derivatives are considered some of the most noxious compounds in the water-soluble fraction of petroleum (Heitkamp et al.,
1987).
Naphthalene has often been used as a model compound to investigate the
ability of bacteria to degrade PAHs because it is the simplest and the most soluble PAH (Goyal and Zylstra, 1997).Therefore, information of bacterial degradation of naphthalene has been used to understand and predict pathways in the degradation of (three or more) -ring PAHs (Jong-Su et al., 2009). Naphthalene has low water solubility and high solid–liquid distribution ratio
which stand against their microbial utilization and promote their accrual in the solid phase of the terrestrial environment. Microbial degradation of naphthalene has been studied extensively and the pathway of microbial naphthalene metabolism is well
elucidated, aerobically as well as anaerobically (Aranha and Brown, 1981).
The extent and rate of biodegradation depends on many factors including pH,
temperature, oxygen, microbial load and strain, degree of acclimation, accessibility of nutrients, chemical structure of the compound, cellular transport properties, andchemical partitioning in growth medium (Singh and Ward, 2004).The activity and viability of the introduced bacteria often decreases at the contaminated sites when compared with those observed under laboratory
conditions, probably due to diverse environmental stresses. These include predation by protozoa, competition with other bacteria, unfavorable pH and temperature
conditions, and unavailability of nutrients and oxygen (Van Veen et al., 1997).The aim of this work isnto examine the ability of individual.