|Abstract||Qatar is one of the leading countries in oil and gas industry worldwide. Qatar is located in the middle of the Arabian Gulf sea, a semi-closed sea surrounded by many petrochemical sites, besides the active offshore traffic of oil and gas transportation. Side-effects of production and transportation activities are expected and can affect the environment seriously. Bioremediation offers alternatives to alleviate such pollution caused by the thousands of oil components known by their high diversity, instability, toxicity and low bioavailability and biodegradability. Weathering, is an additional factor, making bioremediation of oil-polluted areas more difficult. Oil Weathering Processes results to changes of oil in terms of properties and composition. This is why Petroleum-derived contamination events constitute a unique environmental issue. In Qatar and the region in general, the weathering processes are accentuated due to harsh conditions, representing the main origin of failure of bioremediation applications. Some bacteria are able to adapt to such weathering conditions and absorb particles rich in pollutants through their hydrophobic wall to form biofilms. Others produce surfactants to improve accessibility.
In this study, a multidisciplinary approach was implemented to solve such an environmental issue, starting from the identification of the potential sources of the polluting oil along AlZubara coast to Chemometric investigations allowing determination of weathered status. Following systematic sampling and chemical analyses of soils, biodiversity of hydrocarbon-degrading bacteria was studied. Through an integrated isolation and screening program, isolates were identified and differentiated through several molecular techniques and screened for their potential to remove classes of hydrocarbons with special focus on high efficiencies never reported with concentrations and weathered status. Biostimulation of indigenous bacteria showed low rates of removal. However, combining stimulation to augmentation improved the removal of weathered oil. Interestingly, by using ex-situ biopiling, augmentation using indigenous bacteria exhibited the best approach, but a high negative interaction was observed by using exogenous bacteria. These findings confirm the initial hypothesis of this work, that weathered hydrocarbons removal was enhanced by using adapted indigenous bacteria. It is then considered that bioremediation of a given area should be separately treated, using corresponding appropriate bioremediation strategy.