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Crude oil is comprised of four groups: Saturates Aromatics, Resins and Asphaltenes. Oil pollution has irreversible effects on marine ecosystems. Therefore paying attention to oil pollution and the management of the ports is very important. Biodegradation of oil derivatives is more effective, more powerful and more economically efficient method for remediation in polluted sites rather than physicochemical methods. In this study, for isolation of crude oil degrading bacteria, seawater and mussels were collected from Persian Gulf. Enumeration of bacteria were done in collected samples. Isolated bacteria were identified by biochemical and molecular tests. Crude oil biodegradation for each strain was assessed by spectrophotometer and Gas Chromatography (GC). The results of this study show that the quantity and biodiversity of heterotrophic and crude oil degrading bacteria in Crassostrea gigas mussels was higher than surrounding environment (seawater). Eleven crude oil degrading bacteria were isolated from Persian Gulf, 7 strains were identified biochemically and 2 strains were selected on the basis of higher degradation. These isolated strains were identified as Shewanella and Alcanivorax. The half percentage of oil was removed by these strains in 15 days of incubation. These bacteria could be used for cleanup oil-polluted marine areas after more research and field observation.