Four bacterial strains were isolated from Khor Al-Zubair channel, southern Iraq based on a high growth rate on crude oil and on hydrocarbon degradation ability. The strains were preliminarily identified based on morphological observation, and by the Vitek II system. The isolates were identified as Brevundimonas diminuta /vesicularis, Vibrio vulnificus, Sphingomonas paucimobilis and Ochrobactrum anthropic. However, the ability of these strains to utilize crude oil (0.25%; 0.5%; 1% and 2% v/v) varied both in rates of utilization and in growth profiles. The components of crude oil degraded by the isolates were determined by capillary gas chromatography. Sphingomonas paucimobilis and Vibrio vulnificus were the most effective bacteria degrade PAH on seventh day incubation, especially in concentration 2.0 mg/l (97.39% and 84.23%) respectively, meanwhile, Brevundimonas diminuta/ vesicularis was highly effective degrade PAH (73.41% a nd 62.08%) in concentration 1.0 and 0.5 mg/l, respectively. On the other hand, Ochrobactrum anthropi was the lowest in all concentrations.

Four bacterial strains capable of using crude oil as the sole carbon source were isolated from Khor Al-Zubair channel, southern Iraq. The isolates were identified as Vibrio vulnificus; Brevundimonas diminuta/vesicularis; Ochrobactrum anthropic and Sphingomonas paucimobilis by the Vitek II system. The bacteria grew aerobically in liquid culture containing four concentrations (0.25%, 0.5%, 1% and 2% v/v) of crude oil at 30ᵒC for a seven day period. The components of crude oil degraded by the isFolates were determined by capillary gas chromatography. Vibrio vulnificus was the most effective bacteria to degrade crude oil, especially in concentration 2% (93.05%). Meanwhile, Ochrobactrum anthropi was the lowest (9.63%) in concentration 0.25%.