Two barcteria, capable of petroleum biodegradation were isolated from Persian Gulf seawater. Both strains (designated as PGOI and PGO2) were. marine halophile, strictly aerobic, motile, gram-positive short rods. During growth (in 250 ml erlen meyer containing 100 ml mineral base medium with 1% crude oil as sole carbon source, crude oil medium), under shaking condition (150 rpm), both strains produced biosurfactant which emulsified petroleum and bacterial cells were found to attach to generated oil droplets. The optimum pH for both isolated growth in the crude oil medium was 8-8.4, similar to the pH of seawater. Both isolates could grow in mollasses medium (1%) but biosurfactant production in this hydrophilic substrate was not observed.
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