Among 25 crude oil-degrading bacteria isolated from a marine environment, four strains, which grew well on crude oil, were selected
for more study. All the four isolated had maximum growth on 2.5% of crude oil and strain BC (Pseudomonas) could remove crude oil by
83%. The drop collapse method and microtiter assay show that this strain produces more biosurfactant, and its biofilm formation is
higher compared to other strains. Bacterial adhesions to crude oil for strains CS-2 (Pseudomonas), BC, PG-5 (Rhodococcus) and H
(Bacillus) were 30%, 46%, 10% and 1%, respectively. Therefore, strain H with a low production of biosurfactant and biofilm formation
had showed the least growth on these compounds. PCR analysis of these four strains showed that all isolates had alk-B genes from group
(III) alkane hydroxylase. All isolate strains could utilize cyclohexan, octane, hexadecane, octadecan and diesel fuel oil; however, the
microtiter plate assay showed that strain BC had more growth, respiration and biofilm formation on octadecan.
