Instability of petroleum oil degradation by induction of mutation in 45 kb and 60 kb plasmids

A strain of Pseudomonas sp. was isolated from oil‐contaminated soil on petroleum oil agar. This isolate used different alkenes and had two plasmids on gel agarose. These plasmids are probably involved in oil degradation. The mutant strain, which were obtained by sub‐culturing in nutrient broth (oil − ), lost one plasmid (60 Kb) and had deletion in another plasmid (45 Kb). This result suggests that the ability to degrade petroleum oil must depend on these plasmids. The wild isolate has maximum OD of 2.5 for growth on petroleum oil, however the mutant did not have any significant growth on petroleum. GC Profiles of petroleum oil after degradation by wild and mutant were investigated.