Identification of Polycyclic Aromatic Hydrocarbon Degrading Bacterial Strain and its Ability to Degrade Pyrene

Four bacterial isolates were previously isolated from soil polluted with petroleum oil from Cairo Refining Company, Qalyubia, Egypt. These isolates (MAM-26, 29, 62 and 68) and standard strain Enterobacter cloacae MAM-4 were grown on five concentrations of pyrene (Pyr.) as a sole carbon and energy source. The abilities of these isolates to degrade Pyr. have been investigated. The growth (O.D) and extracellular protein secretion were determined after 1, 2, 3,4,5,6,7,14 and 21 days incubation for each strain. Degradation of Pyr. was quantified by High Performance Liquid Chromatography (HPLC). The results revealed that isolate MAM-29 degrade 95.0%, 90.5% and 90.3% of 100, 200 and 300 μg/L of Pyr., respectively. The best Pyr. degrader bacterial isolate MAM-29 was identified by 16S-rRNA. This isolated strain showed 100% similarity with Achromobacter xylosoxidans strain R8-558 with accession No. JQ 659958.1 So isolate MAM-29 was identified as Achromobacter xylosoxidans with accession No. JN 038055. Pyrene degradation by B. amyloliquifaciens MAM-62, the most potent strain in degrading PAHs in general, produced 4 intermediates compounds after 24 hrs. incubation as determined by GC/ MS. These intermediates were benzeneethanol, hexanoic acid 3, 5, 5'-trimethyl, 2, 4, 6cycloheptatriene -1-one and tetradecanoic acid. Mutant of B. amyloliquifaciens MAM-62 (4) resulted from exposure to gamma radiation produced five different intermediates.