Abstract: In order to obtain PAHs-degrading bacteria tolerant to diverse physical settings, a high efficient polycyclic aromatic hydrocarbons-degrading bacterial strain was isolated by heavy metal tolerance capacity and lack of nitrogen source culture method from a soil collected from Nanyang petroleum contaminated soil. The strain was identified by morphological characteristics and molecular biological methods, and its tolerance to heavy metals (Cr6+ and Cu2+ ), lack of nitrogen source and acid-base tolerance was studied to further explore the degradation effect of phenanthrene and pyrene under these adverse environmental conditions. The isolated strain was Rhizobium pusense, named F3-1. The result showed that the higher tolerance mass concentration of metals (Cr6+ and Cu2+ ) of the strain F3-1 was 20 mg/ L. The strain F3-1 could grow normally under the condition of absence of nitrogen source, pH 5. 0 and pH 7. 4. The strain F3-1 could degrade single phenanthrene or single pyrene under extreme conditions. After 5 days, the strain F3-1 could degrade 35. 54% of phenanthrene(50 mg/ L) at pH 7. 4, and the degradation rate of pyrene (50 mg/ L) was up to 35. 54% at pH 5. 0.

Key words: heavy metal, lack of nitrogen source, phenanthrene, pyrene, degradation, Rhizobium pusense, PAHs