Abstract:An efficient phenanthrene-degrading endophytic bacterial strain Pn2 was isolated from Alopecurus aequalis Sobol grown in PAH-contaminated soils. Pn2 was identified as Naxibacter Sp. based on physiological characteristics and 16S rDNA Sequence homology analysis. The experiments on phenanthrene-degrading features and growth characteristics of the strain showed that strain Pn2 can utilize phenanthrene as the sole carbon source. At 30℃ and 150 r/min, the degrading ratio of phenanthrene (49.92mg/L) in solution was 98.78% after 72 hours rotary culture. The inoculation amount and pollution intensity positively influenced the phenanthrene degradation: the larger amount of Pn2 inoculation, the higher phenanthrene degradation ratio. With increasing the pollution intensity, phenanthrene degradation ratio enlarged at first and reduced thereafter. 150mg/L of phenanthrene is the optimum pollution intensity under the test condition. Pn2 grew well under the condition of 25~37℃, pH 6.0~8.0 and 1%~2% salinity. Strain Pn2 grew aerobically, and the stronger aeration, the better Pn2 growth. It was observed that Pn2 can resist the low concentration of penicillin and chloramphenicol.