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.%从长期受PAHs污染的植物看麦娘中分离出1株可高效降解菲的内生细菌Pn2,经生理生化特征分析和16S rDNA序列同源性分析,初步鉴定为Naxibacter sp.,研究了菌株Pn2的生长特性及其对菲的降解作用.结果表明,菌株Pn2能以菲为唯一碳源生长,并对菲有良好的降解性能.菲浓度为49.92mg/L时,30℃下150r/min振荡培养72h,菲降解率高达98.78％.接种量和污染强度显著影响Pn2对菲的降解:接种量越大,菲降解率越高；随污染强度升高,菲降解率先增大后减小,最适污染强度为150mg/L.菌株Pn2有较强的环境适应能力.温度为25～37℃、环境pH值为6.0～8.0、盐浓度1％～2％范围内,菌株Pn2生长状况良好.菌株Pn2为好氧生长,通气量越大,菌株生长越旺盛.菌株Pn2对低浓度的氨苄青霉素和氯霉素有抗性.
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