Abstract: We aimed to isolate and identify highly efficient and highly-adapted engine oil-degrading bacteria for enriching the engine oil-degrading microbial strain library. Efficiently oil-degrading bacteria were obtained using the media individually supplemented with No.20 oil and vacuum pump oil as the sole carbon source，and were identified by morphology，physiological and biochemical properties，and 16S rRNA gene phylogenetics. Degradation characteristics of the strains were analyzed using UV spectrophotometry and gas chromatography mass spectrometry（GC-MS）. The most efficient oil-degrading strains，designed as JZ6，JZ18，JZ41，and JZ50，from 22 oil-degrading strains were classified as Massilia sp，Pseudomona sp，Sphingobacterium sp，and Shinella zoogloeoides sp，respectively. The degradation rate of oil reached 42.62%，33.67%，33.36% and 40.52%，when these strains were cultured in oil-containing media at 30℃ for 7 d. The strains were capable of degrading oil under the condition of pH5-9 and 20-40℃. The four strains grew on the media respectively added by dodecane，hexadecane，octadecane，benzene and naphthalene as the sole carbon source，and the strain JZ6 and JZ50 also grew well in the media containing pyrene and phenanthrene. GC-MS analysis showed that the degradation rate of strain JZ6，JZ18，JZ41 and JZ50 to total alkane was 68.66%，52.69%，49.37%，and 61.4%，and that to straight chain was 86.89%，55.98%，58.42%，and 89.13%，respectively. The strain JZ6 and JZ50 also degraded other aromatic hydrocarbon ta varied degree. The four strains of efficient oil-degrading bacteria were obtained，and had strong adaptability，thus these isolates can be used in the biological remediation of oil-polluted environment.

Key words: engine oil-degrading strain, 16SrRNA, UV spectrophotometry, GC-MS