Characteristics of phenanthrene-degrading bacterium and the influence of phenanthrene to its cell surface morphology

A phenanthrene-degrading bacterium,Arthrobacter oxydans B4 which can grow in with a high concentration of phenanthrene has been isolated from a long-term PAHs-contaminated soil.The tolerance of strain B4 to phenanthrene and its biodegradation characteristics were studied.The results showed that the strain B4 in the aerobic environment was able to tolerate phenanthrene as high concentration as 2 000 mg/L,and it had a significant efficiency of phenanthrene degradation.The degradation rate of phenanthrene reached about 60% within 5 days when the initial concentration of phenanthrene in mineral salts medium(MSM) was 50 mg/L,the inoculum dosage was 20 g/L(wet weight,moisture content: 94.55%),the cell age was 48 h and pH was 7.0-8.0.Atomic force microscopy was applied to observe the surface morphology of strain B4 before and after biodegradation.The results demonstrated that phenanthrene had toxicity on B4.The cell morphology significantly changed and its ultrastructure was also complicated as reaction time increased.