[Screening of a phenanthrene-degrading bacterium and its degradation conditions]

Several PAHs-degrading bacteria were isolated from the soil near a petrochemicals factory, and one strain Fl0a identified as B. sphaericus was chosen for use. The study on the phenanthrene-degradation potential of the strain and its affecting factors showed that at 28 degrees C, the degradation rate of phenanthrene (50 mg x L(-1)) was 98.12% after 27 hours rotary culture, and 98.47% after 84 hours static culture. F10a had a good phenanthrene-degradation capability when the pH was 4, 6 and 8, but its growth was inhibited when pH was 10. Cr2+ was toxic to the strain, Cu2+ could delay the degradation of phenanthrene, while Zn2+ and Pb2+ had no significant effects. The degradation rate of phenanthrene (200 mg x L(-1)) was 99.6% after 84 hours rotary culture. A significant positive relationship was found between bacterial growth and phenanthrene degradation.