Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by bacterial mixture

Polycyclic aromatic hydrocarbons (PAHs) are widespread pollutants and they can cause cancer, abnormality and mutation. Nine natural PAHs-degrading bacteria were obtained from polluted areas. These bacteria and the bacterial mixture can degrade phenanthrene, anthracene, pyrene and benzo[a]pyrene. The bacterial mixture can increase the degradation rates of several PAHs compounds, such as phenanthrene and benzo[a]pyrene, during the repaired process, and the degradation rates of these compounds were over 83%. The efficient degradation of PAHs should be the cooperation of key enzymes, such as dioxygenase and dehydrogenase, in the bacterial mixture. The main accumulated metabolite of above four PAHs was dibutyl phthalate detected by gas chromatography mass spectrometry, indicating that the degradation process of PAHs mainly represented the phthalic acid pathway in this work. And the toxicity of PAHs could be decreased by biodegradation. The effects of cultural factors, such as culture time, temperature, metal ions and pH on PAHs degradation efficiency were also studied.