Isolation, Identification And Characteristics Of High-molecular-weight Polycyclic Aromatic Hydrocarbons Degradation Strains

How to remediate the Polycyclic aromatic hydrocarbons (PAHs) organic pollutants in groundwater has been a major research in recent years. With high bioaccumulation polycyclic aromatic hydrocarbons (PAHs) have been confirmed to be teratogenicity, carcinogenicity and mutagenicity. Especially for the PAHs with4or more rings which are called high molecular weight PAHs (HMW-PAHs). The chemical structure of high molecular weight PAHs (HMW-PAHs) are so complex that it is difficult for them to be oxidized and bioavailabed in the environment. So PAHs are treated as a great threat for human health and environment. There are many methods to remediate PAHs pollutants from the groundwater. Among those methods, people put more attention on bioremediation methods. Compared with conventional physical and chemical methods, bioremediation method has its advantage of low cost, effective and without secondary pollution. Getting microorganisms which are capable of degrading PAHs is the primary step of bioremediation.In this paper, fluoranthene and pyrene which are kinds of the typical high molecular weight PAHs are used as the target pollutants. The bacterium Herbaspirillum chlorophenolicum FA1which can degrade fluoranthene are domesticated by both pyrene and fluoranthene for7weeks. The degradation flora are cultured and screened from the oil-contaminated soil. And the flora have been domesticated by both pyrene and fluoranthene for7weeks. Then through PCR (Polymerase chain reaction) technique to identify bacteria’s16SrDNA among the flora symples before and after domesticated. On this basis, try to explore the synergistic effects of fluoranthene and pyrene biodegradation factor. During the degradation of fluoranthene and pyrene, there may be exits synergy, promoting or inhibition between them. With a view to establishing and biological HMW-PAHs contaminated microbial remediation system repair application of technology to provide a theoretical basis. The main findings are as follows.The results of the study include:1、The mixed flora contain four kinds of Pseudomonas、Enterobacter sp.、 Hydrogenophaga sp.and Luteolibacter pohnpeiensis microbial. The Luteolibacter pohnpeiensis are first find to degrade PAHs. The mixed flora can degrade PAHs at a range condition that tempetature at20-35℃,pH from5to9. And the best condition to degrade fluoranthene and pyrene is same.That is pH7.0, temperature30℃, inoculum1014CFU/ml.2、The Herbaspirillum chlorophenolicum FA1can degrade PAHs at a range condition that tempetature at15-35℃, pH from4to9. And the best condition to degrade pyrene is pH5.0, temperature25℃, inoculum1012CFU/ml.3、FAl and mixed flora are gram-negative bacteria (G-). The outer cell of Gram-negative bacterias contains lipids and polysaccharides. So the cell can provide both a hydrophilic lipophilic layer of amphiphilic molecules, leading PAHs can easy access to the cell. It leading this study become more meaningful.4、The HMW-PAHs degradation kinetics of FA1and the mixed flora is similar. At the first time they all have a rapidly degradation, then the dagration decreasing. Probably toxic things appear during the degradation process.5、With the fluorescent and pyrene concentrations different in the degradation system, the target microorganisms show differents degradation of fluoranthene and pyrene. FA1at the system that the fluoranthene and pyrene concentrations in the ratio of 8:2can degradate pyrene better. The mixed flora can degradate the fluoranthene and pyrene better at the system that the fluoranthene and pyrene concentrations in the ratio of5:5.6、The impact of E. coli bacteria is mutually different between FA1and the mixed flora. E. coli promotes FA1’s the degradation of pyrene, at the same time E. coli restrains the mixed flora’s degradation of fluoranthene and pyrene.