Isolation, Identification And Application Research Of PAHs-degrading Microorganism

Polycyclic aromatic hydrocarbons(PAHs) are widely able to be existence in the natural environment and they are harmful to the environment and human health. PAHs have been listed as priority pullants by many countries in the world. Of all the degradation methods, bioremediation is known as one of the most efficient method with the advantages of high efficiency, economic, prevent of second pollution and wide application. Naphthalene is a kind of organic that consists 2 benzenes. It can been seen in the atmosphere, water and soil. It is the most representive organic of all the PAHs.A PAHs-degrading strain DQ-1 was isolated from petroleum-contaminated soils sampled from Da Qing oil field. The strain was identified as Pseudomonas sp.by polyphasic taxonomy including the phenotype,physic-chemical properties and16 Sr DNA sequence, named Pseudomonas sp. DQ-1.The optimum conditions of strain growth and the effects of environmental factor to hydrocarbon degradation were confirmed by adapting single factor experiments. So the best conditions of strain growth and the highest degradation of naphthalene have been acquired. The degradation rate is up to 96.5% with a 3-day incubation. And the degradation potential of naphthalene by the strain was exerted extensively.Then, the tolerance of heavy metals of DQ-1 was studied and the abilities of tolerance of heavy metals of DQ-1 was probed. It proved that strain DQ-1 can grow well within a concentration of Fe3+, Zn2+, Pb2+, Cu2+ or Cr6+. And it can keep a high naphthalene-degradation within a concentration of Fe3+, Zn2+ or Pb2+. With the test of ICP-OES, it proved that the biosorption as a possible mechanism of heavy metal resistance in DQ-1. After that, a simulated soil remediation of DQ-1 was studied. In the autoclaved soils, with a 11-day incubation, the degradation rate can reach 97.9%. So the strain DQ-1 has a great value in practical.In order to overcome the degrade limitation and poor efficiency of the naphthalene by the single bacterial strain the author chose to mix the strains group to carry on the research of the naphthalene bioremediation. The cooperative effect between TN and DQ-1 bacterial strain had been studied. It proved that the concentration of naphthalene was able to be up from 3g/L to 5g/L. The degradation rate was over 80% with 2 days incubation. In the autoclaved soils, after 7 days, the degradation rate was 95.9%. And the period of degradation was 4 days shorter than the degradation with the single bacterial strain. It improved that the efficiency of mixed strains group was higher than the single bacterial strain.