Bacterial Consortium Characteristics And Applied Research On Oil Degradation

With the development of social economy, countries in the world need more and more oil. At the same time caused great harm to the ecological environment. Bioremediation, especially microbial remediation increasingly becomes the focus of scientists studying. The main purpose of this study is enriched in domesticated oil-degrading bacteria consortium, and to study their remediation properties. The main object is to provide a theoretical basis for getting oil-degraded bacteria consortium from the soil polluted by crude oil and its corresponding biofertilizer applied petroleum-contaminated soil remediation.Soil samples contaminated by crude oil came from the Tianjin Dagang Oilfield. We adopted two typical enrichment domesticated medium to screen oil-degrading bacteria consortium, and analyzed the number and structure of the bacterial consortium. Using growth curve experiments to understand the growth characteristics of the bacterial consortium, we selected environmental factors, which affect microbial growth and reproduction, and designed experiments to obtain the influence rules by different factors. The experiment was carried out in shaking culture conditions; last through the laboratory studies, we investigated the practical application effects on petroleum-contaminated soil of the bacterial consortium. The results are as follows:1. After four cycles of enrichment domestication, four oil-degrading bacteria consortium was obtained from the two oil-contaminated soil samples. By degradation experiments, when the initial crude oil concentration is5000mg/L, the bacteria consortium, which was adopted sampling point2to enrich and domesticate, using the inorganic salts plus crude oil medium, showed higher degradation activity.2. Through the experiment of microorganism’s quantity determination and PCR-DGGE experiments, we found that inorganic salts plus crude medium was more conducive to the growth of microorganisms and microbial diversity.3. For the same oil-contaminated soil, the dominant bacteria in the bacterial consortium were different by diverse enrichment domesticated method. The bacterial consortium cultured by inorganic salts plus crude oil dominant bacteria was the Sphingobacterium and Bacillus licheniformis. Meanwhile, the bacterial consortium cultured by beef extract, peptone plus crude oil the dominant bacteria was Chitinophaga.4. Influencing factors experiment showed that the bacterial consortium whose degradation activity was best, when the in the initial oil content was3000-7000mg/L, had a higher oil degradation rate (22.21%～28.08%). when the initial inoculums size was5%～11%, the oil degradation rate was higher than28.08%. The bacterial consortium was highly tolerant to salt, in the initial salt content of12g/L, its oil degradation rate was25.60%. The bacterial consortium can degrade crude oil in the neutral and alkaline conditions, which meaned there were good prospects for the application.5. Petroleum-contaminated soil remediation experiments showed that two enrichment of bacterial consortium, when the cast added to the soil in the form of a bacterial solution, after58d repair, oil degradation rate was40.9%-56.56%, which was higher than CK sterilization group and CK non-sterile group (28.69%～50.67%). It demonstrated that exogenous bacterial flora played a key role in the repair of petroleum-contaminated soil.6. The impact of indigenous microorganisms on exogenous microorganisms was related to the initial microbial dosage. After the second dosing exogenous bacterial flora, there were no apparent growths in degradation of the oil. This was most likely because exogenous flora after the second dosing, the external environment was not suitable for its growth, the survival time become short, and thus the degradation rate had no elevated. Therefore, in considering the practical application, the dosage and climate conditions should be considered.