Microbial Remediation Of Oil Contaminated Soil

According to the actual state of oil polluted soil and main problems in bioremediation of oil polluted soil in china, such as lack of oil degrading microorganisms, confusion of the mechanism between microorganisms, faultiness of the bioremediation techniques and so on, oil degrading microorganisms were isolated firstly in this thesis, and microbial community C9 was constructed by further screening of functional microorganisms based on the components of crude oil. The oil degrading effects of C9 was tested by bioremediation experiment of oil polluted soil. The dynamic changes of C9 and other microorganisms were studied by colony counting, PCR-DGGE and Biolog microplate, in order to clarify the principle between microorganisms. The main results of this thesis were as follows:1) 260 strains oil degrading microorganisms were isolated from oil polluted samples, and community C9 was constructed, the oil degrading rate of C9 reached 55.5% in 5 days, 15.5% higher than any sole oil degrading bacterium. And gas chromatography analysis proved that C9 degraded saturated hydrocarbon and aromatic hydrocarbon effectively.2) The strains among C9 were identified as Rhodococcus erythropolis, Ochrobactrum anthropi, Pseudomonas aeruginosa and Rhodococcus rhodochrous respectively.3) The oil degrading conditions of C9 in laboratory was optimized. The optimal pH value was 7-10, the optimal N and P sources were KNO₃ and K₂HPO₄, the inoculation proportion of each strain was SL-51: SL-84: SL-133: SL-163=1:1:20:1. The optimal conditions of oil degradation was that there were 3g KNO₃, 1g K₂HPO₄, pH 8, 6.9% inoculation volume in 1000mL culture solution with 0.25% oil concentration, under the optimal conditions the degrading rate reached 83%, and saturated hydrocarbon and aromatic hydrocarbon were degraded more drastically.4) The result of bioremediation experiment of simulated oil polluted soil showed that oil degrading rate reached 82% in treatment with addition of community C9 and nutrients in 102 days of remediation period, the result indicated that the community C9 was crucial for accelerating oil degradation in oil polluted soil.5) The result of continuous changes of C9 in bioremediation of oil polluted soil monitored by PCR-DGGE technique showed that Community C9 could colonize stably in oil polluted soil for a long time. Results of micro-ecological study indicated that community C9 was the dominant microbial community at the beginning of bioremediation (from day 0 to day 21), the bacterial amounts in soil began to decrease at the middle and later stage(from day 22 to day 102), and the metabolic abilities also changed with the changes of microbial community structure.The study not only provided microbial resources for microbial remediation of oil polluted soil, but also brought forward a new pathway for construction of microbial community in the future, provided academic basis for optimizing the microbial remediation technology of oil pollution as well.