Enriched Of Oil-degrading Microbial Flora From Sediments In The Bohai Sea And Optimization Of Degradation

Hydrocarbon-degrading microflora are ubiquitous in the sea, including hydrocarbonoclastic bacteria that utilize hydrocarbons almost exclusively as carbon and energy sources. However, the microflora usually could not reproduce their efficient hydrocarbon-degrading ability in the field environment due to the lack of the ability to adapt to the on-site envirnment. Therefore, the technical to strengthen the remediation has major guiding significance in development of the hydrocarbon-degrading. The main purpose of this study is to obtain oil-degrading mixed culture isolated from the sediment of the Bohai Sea oil contaminated areas, and analyzed the environmental conditions of the impact of oil-degrading mixed culture. Mover this study is to optimize the degradation conditions. The main object is to provide degrading strains source, and a theoretical basis for strengthen cleanup measures in the case of an actual spill.Sediments polluted by petroleum was collected from the Bohai Sea. Oil degradation single strain was isolated from sediment by use of plate streaking, and the oil-degrading mixed microflora was constructed with the isolated strains. In addition, the factors of environmental conditions( p H, N/P, oil-contaminated, inoculum concentration) were investigated, which affect crude oil degradation ability. Experiments were designed to obtain the influence rules with different conditions. The experiment was carried out in the simulating mixing system with sedimentaton to study crude oil degradation ability of flora in sediments,and the conditions(N/P, inoculum concentration) were optimized on degradation under different environmental temperatures. The experimental results showed that:1. After 3 cycles of enrichment, oil-degrading mixed culture was obtained from the sediment samples. By degradation experiments, the isolated mixed microflora have high degradation activity using the oily inorganic salts medium, which the degradation rate is58.2%.2. Two hydrocarbon degrading bacteria were isolated from Bohai Sea sediment:Gordonia amicalis D12, Rhodococcus sp.D2.3. Influencing conditions experiment showed that the Gordonia amicalis D12 had a oil degradation rate(43.98%) when the p H was 9, the inoculums account was 11%, and the N/P was 7. The Rhodococcus sp.D2 had a oil degradation rate(23.75%) When the p H was 8, the inoculums account was 9%,and the N/P was 5. the variation of oil-contaminated concentration has fewer affected on the degradation rate.4. Gordonia amicalis D12 combined with Rhodococcus sp.D2. has high efficient in petroleum degrading experiment. The mixed culture was carried out in the simulating mixing system with mud and water. The optimum conditons for crude oil degradation are determined to be inoculum concentration of 20%, N/P of 5:1.5. Mixed culture degradation is increased with the increase of the environmentaltemperature(30 ℃ degradation rate of 84.19%). When the temperatures is lower in winter, the degradation rate is increased with increasing inoculation amount(degradation rate of 40.80%).The oil-degradation rate is the maximum up to 65.90% in spring and autumn when inoculum concentration is 10%, and the oil-degradation rate is the maximum up to 84.19% in summer.