Surfactant Producing Petroleum-degrading Strain And Repair Of Oil Pollution Of Soil Organisms In Northern Pilot Study

With the development of petroleum industry, the soil in in the north of Shanxi Province has been widely and seriously polluted by petroleum hydrocarbons, which not only destroys the local soil ecological environment balance, but also causes harm to life and health of the residents, and even to sustainable development of the local economy. Microbiological remediation technology has been taken as an important and effective way to remediate petroleum- contaminated soil for its low-cost, high-efficiency, safty and free additional pollution. Using biosurfactants to intensify microbiological remediation on petroleum-contaminated soil attracts increasingly wide attention and appreciation at home and abroad for the reasons that biosurfactant can effectively enhance the bioavailability of the petroleum hydrocarbons and greatly improve the degradation efficiency of microbe, and compared with the chemical surfactants, biosurfactants are more effective and have more advantages.This paper is to conduct study in laboratory for the task of repairing petroleum-contaminated soil in the north of Shanxi Province by microbiolgical remediation technique. Aimed at enhancing the efficiency of the contaminated soil in-situ bioremediation, this research focuses on secreening and breeding microbe seeds which are both high-yield biosurfactant and hydroearbons-degrading to enlarge the efficient microbe resource for study and applying, enhancing degradation rate and effect, investigating the characteristics and capability of the strain, and then conducting bioremediation test on the petroleum-contaminated soil. By this study we want to lay foundation and provide information of the strain to this task and explorit a efficient, green and sustainable methods towards bioremediation on petroleum-contaminated soil in the north of Shanxi Province.A petroleum hydrocarbons-degrading strain named LX-6 that is capable of high-producing biosurfactant was finally isolated from crude oil- contaminated soil in the vicinity of Changqing oil-field by hydrocarbon enrichment culture, testing its ability to produce biosurfactant and degrade diesel. The strain was identified as Pseudomonas sp. based on its morphological and physiological characteristics. To induce and breed LX-6 by He-Ne laser, and a ideal mutation strain was screened and named LX-6'(7). It's ability was improved based on the result of measuring:diesel biodegradation rate was increased from 78.2% to 84.7%, emulsifying volume was 5.07mL, oil-discharge diameter was 9.1cm, and the surface tension of the medium was 32.6 mN/m, which are higher than that of the original strain and inherit stably.The biosurfactant produced by strain LX-6'(7) was extracted, purified and studied by various of methods, such as column chromatography experiment, color column chromatography and IR spectrum. Results showed that the purified biosurfactant was yellow powdery crystal and output is 0.92 g/L. It was identified as glycolipid, including rhamnose and the glucose two kinds of monosaccharide ingredient, its CMC is 50mg/L, and it can keep its surface activity at high temperature, in high-salinity solution and in a wide PH arrange. Moreover, the stability of its emulsifing activity performs well. Strain LX-6'(7) showes great stability against temperature, pH and mineralization, therefore, it can be applied in much environment. The strain can use and degrade Straight-chain paraffin and aromatic hydrocarbon, but the cycloalkanes.The strain LX-6'(7) was used for 60 day-long simulation test of bioremediation on the petroleum-contaminated soil in the north of Shanxi Province. The effect of this strain on TPH degradation in soil was investigated through detecting quantity of strain, dehydrogenase activity, surface tension, degradation rate of TPH. GC-MS was used to carry on the qualitative and quantitative analysis to the degeneration effect of petroleum hydrocarbon component. The effect of this bioremediation is satisfying based on each test result. Degradation rate of TPH reached about 82.6% within 60 days, and the components of C16-C24, C24-C28 and that more than C28 had been degraded obviously. The Pseudomonas sp. LX-6'(7) showed powerful potential for bioremediation on pedo-ecological environment in the north of Shanxi.