【作者】 武金装；

【导师】 刘红玉；

【作者基本信息】 湖南大学 ， 环境工程， 2008， 硕士

【摘要】 石油烃降解菌广泛存在于自然界中。影响石油污染物降解效果的因素很多,如石油烃的种类和组成、物理状态、浓度、温度、pH值、供氧及营养物质等。石油烃的降解速率及最终降解效果是上述各种因素综合作用的结果。由于石油烃的自然降解过程缓慢,而向污染环境中添加某些物质,优化降解条件,往往能加速石油污染物的生物降解过程。已有研究表明,表面活性物质可以促进石油烃的乳化,提高石油烃在水中溶解度及生物可利用性。与化学合成的表面活性剂相比,生物表面活性剂因其具有无毒、可生物降解、生态安全和高生物活性等特征越来越受到人们的关注。现在已经成为水体污染治理的热点。本课题首先从长沙市某炼油厂受石油烃污染的土壤中分离筛选出以0#柴油为唯一碳源生长的9株石油烃降解菌。并对菌株的降解能力进行了研究,确定降解优势菌株。其中一株菌能在3d内能使柴油的降解率达到71.7%。经形态学特征和生理生化特性鉴定,这株菌为假单胞菌属。其次本文研究了培养时间、pH值、接种量、温度、柴油浓度、N源对菌株降解率的影响,实验结果表明,该菌株在培养时间为6d、pH值为5.0、接种量为5%、温度为35℃、柴油浓度为1000mg/L、N源为(NH4)2SO4的条件下生长旺盛,降解率达到了80%。此外本文还研究了如何从发酵液中提取表面活性剂,同时测定发酵液的表面张力,证明该菌能够产生生物表面活性剂,对产表面活性剂的条件进行优化,使表面活性剂达到最高产量。结果表明,假单胞菌在温度为30℃、初始pH为8.0～9.0、转速为200r/min、氮源为NH4NO3的条件下培养2d,培养液的表面张力可由69mN/m降至31.4mN/m,此时表面活性物质的产量达到了1.62g/L。将该菌产生的生物表面活性剂用于柴油降解实验,72h柴油去除率达到了85.7%,比不加表面活性剂的效果好。从降解前后柴油GC-MS图谱分析表明,该菌主要将C17-C29之间的直链烃和少量支链烃降解成C14-C18的短链烃。这为该菌株及其合成的表面活性物质应用于柴油污染土壤和水体的生物修复提供了有力的依据。更多还原

【Abstract】 There are many oil degrading strains in the nature. The degradation of the petroleum hydrocarbons is influenced by many factors, such as the sort and composition of petroleum hydrocarbons, the physical state, the concentration, temperature, pH, oxygen supply, nutrients, et al. The degrade speed of petroleum hydrocarbons and the final effect is the interactional result of all the factors.Because the natural degradation ratio of petroleum hydrocarbons is slow, adding some materials to the polluted environment, and optimizing the degradation condition can often accelerate the biodegradation of the petroleum pollutant. Some researches have indicated that surface-active compounds can promote the emulsification of the petroleum hydrocarbons, increase the solubility and the bioavailability of the petroleum hydrocarbons in the water. Compared with the chemical surfactants, biosurfactants are attentioned by more and more people because of their nontoxic, biodegradability, mildness to the environment, high bioactivity and so on. At present, it is becoming the hot of water pollution control. Our research was focus on the following aspects and received several results:Firstly, nine diesel oil degradable strains were obtained from oil-contaminated soil by using screening cultural medium method which using 0# diesel oil as the sole carbon source. The degradation ratio of diesel oil by the strains was tested by using ultraviolet spectrometry method. One of the strains showed potential for further utilization with a degradation ratio of diesel oil by 71.7% incubating for 3 days. Based on the morphological, physiological and biochemical test results, the strain was identified as Pseudomonas sp..Secondly, six factors that affect the strain growth and the degradation ratio to diesel oil, such as pH value of the culture medium, temperature, inoculation amount, N source, initial diesel oil concentration and incubation time, were also studied in the proposed paper. The result showed that the optimum culture condition for Pseudomonas sp. strain was pH5.0, inoculation by 5%, (NH4)2SO4 as the N source in the culture medium and incubation under 30℃. When the proposed strain grows under this condition, 80% of the diesel oil could be degraded with an initial concentration of 1000mg/L and incubating for 6d.Furthermore, this paper also studied the extract of biosurfactant from broth. The Pseudomonas was capable of producing glycolipids biosurfactant by a series of tests including surface tension determination, thin-layer chromatography assay etc, and could reduce the surface tension of fermentation solution. The analysis of different culture conditions indicated that the biosurfactant produced by Pseudomonas was able to reduce the surface tension of fermentation solution from 69mN/m to 31.4mN/m when incubating for two days in conditions that the temperature was 30℃, the initial pH was 8.0～9.0, the shaking speed was 200r/min, the nitrogen source was NH4NO3. At the same time, the output of biosurfactant was 1.62g/L. Employing the biosurfactant to degrade diesel oil, 85.7% of the diesel oil was removed after 72h,it had good effect. Using the techniques of GC-MS, the effect of biosurfactant on degrading the composition of diesel oil was analyzed. The results showed it could degrade C17-C29 straight chain alkanes and some branched ones into C14-C18 short chain alkanes. This paper will provide strong basis for the strain and its biosurfactants applied in oil-contaminated soil and water.更多还原