【作者】 时进钢；

【导师】 袁兴中； 曾光明；

【作者基本信息】 湖南大学 ， 环境工程， 2004， 硕士

【摘要】 生物表面活性剂(Biosurfactant)是由微生物产生的具有高表面活性的生物分子。相对于化学合成的表面活性剂，生物表面活性剂对生态系统的毒性较低，且可生物降解。目前，虽然对微生物产生生物表面活性剂已经有较多的研究，但是这些研究都是通过筛选得到生物表面活性剂生产菌，进而对其各种性质进行研究，而针对已鉴定出的各种微生物进行生物表面活性剂生产能力的研究，以及研究它们产生生物表面活性剂能力差异的根本原因却未见报道。 本文通过对从中国典型培养物保藏中心(CCTCC)购得的4株铜绿假单胞菌(Pseudomonas aeruginosa)和2株枯草芽孢杆菌(Bacillus subtilis)的研究发现，它们产生生物表面活性剂的能力有很大的差异，其中有2株铜绿假单胞菌和1株枯草芽孢杆菌具有生物表面活性剂的生产能力。实验通过正交实验等方法对微生物生长的碳源、氮源以及生长因子等因素进行了研究，确定了两种细菌生产生物表面活性剂的最佳条件，并对制得的生物表面活性剂进行了鉴定，因此本实验在方法上具有一定的创新性。 目前，沉积物的重金属污染已经引起了国内外学者的重视，有关河流沉积物重金属污染的生态风险研究、沉积物中有机质含量和重金属污染的相关性、沉积物中重金属的释放规律等研究已经成为一个研究热点，但有关沉积物重金属污染的修复的研究在国内还未见有报道，在国际上也是一个新的研究领域。有关对沉积物中重金属去除的研究仅有Mulligan C N等人的少量报道。 本文通过铜绿假单胞菌产生的鼠李糖脂生物表面活性剂对沉积物中重金属的去除作用的研究表明，鼠李糖脂对沉积物中的Cd、Pb有明显的去除作用，在鼠李糖脂溶液的pH值为10.0的条件下对重金属的去除效率最好，而且当鼠李糖脂在沉积物上的吸附达到饱和时去除效率达到最大；通过连续萃取对提取前和提取后的沉积物样品中重金属的形态进行了分析，发现鼠李糖脂对重金属的去除效率和重金属的形态有关，对可交换态的去除效率最大，在碱性条件下对有机结合态也有较好的去除效率；通过4次连续的提取，使Cd和Pb的去除效率分别达到80.1％和36.5％；沉积物中重会属是通过和鼠李糖脂生物表面活性剂的胶术结合而得到去除的，当胶术破坏后，鼠李糖脂不再具有和重金属结合的能力。更多还原

【Abstract】 Biosurfactant is a high surface-active agent synthesized by microorganism. Compared with chemical surfactant, biosurfactant has a low toxicity to ecological system of Earth and can be biodegraded by microorganism. There are a lot of researches on biosurfactants and their producers, but most researches are focused on microorganisms that are screened for producing biosurfactant. The researches on the biosurfactant-producing ability of microorganisms that have been identified and the reasons for the difference in their ability have not been reported.Four Pseudomonas aeruginosa and two Bacillus subtilis obtained from China Center for Typical Culture Collection (CCTCC) were studied in this research. The results show that there was a great difference in their ability to produce biosurfactant and only two Pseudomonas aeruginosa and one Bacillus subtilis can produce biosurfactant. The optimal nitrogen sources, carbon sources and growth factors were studied by orthogonal experiments. The best conditions for biosurfactant-producing of Pseudomonas aeruginosa and Bacillus subtilis were determined and then two biosurfactants produced by Pseudomonas aeruginosa and Bacillus subtilis were identified by TLC and HPLC-MS. So this research is innovative in the research method.The pollution of sediment by heavy metals is noted by more and more researchers. The researches vary from ecology risk of metal-polluted sediment, the relation between the organic content in the sediment and heavy metal content, to the releasing regulation of heavy metal in the sediment, but the research on the remediation of polluted sediment is a new research field in the world. The research on the metal removal from sediment is still limited to the reports by Mulligan C N.The potential of microbially-produced surfactant (rhamnolipid) to remove cadmium and lead from sediment was investigated in this study. Batch washings were conducted on the sediment with different solution pH and rhamnolipid concentrations. And the speciation of heavy metals in the sediment before and after washing was analyzed by sequential extraction. The results show that rhamnolipid can remove cadmium and lead from sediment efficiently. The heavy metal removal was optimum when the pH of rhamnolipid solution was 10.0, and the removal efficiency was thehighest when the sorption of rhamnolipid on the sediment reached a plateau. The speciation of the heavy metals had an effect on the removal efficiency, and exchangeable and organic fractions could be removed efficiently. Four successive washings removed 80.1% cadmium and 36.5% lead. Biosurfactant rhamnolipid has a low toxicity to ecological system of the Earth and can be recovered by precipitation, so its potential in the remediation of metal-polluted sediment is great.更多还原