“微生物—金属氧化物”间界面相互作用机制及其应用研究

发布时间：2018-03-29 06:28

本文选题：微生物吸附　切入点：纳米磁珠　出处：《哈尔滨工业大学》2015年硕士论文

【摘要】：微生物在环境治理中发挥着重要的作用,在环境微生物技术中存在各种形式的界面反应,影响微生物在介质表面的贴附。研究微生物与金属氧化物的界面反应,有助于解决膜污染、生物腐蚀等一系列的环境问题,也可指导开发新型微生物选择性富集分离技术,因而在微生物检测以及环境风险预警方面都具有重要的意义。本研究基于DLVO理论指导,开发纳米磁珠分离技术,实现对玻璃纤维滤膜上微生物的分离;结合经典过滤理论与铁载体在金属氧化物表面形成化学键的新型作用形式,表征铁载体介导下,微生物吸附行为特征;开发铁载体修饰的磁性材料,探究修饰后材料选择性富集特定微生物的可行性,取得如下研究成果:纳米磁珠分离技术在酸性条件下,吸附玻璃纤维滤膜上的微生物,具有最大的收率;经16sRNA基因高通量测序及群落分析,酸性条件下磁珠法富集微生物的群落结构与原有微生物组成高度近似。共线性分析显示酸性条件下吸附微生物样品与对照样品间的夹角(16.2°)与同一微生物群落DNA两次PCR扩增的结果近似(14.2°),显示该方法能够实现对滤膜上微生物无差别的吸附。构建了基于滤柱实验的微生物吸附表征体系。胞外聚合物(Extracellular Polymeric Substances,EPS)缺失型菌株EPS-与野生型具有EPS菌株EPS+在玻璃珠滤料中,表现出不同的过滤形式。EPS-符合经典过滤理论的log-linear模型。而EPS+由于EPS影响,表现出与经典过滤模型相偏差的形式,即在滤层15 cm位置出现最大截留浓度的显著拐点。在甲磺酸去铁胺(Deferoxamine B,DFOB)修饰滤料实验中,BW25113表现为与经典过滤理论相偏差。滤料中截留细菌浓度先增后减,在滤层15 cm处能截留最大的细菌浓度。作为对照,在未用DFOB浸泡过的滤料中,由于EPS的存在截留细菌也表现为先增后减,在滤层下10 cm具有最大的截留细菌量。相比较对照组,实验组截留BW25113的细菌量显著增高了50%。制备的铁载体修饰的磁性纳米材料,在编码去铁胺受体蛋白过表达菌fhuE++和编码去铁胺受体蛋白缺失型菌fhuE-组成的混合体系中,铁载体修饰后的磁珠能够优先吸附fhuE++菌株,吸附fhuE++的数量是fhuE-的4倍,且远高于裸Fe_3O_4吸附fhuE++的量。同时,甲磺酸去铁胺修饰后的纳米磁珠,在酸性和中性条件下,吸附深圳湾海水中最易与DFOB结合的放线菌数量显著的高于碱性条件和裸Fe_3O_4磁珠吸附的放线菌量。
[Abstract]:Microorganisms play an important role in environmental treatment. There are various forms of interfacial reactions in environmental microbial technology, which affect the adhesion of microbes to the surface of media. The interfacial reactions between microbes and metal oxides are studied. It helps to solve a series of environmental problems, such as membrane fouling, biological corrosion and so on, and can also guide the development of new microorganism selective enrichment and separation technology. Therefore, it is of great significance in microbial detection and environmental risk early warning. Based on the guidance of DLVO theory, the separation technology of nano-magnetic beads is developed to achieve the separation of microbes on glass fiber filter membrane. Combined with the classical filtration theory and the new form of iron carrier forming chemical bond on the surface of metal oxide, the adsorption behavior of microorganism was characterized by iron carrier, and the magnetic material modified by iron carrier was developed. The feasibility of selective enrichment of specific microbes by modified materials was explored. The following results were obtained: under acidic conditions, the nanomagnetic bead separation technology adsorbed microorganism on glass fiber filter membrane with maximum yield; High throughput sequencing and community analysis of 16sRNA gene were performed. The community structure of microbe enriched by magnetic bead method under acidic condition is similar to that of the original microorganism. Co linear analysis shows that the angle between adsorbed microorganism sample and control sample under acid condition is 16.2 掳) and that of the same microbial community DNA. The results of secondary PCR amplification were approximately 14.2 掳, which showed that the method could achieve the same adsorption of microorganism on filter membrane. A microorganism adsorption characterization system based on filter column experiment was constructed. The extracellular Polymeric substancesEPS-deleted strain EPS- and wild strain EPS- were constructed. Type A strain EPS with EPS in glass bead filter media, Different filtering forms. EPS- log-linear model, which accords with the classical filtering theory, and EPS, because of the influence of EPS, shows the form of deviation from the classical filtering model. In the experiment of deferoxamine methanesulfonate modified with DFOB, BW25113 deviated from the classical filtration theory. The concentration of bacteria in filter media increased first and then decreased. The maximum bacterial concentration could be retained in the filter layer of 15 cm. As a control, in the filter media without DFOB immersion, the amount of bacteria interception was increased first and then decreased because of the presence of EPS, and the maximum amount of bacteria interception was found at 10 cm below the filter layer. Compared with the control group, there was no significant difference between the two groups. The amount of bacteria intercepting BW25113 in the experimental group increased significantly by 50%. The magnetic nanomaterials modified with iron carrier were prepared in a mixed system composed of fhuE encoding the deferramine receptor protein overexpression strain and fhuE- encoding the deferramine receptor protein deletion strain. The magnetic beads modified with iron carrier could preferentially adsorb fhuE strain, and the amount of fhuE adsorbed was 4 times as much as that of fhuE-, and was much higher than that of bare Fe_3O_4 adsorbed fhuE. At the same time, in acidic and neutral conditions, the modified magnetic beads were treated with deferoxylamine mesylate. The quantity of actinomycetes most easily bound to DFOB in Shenzhen Bay seawater was significantly higher than that in alkaline conditions and bare Fe_3O_4 beads.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X172

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