长野雷夫松氏菌RE3-4吸附铅、镉及对芦苇的促生作用研究

发布时间：2018-01-27 06:43

本文关键词： 菌株RE3-4 促生作用铅镉海藻酸钠小球　出处：《安徽大学》2017年硕士论文　论文类型：学位论文

【摘要】：内生菌因具有固氮、促生长、抗病害、耐重金属及降解污染物等特性,通过分泌物质促进植物生长,间接达到净化污染物的目的,且能利用其耐受性和吸附性直接降低环境中污染物含量。本文以一株芦苇内生菌——长野雷夫松氏菌RE3-4为研究对象,考察了该菌株的生物特性及其应用。通过对菌株RE3-4合成生长素及其对重金属耐受性的研究,揭示其促进芦苇苗生长的内在机制;依据拟合Langmuir型、Freundlich型等温吸附曲线,比较菌株RE3-4对铅、镉吸附能力的大小;研制具有防流失、可回收的海藻酸钠(Na-Alg)小球,强化菌株RE3-4在水溶液中去除铅、镉离子的能力;采用SEM(-EDX)、FT-IR分析手段,揭示菌株吸附铅、镉离子的内在机理。主要结论如下:(1)菌株RE3-4在L-色氨酸(L-trp)存在的条件下能够合成生长素类似物吲哚乙酸(IAA)。菌株合成的IAA能显著促进芦苇苗生长,最佳促生浓度为1.0 mg/LO(2)菌株RE3-4对重金属离子具有耐受性,其中菌株对铅的耐受性最强,铜次之,对镉的耐受性最弱;菌株侵染的芦苇种子在不同含铅量培养基上生长不同,且在一定程度(铅浓度400mg/kg)上菌株能提高芦苇种子的萌发率及其幼苗根茎的生长。(3)通过等温吸附曲线拟合发现菌株RE3~4可吸附Pb和Cd;在吸附过程中蛋白质起主要作用,磷脂起次要作用,多糖、氨基酸等物质也对Pb和Cd有吸附作用;菌株通过细胞破损、断裂、聚集、形变等作用对Pb和Cd离子产生抗性。(4)在水溶液pH为5.0,反应运行8 h条件下,Na-Alg小球对Pb和Cd离子的吸附达到平衡;吸附过程中,O-H、C-H、C-O等官能团与Pb和Cd离子发生交互作用,多糖区也吸附了一定量的Pb和Cd;Na-Alg小球表面发生共价结合、晶体沉淀及离子交换等反应从而减少水溶液中金属离子的量;吸附Pb和Cd的Na-Alg小球解吸附后可进行二次吸附,具有较好的循环再利用性能。
[Abstract]:Endophytic bacteria have the characteristics of nitrogen fixation, growth promotion, disease resistance, resistance to heavy metals and degradation of pollutants, through secreting substances to promote plant growth, indirectly achieve the purpose of purifying pollutants. And its tolerance and adsorption can directly reduce the content of pollutants in the environment. In this paper, a Reed endophytic bacterium, RE3-4, was used as the research object. The biological characteristics and application of this strain were investigated. The mechanism of promoting the growth of Reed seedlings was revealed by studying the biosynthesis of auxin and its tolerance to heavy metals by RE3-4. According to fitting the Langmuir type Freundlich isotherm adsorption curve, the adsorption ability of RE3-4 to lead and cadmium was compared. In order to enhance the ability of RE3-4 to remove lead and cadmium ions in aqueous solution, a sodium alginate (Na-Alg) ball with anti-loss and recoverability was developed. It was revealed that the strain adsorbed lead by means of SEMM-EDX FT-IR analysis. The intrinsic mechanism of cadmium ion. The main conclusions are as follows: the strain RE3-4 can synthesize the auxin analogue indoleacetic acid (IIA) in the presence of L-trpL- tryptophan. The IAA synthesized by the strain could significantly promote the growth of Reed seedlings. The best growth promotion concentration was 1.0 mg / L ~ (2)) strain RE3-4 had the highest tolerance to heavy metal ions, among which the strain had the strongest tolerance to lead, followed by copper, and had the weakest tolerance to cadmium. The Reed seeds infected by the strain grew differently on different lead content media. To a certain extent (lead concentration 400 mg / kg), the strain could increase the germination rate of Reed seeds and the growth of seedling rhizomes. The results of isothermal adsorption curve showed that RE3~4 could adsorb Pb and CD. Protein plays a major role in the adsorption process, phospholipid plays a secondary role, polysaccharides, amino acids and other substances also have the adsorption of Pb and CD; The strain produced resistance to Pb and CD ions by cell breakage, breakage, aggregation, deformation and so on. Under the condition of pH 5.0 in aqueous solution, reaction run for 8 h. The adsorption of Pb and CD on Na-Alg beads reached equilibrium. In the process of adsorption, the functional groups such as O-HHU C-HnC-O interact with Pb and CD ions, and some amounts of Pb and CD are also adsorbed in the polysaccharide region. The surface of Na-Alg pellets is covalently bound, crystal precipitation and ion exchange reactions occur so as to reduce the amount of metal ions in aqueous solution. The secondary adsorption of Pb and CD by Na-Alg spheres can be carried out after desorption, and it has good recycling performance.
【学位授予单位】：安徽大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X172

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