耐铅镉菌株的分离筛选及其吸附特性研究

发布时间：2018-04-13 08:39

  本文选题：耐性菌株 + 筛选　； 参考：《江西理工大学》2015年硕士论文

【摘要】：工业生产快速发展导致大量重金属进入环境,造成了严重污染。重金属污染传统的物理化学处理法投资大,运行费用高,易造成二次污染,而生物处理法因其高效、低能、环境友好成为当前处理重金属污染的热点。运用平板分离法,从江西省赣州某钨矿区受铅镉污染的土壤中分离纯化出2株对Pb2+、Cd2+都具有很高耐受性的菌株。S型菌对Pb2+、Cd2+的最大耐受浓度分别为1300mg/L、1800 mg/L,而R型菌对Pb2+、Cd2+的最大耐受浓度分别为1100 mg/L、1200 mg/L。通过对S型和R型两种菌株的生长条件进行优化,两株菌的最适生长温度为40℃,最适p H为7-7.5,最适Na Cl浓度分别为0.5%和1%。根据传统的形态学观察、生理生化实验以及分子生物学方法——16S r DNA测序比对发现:其中一株菌为细菌属于大肠杆菌属(Enterobacter sp.),命名为Enterobacter sp.S。另外一种菌还在鉴定中,命名为R型菌。将两株菌制成无活性吸附剂,该吸附剂对Pb2+、Cd2+有很好的吸附性能。各个单因素影响实验研究表明:处于不同时期的菌体对Pb2+、Cd2+的吸附效果有较大的差异;溶液p H的升高会增加单位菌体的吸附量,然而p H过高不利于菌体的吸附;随着菌体添加量的增加,Pb2+、Cd2+去除率逐渐增大,而单位菌体吸附量呈现下降趋势;随着环境温度的增加,菌体的吸附量先增大后减小;随着溶液中Pb2+、Cd2+增大,菌体吸附量明显增大,但是Pb2+、Cd2+的去除率呈现下降的趋势;通过研究时间对菌体吸附的影响发现,S型和R型对Pb2+、Cd2+的吸附是一个极其快速的过程,5 min时,吸附完成了最佳吸附量的60%以上。S型菌体对Pb2+的吸附对Langmuir和Freundlich两个等温吸附模型相符合的程度都很高;S型菌体对Cd2+的吸附更加适合用Langmuir等温吸附模型来描述,而其与Freundlich模型的相符合程度也较高;R型菌体对Pb2+吸附对Langmuir和Freundlich两个等温吸附模型相符合的程度都不是很高;R型菌体吸附Cd2+的过程更适合用Langmuir等温吸附模型来描述。扫描电镜(SEM)表明菌体表面的结构发生明显变化;能谱(EDX)显示菌体吸附了Pb2+、Cd2+;红外光谱图(FTIR)显示羟基和胺基的混合吸收峰、羧基、磷酸基团特征吸收峰都发生比较明显的强度变化,表明这些基团在Pb2+、Cd2+吸附过程中的重要作用;X射线衍射(XRD)图谱表明在吸附之后有新的物质产生。化学掩蔽胺基、羟基、羧基、磷酸基后的菌体对Pb2+、Cd2+的吸附量均有不同程度的减少,表明这些基团在菌体对Pb2+、Cd2+的吸附过程中发挥了作用。解吸实验表明,EDTA对吸附铅镉后菌体的解吸效果最好,达到90%以上;化学改性实验表明,Na OH对菌体的改性效果最佳。
[Abstract]:The rapid development of industrial production led to a large number of heavy metals into the environment, causing serious pollution of heavy metal pollution. The traditional physical and chemical treatment method of high investment, high operation cost, easy to cause two pollution, and biological treatment because of its high efficiency, low energy, environmentally friendly has become a hot topic in the treatment of heavy metal pollution. Using plate separation method, the lead cadmium pollution from the Jiangxi province Ganzhou tungsten mine soil Pb2+ was isolated in 2 strains of bacteria, strain.S type Cd2+ has very high tolerance to Pb2+, the maximum tolerated concentration of Cd2+ were 1300mg/L, 1800 mg/L, and the R type bacteria to Pb2+, the maximum tolerated concentration of Cd2+ was 1100 mg/L. 1200 mg/L. by optimizing growth conditions for S type and R type two strains, two strains of the optimum temperature is 40 DEG C, the optimum P of H is 7-7.5, the optimum Na concentration of Cl was 0.5% and 1%. respectively according to the traditional morphological observation, physiological and biochemical. Found the testing and molecular biology methods -- 16S R DNA sequencing: one strain of bacteria belonging to the genus Escherichia coli (Enterobacter sp.), named Enterobacter sp.S. is another kind of bacteria identification, named R type bacteria. Two strains from the activated adsorbent, the adsorption of Pb2+, Cd2+ a good adsorption performance. Experimental study on the effect of each single factor showed that at different times of the biomass of Pb2+, Cd2+ adsorption effect is different; the increase of H P solution will increase the adsorption capacity per cell, but p H is too high is not conducive to bacterial adsorption; with the increase of amount of bacteria, Pb2+, Cd2+ the removal rate increased gradually, and the adsorption capacity per cell decreased; with the increase of environmental temperature, the adsorption capacity was increased first and then decreased; with the increase of Cd2+, solution Pb2+, biosorption was significantly increased, but Pb2+, Cd2+ removal The rate of decline was found to influence the adsorption of bacteria; through the study of the S type and R type of Pb2+, the adsorption of Cd2+ is a very rapid process, completed 5 min, adsorption adsorption above the best adsorption amount of 60%.S strains on Pb2+ correspond to Langmuir and Freundlich two isothermal the adsorption models have a high degree of adsorption; S type of Cd2+ was more suitable for the Langmuir isotherm model and the Freundlich model is consistent with a higher degree of type R; biosorption is consistent to Langmuir and Freundlich two adsorption isotherm model is not very high degree of Pb2+; R biosorption of Cd2+ is more suitable for the Langmuir isotherm model to describe. Scanning electron microscopy (SEM) showed that the structure of the cell surface changed significantly; energy spectrum (EDX) showed that biosorption of Pb2+, Cd2+; infrared spectra (FTIR) showed that the hydroxyl and amine Mixed absorption peak, carboxyl group, phosphate group characteristic absorption peak change intensity obviously, suggesting that these groups in Pb2+, Cd2+ has an important role in the adsorption process; X ray diffraction (XRD) spectra showed that after adsorption in new material. Chemical masking of amino, hydroxyl, carboxyl, phosphoric acid medium the cell of Pb2+, reduce the adsorption of Cd2+ in varying degrees, indicating that these groups in the cell of Pb2+, play a role in the process of Cd2+. The adsorption desorption experiments show that EDTA adsorption desorption effect on biomass of lead and cadmium after the best, more than 90%; chemical modification experiments show that Na OH on cell change the effect of the best.

【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X172

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