细菌在粘土矿物表面吸附量测定和微量粘土矿物富集方法的研究

发布时间：2018-04-27 03:10

本文选题：高岭石 + 蒙脱石　；参考：《南京农业大学》2015年硕士论文

【摘要】：矿物与微生物相互作用是自然界中广泛存在的一种现象。矿物-细菌之间的吸附作用是两者进一步相互作用的基础。在粘土矿物与细菌共存时,体系中同时存在游离态的细菌细胞、自由的粘土矿物颗粒以及矿物-细菌复合体,因此,很难直接测定被矿物吸附的细菌数量的方法。本文开展了一系列的试验,试图获得简便、可操作性强且准确的细菌在粘土矿物表面吸附量的测定方法。土壤中经常含有2种或2种以上的粘土矿物,而有时其中的一种矿物含量很低以至于难以检测。同时,在矿物风化化学变化过程中会形成新生矿物,但新生矿物含量极低,更为检测带来相当大的难度。这时,若直接利用X-射线衍射仪(XRD)测定样品,往往极难检测到新生矿物。因此,研究工作中需要探索出一种使微量矿物组分在粘土矿物组合中得到富集的方法。本文就系统阐述了对粘土矿物组合中单一矿物富集方法的探索工作。试验结果表明,用茚三酮作为显色剂的蛋白质含量测定法可以客观地反映细菌数量。吸附时间设定为40 min比较合适。在离心时间10 min的情况下,2000 rpm的转速可以使游离态细菌和自由的矿物颗粒大部分沉淀,而矿物-细菌复合体大部分留在悬浊液中,从而可以比较准确地测定被矿物吸附的细菌数量。三种粘土矿物在溶液中的沉淀速率大小顺序为:高岭石伊利石蒙脱石,而它们对胶质芽孢杆菌YM-1菌株的吸附能力大小顺序则刚好相反:蒙脱石伊利石高岭石。矿物的比表面积、沉淀速率和表面所带电荷数量以及细菌活性是影响矿物吸附细菌的主要因素。粘土矿物与细菌之间的吸附作用力阳离子桥、静电引力等可能也起到一定的作用。利用离心法和沉降法处理高岭石(96%)+蒙脱石(4%)组合(下同)等六种矿物组合,先获得沉淀物A,再将上清液在10000 rpm转速条件下离心10 min,获得微量沉淀物B。最后利用XRD检验富集效果。结果表明,当两种矿物的比重差异较大时容易将它们分离,例如蒙脱石+高岭石、蒙脱石+伊利石、高岭石+蒙脱石和伊利石+蒙脱石组合。比重较大的矿物在沉淀物A中富集,如蒙脱石+高岭石和蒙脱石+伊利石组合。比重较小的矿物在沉淀物B中富集,如高岭石+蒙脱石和伊利石+蒙脱石组合。当两种矿物的比重比较接近时,分离效果较差,如高岭石+伊利石组合和伊利石+高岭石组合。矿物沉淀速率与比重有直接关系,比重越大沉淀越快,三种矿物的沉淀速率是高岭石伊利石蒙脱石。
[Abstract]:The interaction between minerals and microorganisms is a widespread phenomenon in nature. The adsorption between minerals and bacteria is the basis of their further interaction. When clay minerals and bacteria coexist, there are free bacterial cells, free clay mineral particles and mineral-bacterial complexes in the system. Therefore, it is difficult to directly determine the number of bacteria adsorbed by minerals. In this paper, a series of experiments were carried out to obtain a simple, feasible and accurate method for the determination of bacterial adsorption on the surface of clay minerals. Soils often contain two or more clay minerals, one of which is sometimes too low to detect. At the same time, new minerals will be formed in the process of chemical change of weathering, but the content of new minerals is very low, which is more difficult to detect. In this case, it is very difficult to detect new minerals if the samples are directly determined by X- ray diffractometer (XRD). Therefore, it is necessary to explore a method to enrich trace mineral components in clay mineral assemblage. In this paper, the method of single mineral enrichment in clay mineral assemblage is systematically discussed. The results showed that the method of protein content determination with ninhydrin as chromogenic agent could objectively reflect the number of bacteria. The adsorption time was set at 40 min. Under the condition of centrifugation time of 10 min, the rotational speed of 2000 rpm can make the free bacteria and free mineral particles precipitate mostly, while the mineral-bacterial complex remains mostly in the suspensions. Thus, the number of bacteria adsorbed by minerals can be determined more accurately. The order of precipitation rate of the three clay minerals in the solution is kaolinite Illite montmorillonite while their adsorption capacity to Bacillus glia YM-1 strain is in the opposite order: montmorillonite Illite kaolinite. The specific surface area of minerals, precipitation rate, the amount of charge on the surface and the activity of bacteria are the main factors affecting the adsorption of bacteria. The adsorption force bridge between clay minerals and bacteria, electrostatic force and so on may also play a role. Six mineral combinations, I. e., kaolinite and sedimentation, were used to treat kaolinite (96) montmorillonite (the same as the following). The precipitate A was obtained first, and then the supernatant was centrifuged at 10000 rpm rotational speed for 10 mins to obtain the trace precipitate B. Finally, the enrichment effect was tested by XRD. The results show that montmorillonite kaolinite, montmorillonite Illite, kaolinite montmorillonite and Illite montmorillonite combination are easy to separate when the specific gravity of the two minerals is different. Minerals with high specific gravity are enriched in sediment A, such as montmorillonite kaolinite and montmorillonite Illite assemblage. Minerals with small specific gravity are enriched in sediment B, such as kaolinite montmorillonite and Illite montmorillonite combination. When the specific gravity of the two minerals is close, the separation effect is poor, such as kaolinite combination and Illite kaolinite combination. The precipitation rate of the three minerals is kaolinite Illite montmorillonite.
【学位授予单位】：南京农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P57;Q93

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