类芽孢杆菌SB-6菌株对2:1型粘土矿物风化的影响及机理

发布时间：2018-06-06 23:12

本文选题：蛭石 + 蒙脱石　；参考：《南京农业大学》2015年博士论文

【摘要】：粘土矿物的转变过程总体上反映了土壤的形成过程。因此,对粘土矿物的风化过程及风化产物开展系统的研究,有助于深刻理解土壤的形成与演变、地球的生态系统演化及元素地球化学循环。研究表明,微生物不仅能够促进矿物的风化,还能加快矿物的转变,甚至形成新的矿物。但到目前为止,在矿物与微生物相互作用的研究中,研究者主要关注的是营养元素的释放效果,缺乏对矿物转变方向及风化机理等的综合研究。本文选择土壤中三种常见的2:1型粘土矿物—蛭石、蒙脱石、伊利石为矿物材料,以土壤中常见的类芽孢杆菌(Paenibacillus sp.)为微生物材料,通过一系列的粘土矿物-细菌相互作用实验,研究了粘土矿物对类芽孢杆菌SB-6菌株的吸附作用及对其分泌物的影响,重点研究了SB-6菌株作用下粘土矿物结构的变化及元素的溶出规律。本文试图为阐明细菌作用下粘土矿物的风化机理提供科学依据。本文的主要研究结果包括五个方面:(1)类芽孢杆菌SB-6菌株可以加快粘土矿物的风化,主要表现在:粘土矿物-细菌作用后的溶液中主要阳离子浓度均明显高于灭活菌对照实验;随着培养时间的延长,蛭石、蒙脱石的结晶度(V/P比值)呈现下降趋势,伊利石的衍射峰强度比值(1001/1003)和开形指数(Ns)呈上升趋势,这些均表明它们的结晶度有所降低;蒙脱石和伊利石在风化过程中还形成了新生矿物;对照实验中无此现象。(2)矿物结构的变化及新生矿物的形成表明,粘土矿物之间存在如下的演化方向:蒙脱石→伊利石→埃洛石。(3)计算结果表明,金云母/蛭石混层结构中蛭石的比例没有发生明显变化。部分蒙脱石转变为伊利石;在蒙脱石风化实验的后期(第50d以后,此时pH值6),蒙脱石层间域释放出的Ca~(2+)与细菌新陈代谢作用形成的碳酸根离子结合形成方解石。伊利石风化实验的后期,风化产物中出现埃洛石和方解石。(4)细菌分泌的有机酸通过酸解和络合作用促进元素从矿物的晶格和层间释放出来。细菌分泌的胞外多糖对矿物的风化没有明显的促进作用,但可能在碳酸盐矿物的形成过程中充当了成核模板。(5)粘土矿物对SB-6菌株生理特性的影响表现明显。在不同矿物存在时,细菌代谢物种类及浓度等具有明显差异。细菌的生理特性与矿物的种类有关。(6)在SB-6菌株的作用下,三种粘土矿物的风化强弱顺序为蒙脱石伊利石蛭石。
[Abstract]:The transition process of clay minerals reflects the formation process of soil in general. Therefore, a systematic study of the weathering process and weathering products of clay minerals is helpful to understand the formation and evolution of soil, the evolution of the earth's ecosystem and the geochemical cycle of elements. The results show that microbes can not only promote the weathering of minerals, but also accelerate the transformation of minerals, and even form new minerals. But up to now, in the study of the interaction between minerals and microorganisms, the researchers mainly pay attention to the release effect of nutrient elements, and lack of comprehensive research on the direction of mineral transformation and weathering mechanism. Three common 2:1 clay minerals in soil, vermiculite, montmorillonite and Illite, were selected as mineral materials. The adsorption of clay minerals on Bacillus SB-6 strain and the effect of clay minerals on its secretion were studied by a series of experiments on the interaction between clay minerals and bacteria. The variation of clay mineral structure and the dissolution of elements under the action of SB-6 strain were studied. This paper attempts to provide a scientific basis for elucidating the weathering mechanism of clay minerals under the action of bacteria. The main results of this study include five aspects: Bacillus SB-6 can accelerate the weathering of clay minerals. The main results are as follows: the concentration of main cations in the solution after the action of clay minerals and bacteria is obviously higher than that in the control experiment of inactivated bacteria; With the increase of culture time, the crystallinity of vermiculite and montmorillonite (V / P) decreased, the diffraction peak intensity ratio of Illite (1001 / 1003) and the open shape index (Ns) increased, which indicated that the crystallinity of vermiculite and montmorillonite decreased. Montmorillonite and Illite also formed new minerals during weathering. The results show that the ratio of vermiculite to vermiculite in the mixed layer structure of phlogopite / vermiculite does not change obviously. Some of the montmorillonite was transformed into Illite, and at the later stage of the weathering experiment (after 50 days, when the pH value was 6?), the Ca~(2 released from the interlayer domain of montmorillonite combined with the carbonate ions formed by the metabolism of bacteria to form calcite. In the late stage of Illite weathering experiment, the organic acids secreted by the bacteria Eilorite and calcite. 4) the organic acids secreted by bacteria promoted the release of elements from the lattice and interlayer of minerals through acidolysis and complexation. Exopolysaccharide secreted by bacteria did not promote the weathering of minerals, but it may act as a nucleation template. 5) the effect of clay minerals on the physiological characteristics of SB-6 strains was obvious. In the presence of different minerals, the species and concentrations of bacterial metabolites were significantly different. Under the action of SB-6 strain, the weathering order of the three clay minerals was montmorillonite Illite vermiculite.
【学位授予单位】：南京农业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P512.1;Q93

【相似文献】