胶质芽孢杆菌-蒙脱石相互作用实验研究

A study of the interaction between montmorillonite and a strain of Bacillus mucilaginosus

利用硅酸盐细菌研究了微生物对硅酸盐矿物的分解作用。选取层状硅酸盐矿物蒙脱石在30℃与一株编号为3025的硅酸盐细菌B.mucilaginosus进行交互作用,并利用电感耦合等离子体发射光谱仪(ICP-AES)分析溶液中Si、Al、Mg离子的出溶量,利用X射线衍射(XRD)和显微红外光谱(Micro-FTIR)分析微生物作用后矿物物相和微结构变化。发现经硅酸盐细菌作用后,蒙脱石化学成分及晶体结构发生了细微变化,为微生物活动促进粘土矿物分解作用研究提供了实验和理论依据。

The impact of microbes on lithosphere starts with the change of minerals comprising rocks, whereas the impact of microbes on minerals starts with the change of the composition of minerals. Based on previous researches on the interaction between microbes and minerals, this paper studied the interaction between silicate bacteria Bacillus mucilaginosus and bentonite, which is mainly composed of layer silicate montmorillonite and a small amount of other silicate minerals such as quartz and feldspar, and analyzed the impact of microbes on betonite in such aspects as composition and microstructure. The concentrations of elements Si, A1 and Mg in solution were tested by Inductively Coupled Plasma-Atomic Emission Spectrometer （ICP-AES）, after being treated by hydrogen peroxide. The minerals after bacteria dissolution were analyzed by X-ray Diffraction （XRD） and Micro-Fourier Transform Infrared Spectroscopy （Miero-FTIR）. The pH values of the reaction solution rapidly decreased from 7.5 to 4.3 in the first 2 days. Then the pH values became gradually stabilizing. The dissolution quantities of Si, Al and Mg from the mineral crystal lattice were unbalanced. The X-ray diffraction patterns （XRD） showed that the phase of calcite （Ca） disappeared in bacteria dissolution products （BM）, which was probably caused by acid metabolic products of bacteria, and there was a new faint diffraction peak that appearedbetween 9° to 10° in the samples treated by bacteria. According to the Micro-FTIR spectra, the absorption peaks at 3 620 and 3 400 cm-1 shifted to higher wavenumber and the intensity decreased, and the intensity of weak absorption peak at 1 635 cm 1 decreased too, suggesting that the content of ions in montmorillonite was changed. The disappearance of CO3^2- band absorption peak at 1 434 and 880 cm 1 was consistent with the XRD result of the disappearance of calcite phase. Through analyzing pH changes in solution, variations of major elements in solution and minerals, and structural, infrared spectroscopic and specific surface area changes, the authors inferred that the bacteria dissolution process is like this： first, acidic metaholites produced during the growth of bacteria and contact interaction between minerals and bacteria dissolve the vulnerable parts of mineral surface, and some cations in mineral structure are dissolved. With the dissolution, the uneven exsolution of cations may cause the change of mineral grains surface and even the collapse of the silicate layer, and the mineral structure is changed at last.