直接/间接作用模式下一株短小芽孢杆菌对蒙脱石层间域特性的影响研究

Influence of Bacillus pumilus on montmorillonite interlayer domain features under direct/indirect contact mode

为探讨直接/间接作用模式下土壤常驻菌对蒙脱石层间距、层电荷及层间介质的影响,从绵阳地区紫色土壤中分离选取1株短小芽孢杆菌,利用透析袋,建立土壤菌与蒙脱石"接触"与"非接触"体系进行相互作用实验。作用5 d后的结果表明,蒙脱石样品层间距变小,样品M-1和M-2的d001值从1.486 nm分别减小到1.246 nm和1.257 nm,单位半晶胞层电荷数减少,且ξMMT>ξM-2>ξM-1,FTIR分析显示作用后蒙脱石样品出现来自蛋白质酰胺Ⅱ带及蛋白质分子甲基的新特征峰,层间水分子3434 cm-1、1637 cm-1处的峰发生偏移,此外阳离子交换容量也发生明显改变。土壤菌的生物作用能改变蒙脱石的层间距、层电荷及层间介质,使其结构和性质发生改变。对比2种作用方式与作用后蒙脱石层间域特性的改变分析可知,接触作用对蒙脱石层间域特性的改变效果强于非接触作用。

To investigate the influence of soil-resident bacteria contact modes on the interlayer spacing, layer charge and interlayer dielectric properties of montmorillonite, one strain of Bacillus pumilus was separated and selected from purple soil found in the Mianyang area of Sichuan Province, China. Dialysis bags were employed to establish direct and indirect-contact systems for interaction experiments between the soil-resident bacteria and montmorillonite. The results showed that after 5 days of bacteria interaction, the interlayer distances in the mineral samples decreased from 1.486 nm to 1.246 nm(M-1) and to 1.257 nm(M-2). Moreover, the per half unit cell layer charge also decreased. ξMMT> ξM-2> ξM-1. FTIR spectrometry showed that new characteristic peaks appeared on montmorillonite samples consisting amide Ⅱ methyl protein molecules and a shift of the interlayer water molecules peaks at 3434 cm-1 and 1637 cm-1. In addition, the cation exchange capacity of samples changed. Therefore, we concluded that the soil bacteria can change the layer spacing, layer charge and interlayer dielectric properties of montmorillonite, as well as alter its structure and other properties. Two modes of contact were compared and the effect of direct contact on changing the montmorillonite interlayer characteristics was stronger than the effect observed under indirect contact.