蜡状芽孢杆菌SY对镉的吸附机制

 从沈阳张士开发区附近的受镉污染土壤中筛选出1株高耐镉性菌株SY，经形态学观察和生理生化鉴定及16SrDNA序列分析，鉴定SY为蜡状芽孢杆菌（Bacillus cereus）。SY在吸附镉的过程中，伴随着K+、Ca2+、Na+、Mg2+等阳离子的大量释放，同时解吸率也随pH值的改变而改变。利用扫描电镜、能谱及红外光谱分析SY吸附镉前后的细胞微观形貌、元素含量变化和官能团的改变，结果表明，吸附后SY的表面基团本身没有改变，只是基团的特征吸收带位置、强度和宽度都发生了一定的变化。静电吸附、离子交换作用、表面配合作用是SY对镉的吸附过程中最主要的途径。对吸附机制的研究为生物吸附法处理重金属并在实际生产中加以利用提供了理论基础。

The Adsorption Mechanism of Bacillus cereus SY with respect to Cd

A bacterial strain, named as SY, with strong cadmium resistance, is isolated from cadmium-contaminated soil in Zhangshi, Shenyang development zone. According to its morphological and biochemical characteristics and 16SrDNA sequence analysis, it is identified as Bacillus cereus. In the adsorption process of cadmium by SY, a large number of intracellular K+, Na+, Mg2+ and Ca2+, are released from the cells simultaneously. At the same time, the desorption rate of cadmium by SY changes with pH values. Using scanning electron microscopy, the cell micro-morphology is observed before and after adsorption of cadmium by SY. Using energy spectra, the cadmium elemental content changes are analyzed. And using IR spectrum, the changes in functional groups are analyzed in the cell surface. The results show that the surface of SY after adsorption of cadmium is linked up into a single stretch. The characteristic absorption band position, intensity and width see a certain change, while the base of the functional group on the cell surface remains unchanged. Therefore, the role of electrical adsorption，ion exchange and surface complexation are the most important factors in the process of adsorption of cadmium by SY. Mechanism of the absorption provides a theoretical basis for the biological adsorption of heavy metal method used in actual production.