酿酒酵母吸附Pb(Ⅱ)的表面特性研究

为深入探讨酿酒酵母与Pb(II)的相互作用机理，本文利用表面显微分析技术（SEM-EDS、TEM-EDS、AFM）研究了酿酒酵母细胞吸附重金属离子Pb(II)前后的细胞表面特性变化。研究结果表明，酿酒酵母细胞与Pb(II)作用后，细胞表面除吸附Pb(II)外，同时产生大量更高浓度的含Pb(II)沉淀，导致Pb(II)从溶液中被去除。酵母与Pb(II)反应前，酵母细胞表面可检测到的主要元素包括C、O、N、P、S、K、Mg；酵母与Pb(II)作用后，细胞表面始终保持C、O、P吸收峰，而N、K、Mg、S吸收峰随反应条件不同而减弱、消失或增强。P作为细胞表面组分可能与Pb(II)结合。酵母与Pb(II)作用过程中，重金属离子促进酵母细胞释放细胞内含物。原子力显微镜（AFM）证实，云母片表面对酵母吸附Pb(II)后细胞的铺展变形作用明显增大。

Cell surface characteristics of Saccharomyces cerevisiae after interaction with Pb(II) detected by SEM/TEM/AFM

To understand the metal-microbe interaction between Pb(II) and the intact cells of Saccharomyces cerevisiae, the surface characteristics of yeast cells before and after adsorbing Pb(II) were investigate by the technology of the scanning electron microscopy with the energy-dispersive X-ray analysis (SEM-EDX), the transmission electron microscopy with energy-dispersive X-ray analysis (TEM-EDX) as well as atomic force microscopy (AFM). The changes of the component elements, surface configuration and three-dimensional structures of the cells before and after interacting with Pb(II) were detected, which proved that Pb(II) was adsorbed by the cell surface. Simultaneously, the Pb-containing precipitate with higher concentration than the surface-adsorbed Pb was formed on the cell surface, contributing more to removing Pb(II) from the aqueous solution. The intact cells could release intracellular substances during Pb(II) uptake. The morphological distortion of the yeast cells on the surface of mica sheet enlarged after uptaking Pb(II) under AFM observation.