State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Colloids Surf B Biointerfaces. 2013 Oct 1;110:289-95. doi: 10.1016/j.colsurfb.2013.05.005. Epub 2013 May 13.
We investigated the adhesion of Escherichia coli to α-Fe2O3 and γ-Al2O3 and the effects of adhesion on the surface properties of the oxides in batch experiments, where we conducted potentiometric titration, zeta potential measurements, and FTIR spectroscopy. The adhesion isotherms fitted a Langmuir equation well. γ-Al2O3 had a higher adhesion capacity than α-Fe2O3 because of the higher positive charge on γ-Al2O3. The adhesion of E. coli to Fe/Al oxides decreased with increasing pH. Adhesion increased with increasing NaCl concentration, reaching its maximum at 0.05M for α-Fe2O3 and at 0.1M for γ-Al2O3, after which it decreased with further increases in NaCl concentration. Therefore, the electrostatic force plays an important role in the adhesion of E. coli to Fe/Al oxides. The zeta potential-pH curves of the binary-system fell between that for bacteria and those for Fe/Al oxides. Thus, overlapping of the diffuse layers of the electric double layers on the negatively-charged E. coli and positively-charged Fe/Al oxides reduced the effective surface charge density of the minerals and bacteria. E. coli adhesion decreased the point of zero salt effect and the isoelectric point of the Fe/Al oxides. The FTIR spectra indicated that non-electrostatic force also contributed to the interaction between E. coli and Fe/Al oxides, in addition to the electrostatic force between them.
我们通过批式实验研究了大肠杆菌在α-Fe2O3 和 γ-Al2O3 上的附着情况，以及附着对氧化物表面性质的影响，进行了等电滴定、动电电位测量和傅里叶变换红外光谱（FTIR）分析。附着等温线很好地符合 Langmuir 方程。由于 γ-Al2O3 带更高的正电荷，其附着容量高于 α-Fe2O3。大肠杆菌在 Fe/Al 氧化物上的附着随 pH 值增加而降低。附着随 NaCl 浓度增加而增加，在 0.05M 对 α-Fe2O3 和 0.1M 对 γ-Al2O3 达到最大值，之后随 NaCl 浓度进一步增加而降低。因此，静电力在大肠杆菌与 Fe/Al 氧化物的附着中起着重要作用。二元体系的动电电位-pH 曲线位于细菌和 Fe/Al 氧化物之间。因此，带负电荷的大肠杆菌和带正电荷的 Fe/Al 氧化物的双电层扩散层的重叠降低了矿物和细菌的有效表面电荷密度。大肠杆菌附着降低了 Fe/Al 氧化物的盐零点效应和等电点。FTIR 谱表明，除了它们之间的静电力外，非静电力也有助于大肠杆菌与 Fe/Al 氧化物的相互作用。
