Chen Gexin, Walker Sharon L
Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA.
Langmuir. 2007 Jun 19;23(13):7162-9. doi: 10.1021/la0632833. Epub 2007 May 25.
The role of solution chemistry on bacterial adhesion has been investigated using a radial stagnation point flow (RSPF) system. This experimental system utilized an optical microscope and an image-capturing device to directly observe the deposition kinetics of a groundwater bacterium, Burkholderia cepacia G4g, and a marine bacterium, Halomonas pacifica g. Experiments were carried out under well-controlled hydrodynamic and solution chemistry conditions, allowing for the sensitivity of bacterial adhesion behavior to be examined under a range of ionic strength and valence (KCl vs CaCl2) simulating groundwater and marine environments. Complimentary cell characterization techniques were conducted to evaluate the electrophoretic mobility, hydrophobicity, surface charge density, and viability of the bacteria under the same range of conditions. Solution chemistry was found to have a marked effect on the electrokinetic and surface properties of bacteria and the quartz collector, as well as on the resulting rate of bacterial deposition. Comparable adhesion trends were observed for B. cepacia G4g and H. pacifica g. Specifically, the deposition rates of the two bacteria species in both KCl and CaCl2 solutions increased with ionic strength, a trend consistent with traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, which considers the combination of van der Waals and electrostatic double-layer interaction forces. However, in some cases, experimental results showed bacterial deposition behavior to deviate from DLVO predictions. On the basis of the systematic investigation of bacterial cell characteristics, it was found that Ca2+ ions play a distinct role on bacterial surface charge, hydrophobicity, and deposition behaviors. It is further suggested that bacterial adhesion is determined by the combined influence of DLVO interactions, electrosteric interactions associated with solution chemistry, and the hydrodynamics of the deposition system.
利用径向驻点流（RSPF）系统研究了溶液化学对细菌黏附的作用。该实验系统利用光学显微镜和图像捕捉设备直接观察地下水细菌洋葱伯克霍尔德菌G4g和海洋细菌太平洋盐单胞菌g的沉积动力学。实验在严格控制的流体动力学和溶液化学条件下进行，以便在模拟地下水和海洋环境的一系列离子强度和化合价（KCl与CaCl2）下考察细菌黏附行为的敏感性。采用互补的细胞表征技术在相同条件范围内评估细菌的电泳迁移率、疏水性、表面电荷密度和活力。发现溶液化学对细菌和石英收集器的电动和表面性质以及由此产生的细菌沉积速率有显著影响。观察到洋葱伯克霍尔德菌G4g和太平洋盐单胞菌g有相似的黏附趋势。具体而言，两种细菌在KCl和CaCl2溶液中的沉积速率均随离子强度增加，这一趋势与传统的德亚金-朗道-韦弗伊-奥弗贝克（DLVO）理论一致，该理论考虑了范德华力和静电双层相互作用力的组合。然而，在某些情况下，实验结果表明细菌沉积行为偏离了DLVO预测。基于对细菌细胞特性的系统研究，发现Ca2+离子在细菌表面电荷、疏水性和沉积行为方面发挥着独特作用。进一步表明，细菌黏附是由DLVO相互作用、与溶液化学相关的电空间相互作用以及沉积系统的流体动力学的综合影响决定的。
