Ruan Bo, Wu Pingxiao, Liu Juan, Jiang Lu, Wang Huimin, Qiao Jialiang, Zhu Nengwu, Dang Zhi, Luo Hanjin, Yi Xiaoyun
School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006, PR China; Foshan Environmental Research Institute, Foshan Environmental Protection Investment Co., Ltd, Foshan 528000, PR China.
School of Environment and Energy, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, PR China; Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, Guangzhou 510006, PR China.
Colloids Surf B Biointerfaces. 2020 Apr 28;192:111085. doi: 10.1016/j.colsurfb.2020.111085.
Bacterial adhesion on mineral surface are of fundamental importance in geochemical processes and biogeochemical cycling, such as mineral transformation and clay-mediated biodegradation. In this study, thermodynamics analysis combined with classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory as well as the extended DLVO (XDLVO) theory were employed to investigate the adhesion of the Gram-negative PAH-degrading bacteria Sphingomonas sp. GY2B on montmorillonite (Mt). Scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated the affinity of GY2B for Mt, and the experimental results could be described well by pseudo-second-order (R = 0.997) and Langmuir model (R = 0.995). The thermodynamics analysis revealed the physical nature of bacterial adhesion onto Mt, which was confirmed by the XDLVO theory. The related surface properties (Zeta potential, hydrodynamic diameter and hydrophobicity) at different ionic strength were determined and the interaction energy between Mt and GY2B were also calculated using the DLVO and XDLVO theories in KCl or CaCl solution. At low ionic strength (≤ 20 mM), GY2B adhesion onto Mt was primarily driven by long-range DLVO forces (e.g. electrostatic repulsion), while short-range (separation distance < 5 nm) Van der Waals and hydrophobic interactions played more important roles in the bacterial adhesion at higher ionic strength (50-100 mM). In addition, Mt had a better adhesion capacity to bacteria in Ca solution than that in K solution, owing to less negative charge and lower energy barrier in mineral-bacteria system in Ca solution. Overall, the adhesion of bacteria onto Mt could be evaluated well on the basis of the XDLVO theory along with thermodynamics analysis. This study provides valuable insights into the clay-mediated microbial remediation of hydrophobic organic contaminants in the environment.
细菌在矿物表面的黏附在地球化学过程和生物地球化学循环中具有至关重要的意义，例如矿物转化和黏土介导的生物降解。在本研究中，采用热力学分析结合经典的德亚金-朗道-维韦-奥弗比克（DLVO）理论以及扩展的DLVO（XDLVO）理论，研究革兰氏阴性多环芳烃降解菌鞘氨醇单胞菌属GY2B在蒙脱石（Mt）上的黏附。扫描电子显微镜（SEM）、傅里叶变换红外光谱（FTIR）和X射线光电子能谱（XPS）表明了GY2B与Mt之间的亲和力，实验结果可用准二级动力学模型（R = 0.997）和朗缪尔模型（R = 0.995）很好地描述。热力学分析揭示了细菌在Mt上黏附的物理本质，这一点得到了XDLVO理论的证实。测定了不同离子强度下的相关表面性质（ζ电位、流体动力学直径和疏水性），并使用DLVO和XDLVO理论在KCl或CaCl₂溶液中计算了Mt与GY2B之间的相互作用能。在低离子强度（≤20 mM）下，GY2B在Mt上的黏附主要由长程DLVO力（如静电排斥）驱动，而在高离子强度（50 - 100 mM）下，短程（分离距离<5 nm）范德华力和疏水相互作用在细菌黏附中发挥了更重要的作用。此外，由于Ca溶液中矿物-细菌体系的负电荷较少且能垒较低，Mt对细菌在Ca溶液中的黏附能力优于在K溶液中的黏附能力。总体而言，基于XDLVO理论和热力学分析能够很好地评估细菌在Mt上的黏附情况。本研究为环境中黏土介导的疏水性有机污染物的微生物修复提供了有价值的见解。
