Center for Geomicrobiology and Biogeochemistry Research, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, P.R. China.
Environ Sci Technol. 2021 Nov 16;55(22):15256-15265. doi: 10.1021/acs.est.1c04367. Epub 2021 Nov 1.
Reduced nontronite has been demonstrated to be antibacterial through the production of hydroxyl radical (OH) from the oxidation of structural Fe(II). Herein, we investigated the antibacterial activity of more common smectite-illite (S-I) clays toward cells, including montmorillonite SWy-3, illite IMt-2, 50-50 S-I rectorite RAr-1, 30-70 S-I ISCz-1, and nontronite NAu-2. Under an oxic condition, reduced clays (with a prefix r before mineral names) produced reactive oxygen species (ROS), and the antibacterial activity followed the order of rRAr-1 > rSWy-3 ≥ rNAu-2 ≫ rIMt-2 ≥ rISCz-1. The strongest antibacterial activity of rRAr-1 was contributed by a combination of OH and Fe(IV) generated from structural Fe(II)/adsorbed Fe and soluble Fe, respectively. Higher levels of lipid and protein oxidation, intracellular ROS accumulation, and membrane disruption were consistent with this antibacterial mechanism of rRAr-1. The antibacterial activity of other S-I clays depended on layer expandability, which determined the reactivity of structural Fe(II) and the production of OH, with the expandable smectite being the most antibacterial and nonexpandable illite the least. Our results provide new insights into the antibacterial mechanisms of clay minerals.
通过结构 Fe(II)氧化产生的羟基自由基 (OH)，已经证明减少的非皂石具有抗菌作用。在此，我们研究了更常见的蒙脱石-伊利石 (S-I) 粘土对 细胞的抗菌活性，包括蒙脱石 SWy-3、伊利石 IMt-2、50-50 S-I 累托石 RAr-1、30-70 S-I ISCz-1 和非皂石 NAu-2。在有氧条件下，还原粘土（在矿物名称前加 r 前缀）产生活性氧物种 (ROS)，抗菌活性的顺序为 rRAr-1 > rSWy-3 ≥ rNAu-2 ≫ rIMt-2 ≥ rISCz-1。rRAr-1 最强的抗菌活性归因于分别来自结构 Fe(II)/吸附 Fe 和可溶性 Fe 的 OH 和 Fe(IV) 的组合。更高水平的脂质和蛋白质氧化、细胞内 ROS 积累和膜破坏与 rRAr-1 的这种抗菌机制一致。其他 S-I 粘土的抗菌活性取决于层膨胀性，这决定了结构 Fe(II)的反应性和 OH 的产生，可膨胀的蒙脱石的抗菌性最强，不可膨胀的伊利石的抗菌性最弱。我们的结果为粘土矿物的抗菌机制提供了新的见解。
