Antibacterial Mechanisms of Reduced Iron-Containing Smectite-Illite Clay Minerals.
Dongyi GuoQingyin XiaQiang ZengXi WangHailiang DongPublished in: Environmental science & technology (2021)
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 Escherichia coli 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 Fe2+ and soluble Fe2+, 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.
Keyphrases
- silver nanoparticles
- reactive oxygen species
- escherichia coli
- metal organic framework
- visible light
- anti inflammatory
- aqueous solution
- dna damage
- small molecule
- cell proliferation
- cell cycle arrest
- nitric oxide
- staphylococcus aureus
- oxidative stress
- biofilm formation
- pseudomonas aeruginosa
- endoplasmic reticulum stress
- high resolution
- multidrug resistant
- single molecule
- klebsiella pneumoniae