Nanosilver-Induced Pseudo Cuproptosis of Potentially Pathogenic Bacteria during the Storage of Ozone-Treated Wastewater

The reuse of ozone-treated wastewater, especially for agricultural irrigation, is a crucial strategy to address water scarcity. However, the storage of ozone-treated wastewater contributes to the growth of potentially pathogenic bacteria. This study explores using nanosilver-loaded hydrogels as liners in storage containers to provide sustained antibacterial effects. The results indicate that the antibacterial effect of nanosilver-loaded hydrogels, possessing a three-dimensional porous network structure, is more efficient due to a relatively low concentration of nanosilver in the stored water while increasing the concentration in the immediate vicinity of K-12 Escherichia coli (E. coli) anchored in the pores. The antibacterial mechanism of nanosilver against K-12 E. coli involves a process termed pseudo cuproptosis. Nanosilver did not lead to a significant reduction in basal or ATP-linked respiration, but it did notably decrease the spare capacity of respiration and disrupt bacterial metabolism by binding to lipoylated proteins, including 2-oxoglutarate dehydrogenase E2 subunit (sucB) and dihydrolipoamide S-acetyltransferase (aceF), which are related to the tricarboxylic acid cycle. It also leads to the oligomerization of aceF, and finally causes proteotoxicity to the K-12 E. coli. This process is distinct from known bacterial growth stasis pathways. By understanding this mechanism, the dosage of nanosilver can be effectively controlled, ensuring the safety and efficacy of wastewater reuse for agricultural purposes in the near future.