The removal of antibiotic resistant bacteria and antibiotic resistance genes by sulfidated nanoscale zero-valent iron activating periodate: Efficacy and mechanism

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have drawn much more attention due to their high risk on human health and ecosystem. In this study, the performance of sulfidated nanoscale zerovalent iron (S-nZVI)/periodate (PI) system toward ARB inactivation and ARGs removal was systematically investigated. The S-nZVI/PI system could realize the complete inactivation of 1 x 108 CFU/mL kanamycin, ampicillin, and tetracycline-resistant E. coli HB101 within 40 min, meanwhile, possessed the ability to remove the intracellular ARGs (iARGs) (including aphA, tetA, and tnpA) carried by E. coli HB101. Specifically, the removal of aphA, tetA, and tnpA by S-nZVI/PI system after 40 min reaction was 0.31, 0.47, and 0.39 log10copies/ mL, respectively. The reactive species attributed to the E. coli HB101 inactivation were HO & BULL; and O2 & BULL;, which could cause the destruction of E. coli HB101 morphology and enzyme system (such as superoxide dismutase and catalase), the loss of intracellular substances, and the damage of iARGs. Moreover, the influence of the dosage of PI and S-nZVI, the initial concentration of E. coli HB101, as well as the co-existing substance (such as HCO3 , NO3 , and humic acid (HA)) on the inactivation of E. coli HB101 and its corresponding iARGs removal was also conducted. It was found that the high dosage of PI and S-nZVI and the low concentration of E. coli HB101 could enhance the disinfection performance of S-nZVI/PI system. The presence of HCO3  , NO3 , and HA in S-nZVI/PI system showed inhibiting role on the inactivation of E. coli HB101 and its corresponding iARGs removal. Overall, this study demonstrates the superiority of S-nZVI/PI system toward ARB inactivation and ARGs removal.

Automated summary

This study investigated the performance of sulfidated nanoscale zerovalent iron (S-nZVI)/periodate (PI) system in inactivating antibiotic resistant bacteria (ARB) and removing antibiotic resistance genes (ARGs). The results showed that the S-nZVI/PI system could completely inactivate kanamycin, ampicillin, and tetracycline-resistant E.coli HB101 within 40 minutes, and also remove the intracellular ARGs carried by E.coli HB101. The study also examined the effects of PI and S-nZVI dosage, initial concentration of E.coli HB101, and co-existing substances on the disinfection and removal process.