Synergistic nanowire-assisted electroporation and chlorination for inactivation of chlorine-resistant bacteria in drinking water systems via inducing cell pores for chlorine permeation

The widespread use of chlorination (Cl-2) in drinking water systems causes the selection of chlorine-resistant bacteria commonly with dense extracellular polymeric substance (EPS) against chlorine permeation, posing significant threat to public health. Herein, a nanowire-assisted electroporation (EP) via locally enhanced electric field was combined with Cl-2 to construct the synergistic EP/Cl-2 disinfection, with the purposes of inducing cell pores for chlorine permeation and bacterial inactivation. The synergistic effects of EP/Cl-2 were observed for inactivation of chlorine-resistant Bacillus cereus (G+, 304 mu g DOC-EPS/109 CFU) and Aeromonas media (G-, 35.8-g), and chlorine-sensitive Escherichia coli (G-, 5.1 mu g) that were frequent occurrence in drinking water systems. The EP/Cl-2 enabled above 6 log B. cereus inactivation (undetectable live bacteria) at 1.5 V-EP and 0.9 mg/L-Cl-2, which was much higher than the individual EP (1.11 log) and Cl-2 (1.13 log) disinfection. The cell membrane integrity, intracellular free chlorine levels, and morphology analyses revealed that the electroporation-induced pores on cell wall/membrane destructed the bound EPS barrier for chlorine permeation, and the pore sizes were further enlarged by chlorine oxidation, hence facilitating bacterial inactivation via destroying the cell structures. The excellent disinfection performance for tap water and lake water also suggested its sound application potentials.

Automated summary

The combination of nanowire-assisted electroporation and chlorination is an effective method for disinfection of chlorine-resistant bacteria. It can destroy bacterial structures and effectively inhibit their growth, which is important for water purification and public health.