Inactivation of antibiotic resistant bacteria and elimination of transforming ability of plasmid carrying single and dual drug resistance genes by electro-oxidation using Ti/Sb-SnO2/PbO2 anode

Abstract

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are one of the major components of environmental antimicrobial resistance (AMR). Wastewater treatment plant is an important source and a contributor of AMR components in environment. The existing tertiary treatment technologies viz., chlorination, ultraviolet treatment and ozonation are not effective in ARB disinfection or ARG removal. Therefore, it is important to evaluate the potential of advanced wastewater treatment technologies in removing ARB and ARGs. In this study, the potential of Ti/Sb-SnO2/PbO2 anode in disinfecting single ARB (pUC19-ampR), dual ARB (pBR322-ampR and tetR), regrowth inhibition, removal of intracellular and extracellular ARGs and loss of transformation efficiency were evaluated. Upto 7 log (99.99 %) removal of single ARB (0.212 min−1) and dual ARB (0.185 min−1) was achieved in 40 min and 35 min, respectively at an applied current density 30 mA cm−2. Scanning electron microscopy images confirmed extensive and irreparable cell damages. Therefore, no re-growth was observed upto 30 days. Agarose gel electrophoresis and qubit analysis confirmed degradation of intracellular and extracellular genetic material. Upto ∼7.5 log (53.14 ± 1.23 %) of intracellular and ∼5.3 log (41.43 ± 0.89 %) of extracellular ampR (pUC19) reduction was observed. Similarly, reduction of intracellular ampR and tetR (pBR322) were ∼6.5 log (55.19 ± 0.92 %) and ∼7.5 log (64.89 ± 2.39 %). While, extracellular ampR and tetR (pBR322) were ∼4.1 log (41.85 ± 1.62 %) and ∼4.9 log (52.49 ± 1.35 %), respectively. Despite low ARG removal efficiency, complete loss of transformation ability of intracellular and extracellular pUC19 and pBR322 was observed. From the results, it is evident that electro-oxidation is effective in disinfecting both the ARB, removal of intracellular and extracellular ARGs. Therefore, EOP is proposed as an effective and promising tertiary treatment technology.