Electrochemical disinfection may increase the spread of antibiotic resistance genes by promoting conjugal plasmid transfer

Hua Li, Arnaud Dechesne, Zhiming He, Marlene Mark Jensen, Hai Liang Song, Barth F. Smets*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Current in the milliampere range can be used for electrochemical inactivation of bacteria. Yet, bacteria-including antibiotic resistant bacteria (ARB)-may be subjected to sub-lethal conditions due to imperfect mixing or energy savings measures during electrochemical disinfection. It is not known whether such sublethal current intensities have the potential to stimulate plasmid transfer from ARB. In this study, conjugal transfer of plasmid pKJK5 was investigated between Pseudomonas putida strains under conditions reflecting electrochemical disinfection. Although the abundance of culturable and membrane-intact donor and recipient cells decreased with applied current (0–60 mA), both transconjugant density and transconjugant frequency increased. Both active chlorine and superoxide radicals were generated electrolytically, and ROS generation was induced. In addition, we detected significant over expression of a core oxidative stress defense gene (ahpCF) with current. Expression of selected conjugation related genes (traE, traI, trbJ, and trbL) also significantly correlated with current intensity. A link between ROS accumulation, SOS response and enhanced conjugation is therefore the plausible consequence of sublethal current exposure. These findings suggest that sub-lethal intensities of current can enhance conjugal plasmid transfer, and that it is essential that conditions of electrochemical disinfection (applied voltage, current density, time and mixing) be carefully controlled to avoid conjugal ARG transmission.
Original languageEnglish
Article number159846
JournalScience of the Total Environment
Number of pages8
Publication statusPublished - 2023


  • Conjugal transfer
  • Pseudomonas putida
  • Conjugative plasmid
  • Electrochemical disinfection
  • Active chlorine


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