Inhibition of Bacterial Conjugation in Escherichia Coli by Dietary Zinc

Abstract

Antimicrobial resistance (AR) in bacteria is a growing concern for mammalian health. AR genes are shared between bacteria mainly via extrachromosomal plasmids in Enterobacteriaceae through bacteria conjugation. This experiment aimed to reduce AR plasmid transfer by using dietary zinc to inhibit bacterial conjugation. We found that conjugations supplemented with dietary zinc significantly reduced (P < 0.05) AR plasmid transfer between the donor strain E. coli APEC-02-211 and the recipient strain E. coli HS-4. Additionally, we performed RT-qPCR on individual transfer (tra) genes of the plasmid which are responsible for encoding the conjugative pilus. The conjugations supplemented with zinc displayed significant downregulation of traA and traS. The traA gene encodes the conjugal propilin protein, which after post-translational modification, is essential for facilitating bacterial conjugation. The traS gene encodes the entry exclusion protein which mediates plasmid entry in recipient cells. Downregulation of both of these genes resulted in bacterial host lethality and strengthened evidence for use of dietary zinc as a therapeutic to mitigate antimicrobial resistance in the mammalian gut.