Contrasts and similarities in the transcriptomic response to antimicrobial coinage metals in Escherichia coli

With the rise of resistance to last resort antibiotics, metal-based antimicrobials have re-emerged as an alternative to prevent and manage infections. The group 11 metals (copper, silver, gold), historically known for their usage in coins and similar chemical properties, have demonstrated promising bactericidal activity. Despite their efficiency, we do not have a complete understanding for how bacteria are eradicated by metal ions and how they respond to metal-induced stress. One understudied aspect of these metal-bacteria interactions are prolonged exposure models, as other studies tend to focus on the acute toxic response of antimicrobial metals. We used RNA-seq profiling to understand the Escherichia coli physiological response to sublethal inhibitory antimicrobial coinage metal stress after 10 hours of incubation. Gene expression patterns of the adaptive and intrinsic response elicited by each metal were identified, including increased essential metal uptake (Ag, Cu, Au), cysteine biosynthesis (Cu, Au), change of the metal ion oxidation state (Cu, Au), efflux of metal stressor (Cu), protein translation and ribosome biogenesis (Au), and cell envelope stress response (Ag). In this paper, we highlight the remarkable differences and similarities in the transcriptomic response profile of E. coli to these antimicrobial metal elements.