Natural sphalerite nanoparticles can accelerate horizontal transfer of plasmid-mediated antibiotic-resistance genes

Minerals and microorganisms are integral parts of natural environments, and they inevitably interact. Antibiotic-resistance genes (ARGs) significantly threaten modern healthcare. However, the effects of natural minerals on ARG propagation in aquatic systems are not fully understood. The present work studied the effects of natural sphalerite (NS) nanoparticles on the horizontal transfer of ARGs from Escherichia coli DH5α (CTX) (donor) to E. coli C600 (Sm) (recipient), and from E. coli DH5α (MCR) (donor) to E. coli C600 (Sm), and their underlying mechanisms. NS particles (0.5-50 mg L-1) induced an NS-concentration-dependent increase in conjugative transfer frequency. The underlying mechanisms associated with the facilitated ARG transfer included the production of intracellular reactive oxygen species, the SOS response, changes in bacterial cell morphology, and alteration of mRNA levels of bacterial cell membrane protein-related genes and genes associated with conjugative ARG transfer. The information herein offers new mechanistic understanding of risks of bacterial resistance resulting from NS.