Regulatory mechanism of montmorillonite on antibiotic resistance genes in Escherichia coli induced by cadmium

The emergence and spread of antibiotic resistance genes (ARGs) induced by the overuse of antibiotics has become a serious threat to public health. Heavy metals will bring longer-term selection pressure to ARGs when the concentration of their residues is higher than that of antibiotics in environmental media. To explore the potential roles of montmorillonite (Mt) in the emergence of ARGs under divalent cadmium ion (Cd2+) stress, Escherichia coli (E. coli) was induced continuously for 15 days under Cd2+ gradient concentrations (16, 32, 64, 96, and 128 mu g center dot mL(-1)) with and without Mt. Subsequently, antibiotic resistance testing, transcriptomics, transmission electron microscope, scanning electron microscopy, and Fourier transform infrared were conducted for analysis. The results of characterization analysis showed that Cd(2+)could enhance the expression of resistance genes such as penicillin, tetracycline, macrolactone, and chloramphenicol in E. coli. Moreover, compared with Cd2+, Mt-Cd could inhibit the promotion of these resistances by alleviating the expressions of genes involved in cell wall/membrane, protein synthesis, transport systems, signal transduction, and energy supply processes. Therefore, the study promoted the understanding of Cd2+ in triggering bacterial antibiotic resistance and highlighted a novel theme of clay's ability to mitigate ecological risk of antibiotic resistance caused by heavy metals.

Automated summary

The emergence and spread of antibiotic resistance genes (ARGs) due to the overuse of antibiotics poses a serious threat to public health. Heavy metals, when present in higher concentrations than antibiotics in the environment, can exert long-term selection pressure on ARGs. The study found that montmorillonite (Mt) can mitigate the antibiotic resistance caused by heavy metals, highlighting its potential role in reducing ecological risks.