Exploring molecular mechanisms of aminoglycoside resistance in Escherichia coli MG1655 using the antibiotic resistance growth plate.

The overuse of antibiotics in human and animal health has driven the rapid emergence of multi-drug-resistant bacterial strains. To investigate the molecular mechanisms underlying resistance, we developed the Antibiotic Resistance Growth Plate (ARGP), an experimental evolution tool that imposes a spatiotemporal antibiotic gradient. Using the ARGP, Escherichia coli MG1655 populations developed resistance to gentamicin up to 10x MIC within two days. Whole-genome sequencing of wildtype and resistant strains revealed mutations in 16 S rRNA genes and the fusA gene. Bioinformatic, phylogenetic, and molecular docking analyses were used to demonstrate the mechanical significance of the fusA gene in the molecular pathways of gentamicin resistance in E. coli MG1655, where mutations in fusA alter EF-G function, disrupting gentamicin's inhibition of ribosomal translocation. These results highlight the rapidity and specificity of adaptive responses to aminoglycosides and establish the ARGP as a versatile tool for studying the molecular pathways driving antibiotic resistance.