Prospecting for efflux pump and repressor genes in rivers of the Amazon region of Brazil

BACKGROUND: The spread of multidrug-resistant bacteria in water bodies poses a significant public health concern. Efflux pumps represent critical mechanisms of antimicrobial resistance, regulated by genetic repressors that aid bacterial adaptation to environmental stress. This study profiles the diversity of efflux pump genes and genetic repressors in the surface waters of the Cereja (Bragança) and Uraim (Paragominas) rivers in the Amazon region of Brazil. METHODS AND RESULTS: Surface water samples were collected along a gradient of anthropogenic impact, and environmental DNA was sequenced on the Illumina platform. The resulting sequencing data were subsequently subjected to metagenomic analysis, which identified a higher abundance of efflux pump genes in the Cereja River compared to the Uraim River, dominated by the RND and SMR families. Additionally, two-component system (TCS) repressor genes, particularly cbrB, were successfully recovered and modeled using Swiss-Model homology modeling. CONCLUSIONS: The higher coverage of the cbrB repressor gene in anthropogenically impacted sites underscores its regulatory role in bacterial stress responses, suggesting its potential application as a novel biomarker of environmental pollution and antibiotic resistance spread in aquatic ecosystems.