Genomic signatures of resistance and adaptability in Aeromonas and Pseudomonas from a Brazilian Hope Spot

Abstract

The Cagarras Islands Archipelago, a marine protected area in Rio de Janeiro, Brazil, is endowed with a rich and abundant biodiversity. Despite being a "Hope Spot" for marine conservation, it suffers from the impacts of urban pollution, given its proximity to a major metropolis. To date, few studies have delved into the characterization of the bacterial community in the Cagarras Islands, and limited knowledge regarding the pollution effects on a microbiological scale is available. This study presents the first genomic characterization of seven potentially pathogenic strains of Aeromonas and Pseudomonas isolated from water samples collected in four expeditions. Whole genome sequencing was conducted to assess antimicrobial and heavy metal resistance, as well as pathogenicity. Comparative genomic analyses were performed using additional Aeromonas and Pseudomonas genomes from different sources. The identification of multiple genes associated with heavy metal resistance, alongside clinically relevant antimicrobial resistance genes such as mcr-3 (conferring resistance to the last-resort antimicrobial colistin) and bla_OXA (associated with beta-lactam resistance), showcases the adaptability of these strains and the presence of potentially pathogenic, and antibiotic-resistant bacteria in a protected marine ecosystem. This study highlights the complex genomic landscape of bacteria isolated from a Brazilian Hope Spot, underscoring the importance of integrated microbial monitoring strategies.

Keywords: Aeromonas; Antimicrobial resistance; Cagarras; Heavy metals; Marine pollution; Pseudomonas.