Nanopore Long-Read Metagenomics Reveals Pollution-Driven Antibiotic Resistance and Xenobiotic Degradation in Urban Beach Microbiomes.

Coastal ecosystems are vital for biodiversity but are increasingly threatened by urbanisation and pollution, which significantly alter local microbial communities. This study assessed bacterial diversity and functional profiles in urban and island beaches in Belém, Brazil. Urban beaches showed significantly higher microbial diversity and evenness, alongside functional plasticity due to pollutant input, while island beaches hosted more specialised and stable communities. Taxonomic analysis revealed the significant enrichment of opportunistic genera such as Comamonas, Clostridium and Paenibacillus in urban areas, and the massive dominance of Prochlorococcus and Candidatus Pelagibacter in island sites. Furthermore, shotgun metagenomics identified a robust genomic potential for xenobiotic degradation and antibiotic resistance in urban microbiomes, whereas island microbiomes were significantly enriched in genes for energy production and biosynthesis. These results underscore the ecological divergence between anthropogenically impacted and natural coastal environments, highlighting the importance of microbiome monitoring for sustainable coastal management.