Taxonomic and Functional Assessment of Microbial Communities in Urban Runoff-Contaminated Mangrove Sediments

Mangroves are vital coastal ecosystems that host diverse microbial communities essential to ecological function and nutrient cycling. Yet, urbanization and pollution are accelerating their degradation. This study explored the sediment microbiota from two impacted mangroves in São Sebastião, the southeastern Brazilian coast, Araçá Bay, and Colhereiro, through microbiota profiling, sediment chemical analysis, and the isolation of native bacteria capable of growing under the exposure of urban landfill leachate, a major pollutant affecting these fragmented environments. Among the two mangroves, Colhereiro exhibited pronounced signatures of chronic urban pollution, including elevated macronutrients and enrichment of sulfur-metabolizing bacteria and Arcobacter, a genus associated with fecal contamination and environmental pollution. Genomic DNA from bacterial isolates showing robust growth on leachate residue was sequenced, and genome mining was conducted to evaluate their functional capabilities. The results offer novel insights into the taxonomic and functional diversity of mangrove microbiota in São Sebastião and underscore their potential for use in bioremediation and environmental restoration of polluted coastal ecosystems.