Mangroves are complex land-sea transition ecosystems whose microbiota are essential for their nutrient recycling and conservation. Brazil is the third-largest estuarine area in the world and “Baía de Todos os Santos” (BTS) is one of the largest bays of the country, with wide anthropogenic exploration. Using a metagenomic approach, we investigated composition and functional adaptability as signatures of the microbiome of pristine and anthropized areas of BTS, including those under petroleum refinery influence. The taxonomic analysis showed dominance of sulfate-reducing Desulfobacteraceae, Rhodobacteraceae, and Flavobacteriaceae. Taxa were significantly diverse between pristine and disturbed areas. Disturbed mangroves showed a notary increase in abundance of halophilic, sulfur-related, and hydrocarbon-degrading genera and a decrease in diatoms compared to pristine area. The metabolic profile of BTS mangroves was correlated with the differentially abundant microbiota. Two ecological scenarios were observed: one marked by functions of central metabolism associated with biomass degradation and another by mechanisms of microbial adaptability to pollution conditions and environmental degradation. Part of the microbiome was distinct and not abundant in Brazilian estuarine soils. The microbiome signature observed in each BTS mangrove reflects how human actions impact the diversity of these ecosystems and also emphasize their role in attempting to restore disturbed mangroves. The microbiome may act as a potential biological indicator of the preservation status of these soils, despite the limitation of soil property conditions. Additionally, our data pointed to metagenomics as an additional tool for environmental assessment and reinforced the need for protective measures for the mangroves under study.

红树林是复杂的陆地-海洋过渡生态系统，其微生物群对其养分循环和保护至关重要。巴西是世界第三大河口区，“Baía de Todos os Santos”（BTS）是该国最大的海湾之一，人类勘探活动广泛。使用宏基因组方法，我们研究了 BTS 原始和人类化区域（包括受炼油厂影响的区域）微生物组的组成和功能适应性特征。分类学分析显示硫酸盐还原脱硫杆菌科、红杆菌科和黄杆菌科占主导地位。原始地区和受干扰地区之间的类群存在显着差异。与原始地区相比，受干扰的红树林显示出嗜盐、硫相关和碳氢化合物降解属的丰度明显增加，而硅藻则减少。BTS 红树林的代谢特征与差异丰度的微生物群相关。观察到两种生态情景：一种以与生物质降解相关的中枢代谢功能为标志，另一种以微生物对污染条件和环境退化的适应机制为标志。巴西河口土壤中的部分微生物组是独特的且并不丰富。在每个 BTS 红树林中观察到的微生物组特征反映了人类行为如何影响这些生态系统的多样性，并强调了人类行为在恢复受干扰的红树林方面的作用。尽管土壤性质条件有限，微生物组仍可以作为这些土壤保存状态的潜在生物指标。此外，我们的数据表明宏基因组学是环境评估的额外工具，并强化了对所研究的红树林采取保护措施的必要性。