Long-Term Impact of the Largest Environmental Disaster in Latin America (Fundão Dam Failure) on Microbial Communities in Lakes of the Doce River Basin, Brazil.

The collapse of the Fundão tailings dam in 2015 stands as the largest environmental disaster in Latin America and the global mining industry. This catastrophic event released around 62 million m of mining waste into the Doce River basin. This study aimed to assess the long-term effects of the disaster by analysing microbial communities in four lakes within the Doce River basin. Conducted over 4 years (2018-2021), with a total of six sampling campaigns. The microbiome of water and sediment was analysed using high-throughput 16S rRNA gene sequencing. The results demonstrate a significant correlation between key microbial groups and metals associated with the disaster, including Deinococcus, Thermoanaerobaculaceae, Pirellula, and Rhodospirillaceae. Moreover, an enrichment of genes associated with xenobiotic degradation and metal metabolism pathways was detected. These findings suggest that microbial communities in the lakes remain functionally adapted to metal contamination, potentially playing a crucial role in ecosystem recovery and bioremediation. These microorganisms could be leveraged to monitor and mitigate the effects of heavy metal contamination. Despite years having passed since the disaster, the microbiota of the lakes remains significantly impacted, reinforcing the need for continued research to fully understand and mitigate long-term ecological consequences.