Structure and putative function of a soil microbial community impacted by the deposition of tailings and subsequent revegetation after the rupture of the Fundao Dam

The rupture of the Fundao Dam containing iron-rich mining tailings, in 2015, was one of the worst environmental disasters in Brazil. The deposition of tailings has generated serious impacts on the soil and, as microorganisms play an important role in these environments, the recovery of the microbial community is a critical step in restoring the soil for sustainable use. Soil microorganisms and their activities are recognized as sensitive bioindicators for environmental changes; however, few experiments have been conducted to investigate the response of the microbial community to the magnitude of the impact caused by the Fundao Dam rupture and the effect of the use of revegetation natural or induced for ecosystem recovery, especially in Brazil. This study aimed to evaluate the dynamics of community structure and putative functions, over time, in response to the deposition of the tailings on the soil by bacterial 16S rRNA sequencing. We evaluated an area affected by tailings, covered with natural and induced revegetation. The results revealed a temporal dynamic of the soil microbiota, which demonstrates that the microbial community structure of these areas differed, mainly in less abundant taxa, and the induced revegetation area was closer to the forest than natural revegetation. These results reveal the importance of implementing revegetation programs to accelerate the initial recovery. Functions related to the use of alternative electron acceptors differed, possibly due to the greater compaction of the affected soil. Despite the improvement of the impacted areas over time, the strong effect of tailings deposition on the bacterial community structure can still be noticed.

Automated summary

The rupture of the Fundao Dam in 2015 caused a severe environmental disaster in Brazil. The deposition of mining tailings has had serious impacts on the soil, and the recovery of the microbial community is crucial for sustainable use of the soil. This study used bacterial 16S rRNA sequencing to evaluate the dynamic changes in community structure and putative functions in response to tailings deposition on the soil.