Figure 4. Relative abundance (percentage) of the main identified bacterial taxonomic groups, i.e., phyla Acidobacteria, Actinobacteria, Bacteroidetes and Firmicutes, classes Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Deltaproteobacteria (within the Proteobacteria phylum).

For each tailings sample, the relative abundance of the sequences assigned to a given taxonomic unit was calculated for each of the three subsamples, and the average value was then used to represent the relative abundance of each tailings sample. The error bars show the standard error of relative abundance of the three subsamples for each tailings sample.