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The microbial communities in mining impacted areas rely on a variety of mechanisms to survive in such extreme environments. In this work, a meta-taxonomic approach using 16S rRNA gene sequences was used to investigate the prokaryotic diversity of sediment samples from water bodies affected by acid mine drainage at the São Domingos mining area in the south of Portugal. Samples were collected in summer and winter from the most contaminated sites from where the water flows downstream to the freshwater of Chança's river reservoir. The prokaryotic diversity on water bodies' sediments allowed us to distinguish the highly contaminated sites (pH ≈ 2) from sites with intermediate levels of contamination (pH ≈ 3–6.5), and from sites without contamination (pH ≈ 7.5). The abundances of acidophiles of genera Acidiphilium, Acidibacter, Acidobacterium and Acidocella in the sediments were correlated with the level of acid mine drainage contamination. The two first genera were among the 30 most abundant prokaryotes in all contaminated samples, including one (SS2w), where the contamination was very diluted, thereby emphasizing the impact that such type of pollution can have in the microbial communities of sediments. In addition, the high abundances of archaeal taxa from class Thermoplasmata and of bacteria from family RCP1-48 in the sediments from the most contaminated site corroborate their importance in such ecosystems and a putative role in the generation of acid mine drainage. [ABSTRACT FROM AUTHOR]

The prokaryotic communities of water bodies contaminated by acid mine drainage from the São Domingos mining area in southern Portugal were analyzed using a meta-taxonomics approach with 16S rRNA gene sequences. Samples were collected in two seasonal sampling campaigns (summer and winter of 2017) from the most contaminated sites from where the water flows downstream to the freshwater reservoir of the river Chança. The physicochemical data indicate a trend of decreasing acid mine drainage contamination downstream of the mining area to the Chança's reservoir. The most contaminated sites (pH = 2.3–3.1) are distinguished by prokaryotic diversity with high abundances of operational taxonomics units related to acidophiles (genera Metallibacterium, Acidibacter, Leptospirillum, Acidobacterium, Thiomonas, Acidicapsa, Acidocella, Acidiphilium; family Acidobacteriaceae, order CPla-3 termite group). Likewise, in the transition zone in the mouth of the contaminated water flow into the Chança´s reservoir (pH = 6.4), a specific prokaryotic flora exists with some acidophiles, but notably with a cyanobacteria bloom and a high abundance of the genus Sediminibacterium (family I; order Subsection III). Moreover, the strong correlation between the abundance of acidophiles and characteristic physiochemical parameters (metals, acidity, and sulfate) confirm their potential as biomarkers of acid mine drainage pollution. [ABSTRACT FROM AUTHOR]