A Snapshot of the Microbiome of a Portuguese Abandoned Gold Mining Area

Microbial communities are known to contribute deeply to geochemical cycles, including weathering, protection from erosion and mineral precipitation. Studies aiming to understand mining areas' microbiomes are of high relevance since they can help pinpoint the occurrence of environmental shifts, key bioremediation species, environmental metals recovery strategies, and microorganisms with relevant industrial properties. Nonetheless, so far, the study of Portuguese gold-rich areas' microbiomes has been largely neglected. The main goal of this study was to apply high-throughput sequencing methods to study the microbiome (Bacteria and Fungi) and predict their functional/metabolic profiles in an abandoned Portuguese gold mining area (considering zones without a history of mining, the tailings and the flooded mine interior). The results obtained revealed high bacterial and fungal diversities at these sites while also pinpointing the presence of relative homogenous bacterial and heterogenous fungal communities. Areas without mining history were mainly dominated by WD2101 soil groups, Sphingomonas, Candidatus Solibacter, Helotiales, unclassified Fungi and Arxotrichum. The tailings were mainly colonized by Bryobacter, WD2101 soil groups, WPS-2 genera, Starmerella, Helotiales and Mollisia. On the other hand, the mine area displayed a dominance of Crossiella, Gemmataceae, Acidobacteriaceae (Subgroup 1), Acidiphilium, Mortierella, unclassified Fungi and Chaetothyriales. Furthermore, we verified that contrary to bacteria, the fungal structural diversity is somewhat more restricted to each site. In addition, metabolic, functional and ecological profiles revealed a strong distinction for both bacterial and fungal communities while also revealing the presence of well-adapted communities to each of the particular microenvironments considered.