Microbial composition of oxic and low pH sediment core layers from Parys Mountain

Parys Mountain or Mynydd Parys (Isle of Anglesey, UK) is a mine-impacted environment, which accommodates a variety of acidophilic bacteria and archaea. To understand the spatial distribution of archaea across sediment layers with different geochemical parameters, we present here a survey of sediment microbiomes using 16S rRNA gene amplicon sequencing. The taxonomic affiliation of sequencing reads pointed at significant proportions of archaea in microbial communities at all analysed sediment depths (0-20 cm). All archaea were associated with the order Thermoplasmatales, with the most abundant group of sequences being clustered closely with phylotype B_DKE , followed by E-plasma, A-plasma, other uncultured Thermoplasmatales and Cuniculiplasma spp. as a minor group. We did not identify any pattern of physical-chemical conditions favoured by these archaea, pointing at a predominance of Thermoplasmatales across the of depth and chemical gradients. This study has revealed a high abundance of Thermoplasmatales not only on the surface of AMD-exposed sediments, but in all layers and pointed points at these organisms being the main contributors to carbon, iron and sulfur cycles in AMD-affected Parys Mt stream sediments.