Microbial communities and geochemical dynamics in an extremely acidic, metal‐rich stream at an abandoned sulfide mine (Huelva, Spain) underpinned by two functional primary production systems

Abstract

An extremely acidic (pH 2.5-2.75) metal-rich stream draining an abandoned mine in the Iberian Pyrite Belt, Spain, was ramified with stratified macroscopic gelatinous microbial growths ('acid streamers' or 'mats'). Microbial communities of streamer/mat growths sampled at different depths, as well as those present in the stream water itself, were analysed using a combined biomolecular and cultivation-based approach. The oxygen-depleted mine water was dominated by the chemolithotrophic facultative anaerobe Acidithiobacillus ferrooxidans, while the streamer communities were found to be highly heterogeneous and very different to superficially similar growths reported in other extremely acidic environments. Microalgae accounted for a significant proportion of surface streamer biomass, while subsurface layers were dominated by heterotrophic acidophilic bacteria (Acidobacteriacae and Acidiphilium spp.). Sulfidogenic bacteria were isolated from the lowest depth streamer growths, where there was also evidence for selective biomineralization of copper sulfide. Archaeal clones (exclusively Euryarchaeota) were recovered from streamer samples, as well as the mine stream water. Both sunlight and reduced inorganic chemicals (predominantly ferrous iron) served as energy sources for primary producers in this ecosystem, promoting complex microbial interactions involving transfer of electron donors and acceptors and of organic carbon, between microorganisms in the stream water and the gelatinous streamer growths. Microbial transformations were shown to impact the biogeochemical cycling of iron and sulfur in the acidic stream, severely restricting the net oxidation of ferrous iron even when the initially anoxic waters were oxygenated by indigenous acidophilic algae. A model accounting for the biogeochemistry of iron and sulfur in the mine waters is described, and the significance of the acidophilic communities in regulating the geochemistry of acidic, metal-rich waters is described.

Microbial community structure across the tree of life in the extreme Río Tinto

“…At least some of the members of the Bacteroidetes-related sequences branched with sequences identified as symbionts of Acanthamoeba spp. In addition to new acidobacterial sequences, some of the Acidobacteria that we obtained from OR2 were related to sequences from a metagenomic survey from the RT rhizosphere, whereas others were related to those recovered from acid-mine tailings, including acidobacterial sequences from a nearby copper mine in the Odiel River basin (Rowe et al, 2007). The presence of Acidobacteria in the RT was detected previously by an oligonucleotide array experiment (Garrido et al, 2008), but here we report the actual sequences from acidobacteria new to the RT.…”

Synthesis of Copper Sulfide Nanoparticles Using Biogenic H2S Produced by a Low-pH Sulfidogenic Bioreactor

“…Bacteria were isolated from the bioreactor by streaking liquid samples onto overlay SRB medium to promote the growth of acidophilic SRB [7]. Phylogenetic analysis of the isolates was carried out using the method described by Rowe and colleagues [16].…”

Oxygen-dependent niche formation of a pyrite-dependent acidophilic consortium built by archaea and bacteria

“…The Thermoplasmatales sequences are mainly related to a branch with uncultured representatives of this order, whereas one type (Archaea-Clone_HM_ 19-40% from all archaea clones) is related to Ferroplasma (Figure 5). The closest relatives to Archaea-Clone_HM_2 (42%), Archaea-Clone_ HM_20 (6%) and Archaea-Clone_HM_21 (13%) are so far uncultured representatives from other acidic environments found in the Iberian Pyrite Belt ( Figure 5) (Rowe et al, 2007;Amaral-Zettler et al, 2011;Gonzalez-Toril et al, 2011). Based on the restriction fragment length polymorphism results, more specific probes for the detection of ARMAN and Thermoplasmatales were used.…”

“…The more related sequences from uncultured organisms stem from other acidic environments like the Iberian Pyrite Belt, including Rio Tinto (Rowe et al, 2007;Amaral-Zettler et al, 2011;Gonzalez-Toril et al, 2011). Due to their remote position in the phylogenetic tree and as there is no isolated species belonging to these deeply branching organisms, it is not possible to assign certain physiological characteristics yet.…”

“…(Bond et al, 2000;Dopson et al, 2004;García-Moyano et al, 2007;Ziegler et al, 2009;Kimura et al, 2011). Interestingly, some of the members of the Thermoplasmatales found by culture-independent methods in acidic mining areas are-judging from the 16S rDNA sequences-quite distinct from the isolated representatives (Rowe et al, 2007;Gonzalez-Toril et al, 2011). Hence, it is possible to taxonomically classify them, but it has to be questioned whether these organisms have the same capabilities as the known isolates.…”