Geomicrobiology of La Zarza-Perrunal Acid Mine Effluent (Iberian Pyritic Belt, Spain)

Abstract

Effluent from La Zarza-Perrunal, a mine on the Iberian Pyrite Belt, was chosen to be geomicrobiologically characterized along a 1,200-m stream length. The pH at the origin was 3.1, which decreased to 1.9 at the final downstream sampling site. The total iron concentration showed variations along the effluent, resulting from (i) significant hydrolysis and precipitation of Fe(III) (especially along the first reach of the stream) and (ii) concentration induced by evaporation (mostly in the last reach). A dramatic increase in iron oxidation was observed along the course of the effluent [from Fe(III)/Fe total ‫؍‬ 0.11 in the origin to Fe(III)/Fe total ‫؍‬ 0.99 at the last sampling station]. A change in the O 2 content along the effluent, from nearly anoxic at the origin to saturation with oxygen at the last sampling site, was also observed. Prokaryotic and eukaryotic diversity throughout the effluent was determined by microscopy and 16S rRNA gene cloning and sequencing. Sulfatereducing bacteria (Desulfosporosinus and Syntrophobacter) were detected only near the origin. Some ironreducing bacteria (Acidiphilium, Acidobacterium, and Acidosphaera) were found throughout the river. Ironoxidizing microorganisms (Leptospirillum spp., Acidithiobacillus ferrooxidans, and Thermoplasmata) were increasingly detected downstream. Changes in eukaryotic diversity were also remarkable. Algae, especially Chlorella, were present at the origin, forming continuous, green, macroscopic biofilms, subsequently replaced further downstream by sporadic Zygnematales filaments. Taking into consideration the characteristics of this acidic extreme environment and the physiological properties and spatial distribution of the identified microorganisms, a geomicrobiological model of this ecosystem is advanced.The peculiar ecology and physiology of extremophiles and the environments in which they develop have intrigued microbiologists since their discovery. The biotechnological potential of their unusual properties make their study of great interest (32,34,37,41). Environments with extremely low pH values do not abound. They are mainly associated with two phenomena: volcanic and hydrothermal activities (hot sulfur springs, mud spots, etc.) and metal mining activities (16). The second category is especially interesting, because, in general, the extreme low pH of the habitat is a consequence of microbial metabolism (18) and not a condition imposed by the system, as is the case in many other extreme environments (e.g., high temperature, ionic strength, radiation, and pressure). Acidophilic chemolithotrophic microorganisms present in these environments have the potential to accelerate the oxidation and dissolution reactions of metal sulfides, resulting in acidic waters with high concentrations of sulfate and heavy metals (35).These acidic waters are known as acid mine drainage (AMD), and they are a serious environmental problem in the province of Huelva (southwestern Spain). These acidic solutions emerge from mine portals, waste-rock piles, and/or tailings fr...

Microbial Diversity and Community Assembly across Environmental Gradients in Acid Mine Drainage

“…The distribution of microbial communities in AMD is mostly correlated to pH or the so-called oxidation stage in sulfide minerals, as shown in previous studies [48,54,[59][60][61]. In our investigation of AMD (pH < 4.0) in South China, diverse environmental factors were applied to explain the variation of microbial community assembly [24,29].…”

Geomicrobiology of Acid Mine Drainage in the weathering zone of pyrite-bearing schists in the Rudawy Janowickie Mountains (Poland)

“…With re gard to chem ical com po si tion, they are sim i lar to other widely dis cussed oc cur rences of AMD (Murad et al, 1994;Web ster et al, 1994;Leduc et al, 2002;Joeckel et al, 2005). Limno logi cal, mi cro bi o log i cal and hydrogeochemical stud ies of such res er voirs, formed in py rite mines near Rio Tinto in the "Span ish Py rite Belt", have been pub lished by Sánchez-EspaÔa et al (2008), González-Toril et al (2011) andSánchez-Andrea et al (2011). Wa ter from these res er voirs is charac ter ized by phys i cal and chem i cal prop erties sim i lar to those found in the work ings of the Wieoeciszowice mine.…”

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

“…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.…”

“…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.…”