New insights into the biogeochemistry of extremely acidic environments revealed by a combined cultivation-based and culture-independent study of two stratified pit lakes

Abstract

The indigenous microbial communities of two extremely acidic, metal-rich stratified pit lakes, located in the Iberian Pyrite Belt (Spain), were identified, and their roles in mediating transformations of carbon, iron, and sulfur were confirmed. A combined cultivation-based and culture-independent approach was used to elucidate microbial communities at different depths and to examine the physiologies of isolates, which included representatives of at least one novel genus and several species of acidophilic Bacteria. Phosphate availability correlated with redox transformations of iron, and this (rather than solar radiation) dictated where primary production was concentrated. Carbon fixed and released as organic compounds by acidophilic phototrophs acted as electron donors for acidophilic heterotrophic prokaryotes, many of which catalyzed the dissimilatory reduction in ferric iron; the ferrous iron generated was re-oxidized by chemolithotrophic acidophiles. Bacteria that catalyze redox transformations of sulfur were also identified, although these Bacteria appeared to be less abundant than the iron oxidizers/reducers. Primary production and microbial numbers were greatest, and biogeochemical transformation of carbon, iron, and sulfur, most intense, within a zone of c. 8-10 m depth, close to the chemocline, in both pit lakes. Archaea detected in sediments included two Thaumarchaeota clones, indicating that members of this recently described phylum can inhabit extremely acidic environments.

Formation of biogenic sulphides in the water column of an acidic pit lake: biogeochemical controls and effects on trace metal dynamics

“…The presence of planktonic and benthic SRB in this lake has been reported by Wendt-Potthoff et al (2012). This presence of SRB has been later confirmed by Falagán et al (2014), who have identified Desulfomonile sp. at a water depth of 10.5 m (i.e., immediately below the redoxcline) and Desulfosporosinus sp.…”

<b>Reassessment of the suitable range of water pH for culture of Nile tilapia <i>Oreochromis niloticus</i> L. in eutrophic water

“…The water acidification has led to soil acidification: the pH of soil in the control and moderately acidified tanks were 7.9 ± 0.5 (7.3 -8.9) and 6.4 ± 1.1 (4.6 -7.6), respectively. The increase in the concentrations of phosphorus and iron in water in the moderately acidified tanks may be explained by the release of these ions from the acidic soils into the water (Falagán, Sánchez-España, & Johnson, 2014). The concentrations of organic carbon in soil were not significantly affected by the treatments (ANOVA p < 0.05).…”

Effect of Sewage and Industrial Effluents on Bacterial and Archaeal Communities of Creek Sediments in the Taihu Basin

“…Previous studies indicated that Chloroflexia was suited to live under brackish, nutrient-rich conditions [78]. Nitrospira, which was found to be more abundant at sites far away from the pollution source (D2, D3, J2, and J3), has often been found in freshwater ecosystems [79,80], sewage treatment systems [81], and anoxic environments as nitrite oxidizers [82]. Based on the results of RDA (Figure 9a), Nitrospira was positively correlated with NH 4 + -N, NO 3 Cl − -N, TOC, and TSI, but negatively correlated with RI.…”