Metal Mobilization by Iron- and Sulfur-Oxidizing Bacteria in a Multiple Extreme Mine Tailings in the Atacama Desert, Chile

Abstract

The marine shore sulfidic mine tailings dump at the Chañaral Bay in the Atacama Desert, northern Chile, is characterized by extreme acidity, high salinity, and high heavy metals concentrations. Due to pyrite oxidation, metals (especially copper) are mobilized under acidic conditions and transported toward the tailings surface and precipitate as secondary minerals (Dold, Environ. Sci. Technol. 2006, 40, 752-758.). Depth profiles of total cell counts in this almost organic-carbon free multiple extreme environment showed variable numbers with up to 10(8) cells g(-1) dry weight for 50 samples at four sites. Real-time PCR quantification and bacterial 16S rRNA gene diversity analysis via clone libraries revealed a dominance of Bacteria over Archaea and the frequent occurrence of the acidophilic iron(II)- and sulfur-oxidizing and iron(III)-reducing genera Acidithiobacillus, Alicyclobacillus, and Sulfobacillus. Acidophilic chemolithoautotrophic iron(II)-oxidizing bacteria were also frequently found via most-probable-number (MPN) cultivation. Halotolerant iron(II)-oxidizers in enrichment cultures were active at NaCl concentrations up to 1 M. Maximal microcalorimetrically determined pyrite oxidation rates coincided with maxima of the pyrite content, total cell counts, and MPN of iron(II)-oxidizers. These findings indicate that microbial pyrite oxidation and metal mobilization preferentially occur in distinct tailings layers at high salinity. Microorganisms for biomining with seawater salt concentrations obviously exist in nature.

Formation and release behavior of iron corrosion products under the influence of bacterial communities in a simulated water distribution system

“…36 H 2 S could be converted to sulfuric acid (H 2 SO 4 ) by SOB, resulting in serious iron corrosion. 37 In the present study, SRB and SOB were mainly found in the inner layer (under anaerobic conditions), and the corrosion rate of cast iron coupons at Stage II was positively correlated with SRB (R ¼ 0.74) and SOB (R ¼ 0.97). This result might indicate that growth and interaction of SRB and SOB were mainly associated with anaerobic iron corrosion.…”

Correlating Microbial Diversity Patterns with Geochemistry in an Extreme and Heterogeneous Environment of Mine Tailings

“…Because of their biological and geochemical simplicity and the steep environmental gradients associated with different oxidation stages, the extreme tailing environments are ideal targets for the study of local microbial diversity and how communities respond to environmental changes. The microbial community diversity in mine tailings has recently been investigated by comparative 16S rRNA sequencing (12)(13)(14)(15)(16). While these studies have significantly expanded our knowledge of the biodiversity of extreme tailing environments (including the detection of less-well-known or novel taxa), systematic exploration of the driving factors in local community composition and how microbial populations interact with changing environmental conditions has thus far been impossible.…”

Biological Influence on the Mobility of Metals from Mine Tailing Dump Located in Krugersdorp Area

“…According to the literature these microorganisms often occur in dumps of mine waste rockandtailingsfrom sulfide ore processingplants. Acidophiliciron(II)-andsulfuroxidizing bacteria are responsible for the release of sulfuric acid which are able to promote the release of metals from the tailing dumps [21].Heterotrophic bacteria were represented by Bacillussp and Pseudomonassp which are among the bacteria species must likely to degrade the organic matter to form organic acids; these species were found at all the sampling sites. …”