Some aspects of the effect of pH and acid stress in heap bioleaching

Tupikina, O. V.; Ngoma, I. Emmanuel; Minnaar, Sanet H.; Harrison, Susan T.L.

doi:10.1016/j.mineng.2011.06.001

Cited by 16 publications

(6 citation statements)

References 8 publications

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“…Bootstraps values are percentages based on 1,000 resampling. Scale bar indicates 0.05 sequence divergence Table 4 Comparison of metabolic and molecular characteristics between strain ALE1 and different members of Acidianus genus role in almost all the different local environments that could be created into bioleaching heaps [33]. Currently, our group is carrying laboratory scale assays with promising results.…”

Section: Molecular Biology Characterisationmentioning

confidence: 99%

Physiologic Versatility and Growth Flexibility as the Main Characteristics of a Novel Thermoacidophilic Acidianus Strain Isolated from Copahue Geothermal Area in Argentina

et al. 2012

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A novel thermoacidophilic archaeal strain has been isolated from three geothermal acidic hot springs in Copahue, Argentina. One of the most striking characteristic of ALE1 isolate is its metabolic versatility. It grows on sulphur, tetrathionate, iron (II) and sucrose under aerobic conditions, but it can also develop under anaerobic conditions using iron (III) or sulphur as electron acceptors and sulphur or hydrogen as electron donors autotrophically. A temperature of 75 °C and a pH between 2.5 and 3.0 are strain ALE1 optimal growth conditions, but it is able to oxidise iron (II) even at pH 1.0. Cells are irregular cocci surrounded by a regularly arrayed glycoprotein layer (S-layer). Phylogenetic analysis shows that strain ALE1 belongs to the family Sulfolobaceae in the class Thermoprotei, within the phylum Crenarchaeota. Based on 16S rRNA gene sequence similarity on NCBI database, ALE1 does not have closely related relatives, neither in culture nor uncultured, which is more surprising. Its closest related species are strains of Acidianus hospitalis (91 % of sequence similarity), Acidianus infernus (90 %), Acidianus ambivalens (90 %) and Acidianus manzanensis (90 %). Its DNA base composition of 34.5 % mol C + G is higher than that reported for other Acidianus species. Considering physiological and phylogenetic characteristics of strain ALE1, we considered it to represent a novel species of the genus Acidianus (candidatus "Acidianus copahuensis"). The aim of this study is to physiologically characterise this novel archaea in order to understand its role in iron and sulphur geochemical cycles in the Copahue geothermal area and to evaluate its potential applications in bioleaching and biooxidation.

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Section: Molecular Biology Characterisationmentioning

confidence: 99%

Physiologic Versatility and Growth Flexibility as the Main Characteristics of a Novel Thermoacidophilic Acidianus Strain Isolated from Copahue Geothermal Area in Argentina

et al. 2012

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“…Halinen et al [ 32 ] operated unsaturated pH-controlled columns of polymetallic black schist ore in the range pH 1.5–3.0 and concluded that pH 2 was optimum for good metal extraction and would minimise excess acid consumption due to gangue mineral dissolution. Tupikina et al [ 33 ] reported that irrigation of unsaturated columns with a solution pH 1.7 or higher resulted in loss of the soluble iron, but with a solution feed of pH 1.4, there was a net increase in soluble iron.…”

Section: Resultsmentioning

confidence: 99%

Extremophiles in Mineral Sulphide Heaps: Some Bacterial Responses to Variable Temperature, Acidity and Solution Composition

2015

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In heap bioleaching, acidophilic extremophiles contribute to enhanced metal extraction from mineral sulphides through the oxidation of Fe(II) and/or reduced inorganic sulphur compounds (RISC), such as elemental sulphur or mineral sulphides, or the degradation of organic compounds derived from the ore, biota or reagents used during mineral processing. The impacts of variable solution acidity and composition, as well as temperature on the three microbiological functions have been examined for up to four bacterial species found in mineral sulphide heaps. The results indicate that bacteria adapt to sufficiently high metal concentrations (Cu, Ni, Co, Zn, As) to allow them to function in mineral sulphide heaps and, by engaging alternative metabolic pathways, to extend the solution pH range over which growth is sustained. Fluctuating temperatures during start up in sulphide heaps pose the greatest threat to efficient bacterial colonisation. The large masses of ores in bioleaching heaps mean that high temperatures arising from sulphide oxidation are hard to control initially, when the sulphide content of the ore is greatest. During that period, mesophilic and moderately thermophilic bacteria are markedly reduced in both numbers and activity.

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“…Very few acidophiles prefer or are active in habitats poised below pH 1. This was demonstrated in column tests where solution ORP fell, indicative of lower iron(II)-biooxidation activity, when the recycled, pH 1.7 solution, was acidified further to pH < 1 [58]. Similarly, the addition of acid to raffinate prior to recycle to a heap also caused decreased iron(II)-and RISC-oxidising activity in a heap microbial population [59].…”

Section: Aciditymentioning

confidence: 87%

Microbiological Advances in Biohydrometallurgy

Watling

2016

Minerals

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The most exciting advances in biohydrometallurgy are occurring in the field of microbiology. The two main technologies employed in biohydrometallurgy, agitated tanks for the processing of refractory concentrates and heaps and dumps for the processing of low-grade ores, are technologically sound and widely practised at commercial scale, but their development began at a time when very little was known of the microorganisms that assisted metals extraction from sulfide ores. During and subsequent to those developments it has been shown that microbial communities in metals extraction are more diverse than originally thought, and extremely robust and adaptable to different and variable environments. Recent advances in genomics and proteomics, exploiting hugely increased computing power and speed, have made it possible to describe not only which microorganisms are present in bioleaching systems, but also what physiological functions are being exercised. The body of knowledge being acquired through the application of molecular biology methods will be used increasingly to monitor microbial behaviour, optimise conditions for more appropriate microbiological activity and/or infer the "microbiological health" of bioreactors (tanks and heaps).

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Some aspects of the effect of pH and acid stress in heap bioleaching

Cited by 16 publications

References 8 publications

Physiologic Versatility and Growth Flexibility as the Main Characteristics of a Novel Thermoacidophilic Acidianus Strain Isolated from Copahue Geothermal Area in Argentina

Physiologic Versatility and Growth Flexibility as the Main Characteristics of a Novel Thermoacidophilic Acidianus Strain Isolated from Copahue Geothermal Area in Argentina

Extremophiles in Mineral Sulphide Heaps: Some Bacterial Responses to Variable Temperature, Acidity and Solution Composition

Microbiological Advances in Biohydrometallurgy

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