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Microorganisms 2015, 3(3), 364-390; doi:10.3390/microorganisms3030364

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

CSIRO Mineral Resources Flagship, Australian Minerals Research Centre, P.O. Box 7229, Karawara, WA 6152, Australia
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Academic Editors: Ricardo Amils and Elena González Toril
Received: 4 June 2015 / Revised: 26 June 2015 / Accepted: 29 June 2015 / Published: 9 July 2015
(This article belongs to the Special Issue Extremophiles)

Abstract

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. View Full-Text
Keywords: heap bioleaching; bacterial acid stress; bacterial heat stress; bacterial metal tolerance heap bioleaching; bacterial acid stress; bacterial heat stress; bacterial metal tolerance
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Watling, H.R.; Shiers, D.W.; Collinson, D.M. Extremophiles in Mineral Sulphide Heaps: Some Bacterial Responses to Variable Temperature, Acidity and Solution Composition. Microorganisms 2015, 3, 364-390.

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