Acidophiles - Explore the Science & Experts | ideXlab


Scan Science and Technology

Contact Leading Edge Experts & Companies

Acidophiles

The Experts below are selected from a list of 2667 Experts worldwide ranked by ideXlab platform

Acidophiles – Free Register to Access Experts & Abstracts

Mark Dopson – One of the best experts on this subject based on the ideXlab platform.

  • metal resistance or tolerance Acidophiles confront high metal loads via both abiotic and biotic mechanisms
    Frontiers in Microbiology, 2014
    Co-Authors: Mark Dopson, Francisco J Ossandon, Lars Lovgren, David S Holmes

    Abstract:

    All metals are toxic at high concentrations and consequently their intracellular concentrations must be regulated. Extremely acidophilic microorganisms have an optimum growth of pH <3 and proliferate in natural and anthropogenic low pH environments. Some Acidophiles are involved in the catalysis of sulfide mineral dissolution, resulting in high concentrations of metals in solution. Acidophiles are often described as highly metal resistant via mechanisms such as multiple and/or more efficient active resistance systems than are present in neutrophiles. However, this is not the case for all Acidophiles and we contend that their growth in high metal concentrations is partially due to an intrinsic tolerance as a consequence of the environment in which they live. In this perspective, we highlight metal tolerance via complexation of free metals by sulfate ions and passive tolerance to metal influx via an internal positive cytoplasmic transmembrane potential. These tolerance mechanisms have been largely ignored in past studies of acidophile growth in the presence of metals and should be taken into account.

    Free Register to Access Article

  • Gene Identification and Substrate Regulation Provide Insights into Sulfur Accumulation during Bioleaching with the Psychrotolerant Acidophile Acidithiobacillus ferrivorans
    Applied and Environmental Microbiology, 2012
    Co-Authors: Maria Liljeqvist, Olena Rzhepishevska, Mark Dopson

    Abstract:

    The psychrotolerant acidophile Acidithiobacillus ferrivorans has been identified from cold environments and has been shown to use ferrous iron and inorganic sulfur compounds as its energy sources. A bioinformatic evaluation presented in this study suggested that Acidithiobacillus ferrivorans utilized a ferrous iron oxidation pathway similar to that of the related species Acidithiobacillus ferrooxidans. However, the inorganic sulfur oxidation pathway was less clear, since the Acidithiobacillus ferrivorans genome contained genes from both Acidithiobacillus ferrooxidans and Acidithiobacillus caldus encoding enzymes whose assigned functions are redundant. Transcriptional analysis revealed that the petA1 and petB1 genes (implicated in ferrous iron oxidation) were downregulated upon growth on the inorganic sulfur compound tetrathionate but were on average 10.5-fold upregulated in the presence of ferrous iron. In contrast, expression of cyoB1 (involved in inorganic sulfur compound oxidation) was decreased 6.6-fold upon growth on ferrous iron alone. Competition assays between ferrous iron and tetrathionate with Acidithiobacillus ferrivorans SS3 precultured on chalcopyrite mineral showed a preference for ferrous iron oxidation over tetrathionate oxidation. Also, pure and mixed cultures of psychrotolerant Acidophiles were utilized for the bioleaching of metal sulfide minerals in stirred tank reactors at 5 and 25°C in order to investigate the fate of ferrous iron and inorganic sulfur compounds. Solid sulfur accumulated in bioleaching cultures growing on a chalcopyrite concentrate. Sulfur accumulation halted mineral solubilization, but sulfur was oxidized after metal release had ceased. The data indicated that ferrous iron was preferentially oxidized during growth on chalcopyrite, a finding with important implications for biomining in cold environments.

    Free Register to Access Article

  • Biodiversity, metabolism and applications of acidophilic sulfur-metabolizing microorganisms.
    Environmental Microbiology, 2012
    Co-Authors: Mark Dopson, D. Barrie Johnson

    Abstract:

    Extremely acidic, sulfur-rich environments can be natural, such as solfatara fields in geothermal and volcanic areas, or anthropogenic, such as acid mine drainage waters. Many species of acidophilic bacteria and archaea are known to be involved in redox transformations of sulfur, using elemental sulfur and inorganic sulfur compounds as electron donors or acceptors in reactions involving between one and eight electrons. This minireview describes the nature and origins of acidic, sulfur-rich environments, the biodiversity of sulfur-metabolizing Acidophiles, and how sulfur is metabolized and assimilated by Acidophiles under aerobic and anaerobic conditions. Finally, existing and developing technologies that harness the abilities of sulfur-oxidizing and sulfate-reducing Acidophiles to extract and capture metals, and to remediate sulfur-polluted waste waters are outlined.

    Free Register to Access Article

D. Barrie Johnson – One of the best experts on this subject based on the ideXlab platform.

  • Biodiversity, metabolism and applications of acidophilic sulfur-metabolizing microorganisms.
    Environmental Microbiology, 2012
    Co-Authors: Mark Dopson, D. Barrie Johnson

    Abstract:

    Extremely acidic, sulfur-rich environments can be natural, such as solfatara fields in geothermal and volcanic areas, or anthropogenic, such as acid mine drainage waters. Many species of acidophilic bacteria and archaea are known to be involved in redox transformations of sulfur, using elemental sulfur and inorganic sulfur compounds as electron donors or acceptors in reactions involving between one and eight electrons. This minireview describes the nature and origins of acidic, sulfur-rich environments, the biodiversity of sulfur-metabolizing Acidophiles, and how sulfur is metabolized and assimilated by Acidophiles under aerobic and anaerobic conditions. Finally, existing and developing technologies that harness the abilities of sulfur-oxidizing and sulfate-reducing Acidophiles to extract and capture metals, and to remediate sulfur-polluted waste waters are outlined.

    Free Register to Access Article

  • Biodiversity, metabolism and applications of acidophilic sulfur-metabolizing microorganisms: Sulfur metabolizing Acidophiles
    Environmental microbiology, 2012
    Co-Authors: Mark Dopson, D. Barrie Johnson

    Abstract:

    Extremely acidic, sulfur-rich environments can be natural, such as solfatara fields in geothermal and volcanic areas, or anthropogenic, such as acid mine drainage waters. Many species of acidophilic bacteria and archaea are known to be involved in redox transformations of sulfur, using elemental sulfur and inorganic sulfur compounds as electron donors or acceptors in reactions involving between one and eight electrons. This minireview describes the nature and origins of acidic, sulfur-rich environments, the biodiversity of sulfur-metabolizing Acidophiles, and how sulfur is metabolized and assimilated by Acidophiles under aerobic and anaerobic conditions. Finally, existing and developing technologies that harness the abilities of sulfur-oxidizing and sulfate-reducing Acidophiles to extract and capture metals, and to remediate sulfur-polluted waste waters are outlined.

    Free Register to Access Article

  • Attachment of acidophilic bacteria to solid surfaces: The significance of species and strain variations
    Hydrometallurgy, 2006
    Co-Authors: M. Afzal Ghauri, Naoko Okibe, D. Barrie Johnson

    Abstract:

    Abstract Sixteen strains of acidophilic bacteria were screened for their abilities to adhere to pyrite ore, glass beads and ferric hydroxysulfates. These were three culture collection and two isolated strains of the iron- and sulfur-oxidizer, Acidithiobacillus ferrooxidans, two each of the sulfur-oxidizer Acidithiobacillus thiooxidans and the iron-oxidizer Leptospirillum ferrooxidans (the type strain and a mine isolate in either case), five heterotrophic Acidophiles (four Acidiphilium and one Acidocella sp.) and two moderately thermophilic iron/sulfur-oxidizers (Sulfobacillus thermosulfidooxidans and Sulfobacillus acidophilus). Considerable variations were found between different species of Acidophiles, and also between different strains of the same species, in how they attached to the three solid materials tested. Attachment to the solid substrata generally increased with time (over 100 min) though > 99% of one At. ferrooxidans isolate (strain OP14) were attached to pyrite after just 10 min exposure. Most Acidophiles attached more readily to pyrite than to glass beads, and attachment to ferric hydroxysulfates was highly variable, though one At. ferrooxidans isolate (strain SJ2) and one heterotrophic acidophile (Acidocella sp. het-4) both attached strongly to ferric iron precipitates (jarosites and schwertmannite) that formed in cultures of At. ferrooxidans grown at pH > 2. The results of these experiments showed that even closely related strains of acidophilic bacteria can display very different propensities to attach to solid materials, an observation that may explain the somewhat disparate results reported on occasions by research groups that have examined single, or limited numbers of strains, of Acidophiles (mostly At. ferrooxidans). The significance of differential attachment of mineral-oxidizing and other Acidophiles to pyrite and other solids is discussed in the context of biohydrometallurgy.

    Free Register to Access Article

Elizabeth L.j. Watkin – One of the best experts on this subject based on the ideXlab platform.

  • Draft Genome Sequence of Acidihalobacter ferrooxidans DSM 14175 (Strain V8), a New Iron- and Sulfur-Oxidizing, Halotolerant, Acidophilic Species.
    Genome Announcements, 2017
    Co-Authors: Himel N. Khaleque, Joshua P. Ramsay, Riley J. T. Murphy, Anna H. Kaksonen, Naomi J. Boxall, Elizabeth L.j. Watkin

    Abstract:

    ABSTRACT The use of halotolerant Acidophiles for bioleaching provides a biotechnical approach for the extraction of metals from regions where high salinity exists in the ores and source water. Here, we describe the first draft genome of a new species of a halotolerant and iron- and sulfur-oxidizing acidophile, Acidihalobacter ferrooxidans DSM-14175 (strain V8).

    Free Register to Access Article

  • Bioleaching in brackish waters–effect of chloride ions on the acidophile population and proteomes of model species.
    Applied Microbiology and Biotechnology, 2011
    Co-Authors: Carla M. Zammit, Mark Dopson, Stefanie Mangold, Venkateswara Rao Jonna, Lesley Mutch, Helen R. Watling, Elizabeth L.j. Watkin

    Abstract:

    High concentrations of chloride ions inhibit the growth of acidophilic microorganisms used in biomining, a problem particularly relevant to Western Australian and Chilean biomining operations. Despite this, little is known about the mechanisms Acidophiles adopt in order to tolerate high chloride ion concentrations. This study aimed to investigate the impact of increasing concentrations of chloride ions on the population dynamics of a mixed culture during pyrite bioleaching and apply proteomics to elucidate how two species from this mixed culture alter their proteomes under chloride stress. A mixture consisting of well-known biomining microorganisms and an enrichment culture obtained from an acidic saline drain were tested for their ability to bioleach pyrite in the presence of 0, 3.5, 7, and 20 g L−1 NaCl. Microorganisms from the enrichment culture were found to out-compete the known biomining microorganisms, independent of the chloride ion concentration. The proteomes of the Gram-positive acidophile Acidimicrobium ferrooxidans and the Gram-negative acidophile Acidithiobacillus caldus grown in the presence or absence of chloride ions were investigated. Analysis of differential expression showed that acidophilic microorganisms adopted several changes in their proteomes in the presence of chloride ions, suggesting the following strategies to combat the NaCl stress: adaptation of the cell membrane, the accumulation of amino acids possibly as a form of osmoprotectant, and the expression of a YceI family protein involved in acid and osmotic-related stress.

    Free Register to Access Article