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Physiology and Genetics of Acidithiobacillus species: Applications for Biomining
Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology).
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Bacteria from the genus Acidithiobacillus are often associated with biominingand acid mine drainage. Biomining utilises acidophilic, sulphur and ironoxidising microorganisms for recovery of metals from sulphidic low grade oresand concentrates. Acid mine drainage results in acidification and contaminationwith metals of soil and water emanating from the dissolution of metal sulphidesfrom deposits and mine waste storage. Acidophilic microorganisms play acentral role in these processes by catalysing aerobic oxidation of sulphides.Acceleration of mineral solubilisation is a positive aspect in biomining whereas,in acid mine drainage it is undesirable and accordingly, microbial iron andsulphur oxidation is promoted in the first case and measures are taken to inhibitit in the second case. In this thesis, several approaches were taken in order tounderstand and increase oxidation efficiency in biomining and to gain an insightinto the biochemical reactions taking place in these environments. A laboratoryscale bioreactor was designed and tested allowing simulation of bioleaching inheaps of mine tailings at different aeration, irrigation and particle size conditions(Paper I). A new psychrotolerant strain of Acidithiobacillus ferrooxidans wascharacterised that has an application in boreal heap bioleaching. Iron, reducedinorganic sulphur compound oxidation and bioleaching of various ores by thisstrain was studied as well as gene expression during oxidation of tetrathionateand/or ferrous iron (Papers III & IV). Expression and regulation of atetrathionate hydrolase from Acidithiobacillus caldus, a key enzyme in reducedinorganic sulphur compound metabolism of this bacterium was investigated andthe presence of this enzyme in a bioleaching mixed culture was shown. The genecluster that harbours the gene coding for tetrathionate hydrolase (tetH) wasdescribed for the first time (Paper II).

Place, publisher, year, edition, pages
Umeå: Molekylärbiologi (Teknisk-naturvetenskaplig fakultet) , 2008. , 73 p.
National Category
URN: urn:nbn:se:umu:diva-1545ISBN: 978-91-7264-509-7OAI: diva2:141351
Public defence
2008-03-07, Major Grove, 6L, Umeå University, Dept. of Molecular Biology, 10:00 (English)
Available from: 2008-02-15 Created: 2008-02-15 Last updated: 2009-06-30Bibliographically approved
List of papers
1. Bioleaching of sulfidic tailing samples with a novel, vacuum-positive pressure driven bioreactor.
Open this publication in new window or tab >>Bioleaching of sulfidic tailing samples with a novel, vacuum-positive pressure driven bioreactor.
2005 (English)In: Biotechnology and Bioengineering, ISSN 0006-3592, E-ISSN 1097-0290, Vol. 92, no 5, 559-67 p.Article in journal (Refereed) Published
Abstract [en]

This study presents a design for a novel bioreactor that uses alternating vacuum and positive pressure cycles to transfer acidic leach solution in and out of contact with finely ground sulfidic mine tailings. These tailings constitute an environmental problem that needs experimental data to support the development of management and control strategies. A conventional stirred tank bioreactor was used as a reference system. Both bioreactors were inoculated with mixed cultures of acidophilic iron and sulfur oxidizers. The rate of the bioleaching of tailings was 0.50 +/- 0.14 g Fe/L . day in the stirred tank bioreactor and 0.17 +/- 0.05 g Fe/L . day in the novel bioreactor. Microbial populations were identified in the two-bioreactor systems by analysis of 16S rRNA genes involving amplification, denaturing gradient gel electrophoresis (DGGE), cloning, and sequencing. The inoculum contained sulfur-oxidizing Acidithiobacillus caldus and Acidithiobacillus thiooxidans, iron oxidizers from the genera Leptospirillum and Ferroplasma, and a chemoorganotrophic Alicyclobacillus sp. During bioleaching of the tailings, the microbial populations in both bioreactors were similar to the inoculum culture, except that At. thiooxidans outgrew At. caldus. Sequences consistent with a Sulfobacillus sp. were amplified from both bioreactor samples although this bacterium was initially below the level of detection in the inoculum. After prolonged operation, Ferroplasma acidiphilum and an uncultured bacterium related to the CFB group were also detected in the novel bioreactor, whereas Sulfobacillus sp. was no longer detected. The novel bioreactor has potential uses in other areas of environmental biotechnology that involves periodic contact of liquids with solid substrates. (c) 2005 Wiley Periodicals, Inc.

Acidithiobacillus thiooxidans/*metabolism, Bioreactors/*microbiology, Cell Culture Techniques/*instrumentation/methods, Chemical Fractionation/*instrumentation/methods, Equipment Design, Equipment Failure Analysis, Pressure, Sulfides/*isolation & purification/*metabolism, Vacuum
urn:nbn:se:umu:diva-16789 (URN)10.1002/bit.20609 (DOI)16245345 (PubMedID)
Available from: 2008-01-12 Created: 2008-01-12 Last updated: 2016-06-17Bibliographically approved
2. Regulation of a novel Acidithiobacillus caldus gene cluster involved in metabolism of reduced inorganic sulfur compounds
Open this publication in new window or tab >>Regulation of a novel Acidithiobacillus caldus gene cluster involved in metabolism of reduced inorganic sulfur compounds
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2007 (English)In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 73, no 22, 7367-7372 p.Article in journal (Refereed) Published
Abstract [en]

Acidithiobacillus caldus has been proposed to play a role in the oxidation of reduced inorganic sulfur compounds (RISCs) produced in industrial biomining of sulfidic minerals. Here, we describe the regulation of a new cluster containing the gene encoding tetrathionate hydrolase (tetH), a key enzyme in the RISC metabolism of this bacterium. The cluster contains five cotranscribed genes, ISac1, rsrR, rsrS, tetH, and doxD, coding for a transposase, a two-component response regulator (RsrR and RsrS), tetrathionate hydrolase, and DoxD, respectively. As shown by quantitative PCR, rsrR, tetH, and doxD are upregulated to different degrees in the presence of tetrathionate. Western blot analysis also indicates upregulation of TetH in the presence of tetrathionate, thiosulfate, and pyrite. The tetH cluster is predicted to have two promoters, both of which are functional in Escherichia coli and one of which was mapped by primer extension. A pyrrolo-quinoline quinone binding domain in TetH was predicted by bioinformatic analysis, and the presence of an o-quinone moiety was experimentally verified, suggesting a mechanism for tetrathionate oxidation.

National Category
Chemical Sciences
urn:nbn:se:umu:diva-2961 (URN)10.1128/AEM.01497-07 (DOI)17873067 (PubMedID)
Available from: 2008-02-15 Created: 2008-02-15 Last updated: 2013-02-15Bibliographically approved
3. Bacterial oxidation of ferrous iron at low temperatures.
Open this publication in new window or tab >>Bacterial oxidation of ferrous iron at low temperatures.
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2007 (English)In: Biotechnology and Bioengineering, ISSN 0006-3592, Vol. 97, no 6, 1470-1478 p.Article in journal (Refereed) Published
Abstract [en]

This study comprises the first report of ferrous iron oxidation by psychrotolerant, acidophilic iron-oxidizing bacteria capable of growing at 5 degrees C. Samples of mine drainage-impacted surface soils and sediments from the Norilsk mining region (Taimyr, Siberia) and Kristineberg (Skellefte district, Sweden) were inoculated into acidic ferrous sulfate media and incubated at 5 degrees C. Iron oxidation was preceded by an approximately 3-month lag period that was reduced in subsequent cultures. Three enrichment cultures were chosen for further work and one culture designated as isolate SS3 was purified by colony isolation from a Norilsk enrichment culture for determining the kinetics of iron oxidation. The 16S rRNA based phylogeny of SS3 and two other psychrotolerant cultures, SS5 from Norilsk and SK5 from Northern Sweden, was determined. Comparative analysis of amplified 16S rRNA gene sequences showed that the psychrotolerant cultures aligned within Acidithiobacillus ferrooxidans. The rate constant of iron oxidation by growing cultures of SS3 was in the range of 0.0162-0.0104 h(-1) depending on the initial pH. The oxidation kinetics followed an exponential pattern, consistent with a first order rate expression. Parallel iron oxidation by a mesophilic reference culture of Acidithiobacillus ferrooxidans was extremely slow and linear. Precipitates harvested from the 5 degrees C culture were identified by X-ray diffraction as mixtures of schwertmannite (ideal formula Fe(8)O(8)(OH)(6)SO(4)) and jarosite (KFe(3)(SO(4))(2)(OH)(6)). Jarosite was much more dominant in precipitates produced at 30 degrees C. (c) 2007 Wiley Periodicals, Inc.

Acidithiobacillus/*classification/genetics/isolation & purification/*metabolism, Iron/*metabolism, Oxidation-Reduction, Temperature
urn:nbn:se:umu:diva-16764 (URN)10.1002/bit.21371 (DOI)17304566 (PubMedID)
Available from: 2007-10-10 Created: 2007-10-10Bibliographically approved
4. Sulphur Accumulation During Low Temperature Bioleaching
Open this publication in new window or tab >>Sulphur Accumulation During Low Temperature Bioleaching
(English)Manuscript (preprint) (Other (popular science, discussion, etc.))
urn:nbn:se:umu:diva-2963 (URN)
Available from: 2008-02-15 Created: 2008-02-15 Last updated: 2016-02-25Bibliographically approved

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