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  • 1
    Electronic Resource
    Electronic Resource
    Thiosulfate and tetrathionate degradation as well as biofilm generation by Thiobacillus intermedius and Thiobacillus versutus studied by microcalorimetry, HPLC, and ion-pair chromatography (1994)
    Springer
    Archives of microbiology 161 (1994), S. 116-125 
    Details
    ISSN: 1432-072X
    Keywords: Key words:Thiobacillus intermedius–Thiobacillus versutus– Thiosulfate – Polythionates – Ion-pair chromatography – Microcalorimetry – Biofilm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The growth of Thiobacillus (T.) intermedius strain K12 and Thiobacillus versutus strain DSM 582 on thiosulfate and tetrathionate was studied combining on-line measurements of metabolic activity and sulfur compound analysis. Most results indicate that T. intermedius oxidized thiosulfate via tetrathionate to sulfate. Concomittantly, sulfur compound intermediates like tri- and pentathionate were detectable. The formation is probably the result of highly reactive sulfane monosulfonic acids. The formation of tetrathionate allows the cells to buffer temporarily the proton excretion from sulfuric acid production. With T. versutus intermediate sulfur compounds were not detectable, however, sulfur was detectable. The possibility of a thiosulfate oxidation via dithionate, S2O |lefbop| 2− |clobop||opnbop| 6 |clobop| , is discussed. The on-line measurement of metabolic activity by microcalorimetry enabled us to detect that cells of T. intermedius adhere to surfaces and produce a biofilm by a metabolic process whereas those of T. versutus fail to do so. The importance of the finding is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276471
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  • 2
    Electronic Resource
    Electronic Resource
    Thiosulfate and tetrathionate degradation as well as biofilm generation by Thiobacillus intermedius and Thiobacillus versutus studied by microcalorimetry, HPLC, and ion-pair chromatography (1994)
    Springer
    Archives of microbiology 161 (1994), S. 116-125 
    Details
    ISSN: 1432-072X
    Keywords: Thiobacillus intermedius ; Thiobacillus versutus ; Thiosulfate ; Polythionates ; Ion-pair chromatography ; Microcalorimetry ; Biofilm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of Thiobacillus (T.) intermedius strain K12 and Thiobacillus versutus strain DSM 582 on thiosulfate and tetrathionate was studied combining on-line measurements of metabolic activity and sulfur compound analysis. Most results indicate that T. intermedius oxidized thiosulfate via tetrathionate to sulfate. Concomittantly, sulfur compound intermediates like triand pentathionate were detectable. The formation is probably the result of highly reactive sulfane monosulfonic acids. The formation of tetrathionate allows the cells to buffer temporarily the proton excretion from sulfuric acid production. With T. versutus intermediate sulfur compounds were not detectable, however, sulfur was detectable. The possibility of a thiosulfate oxidation via dithionate, S2O inf6 sup2- , is discussed. The on-line measurement of metabolic activity by microcalorimetry enabled us to detect that cells of T. intermedius adhere to surfaces and produce a biofilm by a metabolic process whereas those of T. versutus fail to do so. The importance of the finding is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276471
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  • 3
    Electronic Resource
    Electronic Resource
    C-di-GMP Pathway in 〈i〉Acidithiobacillus ferrooxidans〈/i〉: Analysis of Putative Diguanylate Cyclases (DGCs) and Phosphodiesterases (PDEs) Bifunctional Proteins (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 20-21 (July 2007), p. 551-555 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Acidithiobacillus ferrooxidans, an acidophilic, chemolithotrophic, γ-proteobacterium, isinvolved in the bioleaching of metal sulfides. For this process, bacterial attachment to mineralsurface and biofilm development play a pivotal role. Generally, biofilm formation and production ofexopolysaccharides is regulated by the second messenger cyclic diguanylic acid (c-di-GMP) whosecellular level depends on the synthesis and degradation activities of diguanylate cyclase (DGCs,with GGDEF domain) and phosphodiesterase (PDE, with EAL or HD-GYP domains), respectively.The analysis of the genomic sequence of A. ferrooxidans ATCC 23270 allowed us to identify 5putative orfs encoding DGC and/or PDE-like proteins. Four of them encode for bifunctionalputative proteins with GGDEF and EAL domains and are named AFE_0053, AFE_1360,AFE_1373 and AFE_1379. The fifth one named AFE_1852 has an EAL domain. The putativeproteins also include PAS and GAF domains involved in signal transduction. These features suggestan involvement in signalling transduction through the metabolism of c-di-GMP. The amino acidsequences of these putative proteins were aligned with known DGCs and PDEs. Alignmentsindicate that AFE_1360 and AFE_1373 share more consensus sequences with active PDEs, whereasAFE_0053 and AFE_1379 do with active DGCs. On the other hand, in AFE_1852 some conservedresidues of known active PDEs are changed. RT-PCR-experiments revealed that the genes thatencode for these putative DGCs and/or PDEs are expressed by growth on two different substrates.These preliminary results suggest that A. ferrooxidans possesses a c-di-GMP pathway that should beinvolved in biofilm formation, as it occurs in many bacteria
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.20-21.551.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Combined Atomic Force and Fluorescence Microscopy of Biofilms formed by Leaching Bacteria on Opaque Substrata (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 20-21 (July 2007), p. 371-374 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Leaching bacteria attach to their substrates, i.e. mineral sulfides, and form monolayeredbiofilms. In this study the biofilm formation of Acidithiobacillus ferrooxidans A2 on pyrite wasexamined using atomic force and epifluorescence microscopy (AFM and EFM, respectively). Anovel system by JPK instruments, the BioMaterial WorkstationTM, allows the investigation of thesame location on an opaque sample with AFM and EFM. Until recently this was only possible fortranslucent samples. Sessile bacteria on pyrite coupons were stained with 4’,6-diamidino-2-phenylindol (DAPI) and visualized by EFM as well as AFM. The best imaging conditions for AFMwere assessed. Scans of bacteria attached to pyrite were performed in contact mode in air as well asin tapping mode in fluid. Imaging in fluid was more challenging than imaging in air as bacteria tendto detach from their substratum. To avoid the dislocation of microorganisms by the AFM probe thesample was dried in air for 1 h prior to scanning in fluid. Scanning in air was performed with thewhole range of cantilever spring constants tested (k = 0.03 N/m to k = 0.65 N/m) while, forscanning in fluid, best results were achieved using stiffer cantilevers (k = 0.65 N/m)
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.20-21.371.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Novel Steel Corrosion Protection by Microbial Extracellular Polymeric Substances (EPS) – Biofilm-Induced Corrosion Inhibition (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 20-21 (July 2007), p. 375-378 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Microbially influenced corrosion (MIC) of steel has gained increasing attention in recentyears because the damage caused by this process is a significant cost factor for industry.Consequently, inhibition of corrosion and especially the development of corrosion protective filmsis an important present-day research topic. In this connection, application of microbially producedEPS for mitigating steel corrosion is an innovative idea. However, observations of ”protective”biofilms on metallic surfaces have been previously reported. Their inhibiting effect is generallythought to be caused by oxygen depletion or the formation of passivating layers. In contrast to manyconventional corrosion protective methods, EPS or EPS-derived agents would be a cheap andenvironmentally friendly solution. Extensive research activities are still required, before biofilms orcell-free EPS can be used for corrosion protection on larger scale. In this study, we are developing anovel EPS-based corrosion protection method for unalloyed and corrosion resistant steel in aqueousmedia, which is based upon the application of microbial metabolic products. EPS of various sulfatereducingbacteria and other microorganisms are investigated for their inhibiting effect. The extent ofsuch inhibition is evaluated in a model test system, in which different steels are subjected tocorrosive conditions under sulfate-reducing conditions. To elucidate the protective mechanisms,comparative analyses of the chemical composition of the applied EPS are performed
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.20-21.375.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Influence of Growth Substrate and Attachment Substratum on EPS and Biofilm Formation by 〈i〉Acidithiobacillus ferrooxidans〈/i〉 (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 20-21 (July 2007), p. 385-385 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Extracellular polymeric substances (EPS) of Acidithiobacillus ferrooxidans and otherleaching microorganisms mediate the attachment of cells to pyrite and other minerals. They alsoplay a pivotal role in indirect leaching of base and precious metals via the contact mechanism. Theaim of this study is to get more insight on the influence of the growth substrates iron(II) ions, pyrite,chalcopyrite and elemental sulfur on EPS formation, attachment and biofilm formation. Thesynthesis of EPS by cells of A. ferrooxidans strain A2 is strongely influenced by the growthsubstrate or attachment substratum of the cells. Cells grown with soluble iron(II) ions generallygenerate less EPS than cells grown with solid pyrite, chalcopyrite or elemental sulfur. Planktoniccells grown in the presence of solid substrate produce two to four times more EPS than iron(II) iongrown cells. With sessile cells, this factor is further increased to 50 to 240 depending on the specificsubstrate. The EPS of all the differently grown planktonic and sessile cells of A. ferrooxidans strainA2 contained neutral sugars, fatty acids, uronic acids, proteins and metal ions. The composition ofthese compounds varied with the growth substrate and type (planktonic or sessile). The attachmentbehavior of cells of A. ferrooxidans strain A2 also differed with the substrate of the pre-culture.Cells grown on iron(II) ions, pyrite or chalcopyrite attached rapidly to pyrite and chalcopyrite,while attachment to elemental sulfur was poor. On the contrary, sulfur grown cells attached well toelemental sulfur but weakly to pyrite and chalcopyrite. Attachment of EPS-free cells to allsubstrates was also diminished. Cells of A. ferrooxidans strain A2 cover mineral surfaces with adense biofilm after a few days of cultivation, as visualized by fluorescence microscopy and AFM.Large amounts of EPS are formed, which eventually cover the cells and the mineral surface. Evenafter a few weeks of cultivation the biofilm remained monolayered on all substrates
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.20-21.385.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Study of the Attachment Behaviour of Different Strains of 〈i〉Acidithiobacillus〈/i〉 spp. to Pyrite (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 20-21 (July 2007), p. 386-386 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Attachment to metal sulfide surfaces is a prerequisite of bioleaching activity via thecontact mode [Rohwerder et al.: Appl. Microbiol. Biotechnol. Vol. 63 (2003), p. 239]. Until now,the mechanisms and possible variations of this attachment process among leaching bacteria is notwell understood. Therefore, we are studying the diversity in the attachment behaviour of differentstrains of the genus Acidithiobacillus, which is one of the main bacterial group involved in thebioleaching of metal sulfides. Among the species At. ferrooxidans, cells of the type strain (ATCC23270) were found to attach the least. Whereas bacterial cells of strains A2 and R1 attached themost. Other strains that were investigated in this study included At. ferrooxidans D-26 and R7.Highly likely, these strains exhibit different attachment behaviour due to specific variations in theirextracellular polymeric substance (EPS) composition as loss of part of the EPS has previously beenobserved to have a negative effect on attachment and bioleaching activities. Differences in severalEPS parameters such as the amount of complexed Fe(III) ions and the sugar composition arepossible reasons for the observed strain-specific attachment behaviour. In addition to attachmentassays and microscopic studies (AFM and epifluorescence), leaching activities of the strains werecomparatively investigated by short-term as well as growth experiments
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.20-21.386.pdf
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  • 8
    Electronic Resource
    Electronic Resource
    Is the Quorum Sensing Type AI-1 System of 〈i〉Acidithiobacillus ferrooxidans〈/i〉 Involved in its Attachment to Mineral Surfaces? (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 20-21 (July 2007), p. 345-349 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Biofilm development plays a pivotal role in the bioleaching process. The attachment ofthe acidophilic chemolithotrophic Acidithiobacillus ferrooxidans to mineral surfaces is mediated byextracellular polymeric substances (EPS) involved in biofilm development. Previous work suggeststhat EPS composition of A. ferrooxidans is adapted to the energy source and, accordingly, thebacterium must be able to sense the surface to which attachment occurs with the consequenttriggering of the expression of different EPS-genes. Quorum sensing (QS) is recognized as one ofthe main regulators of biofilm formation. A. ferrooxidans possesses a functional QS type AI-1system and the analysis of culture supernatants revealed us that this bacterium is able to synthesizenine different homoserine lactones (AHLs) whose acyl-chain lengths oscillate between 8 and 16carbons and include an alcohol or a ketone function at the C3 position. The transcription levels ofthe afeI gene encoding for the AHL synthase are higher in cells grown in sulfur and thiosulfatemedia than in iron-grown cells, suggesting that biofilm formation in A. ferrooxidans would beregulated by the QS type AI-1 system. In the present study, the effect of several synthetic AHLsand analogues on the attachment of A. ferrooxidans to pyrite was analyzed. Preliminary resultssuggest that some of these molecules are changing the bacterial attachment to pyrite
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.20-21.345.pdf
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  • 9
    Electronic Resource
    Electronic Resource
    Combined Test for Bioleaching Activities (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 20-21 (July 2007), p. 171-171 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Both, the employment of leaching bacteria for metal winning as well as the mitigation ofbioleaching processes at AMD/ARD sites, require reliable monitoring methods for assessingbacterial activities. Therefore, we have developed a robust and rapid test system combining twosensitive analytical techniques: quantification of heat evolution by microcalorimetry anddetermination of all relevant inorganic sulfur species by chromatographic methods (IC and HPLC).Generally, only about 1 g of sample is sufficient for a complete analysis. The combined test hasbeen applied to various leaching biotopes such as bioreactors, columns, heaps and natural sites. Thebacterial activity of diverse sulfidic materials such as lignite and coal wastes, pure metal sulfidesand complex ores has been investigated. In our labs, microcalorimetry can be performed in therange of 5 to 80 °C, covering most of the temperature spectrum of leaching bacteria. Hence, theheat evolution values of samples as a direct measure for calculating leaching rates can be obtainedat nearly all relevant in situ temperatures. The combination with sulfur species determination resultsin additional information on leaching mechanisms (thiosulfate or polysulfide pathway) and generalleaching performance (e. g. accumulation of sulfur intermediates)
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.20-21.171.pdf
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  • 10
    Electronic Resource
    Electronic Resource
    Elemental Sulfur Oxidation in 〈i〉Acidiphilium〈/i〉 spp (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 20-21 (July 2007), p. 583-583 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The alpha-proteobacterial genus Acidiphilium consists of several acidophilic species,generally known as a part of the mesophilc microbial flora of leaching biotopes. All of them cangrow chemoorganotrophically on carbon sources like sugars and many express additionalphotosynthetic pigments. Thus far, only Ap. acidophilum is known to be capable ofchemolithotrophic growth on elemental sulfur oxidation. The oxidation potential of inorganic sulfurspecies by the other strictly heterotrophic species has not yet been thoroughly investigated. Here,we demonstrate the unequivocal evidence of inorganic sulfur compound oxidation by strains of Ap.cryptum and other Acidiphilium species. Evolutionary and biochemical aspects of this new featureamong the heterotrophic Acidiphilium spp. are discussed. This finding will possibly help to solvethe long-standing question about the biochemical nature of elemental sulfur oxidation in mesophilicleaching bacteria
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/39/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.20-21.583.pdf
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