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1
Bridge, Toni A. M. "Iron reduction by acidophilic bacteria". Thesis, Bangor University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295276.
Testo completo
2
Granger, Julie. "Iron acquisition by heterotrophic marine bacteria". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0002/MQ44173.pdf.
Testo completo
3
MacLean, Martin. "Autotrophy in iron-oxidizing, acidophilic bacteria". Thesis, University of Warwick, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357855.
Testo completo
4
Fang, Wen. "Microbial Biomineralization of Iron". PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/664.
Testo completoAbstract (sommario):
Iron is a common cation in biomineral sand; it is present for example in magnetite produced by magnetotactic bacteria and in iron sulfides produced by sulfate reducing microorganisms. The work presented in this thesis focused on two types of microorganisms capable of forming iron biominerals. In the first project I have studied the effect of O2 on the respiratory physiology and the formation of magnetosomes by Magnetospirillum magneticum AMB-1. In the second project I have studied the relationship between olivine and the activity of dissimilatory sulfate reducing (DSR) microorganisms. For the first project, I grew cells of AMB-1 in cultures with various concentrations of O2 and monitored growth and the formation of magnetic mineral particles (MMP). Results have shown that AMB-1 cells grew better at 100-225 uMO2(aq) than at lower [O2], yet the formation of MMP was repressed at ~45 uM O2(aq) and strongly inhibited at >100 uM O2(aq).These results have helped better understand the dissimilarity between the optimal growth conditions of magnetotactic bacteria and the conditions needed for the formation of MMPs. My results have also shown that the reaction between H2S produced by DSRs and olivine is abiotic, not catalyzed and exergonic. The pH did not vary significantly during this reaction and pH variation (in the 5-9 range) did not significantly influence this chemical reaction. Bicarbonate inhibited the reaction between H2S and olivine, but not the chemical equilibrium. Phosphate, a weak iron chelator, influenced the equilibrium of the reaction and it is assumed to help increase the rate of olivine weathering in the presence of DSRs. The activity of DSRs was positively influenced by the presence and abundance of olivine. Based on my results I propose that olivine help DSR obtain energy more efficiently, but does not represent a source of energy or nutrients for the cells. These results helped better understand the formation of iron biominerals and signatures of this activity.
5
Green, Robert. "Iron and manganese homeostasis in marine bacteria". Thesis, University of East Anglia, 2012. https://ueaeprints.uea.ac.uk/47962/.
Testo completoAbstract (sommario):
Using a mixture of bioinformatic analyses, microarrays on cells that were grown in media that were either replete or depleted for manganese or for iron, and by making targeted mutations and reporter fusions, several important observations were made on the mechanisms of Mn and Fe homeostasis in the marine α‐proteobacterium Ruegeria pomeroyi (the main species studied here), and in other important marine bacteria. R. pomeroyi lacks most of the known Fe uptake systems, including TonB and outer‐membrane receptors, but has a predicted, but incomplete iron uptake ABC‐class transporter operon, whose expression is much enhanced in Fe‐depleted conditions, although a strain lacking these genes was unaffected in growth. The Fe‐specific regulatory network of R. pomeroyi was found to involve the Irr transcriptional regulator, which controlled the expression of several genes. Microarrays revealed many other genes whose expression was enhanced or diminished in Fe‐replete conditions, providing material for future work on the iron regulon of this bacterium, Turning to manganese, here too the expression of many genes was affected (up or down) by Mn availability. These included an operon corresponding to sitABCD, an effective ABC‐type Mn2+ transporter in many other bacteria. This was confirmed, directly, to be the case for Ruegeria. Bioinformatic analyses showed that some other Roseobacter strains lacked any previously known Mn2+ transporter, but instead, had a gene that likely encoded an inner membrane protein and was preceded by a motif (MRS box) that was known to be recognised by the Mn2+ ‐responsive transcriptional regulator Mur. It was confirmed that this gene, termed mntX, did indeed encode a manganese transporter and that MntX orthologues occurred in several other, unrelated marine bacteria, notably most strains of the pathogenic genus Vibrio (including V. cholerae) and some of the most abundant bacteria in the oceans, namely the SAR11 clade (Pelagibacter).
6
Barr, David William. "Comparison of iron oxidation by acidophilic bacteria". Thesis, University of Warwick, 1989. http://wrap.warwick.ac.uk/106735/.
Testo completoAbstract (sommario):
A rang« of obligate acidophilic Iron oxidising bacteria war« compared physiologically, kinetically and biochemically. The organisms ware mesophiles, Thiobacillus ferrooxidans and Leptospirillum ferrooxldans, moderate thermophiles designated strains ALV, BC1, LH2, TH1 and TH3 and thermophlle Sulfolobus BC65. Each organism retained iron oxidizing activity in non-growing cell suspensions. Measurement was made of apparent Km and K. for ferrous Iron oxidation and its inhibition by ferric Iron in these suspensions. Values were derived from three graphical representations of the data. Values differed where identical strains had been previously reported. Evidence of a fixed relationship between Km and K1 suggested that these differences were derived from experimental variation. Ferric iron was a competitive Inhibitor of iron oxidation but copper was an uncompetitive inhibitor of L.ferrooxidans. Responses of calls to ferric Iron during growth indicated the predictive power of suspension kinetics, extremes In batch culture coinciding with the lowest and highest measured values of K. Continuous culture provided evidence of the relevance of this data to growth and explained relative cell numbers during competition in mixed mesophilic culture. These could also explain previously reported observations in mineral cultures. The production of ferric iron was controlled both by pH and process design with T.ferrooxidans. Comparable production was provided with L.ferrooxidans, utilising its ability to form macroscopic cell aggregates in sub- optimal conditions. Optimum growth conditions varied nutritionally with each strain and with particle size, ore mineralogy and carbon dioxide concentration during mineral dissolution by Sulfolobus BC63. The sulphur requirement for growth was strain dependent, quantitatively and qualitatively. Strain ALV indicated that reduced sulphur was not an obligate requirement for thermophilic iron oxidation. Iron oxidation appeared to be the controlling factor in mineral dissolution at 68°C. Iron oxidation was limited prior to maximum target metal release. Based on optical spectra each organism contained a range of (different) respiratory chain components. Both L.ferrooxidans and Sulfolobus BC65 had absorbance maxima not attributable to known cytochrome species. The peak at 578 nm for L.ferrooxidans was due to a red-pigmented, acid stable soluble protein which was reduced by ferrous Iron.
7
Kerin, Elizabeth Johanna. "Mercury methylation in dissimilatory iron reducing bacteria". College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7385.
Testo completoAbstract (sommario):
Thesis (M.S.) -- University of Maryland, College Park, 2007.Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
8
Timmons, John D. III. "Selective Precipitation of Iron in Acid Mine Drainage using Iron-oxidizing Bacteria". Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1525446228184635.
Testo completo
9
Chan, Anson Chi-Kit. "Iron transport in two pathogenic Gram-negative bacteria". Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/32406.
Testo completoAbstract (sommario):
Campylobacter jejuni and Escherichia coli strain F11 are two Gram-negative pathogens with a versatile armament of iron uptake systems to cope with the fluctuating host nutrient environment. Our current understanding of Gram-negative iron uptake systems focuses heavily on a prototypical scheme involving a TonB-dependent outer membrane receptor and an ABC transporter, with little knowledge on systems that do not fall neatly into this paradigm. The primary focus of this thesis is the characterization of three such atypical iron uptake proteins from C. jejuni (ChaN and P19) and pathogenic E. coli (FetP).
C. jejuni ChaN is a 30 kDa, iron-regulated lipoprotein hypothesized to be involved in iron uptake. The crystal structure of ChaN reveals that it can bind two cofacial heme groups in a pocket formed by a ChaN dimer. Each heme iron is coordinated by a single tyrosine from one monomer and the propionate groups are hydrogen bonded by a histidine and a lysine from the other monomer. Analytical ultracentrifugation studies demonstrate heme-dependent dimerization in solution. Cell fractionation of C. jejuni shows that ChaN is localized to the outer membrane. Based on these findings, the predicted in vivo role of ChaN in iron uptake is discussed.
C. jejuni cFtr1-P19 and E. coli FetMP are homologous iron-regulated systems also proposed to be iron transporters. Through growth studies in both organisms, we show that P19 and FetMP are required for optimal growth under iron-limited conditions. Furthermore, metal binding analysis demonstrates that recombinant P19 and FetP bind both copper and iron. Dimerization of P19 is shown to be metal dependent in vitro and is detected in vivo by cross-linking. Through x-ray crystallography, we have determined the structures of P19 and FetP with various metals bound, thus revealing the locations of the highly conserved copper and iron binding sites. Additionally, the crystal structure of FetP reveals two copper positions in each binding site that is likely functionally important. Through mutagenesis, residues contributing to the alternative copper positions were identified. Together, these studies provide insight into the mechanism of iron transport by the two systems and allow for the development of functional models.
10
Marshall, Rowena Margaret. "Thermophilic acidophilic bacteria : iron, sulphur and mineral oxidation". Thesis, University of Warwick, 1985. http://wrap.warwick.ac.uk/2613/.
Testo completoAbstract (sommario):
The aim of this study was to investigate the iron- and sulphur-oxidizing activities of thermophilic bacteria with reference to the possible use of such bacteria in the extraction of metals from mineral sulphides. The initial characterization of a range of isolates was based on growth studies with iron and sulphur substrates and on the comparison of whole cell protein electrophoresis patterns. Three groups of bacteria were isolated and studied: moderately thermophilic iron- and mineral sulphide-oxidizing bacteria, moderately thermophilic sulphur oxidizers and extremely thermophilic Sulfolobus-like organisms. Both moderately and extremely thermophilic acidophiles were isolated from hot spring and coal pile samples. The moderately thermophilic iron-oxidizing bacteria and the extreme thermophiles which were examined were sub-divided into three and four sub-groups respectively. In a comparative study of continuous flow iron-oxidation reactors, moderate thermophiles did not produce higher rates of ferric iron production than the mesophile T. ferrooxidans but iron oxidation was less sensitive to inhibition by chloride in a vessel containing a thermophile than in a vessel operating with the mesophile. Iron oxidation during autotrophic growth of moderately thermophilic acidophiles and the rapid dissolution of mineral sulphides during the autotrophic growth of both the moderate and the extreme thermophiles were demonstated, thus considerably increasing the potential industrial significance of these bacteria. The yield of soluble copper from a chalcopyrite concentrate was shown to increase with temperature from relatively low yields with the mesophile T. ferrooxidans, through moderate yields with the moderately thermophilic bacteria to almost complete mineral solubilization with the newly isolated Sulfolobus strains.
11
Gomez, Perez Laura. "Alternative electron transfer pathways in iron-metabolising bacteria". Thesis, University of East Anglia, 2018. https://ueaeprints.uea.ac.uk/69911/.
Testo completoAbstract (sommario):
Ferric iron (Fe3+) can be used as a terminal electron acceptor by iron-reducing microorganisms to facilitate cellular respiration under anoxic conditions. In contrast, ferrous iron (Fe2+) is used as an electron donor by iron-oxidising microorganisms. The presence of dissimilatory pathways in iron metabolisers maintain bioavailable iron in the environment for other organisms. Redox reactions between gram-negative bacteria and iron usually occur through an extracellular electron transport (EET) pathway that allows electrons to cross from the inner membrane to the extracellular environment or vice versa. The study of the redox pathway has been thoroughly studied in the iron reducer Shewanella oneidensis, however, there is little information about the metabolic pathways used by other iron metabolisers. In this thesis, the environmental isolates Acinetobacter and Citrobacter have been described as novel iron reducing bacteria by using a combination of techniques including ferrozine assays, cytochrome identification methods and transcriptomic analysis. Results in this thesis suggest that Acinetobacter (previously described as a strict aerobic microorganism) in fact is capable of respiring using iron when oxygen is not available. In contrast, Citrobacter's iron reduction pathway seems to involve fermentative processes. These results point out that extracellular electron transport is not the only mechanism in dissimilatory iron metabolism. Moreover, these results suggest that anaerobic environments could be a reservoir for pathogenic strains of Acinetobacter, as it has been shown that this species do not require oxygen to survive. In addition to the study of new iron reducers, an overexpression system has been developed to study proteins involved in metal oxidation pathways without the need of culturing the notoriously slow-growing iron oxidising bacteria. The genes cyc2 and cyc2PV-1, which encode outer membranes cytochromes from Acidithiobacillus ferrooxidans and Mariprofundus ferrooxydans respectively, have been transformed into the iron reducer Shewanella oneidensis for protein expression optimization. The optimization of this process offers great possibility for the future study and applications of metal oxidation pathways.
12
Gouin, Marlena. "Acid Mine Drainage Remediation Utilizing Iron-Oxidizing Bacteria". University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1303244416.
Testo completo
13
Coram, Nicolette Joanne. "Molecular characterization of iron-oxidizing Leptospirillum strains from around the world". Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52944.
Testo completoAbstract (sommario):
Dissertation (PhD) -- University of Stellenbosch, 2002.ENGLISH ABSTRACT: More than sixteen isolates of iron-oxidizing bacteria belonging to the genus Leptospirillum were included in this study, with the finding that they were clearly divisible into two major groups. Group I leptospirilla had mol% G+C ratios within the range 49-52%, three copies of rrn genes and based on 16S rRNA sequence data, clustered together with the Leptospirillum ferrooxidans type strain (DSM2705or LI5). Group II leptospirilla had mol% G+C ratios of 55-58%, two copies of rrn genes and based on 16S rRNA sequence form a separate cluster. Genome DNA-DNA hybridization experiments indicated that three similarity subgroups were present amongst the leptospirilla tested with two DNA-DNA hybridization similarity subgroups being found within group I. The two groups could also be distinguished based on the sizes of their 16S-23SrRNA gene spacer regions. We propose that the group II leptospirilla should be recognized as a new species with the name Leptospirillum ferriphilum sp. nov. Members of the two species can be rapidly distinguished from each other by amplification of their 16S rRNA genes and carrying out restriction enzyme digests of the products. Several but not all isolates of the group II leptospirilla, but none from group I (L. ferrooxidans) were capable of growth at 45°C. Plasmid DNA was isolated from strain ATCC49879 (L. ferrooxidans). Restriction endonuclease mapping of what appeared to be about 60 kb of plasmid DNA, established that two plasmids of approximately 30.0 kb and 27.0 kb were present. These were named p49879.1 and p49879.2 respectively. Attempts to isolate the plasmids separately were not successful. Partial sequencing of the two plasmids was carried out and sequence analysis of p49879.1 and p49879.2 indicated that the plasmids shared regions of homology. Total plasmid DNA was DIG-labelled and used as a probe in Southern hybridization experiments with genomic DNA from all sixteen original leptospirilla isolates as the target DNA. All leptospirilla belonging to Group I gave a positive signal, little or no homology to Group II leptospirilla was obtained. The region of homology present in all L. ferrooxidans strains was localized to an area on plasmid p49879.2 showing high amino acid identity to a transposase/putative transposase of Methanosarcina acetivorans and plasmid CPl from Deinococcus radiodurans Rl respectively. Whether these regions of homology indicate that complete, functional transposons are present in all L. ferrooxidans isolates still remains to be determined. Preliminary sequence analysis of both plasmids resulted in the identification of regions with amino acid sequence identity to the TnpA and TnpR of the Tn2l-like transposon family, and the mobilization regions of IncQ-like plasmids (particularly that of pTFl from At. ferrooxidans). Another potentially interesting ORF was identified in p49879.2 with high amino acid sequence identity to an ArsR-like protein that belongs to a second atypical family of ArsR transcriptional regulators. Whether this protein is functional in the regulation of arsenic resistance genes has not yet been determined, nor have other arsenic resistance genes been identified. Future work includes further sequence analysis of these plasmids to better understand their contribution to the isolates in which they are found.
AFRIKAANSE OPSOMMING: Meer as sestien isolate van die yster-oksiderende bakterieë, wat aan die genus Leptospirillum behoort, is in die studie ingesluit en die resultate het getoon dat dié groep verder in twee hoof groepe verdeel kan word. Groep I het "n mol% G+C van tussen 49% en 52% gehad, sowel as drie kopieë van die ribosomale gene (rrn). Hiermeesaam het die 16SrRNA volgorde data getoon dat hierdie isolate groepeer saam met Leptospirillum ferrooxidans (DSM2705T en LI5). Groep II leptospirilla het "n mol% G+C van tussen 55% en 58% gehad sowel as twee kopieë van die rrn gene en saam met die 16SrRNA volgorde data het hierdie isolate "n aparte groep gevorm. Genoom DNA-DNA hibridisasie eksperimente het gewys dat daar drie subgroepe onder die Leptospirillum wat getoets was is, met twee naverwante groepe wat onder Groep I val. Daar kan ook tussen die twee hoof groepe onderskei word op grond van die grootte van hul 16S- 23SrRNA intergeniese gebiede. Ons stel dus hier voor dat die Groep II leptospirilla as "n nuwe spesie beskou word naamlik, Leptospirillum ferriphilum sp, nov. Die twee spesies kan maklik onderskei word deur die PKR amplifikasie produk van die 16SrRNA te verteer met restriksie ensieme. Vele, maar nie al van die Groep II isolate kan by 45°C groei nie, terwyl geen van die Groep I leptospirilla (L.ferrooxidans) kan nie. Plasmied DNA was geisoleer uit Leptospirillum ferrooxidans ATCC49879. Aanvanklike analise het gedui op die teenwoordigheid van een 60.0 kb plasmied. Verdere restriksie ensiem kartering het wel getoon dat hierdie, in teen deel, twee plasmiede van ongeveer 30.0 kb en 27.0 kb in grootte is: p49879.1 en p49879.2. Pogings om die twee plasmiede apart te isoleer was onsuksesvol. Totale plasmied DNA is gemerk met die Random primed DNA labelling kit (Roche diagnostics) en gebruik as peiler in Southern klad eksperimente met genoom DNA, van al sestien isolate, as teiken. Alle leptospirilla wat aan Groep I behoort het "n positiewe sein gegee terwyl geen sein teen Groep II DNA opgemerk was nie. Die area wat, tussen die plasmiede en Groep I homologie getoon het, is gelokaliseer tot "n area op plasmied p49879.2 wat hoë amino suur identiteit toon aan "n transposase geen van Methanosarcina acetivorans, en "n voorgestelde transposase geen op plasmied CPI van Deinococcus radiodurans Rl. Dit moet nog vasgestel word of hierdie area van homologie dui op die teenwoordigheid van "n volledige, funksionele transposon in alle L. ferrooxidans isolate. Gedeeltelike DNA volgorde bepalings van beide plasmiede het gelei tot die identifikasie van areas met hoë amino suur volgorde identiteit aan die TnpA en TnpR gene van die Tn21-tipe transposon familie, sowel as aan die mobilisasie gene van IncQsoortige plasmiede (veral die van pTFI uit Acidithiobacillus ferrooxidans). "n Oop lees raam van belang, wat op plasmied p49879.2 geidentifiseer was, het hoë amino suur volgorde identiteit aan "n ArsR-tipe geen getoon wat aan "n tweede atiepiese familie van ArsR transkripsionele reguleerders behoort. Op die stadium is dit nog onbekend of hierdie protein funksioneel is in die regulering van arseen weerstandbiedenheidsgene.
14
Meyers, Emily. "Phosphate Cycling in the Presence of Biogenic Iron Oxides and Iron-Reducing Bacteria". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37306.
Testo completoAbstract (sommario):
Nutrient pollution from industrial activity is an environmental problem that persists in
water bodies near urban settings, and has been a primary contributor to eutrophication,
bacterial contamination, and harmful algal blooms. Biogenic iron oxides offer a
potential solution to the treatment of lakes and rivers containing high concentrations of
phosphate, the limiting nutrient in aquatic systems. Soluble ferrous iron can act as an
electron donor for iron-oxidizing bacteria, which thrive in low-oxygen environments.
This results in the formation of insoluble ferric iron minerals, ideal adsorbents for
negatively charged phosphate. Conversely, iron-reducing bacteria reduce ferric iron to
form ferrous iron, resulting in the formation of secondary minerals depending on the
chemistry of the particular environment.
This project investigates the chemical conditions at which biogenic iron oxides have the
maximum adsorptive capacity, especially with respect to organic carbon content. A
simplified model of natural biogenic iron oxides was synthesized by co-precipitating the
mineral ferrihydrite (a common iron oxide) with the polysaccharide alginate, an
analogue to bacterial exopolysaccharides. At the levels of carbon investigated, organic
matter was not found to affect the adsorptive capacity of iron oxides at the C/Fe ratios
analyzed. Similarly, organic matter did not appear to significantly influence the rate of
reduction of ferrihydrite by the iron-reducing bacterium Shewanella putrefaciens CN32.
Presence of organics did however influence rates of reduction and the mineralogy of the
post-reduction precipitates. Phosphate adsorbed to iron oxides prior to microbial
reduction greatly increased both the rate and the extent of ferric iron reduced, and also
had an impact on the secondary minerals that formed (vivianite, green rust).
An improved understanding of these conditions could contribute to a more efficient
process by which iron-oxidizing bacteria are used for large-scale industrial water
treatment.
15
Maddocks, Sarah Elizabeth. "Iron metabolism in bacteria : examination of the Feo system (Ferrous iron transporter) and Dps-iron storage proteins". Thesis, University of Reading, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434313.
Testo completo
16
Burton, Claire Louise. "Norepinephrine, iron and Escherichia coli". Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342475.
Testo completo
17
Adly, Carol. "The role of iron in the ecology and physiology of marine bacteria /". Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97884.
Testo completoAbstract (sommario):
Despite being abundant in the earth's crust, the concentration of Fe in many oceanic regions is so low that it is limiting to the growth of photosynthetic plankton. Heterotrophic bacteria play key roles in the oceanic cycling of carbon and nutrients, but it is unclear whether they can be Fe-deficient in nature, or what possible effects Fe-deficiency might have on their ecology and physiology. In chapter 1, I investigated the response of a natural bacterial community to a mesoscale Fe-enrichment experiment in the northeast subarctic Pacific. The addition of Fe to surface waters caused a rapid stimulation of bacterial growth and production, and induced the organic Fe uptake systems of bacteria. These findings suggest that bacteria responded directly to increased Fe availability, and may be Fe-deficient in situ. In chapter 2, I examined the effects of Fe-deficiency on the coupled processes of carbon catabolism and adenosine triphosphate (ATP) production in cultures of the marine bacterium Pseudoalteromonas haloplanktis. In Fe-limited cells, Fe-dependent oxidative pathways of ATP production were downregulated, leading to an intracellular energy deficit. Thus, by altering carbon metabolism and energy acquisition of heterotrophic bacteria, Fe may affect the cycling of carbon in parts of the sea.
18
Clark, Darren Alan. "The study of acidophilic, moderately thermophilic iron-oxidizing bacteria". Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/2544/.
Testo completoAbstract (sommario):
This study has divided the most frequently isolated types of moderate thermophiles into three groups: isolates of Sulfobacillus thermosulfidooxidans (mol% G + C 47-50), an isolate referred to as strain NAL and other closely related species (mol% G+C 54-57), and the type previously referred to as strain TH3 (mol% G+C 68). An enrichment culture was obtained that could efficiently solubilise a range of mineral sulphides at 48oC under air. Characterisation of this culture indicated the presence of two organisms essential for efficient growth under air: a typical S. thermosulfidooxidans group organism (isolate ICH), and a strain TH3 group organism (isolate ICP). Strain ICP appeared to possess an inducible, high affinity transport system for carbon dioxide during growth under air (unlike any previously studied moderate thermophiles), but extensive oxidation of ferrous iron was not achieved even at enhanced carbon dioxide levels. This lack of oxidation appeared to be the result of autotrophically-growth strain ICP having an apparent higher affinity for the end-product of iron oxidation, ferric iron (Ki 0.4 mM), than the substrate, ferrous iron (Km 0.5 mM). Only when a mixed culture of strain ICP and strain ICH was grown did extensive oxidation occur. A comparative mineral leaching study, with a mesophilic, a moderately thermophilic, and an extremely thermophilic culture indicated that the moderately thermophilic culture was the most robust during the dissolution of a range of minerals. This culture gave consistently better mineral dissolution rates than the mesophilic culture, clearly indicating their immediate commercial potential. In comparison the extremely thermophilic culture often produced faster rates of mineral dissolution than the moderately thermophilic culture, but appeared sensitive to agitation at high mineral pulp densities (10% (w/v)), limiting any present commercial applications of these organisms.
19
Cox, Simon Peter. "Iron oxidation and mineral oxidation by moderately thermophilic bacteria". Thesis, University of Warwick, 1992. http://wrap.warwick.ac.uk/109481/.
Testo completoAbstract (sommario):
The microbial oxidation of minerals is a commercially important process. Until comparatively recently only one organism capable of mineral oxidation has been extensively studied - Thiobacillus ferrooxidans. Several new, potentially commercially important isolates were studied in comparison with T.ferrooxidans. This was done with regard to their iron and sulphur oxidation systems, which are vital to the process of mineral solubilisation, and their ability to solubilise the minerals pyrite or chalcopyrite. The study of the latter was undertaken with particular reference to mixed culture leaching. The effect of growth substrate history on iron and sulphur oxidation varied between organisms. In particular, strain BC1 lost very little of its iron or sulphur oxidation capacity whether it was grown on either substrate. Conversely, the oxidation systems of T.ferrooxidans were directly influenced by growth substrate. SDS PAGE analysis and optical spectroscopy of T.ferrooxidans and strains BC1, LM2 and TH3 were used to investigate iron and sulphur oxidation systems and principally to indicate target components of these systems for further detailed study. Further study of the iron oxidation system in strain BC1 showed that there was only one major chromophore, a membrane bound cytochrome aa_. This had absorption peaks at 443 nm, 560 nm and 604.5 nm. Spectra run at 77°K indicated a shoulder on the Soret peak at approximately 450 nm. Extensive investigation into the effect on the cytochrome aa_ of various detergents culminated in the solubilisation from the membrane of the terminal oxidase in an intact form. This allowed the mid-point redox potential of this cytochrome to be determined as +524 mV. The mid-point redox potentials of T.ferrooxidans cytochrome £ and fi. were determined as +317 mV and +497 mV respectively. SDS PAGE analysis indicated two proteins that could be involved in growth on ferrous iron, at 27 kD and 31 kD. One or both of these proteins appeared to contain very high levels of iron. High levels of iron were also found in fractions from column chromatography which contained cytochrome aa_. Mineral oxidation studies showed that there was a slight increase in the rate of leaching of chalcopyrite in mixed cultures of strain BC1 and strain BC13 when compared to a pure culture of strain BC1, when the organisms where grown in shake flasks. In airlift reactor leaching of chalcopyrite the addition of strain BC13 to strain BC1 had several major effects. The pH in the mixed culture reactor was kept far more constant. Despite this, the leaching of copper from the mineral was not significantly altered in the mixed culture. However, a notable phenomenon in this mixed culture of strain BC1 and strain BC13 was the apparent reduction of the specific iron oxidation capacity of strain BC1 in comparison with its activity in pure culture.
20
Ekins, Andrew John. "Iron acquisition by Histophilus ovis". Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38481.
Testo completoAbstract (sommario):
Five strains (9L, 642A, 714, 5688T and 3384Y) of Histophilus ovis were investigated with respect to iron acquisition. All strains used ovine, bovine and goat, but not porcine or human, transferrins (Tfs) as iron sources for growth. In solid phase binding assays, total membranes from only two (9L and 642A) of the five strains, grown under iron-restricted conditions, were able to bind Tfs (ovine, bovine and goat, but not porcine or human). However, when the organisms were grown under iron-restricted conditions in the presence of bovine Tf, total membranes from all strains exhibited Tf binding (as above); competition experiments demonstrated that all three Tfs (ovine, bovine and goat) were bound by the same receptor(s). An affinity isolation procedure allowed the isolation of two putative Tf-binding polypeptides (78 and 66 kDa) from total membranes of strains 9L and 642A grown under iron-restricted conditions, and from membranes of all strains if the growth medium also contained Tf. A gene encoding a Pasteurella multocida TbpA homologue was shown to be present in each of two representative strains (9L and 3384Y); these genes were sequenced and determined to be the structural genes encoding the 78-kDa Tf-binding polypeptides. The identification of a fur homologue and a Fur box within the promoter region of tbpA in both strains indicated that Fur (and iron) is responsible for the iron-repressible nature of Tf-binding activity. Although tbpA transcripts were detected by reverse transcription (RT)-PCR with RNA isolated from strains 9L and 3384Y grown under iron-restricted conditions, with strain 3384Y, and depending on the primer pair, tbpA transcripts were detected by RT-PCR predominantly when the RNA was isolated from cells grown under conditions of iron-restriction in the presence of Tf. The presence of an additional G in the tbpA gene of strain 3384Y grown under iron-replete conditions, compared to organisms grown under iron-restricted conditions plus bovine Tf, is
21
Nicolau, Paula Bacelar V. C. "Novel iron-oxidising acidophilic heterotrophic bacteria from mineral leaching environments". Thesis, Bangor University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321390.
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22
Paul, Varun. "Electricity generation and ethanol production using iron-reducing, haloalkaliphilic bacteria". Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Paul_09007dcc8069dfe5.pdf.
Testo completoAbstract (sommario):
Thesis (M.S.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed August 10, 2009) Includes bibliographical references (p. 58-64).
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Smith, Mark Andrew. "Iron, siderophores and the virulence of Klebsiella pneumoniae". Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291894.
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Chakraborty, Ranjan. "Iron Uptake in Bacteria with Emphasis on E. coli and Pseudomonas". Digital Commons @ East Tennessee State University, 2013. http://amzn.com/9400760876.
Testo completoAbstract (sommario):
Contents: Ferric Siderophore Transport via Outer Membrane Receptors of Escherichia coli: Structural Advancement and A Tribute to Dr. Dick van der Helm -- An 'Ironman' of Siderophore Biology -- The Tricky Ways Bacteria Cope with Iron Limitation -- Iron Transport Systems and Iron Homeostasis in Pseudomonas.
Abstract: Iron is essential for the growth of most bacteria because it serves as a cofactor for vital enzymes and for the components of the electron transport chain. Moreover, Iron plays an important role in bacterial pathogenicity; in fact, the iron transport systems in bacteria works as target for designing novel antibiotics. Because iron is not soluble under aerobic conditions, bacteria have had to find ways to overcome iron deficiency. One of them is producing an iron-chelating small organic molecule called siderophore. Indeed, most bacteria and fungi produce structurally and chemically diverse siderophores which are transported back to the cytoplasm using complex energy dependent transport systems.https://dc.etsu.edu/etsu_books/1036/thumbnail.jpg
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Yupanqui, Zaa Carmen Lourdes. "Dechlorinating and Iron Reducing Bacteria Distribution in a Trichloroethene Contaminated Aquifer". DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/41.
Testo completoAbstract (sommario):
The Operable Unit 5 (OU 5) area of Hill Air Force Base currently has two trichloroethene-contaminated groundwater plumes underneath residential areas in Sunset and Clinton, Utah. Bioremediation by biological reductive dechlorination can be an important mechanism for the removal of chlorinated compounds from the plumes. The presence of suitable bacteria to carry on reductive dechlorination is the key in the bioremediation process. The goal of this study was to determine the distribution and population density of the 16S rRNA genes of Bacteria, Dehalococcoides ethenogenes, Desulfuromonas michiganensis, Geobacter spp and Rhodoferax ferrireducens-like bacteria, as well as the functional genes trichloroethene reductive dehalogenase (tceA) and vinyl chloride reductase gene (vcrA). This study also evaluated the influence of the physical-chemical properties of the OU 5 aquifer material on the observed bacterial distribution. Twenty OU 5 soil cores were obtained from a 14-ha area that included a trichloroethene (TCE) plume. DNA was extracted from each core. Molecular analysis with qRT-PCR was used to quantify the densities of the mentioned 16S rRNA and functional genes. Separately, total arsenic and iron in the II and II+III oxidation states were extracted by two methods (HCl and hydroxylamine HCl in HCl) in each core. Concentrations of TCE, cis-dichloroethene (cis-DCE), vinyl chloride (VC) and ethane in well water were included. Dehalococcoides population density was low and its distribution was uneven with densities lower than 3.2x104 copies/g (detection limit of 2.5x103). D. michiganensis distribution was not uniform but was clustered near the TCE-source area with densities of 7.9x103-1x105 copies/g (detection limit of 6.3x103). Geobacter spp. distribution was uneven but broader, with densities of 4x103-1.6x106 copies/g (detection limit of 3.2x103). The vcrA gene distribution was relatively uniform and broad. Densities were the lowest measured (detection limit of 63 copies/g). TceA was measured in two cores with densities close to detection limit of 1.6x103 copies/g. Rhodoferax ferrireducens-like bacteria had a broader distribution with the highest densities of 1.6x106-1.3x108 copies/g (detection limit of 7.9x103). Total Bacteria were measured in all cores with densities 3.2x104-3.2x106 copies/g (detection limit of 1x103). Three multivariate statistical methods were used to determine the effect of physical-chemical properties on the target gene distributions. Cluster and discriminant analysis selected five properties (pH, sand and silt content, NO3--N and NH4+-N) as the most discriminating factors among thirty-one physical-chemical properties. However, no effect in the bacterial distribution was observed. The tree classification method identified nine variables that described higher or lower densities of the target genes. Variables such as Bacteria, Fe(II+III) (by hydroxylamine HCl in HCl), organic matter and cis-DCE were selected by the method.. All methods agreed on the selection of pH and sand content as the physical/chemical factors most influencing in the bacterial distribution. Based on the findings of low densities of dechlorinating bacteria and dechlorinating-associated functional genes, low available carbon donor and sandy mineral composition, the partial TCE-dechlorination at this site can be ascribed to the nature of the site and incomplete set of required factors for complete reductive dechlorination.
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Ng-Muk-Yuen, Jennifer Diane. "Prevention of bacterial growth in platelet products via inclusion of iron chelators". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1338.
Testo completoAbstract (sommario):
Bacterial infection is a leading cause of morbidity and mortality arising from platelet transfusions (1, 2). Storage of platelet products at room temperature (20 to 24ºC) provides ideal conditions for bacterial proliferation (1, 3-6). Furthermore, platelets are stored in plasma containing bioavailable iron that bacteria require to survive (7). Thus we hypothesize that the inclusion of iron chelators will bind and remove iron, thereby inhibiting bacterial growth in both culture medium and platelet concentrates. Additionally, we hypothesize that residual red blood cells (RBCs) in platelet units may contribute bioavailable iron that promotes bacterial growth.
To test these hypotheses, we first assessed growth of Staphylococcus epidermidis in culture medium after treatment with the iron chelators deferoxamine (DFO) or phytic acid. DFO significantly inhibited bacterial growth in a dose dependent manner (p < 0.009). Conversely, phytate only inhibited bacterial growth at concentrations ≥ 100 mM (p < 0.001); at ≤ 5 mM, phytate supplied S. epidermidis with additional nutrients and significantly promoted growth (p < 0.001). Subsequently, we monitored the change in RBCs over time. Hemolysis, methemoglobin, and iron levels all significantly increased over the 7-day storage period (p < 0.001) releasing bioavailable iron. Indeed, we found that S. epidermidis growth in iron-poor medium drastically increased with the addition of RBCs, thus supporting our second hypothesis. Surprisingly, the inclusion of DFO in minimal medium did not demonstrate a bacteriostatic effect in the presence of RBCs. The inhibitory effect of DFO was likely overcome by iron released from the elevated methemoglobin levels arising from the direct interaction of DFO with hemoglobin. Previous studies demonstrate that methemoglobin releases iron more quickly than normal hemoglobin (8).
Lastly, we evaluated the effect of DFO on microbial growth in platelet concentrates using the BacT/ALERT system. The presence of DFO significantly inhibited S. epidermidis growth in buffy coat platelets in a dose dependent manner (p < 0.001). With these findings, the inclusion of iron chelators is a promising approach to preventing transfusion-transmitted bacterial infection and providing patients with a safer platelet product.
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Okibe, Naoko. "Moderately thermophilic acidophiles and their use in mineral processing". Thesis, Bangor University, 2002. https://research.bangor.ac.uk/portal/en/theses/moderately-thermophilic-acidophiles-and-their-use-in-mineral-processing(9c8b82ee-27ad-453e-baf6-9afb284c7735).html.
Testo completoAbstract (sommario):
This research project focused on moderately thermophilic acidophilic microorganisms and their role in the oxidation of pyrite. A major objective of the work was to assess the relative efficiencies of defined combinations of moderate thermophiles in oxidising pyrite under defined conditions. In addition, various aspects of the physiology and phylogeny of moderately thermophilic acidophiles were investigated. Moderately thermophilic acidophiles, including novel acidophiles (a thermotolerant Leptospirillum and a Ferroplasma sp. ), were isolated from a commercial stirred-tank pilot plant. Pyrite oxidation by mixed cultures of different combinations of moderate thermophiles, including the novel isolates, was assessed in preliminary shake flask experiments. Data from these experiments were used to select microbial consortia in later experiments in temperature- and pH-controlled bioreactors. These involved monitoring rates of mineral oxidation, and relative numbers of the different microorganisms included in the original inoculum, using a plating technique in conjunction with a molecular approach (FISH). The results from the pyrite oxidation studies indicated that mixed populations of acidophiles may accentuate or diminish the rates and extent of pyrite oxidation, relative to pure cultures. The thermotolerant Leptospirillum isolate was found to be unable to oxidise a pyrite concentrate when grown in pure culture, though this inhibition was overcome when the iron-oxidiser was grown in mixed cultures with various Grampositive acidophiles. Investigation of the effects of fifteen individual and mixtures of flotation chemicals on moderately thermophilic acidophiles revealed different degrees of toxicities of the different reagents and sensitivities of the microorganisms, with the Leptospirillum isolate generally being the most sensitive of those tested. The phenomenon of pH-related ferric iron toxicity to moderately thermophilic and mesophilic Gram-positive bacteria was also investigated. ARDREA (Amplified Ribosomal DNA Restriction Enzyme Analysis) using the 16S rRNA gene sequences of known acidophilic bacteria, was refined and developed, and applied successfully to identify moderate thermophiles isolated from environmental samples.
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Strobel, Philip Scott. "Inhibition of iron-oxidizing bacteria in wastes from coal and hard-rock mines using the anti-bacterial agent". Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42234.
Testo completoAbstract (sommario):
The production of acid mine drainage (AMD) is catalyzed by iron-oxidizing bacteria primarily of the species Thiobacillus ferrooxidans. By inhibiting these bacteria, the production of AMD can be greatly reduced. One compound found to be effective in the inhibition of T. ferrooxidans is nitrapyrine. N-Serve, a product of Dow Chemical, Inc., is the commercially available form of nitrapyrine. This compound has been widely used in agriculture for nitrification inhibition. The purpose of this study was to determine the effectiveness of N-Serve in reducing the production of AMD under simulated field conditions.
A column study was completed using a coal mine waste and a hard-rock mine waste. Eight columns containing 7kg of rock were established for each substrate. Three doses of NServe (22% nitrapyrine) were applied once at the beginning of this study: a high dose 2200 mg/kg, a medium dose 220 mg/kg, and a low dose 22 mg/kg. Duplicate columns were included for each N-Serve dose including two untreated columns to serve as a control for each substrate. Beginning the week after treatment, the columns were leached once a week for 29 weeks with deionized, distilled water (equivalent to 2.5 cm precipitation). Only the highest NServe dose produced a column leachate of significantly better quality than that of the controls. The acidity in the high-dose coal mine columns averaged less than 50 percent of the acidity in the control effluent from week 6 through the end of the study.
A monolithic controlled release system utilizing acrylonitrile rubber was successfully developed and tested for use with nitrapyrine. This formulation should withstand the rigors of the environment and with minor modification could produce a variety of release rates.Master of Science
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Bertel, Douglas E. "Characterizations of Iron Sulfides and Iron Oxides Associated with Acid Mine Drainage". University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1302276664.
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30
Huggins, Cerys Catriona Owen. "Iron storage in bacteria : regulation of the Escherichia coli ferritin gene (ftnA)". Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250697.
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31
Batmanghelich, Farhad. "Effect of mixed denitrifying and sulfate reducing bacterial biofilms on corrosion behavior of cast iron". University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1451311653.
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Yahya, Abidah. "Physiological and phylogenetic studies of some novel acidophilic mineral-oxidising bacteria". Thesis, Bangor University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322564.
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Grogan, Janette M. "Regulation and function of the genes encoding bacterioferritin (BFR) and BFR-associated ferrodoxin (Bfd) of E. coli". Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265864.
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George, Thompson Alayna Michelle. "Molecular Mechanisms of Copper Homeostasis in Gram-negative Bacteria". Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/320968.
Testo completoAbstract (sommario):
Copper is a trace element utilized by organisms as a cofactor involved in redox chemistry, electron transport, photosynthesis, and oxidation reactions. In excess, copper is toxic; it can generate reactive oxygen species causing cellular damage, or poison other metalloproteins by replacing native metal cofactors. Gram-negative bacteria have developed homeostatic mechanisms to maintain the intracellular copper concentration in the face of changing environmental conditions. For Gram-negative enteric bacteria, like Esherichiacoli and Salmonella enterica serovar typhimurium, copper is encountered in industrial and institutional settings, where the metal is used as a broad-spectrum biocide. For environmental bacteria, such as the marine cyanobacterium Synechococcus sp. WH8102, copper stress occurs because human activity changes the concentration of copper in the ocean. This dissertation contains six chapters, relating four stories of our investigations into the molecular mechanisms of copper homeostasis in Gram-negative bacteria. Chapter I contains literature review and background on the implications of bacterial copper homeostasis. Chapter II reports our work investigating the expression of two E. coli proteins, CusF and CusB, upon copper stress; we show that CusF expresses at a ~10-fold molar excess over CusB. Chapter III describes a collaboration between our lab and Jose Argüello's lab at Worcester Polytechnic Institute, and we show that CusF can acquire Cu(I) from CopA. Our results from Chapters II and III show that CusF functions as a major copper chaperone in the periplasm of E. coli. Chapter IV details our work characterizing a novel protein from marine cyanobacteria, Synw_0921. Although Synw_0921 is believed to be involved in copper homeostasis, we show that it is an iron-sulfur cluster protein. Bioinformatic analysis suggests that Synw_0921 represents a new family of proteins that help marine cyanobacteria adapt to copper changes in their unique environment. Chapter V relates our work on CueR and GolS, two homologous sensor proteins with distinct metal-dependent transcriptional activation; we find that the activity cannot be explained by binding affinity differences. Chapter VI concludes with final thoughts on the intersection of biochemistry and molecular biology in the important process of understanding copper homeostasis.
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Kajenthira, Arani. "Mercury immobilisation in situ : Interactions between charcoal, nanoscale iron, and sulphate-reducing bacteria". Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533855.
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Ullrich, Sophie. "Genomic and transcriptomic characterization of novel iron oxidizing bacteria of the genus “Ferrovum“". Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-205981.
Testo completoAbstract (sommario):
Acidophilic iron oxidizing bacteria of the betaproteobacterial genus “Ferrovum” are ubiquitously distributed in acid mine drainage (AMD) habitats worldwide. Since their isolation and maintenance in the laboratory has proved to be extremely difficult, members of this genus are not accessible to a “classical” microbiological characterization with exception of the designated type strain “Ferrovum myxofaciens” P3G.
The present study reports the characterization of “Ferrovum” strains at genome and transcriptome level. “Ferrovum” sp. JA12, “Ferrovum” sp. PN-J185 and “F. myxofaciens” Z-31 represent the iron oxidizers of the mixed cultures JA12, PN-J185 and Z-31. The mixed cultures were derived from the mine water treatment plant Tzschelln close to the lignite mining site in Nochten (Lusatia, Germany). The mixed cultures also contain a heterotrophic strain of the genus Acidiphilium. The genome analysis of Acidiphilium sp. JA12-A1, the heterotrophic contamination of the mixed culture JA12, indicates an interspecies carbon and phosphate transfer between Acidiphilium and “Ferrovum” in the mixed culture, and possibly also in their natural habitat. The comparison of the inferred metabolic potentials of four “Ferrovum” strains and the analysis of their phylogenetic relationships suggest the existence of two subgroups within the genus “Ferrovum” (i.e. the operational taxonomic units OTU-1 and OUT-2) harboring characteristic metabolic profiles. OTU-1 includes the “F. myxofaciens” strains P3G and Z-31, which are predicted to be motile and diazotrophic, and to have a higher acid tolerance than OTU-2. The latter includes two closely related proposed species represented by the strains JA12 and PN-J185, which appear to lack the abilities of motility, chemotaxis and molecular nitrogen fixation. Instead, both OTU-2 strains harbor the potential to use urea as alternative nitrogen source to ammonium, and even nitrate in case of the JA12-like species. The analysis of the genome architectures of the four “Ferrovum” strains suggests that horizontal gene transfer and loss of metabolic genes, accompanied by genome reduction, have contributed to the evolution of the OTUs.
A trial transcriptome study of “Ferrovum” sp. JA12 supports the ferrous iron oxidation model inferred from its genome sequence, and reveals the potential relevance of several hypothetical proteins in ferrous iron oxidation. Although the inferred models in “Ferrovum” spp. share common features with the acidophilic iron oxidizers of the Acidithiobacillia, it appears to be more similar to the neutrophilic iron oxidizers Mariprofundus ferrooxydans (“Zetaproteobacteria”) and Sideroxydans lithotrophicus (Betaproteobacteria). These findings suggest a common origin of ferrous iron oxidation in the Beta- and “Zetaproteobacteria”, while the acidophilic lifestyle of “Ferrovum” spp. may have been acquired later, allowing them to also colonize acid mine drainage habitats.
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Rioux, Jean-Philippe. "Microbial activity of iron-reducing bacteria and sulfate-reducing bacteria isolated from mine tailings in the presence of various electron donors". Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26757.
Testo completoAbstract (sommario):
Two abandoned mine tailings sites (Calumet near Ottawa, and Potter near Timmins, Ontario) have been shown to support active populations of iron- (IRB) and sulfate-reducing bacteria (SRB). The competition between IRB and SRB for similar electron donors was however never assessed. The present study looked into the potential competition between IRB and SRB isolated from those 2 sites since they represent different pH conditions and mineralogy. The Potter tailings are acidic to slightly acidic and contain large quantities of sulfides, whereas the Calumet tailings are alkaline and contain less pyrite and more carbonate minerals. Batch experiments were designed to test the competition between IRB and SRB for 3 electron donors (acetate, formate and lactate) and to determine the role of abiotic Fe(III) reduction. Results from abiotic systems indicated that Fe(II) was released overtime in the various systems due to the reduction of Fe(III)-rich minerals by the organic acids present in the medium and due to the chemical oxidation of pyrite by ferric iron. IRB could only grow in the Calumet systems containing inhibited SRB. In these systems, IRB growth was favored in the presence of acetate. In the systems containing active SRB, IRB growth was minimal in the presence of all electron donors, suggesting that they cannot compete with SRB under the conditions used in the systems. SRB present in all systems were capable of oxidizing all 3 electron donors, including acetate. Our results also showed that complete and incomplete lactate oxidizers were present in the Calumet and Potter systems.
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Macdonald, Alexander James. "Theoretical and in vitro analysis of iron acquisition in Pasteurella multocida A:3". Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4381.
Testo completoAbstract (sommario):
A key bacterial virulence factor is the ability to acquire the micronutrient iron, required by a vast majority of micro-organisms for survival and proliferation within their hosts. The work described here focuses on acquisition of iron in Pasteurella multocida serotype A:3, a Gram-negative opportunistic pathogen that causes pneumonic pasteurellosis in cattle, a severe respiratory infection of significant economic burden and welfare concern. P. multocida A:3 acquires iron primarily from the host iron-chelating molecule transferrin through the expression of specific outer membrane receptors. The correlation between up-regulation of these receptors and of other iron-regulated outer membrane proteins (IROMPs) and an increase in bacterial virulence has been noted elsewhere. To date, there has been no systems analysis of the metabolic processes of iron acquisition published for any bacterial species. The work described here used a systems approach involving elementary flux modes analysis to derive a computational model of iron acquisition and reveal a number of key findings on the mechanisms of iron acquisition and links between iron uptake, glucose metabolism and protein synthesis. This in silico model was subjected to experimental validation through a range of in vitro experiments designed to investigate the links between iron restriction and growth and metabolism of P. multocida. This novel approach was only possible after the development and optimisation of a number of assays to measure key model parameters.
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Tremblay, Yannick. "Acquisition of haemoglobin-bound iron by Histophilus somni". Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82441.
Testo completoAbstract (sommario):
Ovine (strains 9L and 3384Y) and bovine (strains 649, 2336 and 8025) isolates of Histophilus somni were investigated for their ability to acquire iron from haemoglobin (Hb). Bovine isolates were capable of utilizing bovine, but not ovine, porcine or human Hb as a source of iron. Ovine isolates could not obtain iron from Hb. Bovine isolates bound bovine, ovine, and human Hbs by means of the same iron-repressible receptor(s) and produced a ~120-kDa iron-repressible, outer membrane protein. Using PCR approaches, an iron-regulated operon containing hugX and hugZ homologues and a gene (hgbA) that encodes a TonB-dependent, Hb-binding proteins were identified in strains 649, 9L and 3384Y. In strains 9L and 3384Y, HgbA is truncated offering a possible explanation for their lack of utilization of Hb as an iron source. In strains 2336 and 8025, expression of HgbA was also subject to a form of phase variation.
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Ahn, Se Chang. "Removal of perchlorate in ammunition wastewater by zero-valent iron and perchlorate respiring bacteria". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 138 p, 2008. http://proquest.umi.com/pqdweb?did=1601522481&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Yang, Jing, e n/a. "The roles of siderophores in bacterial adhesion to metals and iron transport". University of Otago. Department of Chemistry, 2009. http://adt.otago.ac.nz./public/adt-NZDU20090825.144153.
Testo completoAbstract (sommario):
Siderophores are a series of important iron chelators secreted by many bacteria that normally have high affinity of iron ions and contain hydroxamate, catecholate and carboxylate and other ligand groups. These organic ligands play significant roles in bacterial metabolism: solubilising iron (III) from environments, enabling iron uptake and acting as a cell-signalling molecule to control gene expression. Recent observations of initial stages of Pseudomonas aeriginosa biofilm formation on metal oxides surfaces indicate that siderophores may also facilitate bacterial adhesion to metals. However, details of how siderophores interact with metal surfaces and the relationship of their chemical nature with bacterial adhesion were not fully understood. To test the generality of bacteria attachment to metals via siderophores, the adsorption behaviour of siderophores and their functional ligands groups on particle films of metal oxides were investigated with in-situ ATR-IR spectroscopy.
In this study, nanoparticle films of titanium oxide, boehmite, iron oxide and chromium oxyhydroxide were prepared as substrates to simulate titanium, alumnium, stainless steel surface and more detailed work were carried out on titanium dioxide. Monohydroxamic acids (acetohydroxamic acid, N-methylformohydroxamic acid, N-methyl-acetohydroxamic acid and 1-hydroxy, 2-piperidone) and catechol and catechol-like (L-dopa and esculetin) ligands were selected as modelling compounds for the most frequently occured functional groups in natural siderophores. IR spectra of these ligands in aqueous solution and adsorbed on TiO₂ were obtained with a flowing cell system fit to a horizontal accessory by in situ ATR-IR spectroscopy and interpreted based on vibrational mode analysis with density function theory. Results show that all these ligands can form surface complexes with metal surfaces and possible adsorption modes of these molecules were discussed. The pH dependence of absorbance of IR absorption of these adsorbed ligands showed that most of the ligands exhibited maximium adsorption to TiO₂ at about pH 8, only N-methylformohydroxamic acid, 1-hydroxy, 2-piperidone groups having maximum absorption at pH~3 and pH~6.
Infrared spectroscopic studies of adsorbed siderophores (desferroximme B, enterobactin and pyoverdine) were also carried out in variation of concentration and pH. Possible adsorption modes of these iron scavenger ligands on TiO₂ and other metal oxides were discussed. Results showed that all these ligands adsorbed on metal oxide surfaces and form surface complex via hydroxamate or catecholate lignd groups which confirm the generality of siderphore-metal bond formation.
Siderophore based-bacterial adhesion to metals of was conducted with Pesudomonas aeruginosa and E. coli strains on titanium oxide and iron oxide films. These observations support that siderophore play a significant role in bacterial adhesion to metals. Further work needs to be carried out on the wider involvement of siderophores in bacterial adhesion initiation to metals and siderophore-mediated iron transport.
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Dhakal, Prakash Saunders James A. "Sorption of arsenic by iron sulfide made by sulfate-reducing bacteria implications for bioremediation /". Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/FALL/Geology_and_Geography/Thesis/Dhakal_Prakash_27.pdf.
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Stelzer, Sacha Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "WmpR regulation of antifouling compounds and iron uptake in the marine bacterium Pseudoalteromonas tunicata". Awarded by:University of New South Wales. School of Biotechnology and Biomolecular Sciences, 2006. http://handle.unsw.edu.au/1959.4/29354.
Testo completoAbstract (sommario):
The dark-green pigmented marine bacterium Pseudoalteromonas tunicata produces several extracellular compounds against a range of common fouling organisms including bacteria, fungi, protozoa, diatoms, invertebrate larvae and algal spores. The regulator WmpR, which has N-terminal similarity to ToxR from Vibrio cholerae and CadC from Escherichia coli, controls all of the pigment and antifouling phenotypes. These compounds appear at the onset of stationary phase. The role of WmpR as a stationary phase regulator in P. tunicata was investigated in this thesis. Starvation and stress studies demonstrated that WmpR does not appear to control genes necessary for survival during carbon, phosphate or nitrogen starvation and UV/hydrogen peroxide stress. Intriguingly, phosphate starvation caused pigmentation of wmpR mutant (D2W2) logarithmic phase cells, suggesting a second regulation of the pigments (and thus antifouling compounds) that could be mediated by the PhoR/B twocomponent regulatory system. Proteomic analysis using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) found that 11 proteins were differentially regulated by WmpR, and the identities of some of these proteins suggested a role for WmpR as a general stationary phase regulator rather than a specific starvation or stress regulator. Gene expression studies using RNA-arbitrarily primed PCR introduced a new role for WmpR as a regulator of iron acquisition; a TonB-dependant outer membrane receptor gene and a non-ribosomal peptide synthetase (NRPS) gene were up-regulated in the stationary phase Wt strain compared to the D2W2 strain. An assay for iron-binding activity supported the proposal that the NRPS may be making a siderophore. Further studies demonstrated that WmpR is required for survival under long-term low-iron conditions and that the pigments and antifouling genes are down-regulated during low-iron, while biofilm formation is up-regulated. WmpR also appears to constitutively regulate the production of iron-binding compounds, a novel regulation of iron acquisition that has not been seen in other organisms studied so far. A model is proposed that describes WmpR as responding to environmental signals, including iron, and co-ordinating the expression of a complex regulon including a number of genes involved in iron acquisition, general stationary phase physiology and bioactive secondary metabolite production.
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McMillan, Duncan George Glenn, e n/a. "Proton and iron capture mechanisms of Bacillus sp. strain TA2.A1 at alkaline pH values". University of Otago. Department of Microbiology & Immunology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20081104.090840.
Testo completoAbstract (sommario):
The thermoalkaliphilic Bacillus sp. strain TA2.A1 was able to grow in pH-controlled batch culture containing a fermentable growth substrate (i.e. sucrose) from pH 7.5 to 10.0 with no significant change in specific growth rate, suggesting that this bacterium is a facultative alkaliphile. However, when strain TA2.A1 was grown on non-fermentable carbon sources like succinate, no growth was observed until the external pH was > 9.0, suggesting this bacterium is an obligate alkaliphile. Growth on succinate at pH 9.5 was sensitive to both carbonyl cyanide m-chlorophenylhydrazone (CCCP) and monensin revealing that both the proton and sodium motive force ([Delta][mu][H⁺] and [Delta][mu][Na⁺], respectively) were obligate requirements for growth at alkaline pH values. Transport of succinate was driven by a chemical gradient of Na⁺ ([Delta]pNa⁺) that was strictly coupled to [Delta][Psi]. A single transport system was detected for the uptake of succinate, with an apparent K[m] of 19 [mu]M and V[max] of 0.45 nmol succinate/min/mg protein. Succinate transport was pH-dependent, and showed optimal activity at pH values greater than 8.5. Other C₄-dicarboxylates (e.g. malate, fumarate) inhibited the uptake of succinate suggesting that the permease was general for other C₄-dicarboxylates.
Cytochrome content, succinate dehydrogenase oxidoreductase, and F₁F₀-ATPase activities were lower in membranes from strain TA2.A1 cells grown at pH 7.5 compared to those cultured at 9.5. These data suggest that oxidative phosphorylation-linked processes are down-regulated at neutral pH values, an observation that mirrored oxygen consumption profiles of strain TA2.A1 in whole cells. To study this phenomenon at a molecular level, we measured ATP synthesis by the F₁F₀-ATP synthase from strain TA2.A1 as a function of pH. The strain TA2.A1 F₁F₀-ATP synthase had a pH optimum for ATP synthesis of 9.0-9.5, and significantly lower rates of ATP synthesis observed below pH 9.0. Analysis of the atp operon from the thermoalkaliphilic Bacillus sp. strain TA2.A1 and comparison with other atp operons from alkaliphilic bacteria reveals the presence of a conserved lysine residue at position 180 (Bacillus sp. strain TA2.A1 numbering) within the a subunit of these F₁F₀-ATP synthases. We hypothesize that the basic nature of this residue is ideally suited to capture protons from the bulk phase at high pH. To test this hypothesis, a heterologous expression system for the ATP synthase from Bacillus sp. TA2.A1 (TA2F₁F₀) was developed in Escherichia coli DK8 ([Delta]atp). Amino acid substitutions were made in the a subunit of TA2F₁F₀ at position 180. Lysine (aK180) was substituted for the basic residues histidine (aK180H) or arginine (aK180R), and the uncharged residue glycine (aK180G). ATP synthesis experiments were performed in ADP plus P[i]-loaded right-side out membrane vesicles energized by ascorbate-phenazine methosulfate. When these enzyme complexes were examined for their ability to perform ATP synthesis over the pH range from 7.0 to 10.0, TA2F₁F₀ and aK180R showed a similar pH profile having optimum ATP synthesis rates at pH 9.0 to 9.5 with no measurable ATP synthesis at pH 7.5. Conversely, aK180H and aK180G showed maximal ATP synthesis at pH�s 8.0 and 7.5, respectively. ATP synthesis under these conditions for all enzyme forms was sensitive to DCCD. These data strongly imply that amino acid residue K180 is a specific adaptation within the a subunit of TA2F₁F₀ to facilitate proton capture at high pH. At pH values near the pK[a] of K180, the trapped protons readily dissociate to reach the subunit c binding sites but this dissociation is impeded at neutral pH values causing either a blocking of the proposed H⁺ channel and/or mechanism of proton translocation, and hence ATP synthesis is inhibited.
The mechanisms where by alkaliphilic bacteria obtain iron remains unknown. Growth of strain TA2.A1 at pH 9.5 in the presence of the artificial iron chelators ethylenediamine O-hydroxyphenylacetic acid (EDDHA) and 2�2� dipyridal revealed that iron is an important requirement for aerobic growth at alkaline pH values. Furthermore, biochemical analysis showed that Bacillus alcalophilus and Bacillus pseudofirmus both synthesized orange catecholate siderophores, whilst Bacillus halodurans synthesized a hydroxamate siderophore. These tests showed that strain TA2.A1 synthesized both orange catecholate and hydroxamate siderophore/s. Attempts to purify the catecholate were unsuccessful. No homologues of previously identified non-ribosomal peptide synthase (NRPS) genes in Bacillus subtilis and B.halodurans were detected in the genome of strain TA2.A1 using both PCR and Southern hybridization using known non-ribosomal peptide synthase genes.
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Hwang, Chiachi. "Assessment of bacterial communities and an iron-reducing bacterium in relation to an engineered bioremediation system designed for the treatment of uranium-nitric acid contaminated groundwater". Oxford, Ohio : Miami University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1241117969.
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Murphy, Julianna E. "Catalytic Effect of Iron Oxidizing Bacteria on the Production of Pigment from Acid Mine Drainage". Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou149383043673114.
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Saraiva, Ivo H. "Structural and functional characterization of the gene products responsible for phototrophic iron oxidation by purple bacteria". Doctoral thesis, Universidade Nova de Lisboa. Instituto de Tecnologia Química e Biológica, 2012. http://hdl.handle.net/10362/9758.
Testo completoAbstract (sommario):
Dissertação para a obtenção de grau de doutor em Bioquímica pelo Instituto de Tecnologia Química e Biológica. Universidade Nova de LisboaIron is an essential element in life. It is used in a variety of different processes in the energetic metabolism of different organisms. Among these bioenergetic processes is photoferrotrophy, characterized by the utilization of Fe(II) as the sole electron source for photosynthesis. The metabolic activity of photoferrotrophs is proposed to have had a relevant role in the formation of ancient geological structures consisting of Fe(III) minerals, such as the Banded Iron Formations.(...)
Fundação para a Ciência e Tecnologia
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Doikos, Pavlos E. "Investigation of the potential for microbial reductive dechlorination of hexachlorobenzene under iron-reducing conditions". Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/20970.
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Sun, Yue. "The Influence of Water Chemistry on H2 Production and Uptake during Anaerobic Iron Corrosion". Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/46172.
Testo completoAbstract (sommario):
Iron corrosion is the most important economic and aesthetic problem facing utilities. In the water distribution system, problems caused by iron corrosion include "red water", scale buildup, and pipe failures. It is necessary to improve our mechanistic understanding of anaerobic iron corrosion in order to better address these concerns.
Experiments were conducted to investigate the effect of soluble constituents (Fe2+, PO43-, and NH4+) on H2 evolution during anaerobic iron corrosion. At pH 7.0 when sulfide was absent, variable Fe2+ did not have much influence on H2 release rates, whereas PO43- and NH4+ promoted H2 evolution. If present, soluble sulfide controlled H2 release rates in the solutions with Fe2+ or PO43-; however, NH4+ and S2- combined to inhibit H2 release. A simplistic empirical model was developed that fit data on corrosion rates from previous researchers studying effects of sulfate-reducing bacteria (SRB) on iron corrosion. As a whole, the experimental data and the model results support the notion that water quality controls iron corrosion rates in the presence of SRB. The practical relevance of previous research is somewhat in doubt given the atypical levels of nutrients used in relation to those actually present in water and wastewater.
A second phase of research was aimed at exploring the equilibrium and kinetic aspects of iron corrosion in the presence of phosphate. The hypothesis that anaerobic iron corrosion is influenced by low pressure H2 (<1 atm) buildup was examined. At pH 2.75 and pH 7.0 in the presence of 100 mg/L P-PO43-, variations in H2 release were measured under different circumstances. Addition of PO43- formed a protective film, possibly vivianite Fe3(PO4)2, on the iron surface that eventually stopped H2 release. However, results were consistent with the idea that corrosion is an irreversible process that is relatively insensitive to low level H2 (<1 atm). Possible alternative explanations were provided to reconcile the past research data that purportedly demonstrated that removal of H2 increased corrosion rates. A reaction that caused "decay" of H2 in the presence of high phosphate was discovered that can not be readily explained.Master of Science
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Smalls, Freeman Earl. "Development of an Anti-stenotrophomonas maltophilia Immunoglobulin-G (lgG) that Prevents Iron Transport in Gram Negative Bacteria". DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2009. http://digitalcommons.auctr.edu/dissertations/76.
Testo completoAbstract (sommario):
The resistance of Stenotrophomonas maltophilia to antimicrobial agents has become a major medical and public health problem. The frequent treatment of S. maltophilia borne infections with the same anti-microbial agent over a period of time inherently results in the pathogen developing resistance to the drug. A polyclonal antibody cocktail, D-Squared David L Scott 01 (D2-DLSO1) was used to recover surface exposed immunogenic polypeptides (SEIP’s) from the cell walls of S. maltophilia. Bioinformatics strategies (Blast analysis, sequence alignment hydrophilicity/hydrophobicity plots) were performed to identify epitopes of ferric enterobactin receptor (Fep A) homolog in S. maltophilia. Data showed that D2-DLSO1 recognized regions along the Fep A peptide sequence that was confirmed in an enzyme linked immunosorbent assay (ELISA) assay. The amino acid sequences of Escherichia coli (E. coli) Fep A Iron receptor could serve as a target for the development of anti S.maltophila IgG that are useful in protection against infections caused by S. maltophilia and other Gram negative bacteria. Individual S. maltophilia surface exposed immunogenic polypeptides were evaluated in growth inhibition studies and ELISA was used to determine applicability as targets for immunological neutralization. The data suggest that serial dilution (100-fold increments) of D2-DLSO 1 antisera (1 02 dilutions) representing ljig/ml showed significant binding ofD2-DLSO1 to S.maltophilia antigens as compared to controls. The data indicated that D2-DLSO1 inhibited the proliferation of S. maltophilia and several Gram negative bacteria. However, D2-DLSO1 did not show any inhibition of proliferation on Gram positive bacteria (Staphiococcus. aureus), suggesting that there are no common conserved sequences among Gram negative and Gram positive bacteria. Human monoclonal antibodies (DLS-10/ DLS-1 1) recovered from transgenic mice were capable of inhibiting the proliferation of S. maltophilia in vitro. These monoclonal antibodies showed potential of being excellent therapeutic agents for infections caused by S. maltophilia and possibly other Gram negative nosocomial pathogens.