Publications

TitleAbstractYear(sorted descending)
Filter
PMID
Filter
method development for electrotransformation of acidithiobacillus caldus.acidithiobacillus caldus is an acidophilic, chemoautotrophic bacterium, plays important role in bioleaching. gene transformation into a. caldus is difficult and only the conjugation method was reported successful, which method was relatively sophisticated. in this research, electrotransformation of a. caldus species was achieved for the first time using a. caldus y-3 and plasmid pjrd215. transformants were confirmed by colony pcr specific to the str gene on pjrd215, and the recovery of the plasm ...201020134231
non-homogeneous biofilm modeling applied to bioleaching processes.a two-dimensional non-homogeneous biofilm model is proposed for the first time to study chemical and biochemical reactions at the microorganism scale applied to biological metal leaching from mineral ores. the spatial and temporal relation between these reactions, microorganism growth and the morphological changes of the biofilm caused by solid inorganic precipitate formation were studied using this model. the model considers diffusion limitations due to accumulation of inorganic particles over ...201020229512
[microbial diversity and characteristics of cultivable microorganisms in bioleaching reactors].in order to study the microbial diversity and the characteristics of cultivable microorganisms in bioleaching reactors.201020387468
[separation of magnetic bacteria by using a magnetic separator].a magnetic separator was used to separate magnetic bacteria based on their magnetotactic characteristics. acidithiobacillus ferrooxidans, a bacterium that could synthesize intra-cellular nanometer magnetic particles, was investigated as an example. strong magnetic and weak magnetic cells were separated and collected. on average, the number of the magnetic particles present in the strong magnetic cells is more than that of the weak magnetic cells. moreover, semisolid-plate magnetophoresis showed ...201020432949
an unconventional copper protein required for cytochrome c oxidase respiratory function under extreme acidic conditions.very little is known about the processes used by acidophile organisms to preserve stability and function of respiratory pathways. here, we reveal a potential strategy of these organisms for protecting and keeping functional key enzymes under extreme conditions. using acidithiobacillus ferrooxidans, we have identified a protein belonging to a new cupredoxin subfamily, acop, for "acidophile cco partner," which is required for the cytochrome c oxidase (cco) function. we show that it is a multifunct ...201020442397
the inhibitory effect of antimicrobial zeolite on the biofilm of acidithiobacillus thiooxidans.the inhibitory effect of antimicrobial zeolite coated concrete specimens (z2) against acidithiobacillus thiooxidans was studied by measuring biomass dry cell weight (dcw), biological sulphate generation, and oxygen uptake rates (ours). uncoated (uc), and blank zeolite coated without antimicrobial agent (zc) concrete specimens were used as controls. the study was undertaken by exposing inoculated basal nutrient medium (bnm) to the various specimens. the coating material was prepared by mixing zeo ...201019618279
gene expression modulation by chalcopyrite and bornite in acidithiobacillus ferrooxidans.acidithiobacillus ferrooxidans is a mesophilic, acidophilic, chemolithoautotrophic bacterium that obtains energy from the oxidation of ferrous iron (fe2+), elemental sulfur and reduced sulfur compounds. the industrial interest in a. ferrooxidans resides in its capacity to oxidize insoluble metal sulfides into soluble metal sulfates, thus allowing the recovery of the desired metals from low-grade sulfide ores. in the present work, rna arbitrarily primed pcr (rap-pcr) was performed to identify cdn ...201020480358
isolation and characterization of acidithiobacillus caldus from a sulfur-oxidizing bacterial biosensor and its role in detection of toxic chemicals.a novel toxicity detection methodology based on sulfur-oxidizing bacteria (sob) has been developed for the rapid and reliable detection of toxic chemicals in water. the methodology exploits the ability of sob to oxidize sulfur particles in the presence of oxygen to produce sulfuric acid. the reaction results in an increase in electrical conductivity (ec) and a decrease in ph. the assay is based on the inhibition of sob in the presence of toxic chemicals by measuring changes in ec and ph. we foun ...201020580751
monitoring bacterial community shifts in bioleaching of ni-cu sulfide.the microbial ecology of the bioleaching of ni-cu sulfide is poorly understood and little effort has been made to handle the microbiological components of these processes. in this study, denaturing gradient gel electrophoresis (dgge) analysis of pcr-amplified 16s rrna genes fragments from bacteria was used to evaluate the changes of the bacterial community in the process of ni-cu sulfide bioleaching in a shaken flask system. the results revealed that the bacterial community was disturbed after t ...201020624605
biological extraction of realgar by acidithiobacillus ferrooxidans and its in vitro and in vivo antitumor activities.acidithiobacillus ferrooxidans is a gram-negative, chemolithoautotrophic bacterium involved in metal bioleaching. it is used for the extraction of coarse medical realgar, which is converted into an aqueous solution. to prove its feasibility as an anticancer drug candidate, extracted realgar (er/af) was evaluated for its antitumor activities both in vitro and in vivo. in cytotoxicity tests, er/af displayed significant inhibition on cell proliferation of hepg2, smmc7721, and h22 cells in a time an ...201020645754
insights into the dynamics of bacterial communities during chalcopyrite bioleaching.the microbial ecology of the bioleaching of chalcopyrite ores is poorly understood and little effort has been made to handle the microbiological components of these processes. in this study, the composition and structure of microbial communities in acid mineral bioleaching systems have been studied using a pcr-based cloning approach. denaturing gradient gel electrophoresis (dgge) analysis of pcr-amplified 16s rrna gene fragments from bacteria was used to evaluate the changes in the bacterial com ...201020698885
pdms-based porous particles as support beds for cell immobilization: bacterial biofilm formation as a function of porosity and polymer composition.the objective of this work is to test the performance of new synthetic polydimethylsiloxane (pdms)-based bed particles acting as carriers for bacteria biofilms. the particles obtained have a highly interconnected porous structure which offers a large surface adsorption area to the bacteria. in addition, pdms materials can be cross-linked by copolymerization with other polymers. in the present work we have chosen two hydrophilic polymers: xanthan gum polysaccharide and tetraethoxysilane (teos). t ...201020702072
zinc and lead leaching from contaminated industrial waste sludges using coupled processes.metal pollution of solid matrices, like soils, sediments and sludge, is widespread across the globe, and the clean-up of these matrices presents many difficulties. the aim of this study was to develop an efficient leaching technique for metal removal from an industrial carbon sludge contaminated with zn (8600 mg kg(-1)) and pb (389 mg kg(-1)). to this end, the possibility of coupling processes, such as extraction with mineral acids, edta addition, ultrasound and bioleaching, was investigated. le ...201021275254
heterotrophic microorganism rhodotorula mucilaginosa r30 improves tannery sludge bioleaching through elevating dissolved co2 and extracellular polymeric substances levels in bioleach solution as well as scavenging toxic dom to acidithiobacillus species.the introduction of acid-tolerant heterotrophic microorganisms into sludge bioleaching systems has been proven effective in improving sludge bioleaching processes, and such positive effect is mainly attributed to the biodegradation of low molecular weight organic acids or sludge dissolved organic matter (dom) toxic to acidithiobacillus species by the heterotrophic microorganisms introduced. here we report that elevated dissolved co(2) concentration and resulting extracellular polymeric substance ...201020633920
biofiltration of reduced sulphur compounds and community analysis of sulphur-oxidizing bacteria.the present work aims to use a two-stage biotrickling filters for simultaneous treatment of hydrogen sulphide (h(2)s), methyl mercaptan (mm), dimethyl sulphide (dms) and dimethyl disulphide (dmds). the first biofilter was inoculated with acidithiobacillus thiooxidans (bat) and the second one with thiobacillus thioparus (btt). for separate feeds of reduced sulphur compounds (rsc), the elimination capacity (ec) order was dmds>dms>mm. the ec values were 9.8 g(mm-s)/m(3)/h (btt; 78% removal efficien ...201021216139
recombinant tetrathionate hydrolase from acidithiobacillus ferrooxidans requires exposure to acidic conditions for proper folding.tetrathionate hydrolase (4thase) plays an important role in dissimilatory sulfur metabolism in the acidophilic chemolithoautotrophic iron- and sulfur-oxidizing bacterium acidithiobacillus ferrooxidans. we have already identified the gene encoding 4thase (af-tth) in this bacterium. the heterologous expression of af-tth in escherichia coli resulted in the formation of inclusion bodies of the protein in an inactive form. the recombinant protein (af-tth) was successfully activated after an in vitro ...201020546308
environmental transcriptome analysis reveals physiological differences between biofilm and planktonic modes of life of the iron oxidizing bacteria leptospirillum spp. in their natural microbial community.extreme acidic environments are characterized by their high metal content and lack of nutrients (oligotrophy). macroscopic biofilms and filaments usually grow on the water-air interface or under the stream attached to solid substrates (streamers). in the río tinto (spain), brown filaments develop under the water stream where the gram-negative iron-oxidizing bacteria leptospirillum spp. (l. ferrooxidans and l. ferriphilum) and acidithiobacillus ferrooxidans are abundant. these microorganisms play ...201020576116
cytoplasmic membrane fluidity and fatty acid composition of acidithiobacillus ferrooxidans in response to ph stress.strain variation in the acidophile acidithiobacillus ferrooxidans was examined as a product of membrane adaptation in response to ph stress. we tested the effects of sub and supra-optimal ph in two type strains and four strains isolated from acid mine drainage water around sudbury, ontario, canada. growth rate, membrane fluidity and phase, determined from the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene, and fatty acid profiles were compared. the effect of ph 1.5 was the most prono ...201020582711
life in blue: copper resistance mechanisms of bacteria and archaea used in industrial biomining of minerals.industrial biomining processes to extract copper, gold and other metals involve the use of extremophiles such as the acidophilic acidithiobacillus ferrooxidans (bacteria), and the thermoacidophilic sulfolobus metallicus (archaea). together with other extremophiles these microorganisms subsist in habitats where they are exposed to copper concentrations higher than 100mm. herein we review the current knowledge on the cu-resistance mechanisms found in these microorganisms. recent information sugges ...201020627124
redox status affects the catalytic activity of glutamyl-trna synthetase.glutamyl-trna synthetases (glurs) provide glu-trna for different processes including protein synthesis, glutamine transamidation and tetrapyrrole biosynthesis. many organisms contain multiple glurss, but whether these duplications solely broaden trna specificity or also play additional roles in tetrapyrrole biosynthesis is not known. previous studies have shown that glurs1, one of two glurss from the extremophile acidithiobacillus ferrooxidans, is inactivated when intracellular heme is elevated ...201020541532
biosorption of inorganic and organic arsenic from aqueous solution by acidithiobacillus ferrooxidans by-3.the traditional techniques for removing low concentration arsenic are unsuitable. the biosorption characteristics of arsenite (ias(iii)) and monomethyl arsonate (mma(v)) from aqueous solution by acidithiobacillus ferrooxidans by-3 (at. f by-3) were investigated as a function of ph, contact time, initial arsenic concentration, biomass dosage and temperature in this study. results indicated that langmuir isotherm model fitted better than freundlich model to the equilibrium data. analysis of kineti ...201020122794
acidithiobacillus ferrivorans, sp. nov.; facultatively anaerobic, psychrotolerant iron-, and sulfur-oxidizing acidophiles isolated from metal mine-impacted environments.phenotypic and genotypic analysis was carried out on four iron- and sulfur-oxidizing acidophilic bacteria (the "no-37 group") isolated from different parts of the world. 16s rrna phylogeny showed that they are highly related to each other, but are less related to the type strain of acidithiobacillus ferrooxidans. the no-37 group isolates are obligate chemolithoautotrophs, facultative anaerobes, diazotrophic, and psychrotolerant. they are less tolerant of extremely low ph, and in contrast to at. ...201019787416
bioleaching kinetics and multivariate analysis of spent petroleum catalyst dissolution using two acidophiles.bioleaching studies were conducted to evaluate the recovery of metal values from waste petroleum catalyst using two different acidophilic microorganisms, acidithiobacillus ferrooxidans and acidithiobacillus thiooxidans. various leaching parameters such as contact time, ph, oxidant concentration, pulp densities, particle size, and temperature were studied in detail. activation energy was evaluated from arrhenius equation and values for ni, v and mo were calculated in case of both the acidophiles. ...201019879686
bioleaching of ultramafic tailings by acidithiobacillus spp. for co2 sequestration.bioleaching experiments using various acid-generating substances, i.e., metal sulfides and elemental sulfur, were conducted to demonstrate the accelerated dissolution of chrysotile tailings collected from an asbestos mine near clinton creek, yukon, canada. columns, possessing an acid-generating substance colonized with acidithiobacillus sp., produced leachates with magnesium concentrations that were an order of magnitude greater than mine site waters or control column leachates. in addition, chr ...201019950896
bioleaching of chalcopyrite concentrate using leptospirillum ferriphilum, acidithiobacillus ferrooxidans and acidithiobacillus thiooxidans in a continuous bubble column reactor.to estimate the bioleaching performance of chalcopyrite for various hydraulic residence times (hrts), laboratory-scale bioleaching of chalcopyrite concentrate was carried out in a continuous bubble column reactor with three different hrts of 120, 80 and 40 h, respectively. an extraction rate and ratio of 0.578 g cu l(-1) h(-1) and 39.7%, respectively, were achieved for an hrt of 80 h at a solids concentration of 10% (w/v). lower bioleaching performances than this were obtained for a longer hrt o ...201020012335
electron transfer from cytochrome c to cupredoxins.electron transfer (et) through and between proteins is a fundamental biological process. the activation energy for an et reaction depends upon the gibbs energy change upon et (deltag(0)) and the reorganization energy. here, we characterized et from pseudomonas aeruginosa cytochrome c(551) (pa) and its designed mutants to cupredoxins, silene pratensis plastocyanin (pc) and acidithiobacillus ferrooxidans rusticyanin (rc), through measurement of pseudo-first-order et rate constants (k(obs)). the in ...200919294434
[isolation, identification of acidithiobacillus sp. and its role in the removal of heavy metals from contaminated sediments].a sulfur-oxidizing bacterium fd97 was isolated from heavy metal-contaminated river sediments. according to the morphological characteristics and sequence analysis of 16s rdna of fd97, the strain was identified as acidithiobacillus sp.. the effects of temperature on heavy metals bioleaching efficiencies from contaminated sediments by using acidithiobacillus sp. fd97 were investigated in shake flask experiments. the tests were performed at four different temperatures in the range of 22-40 degrees ...200920063754
investigation and optimization of a passively operated compost-based system for remediation of acidic, highly iron- and sulfate-rich industrial waste water.a passively operated multi-stage bioremediation system utilizing composted agricultural waste products and an artificial wetland system was found to be effective for purification of acidic, iron- and sulfate-rich waste water derived from titanium mineral processing. the main microbial players involved in the remediation system processes and the dynamics were investigated; mineral processing waste water-filled sludge dams possessed stable microbial communities that included acidithiobacillus, des ...200919297003
bioleaching of heavy metals from sewage sludge: a review.during the treatment of sewage, a huge volume of sludge is generated, which is disposed of on land as soil fertilizer/conditioner due to the presence of nitrogen, phosphorus, potassium and other nutrients. however, the presence of toxic heavy metals and other toxic compounds in the sludge restricts its use as a fertilizer. over the years, bioleaching has been developed as an environmentally friendly and cost-effective technology for the removal of heavy metals from the sludge. the present paper ...200919303195
isolation and characterization of ferrous- and sulfur-oxidizing bacteria from tengchong solfataric region, china.microbial oxidation and reduction of iron and sulfur are important parts of biogeochemical cycles in acidic environments such as geothermal solfataric regions. species of acidithiobacillus and leptospirillum are the common ferrous-iron and sulfur oxidizers from such environments. this study focused on the tengchong sofataric region, located in yunnan province, southwest china. based on cultivation, 9 strains that grow on ferrous-iron and sulfuric compounds were obtained. analysis of 16s rrna gen ...200919999973
technological assessment of a mining-waste dump at the dexing copper mine, china, for possible conversion to an in situ bioleaching operation.in order to extract copper metal from the waste dump of dexing copper mine and resolve the environmental problems caused by acidic water and heavy metals, a dump bioleaching plant was designed based on a series of experimental investigations. the investigation shown that the low-grade of the dump, refractoriness of chalcopyrite, leakage of pad, small acidithiobacillus population and low dump permeability are the main factors that contribute to the challenges faced by the plant. stability of the ...200919036579
an xps analytical approach for elucidating the microbially mediated enargite oxidative dissolution.in this work, the microbe-mediated oxidative dissolution of enargite surfaces (cu(3)ass(4)) was studied on powdered samples exposed to 9k nutrient solution (ph 2.3) inoculated by acidithiobacillus ferrooxidans initially adapted to arsenopyrite. these conditions simulate the acid mine environment. the redox potential of the inoculated solutions increased up to +0.72 v vs normal hydrogen electrode (nhe), indicating the increase of the fe(3+) to fe(2+) ratio, and correspondingly the ph decreased to ...200919229526
the role of acidithiobacillus ferrooxidans in alleviating the inhibitory effect of thiosulfate on the growth of acidophilic acidiphilium species isolated from acid mine drainage samples from garubathan, india.several acidophilic chemolithoautotrophic and heterotrophic strains were isolated from acid mine drainage samples from garubathan, west bengal, india. the strains, chemolithoautotrophic dk6.1 and heterotrophic dkap1.1, used in this study were assigned to the species acidithiobacillus ferrooxidans and acidiphilium cryptum, respectively. unamended filtered and subsequently autoclaved elemental sulfur spent medium of a. ferrooxidans was used as the medium to study heterotrophic growth of a. cryptum ...200919898546
importance of different physiological groups of iron reducing microorganisms in an acidic mining lake remediation experiment.iron- and sulfate-reducing microorganisms play an important role for alkalinity-generating processes in mining lakes with low ph. in the acidic mining lake 111 in lusatia, germany, a passive in situ remediation method was tested in a large scale experiment, in which microbial iron and sulfate reduction are stimulated by addition of carbokalk (a mixture of the nonsugar compounds of sugar beets and lime) and straw. the treated surface sediment consisted of three layers of different ph and geochemi ...200919277769
dissolution kinetics of spent petroleum catalyst using sulfur oxidizing acidophilic microorganisms.bioleaching studies of spent petroleum catalyst were carried out using sulfur oxidizing, acidithiobacillus species. leaching studies were carried out in two-stage, in the first stage bacteria were grown and culture filtrate was used in the second stage for leaching purpose. xrd analysis of spent petroleum catalyst showed oxides of v, fe and al and sulfides of mo and ni. the leaching kinetics followed dual rate, initial faster followed by slower rate and equilibrium could be achieved within 7 day ...200919286311
microbial architecture of environmental sulfur processes: a novel syntrophic sulfur-metabolizing consortia.microbial oxidation of sulfur-rich mining waste materials drives acid mine drainage (amd) and affects the global sulfur biogeochemical cycle. the generation of amd is a complex, dynamic process that proceeds via multiple reaction pathways. the role of natural consortia of microbes in amd generation, however, has received very little attention despite their widespread occurrence in mining environments. through a combination of geochemical experimentation and modeling, scanning transmission x-ray ...200919943646
a two-stage process for simultaneous thermophilic sludge digestion, pathogen control and metal leaching.a consortium of aerobic sulphur oxidizing microorganisms native to municipal sewage sludge has been developed that is capable of reducing the ph of sludge from 7.0 to 2.0 under mild-thermophilic (45 degrees c) temperatures. this mild-thermophilic, acidophilic acclimatized consortium has then been used to develop a thermophilic acidophilic culture capable of reducing the ph of municipal sewage sludge from 7.0 to 4.8 at 60 degrees c. furthermore, these two cultures have been used to develop a nove ...200919213462
characterization and reconstitute of a [fe4s4] adenosine 5'-phosphosulfate reductase from acidithiobacillus ferrooxidans.adenosine 5'-phosphosulfate (aps) reductase is a key enzyme involved in the pathways of sulfate reduction and sulfide oxidation in the biological sulfur cycle. in this study, the gene of aps reductase from acidithiobacillus ferrooxidans was cloned and expressed in escherichia coli, the soluble protein was purified by one-step affinity chromatography to apparent homogeneity. the molecular mass of the recombinant aps reductase was determined to be 28 kda using sds-page. according to optical and ep ...200919225840
[sulfur metabolite bacteria from waste water of gold miner tale-depot in kuzbass]. 200919827719
microbial communities in acid mine drainage and their interaction with pyrite surface.microbes such as acidithiobacillus ferrooxidans and leptospirillum ferrooxidans have been investigated a lot, because of their important role in acid mine drainage (amd) generation. in this article, the composition of microbial communities in two amd samples was studied. a culture-independent 16s rdna-based cloning approach, restriction fragment length polymorphism has been used. the interaction between microbes and natural pyrite specimen surface was researched by scanning electrode microscopy ...200919319595
comparison of bioleaching behaviors of different compositional sphalerite using leptospirillum ferriphilum, acidithiobacillus ferrooxidans and acidithiobacillus caldus.two sphalerite samples with different iron/sulphur (fe/s) ratios, shuikousan ore (fe/s 0.2) and dachang ore (fe/s 0.52), were processed using three microbial species, leptospirillum ferriphilum, acidithiobacillus ferrooxidans and acidithiobacillus caldus. following 20 days of bioleaching in shake flask cultures, a higher zinc (zn) extraction (96%) was achieved with shuikousan ore than with dachange ore (72%). the extraction efficiency increased when elemental s was added to dachang ore to attain ...200919333635
effects of l-cysteine on ni-cu sulfide and marmatite bioleaching by acidithiobacillus caldus.the effect of l-cysteine in different concentrations on the bioleaching of ni-cu sulfide and marmatite were studied with a moderately thermophilic, sulfur-oxidizing bacterium, strain of acidithiobacillus caldus. x-ray diffraction (xrd) observations showed the change of bioleached solid residues and the effect of l-cysteine on the surface charges of minerals. it was found that adding certain amounts of l-cysteine to the leaching system of ni-cu sulfide largely enhanced the leaching rate, while l- ...200918829304
real-time pcr analysis of the heat-shock response of acidithiobacillus ferrooxidans atcc 23270.as one of the most important bioleaching bacterial species, acidithiobacillus ferrooxidans is subjected to different kinds of environmental stress such as temperature changes, presence of some toxic heavy metals or ph changes, which normally take place in bioleaching operations and may affect the activity of the bacteria. to obtain further knowledge of the protective mechanisms employed by a. ferrooxidans in response to elevated growth temperature, temporal gene expression profiles were examined ...200919445839
[pyrite oxidation by the diverse microorganisms]. 200919449732
[acidophilic chemolithotrophic microorganisms: growth and pyrite oxidation ]. 200919449733
fractionation behavior of heavy metals in soil during bioleaching with acidithiobacillus thiooxidans.the effects of bioleaching on the fractionation of soil heavy metals were investigated in this study. bioleaching of heavy metals from contaminated soil was carried out in shake flask experiments. acidophilic sulfur oxidizing bacteria acidithiobacillus thiooxidans isolated from soil was used for bioleaching. bioleaching resulted in removal of heavy metals at higher levels. variations in the binding forms of heavy metals before, during and after bioleaching were evaluated. it was noticed that bio ...200919464109
inhibition of microbial concrete corrosion by acidithiobacillus thiooxidans with functionalised zeolite-a coating.the inhibition of the corrosive action of acidithiobacillus thiooxidans on concrete specimens coated by functionalised zeolite-a containing 14% zinc and 5% silver by weight was studied. uncoated concrete specimens, epoxy-coated concrete specimens (ep), and functionalised zeolite-a coated concrete specimens with epoxy to zeolite weight ratios of 3:1 (z1), 2:2 (z2) and 1:3 (z3) were studied. specimens were characterised by x-ray powder diffraction and field emission scanning electron microscopy fo ...200918846450
selection and evaluation of reference genes for improved interrogation of microbial transcriptomes: case study with the extremophile acidithiobacillus ferrooxidans.normalization is a prerequisite for accurate real time pcr (qpcr) expression analysis and for the validation of microarray profiling data in microbial systems. the choice and use of reference genes that are stably expressed across samples, experimental conditions and designs is a key consideration for the accurate interpretation of gene expression data.200919555508
[characteristics of microspheres formed with bacterial genomic dna and plasmid templates in the process of polymerase chain reaction]. 200919580161
transcriptional and functional studies of acidithiobacillus ferrooxidans genes related to survival in the presence of copper.the acidophilic acidithiobacillus ferrooxidans can resist exceptionally high copper (cu) concentrations. this property is important for its use in biomining processes, where cu and other metal levels range usually between 15 and 100 mm. to learn about the mechanisms that allow a. ferrooxidans cells to survive in this environment, a bioinformatic search of its genome showed the presence of at least 10 genes that are possibly related to cu homeostasis. among them are three genes coding for putativ ...200919666734
investigation of elemental sulfur speciation transformation mediated by acidithiobacillus ferrooxidans.the speciation transformation of elemental sulfur mediated by the leaching bacterium acidithiobacillus ferrooxidans was investigated using an integrated approach including scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy, energy dispersive x-ray spectroscopy, and x-ray absorption near edge spectroscopy (xanes). our results showed that when grown on elemental sulfur powder, at. ferrooxidans atcc23270 cells were first attached to sulfur partic ...200919085035
a stoichiometric model of acidithiobacillus ferrooxidans atcc 23270 for metabolic flux analysis.a stoichiometric model of acidithiobacillus ferrooxidans based on the sequenced genome from strain atcc 23270 is derived and parameterized using genome/pathway databases. the model describes the main aspects of catabolism and anabolism. by the construction and utilization of the mathematical determination of the network, metabolic flux analysis is performed for such a bacterium for the first time and results are successfully verified by comparison to literature values. this first metabolic model ...200919090483
soft-particle model analysis of effect of lps on electrophoretic softness of acidithiobacillus ferrooxidans grown in presence of different metal ions.the effect of surface lipopolysaccharides (lps) on the electrophoretic softness and fixed charge density in the ion-penetrable layer of acidithiobacillus ferrooxidans cells grown in presence of copper or arsenic ions have been discussed. the electrophoretic mobility data were analyzed using the soft-particle electrophoresis theory. cell surface potentials of all the strains based on soft-particle theory were lower than those estimated using the conventional smoluchowski theory. exposure to metal ...200919101128
a study on the toxic effects of chloride on the biooxidation efficiency of pyrite.bioleaching operations in areas with limited chloride-free water and use of ashes and dust as neutralizing agents have motivated to study the chloride toxicity and tolerance level of the microorganisms. biooxidation of pyrite using chloride containing waste ash compared with ca(oh)(2)+nacl as neutralizing agent was investigated to evaluate the causes of low pyrite oxidation. both precipitation of jarosite as well as the toxic effect of chloride on the microorganisms were responsible for lower py ...200919720455
identification and characterization of four strains of acidithiobacillus ferrooxidans isolated from different sites in china.four strains of acidithiobacillus ferrooxidans (a. ferrooxidans), af1, af2, af3 and afc, were isolated from samples with different geological sources using a 9k medium. these four isolates were identified as a. ferrooxidans by phenotypic and 16s rdna sequence analyses. all four isolates were able to use ferrous ion (fe(2+)), elemental sulfur (s0) or pyrite as a sole energy source, but they showed differences in ph optima and range of activity, optimum temperature of activity, resistance to chlor ...200917993268
toxicity of select organic acids to the slightly thermophilic acidophile acidithiobacillus caldus.acidithiobacillus caldus is a thermophilic acidophile found in commercial biomining, acid mine drainage systems, and natural environments. previous work has characterized a. caldus as a chemolithotrophic autotroph capable of utilizing reduced sulfur compounds under aerobic conditions. organic acids are especially toxic to chemolithotrophs in low-ph environments, where they diffuse more readily into the cell and deprotonate within the cytoplasm. in the present study, the toxic effects of oxaloace ...200918803441
application of real-time pcr to monitor population dynamics of defined mixed cultures of moderate thermophiles involved in bioleaching of chalcopyrite.to compare oxidative dissolution rates of chalcopyrite by different consortia of moderately thermophilic acidophiles, various defined mixed cultures of three bacteria acidithiobacillus caldus s2, leptospirillum ferriphilum ysk, and sulfobacillus sp. ln and one archaeon ferroplasma thermophilum l1 were studied in batch shake flask cultures incubated at 45 degrees c. chalcopyrite dissolution was determined by measuring variations of soluble copper, ferric iron, and ph. microbial population dynamic ...200919039582
metals tolerance in moderately thermophilic isolates from a spent copper sulfide heap, closely related to acidithiobacillus caldus, acidimicrobium ferrooxidans and sulfobacillus thermosulfidooxidans.selective enrichments enabled the recovery of moderately thermophilic isolates with copper bioleaching ability from a spent copper sulfide heap. phylogenetic and physiological characterization revealed that the isolates were closely related to sulfobacillus thermosulfidooxidans, acidithiobacillus caldus and acidimicrobium ferrooxidans. while isolates exhibited similar physiological characteristics to their corresponding type strains, in general they displayed similar or greater tolerance of high ...200919104861
effects of dissolved low molecular weight organic acids on oxidation of ferrous iron by acidithiobacillus ferrooxidans.a few researchers have reported on work concerning bioleaching of heavy-metal-contaminated soil using acidithiobacillus ferrooxidans, since this acidophile is sensitive to dissolved low molecular weight (lmw) organic acids. iron oxidation by a. ferrooxidans r2 as well as growth on ferrous iron was inhibited by a variety of dissolved lmw organic acids. growth experiments with ferrous iron as an oxidant showed that the inhibition capability sequence was formic acid>acetic acid>propionic acid>oxali ...200918554786
[a two-stage technology for bacterial and chemical leaching of copper-zinc raw materials by fe3+ ions with their subsequent regeneration by chemolithotrophic bacteria].a two-stage technology for bacterial and chemical leaching of nonferrous metals in a specifically designed laboratory unit has been proposed. at the first stage of leaching, ferric iron formed during the second stage of oxidation of fe2+ ions by mesophilic chemolithotrophic microorganisms was used. the optimal parameters of the first stage of the process (flow rate, temperature, and the process duration) were 2 l/h, 75 degrees c, and 2 h, respectively. the results of testing of the two-stage tec ...200919235511
bacterial communities of tyre monofill sites: growth on tyre shreds and leachate.to investigate bacterial communities of tyre monofill sites, colonization of tyre material by bacteria and the effect of tyre leachate on bacteria.200919239530
bioleaching of zinc and iron from steel plant waste using acidithiobacillus ferrooxidans.the bacterial leaching of zinc and iron from solid wastes at the isdemir iron and steel plant has been investigated using acidithiobacillus ferrooxidans as the bacterial agent. the effects of a range of operational parameters, including particle size, solids concentration and ph, on the efficiency of the bioleaching process were investigated. in each test, several variables were determined to assess the efficiency of leaching, including slurry ph and redox potential, temperature, bacteria popula ...200918581266
bioleaching of chalcopyrite concentrate by a moderately thermophilic culture in a stirred tank reactor.a mixed culture of moderately thermophilic microorganisms was enriched from acid mine drainage samples collected from several chalcopyrite mines in china. such mixed culture can be used to effectively extract copper from chalcopyrite. furthermore, after being adapted to gradually increased concentration of chalcopyrite concentrate, the tolerance of the mixed culture to chalcopyrite concentrate was brought up to 80 g/l. the effects of several leaching parameters on copper recovery in stirred tank ...200918657418
cys92, cys101, cys197, and cys203 are crucial residues for coordinating the iron-sulfur cluster of rhda from acidithiobacillus ferrooxidans.by proteomic analysis, we found a rhodanese-like protein(rhda) from acidithiobacillus ferrooxidans atcc 23270 whose c-terminal contained a cysteine motif (cys-xx-trp-xx-cys), known to bind iron-sulfur clusters. but so far, there were no articles to confirm the existence of iron-sulfur cluster in rhda. in this study, rhda gene from a. ferrooxidans atcc 23270 was cloned and expressed in escherichia coli, the protein was purified by one-step affinity chromatography to homogeneity. the uv-vis scanni ...200919727950
extending the models for iron and sulfur oxidation in the extreme acidophile acidithiobacillus ferrooxidans.acidithiobacillus ferrooxidans gains energy from the oxidation of ferrous iron and various reduced inorganic sulfur compounds at very acidic ph. although an initial model for the electron pathways involved in iron oxidation has been developed, much less is known about the sulfur oxidation in this microorganism. in addition, what has been reported for both iron and sulfur oxidation has been derived from different a. ferrooxidans strains, some of which have not been phylogenetically characterized ...200919703284
preliminary x-ray crystallographic analysis of sulfide:quinone oxidoreductase from acidithiobacillus ferrooxidans.the gene product of open reading frame afe_1293 from acidithiobacillus ferrooxidans atcc 23270 is annotated as encoding a sulfide:quinone oxidoreductase, an enzyme that catalyses electron transfer from sulfide to quinone. following overexpression in escherichia coli, the enzyme was purified and crystallized using the hanging-drop vapour-diffusion method. the native crystals belonged to the tetragonal space group p4(2)2(1)2, with unit-cell parameters a = b = 131.7, c = 208.8 a, and diffracted to ...200919652354
seasonal and spatial variations in microbial community structure and diversity in the acid stream draining across an ongoing surface mining site.this study examined the microbial community in an acidic stream draining across the yun-fu pyrite mine (guangdong, china), where extremely acidic mine water is a persistent feature due to the intensive surface mining activities. analysis of terminal restriction fragment length polymorphism (trflp) of 16s rrna gene sequences showed that microbial populations varied spatially and seasonally and correlated with geochemical and physical conditions. after the stream moves from underground to the surf ...200919678846
bioleaching of metals from printed wire boards by acidithiobacillus ferrooxidans and acidithiobacillus thiooxidans and their mixture.bioleaching processes were used to mobilize metals from printed wire boards (pwbs). the bacteria acidithiobacillus ferrooxidans (a. ferrooxidans) and acidithiobacillus thiooxidans (a. thiooxidans) isolated from an acidic mine drainage were grown and acclimated in presence of pwbs and then used as bioleaching bacteria to solubilize metals from pwbs. the experimental results demonstrate that all the percentages of copper, lead, zinc solubilized into the leaching solution from actual pwbs basically ...200919699031
ferrous iron oxidation by foam immobilized acidithiobacillus ferrooxidans: experiments and modeling.ferrous iron bio-oxidation by acidithiobacillus ferrooxidans immobilized on polyurethane foam was investigated. cells were immobilized on foams by placing them in a growth environment and fully bacterially activated polyurethane foams (bapufs) were prepared by serial subculturing in batches with partially bacterially activated foam (pbapufs). the dependence of foam density on cell immobilization process, the effect of ph and bapuf loading on ferrous oxidation were studied to choose operating par ...200919610075
draft genome sequence of the extremely acidophilic bacterium acidithiobacillus caldus atcc 51756 reveals metabolic versatility in the genus acidithiobacillus.acidithiobacillus caldus is an extremely acidophilic, moderately thermophilic, chemolithoautotrophic gammaproteobacterium that derives energy from the oxidation of sulfur and reduced inorganic sulfur compounds. here we present the draft genome sequence of acidithiobacillus caldus atcc 51756 (the type strain of the species), which has permitted the prediction of genes for survival in extremely acidic environments, including genes for sulfur oxidation and nutrient assimilation.200919617360
ferrous iron production mediated by tetrathionate hydrolase in tetrathionate-, sulfur-, and iron-grown acidithiobacillus ferrooxidans atcc 23270 cells.when tetrathionate-grown acidithiobacillus ferrooxidans atcc 23270 cells were incubated with ferric ions and tetrathionate at ph 3.0, ferrous ions were produced enzymatically. fe(3+)-reductase, which catalyzes fe(3+) reduction with tetrathionate, was purified to homogeneity not only from tetrathionate-grown, but also from sulfur- and iron-grown a. ferrooxidans atcc 23270 cells. the results for apparent molecular weight measured by sds-page (52.3 kd) and the n-terminal amino acid sequences of the ...200919502725
an acid-tolerant heterotrophic microorganism role in improving tannery sludge bioleaching conducted in successive multibatch reaction systems.the bioleaching technique with acidithiobacillus species has been shown to be an efficient and cost-effective means in removing heavy metals from tannery sludge. however, tannery sludge dissolved organic matter (dom) is toxic to acidithiobacillus species and results in decreasing the efficiency of cr removal from sludge. here we report the role of an acid-tolerant dom-degrading heterotrophic microorganism p. spartinae d13 successfully isolated from local tannery sludge in improving activities of ...200919569344
expression, purification and molecular structure modeling of thioredoxin (trx) and thioredoxin reductase (trxr) from acidithiobacillus ferrooxidans.the thioredoxin system consists of thioredoxin (trx), thioredoxin reductase (trxr) and nadph, which plays several key roles in maintaining the redox environment of the cell. in acidithiobacillus ferrooxidans, thioredoxin system may play important functions in the activity regulation of periplasmic proteins and energy metabolism. here, we cloned thioredoxin (trx) and thioredoxin reductase (trxr) genes from acidithiobacillus ferrooxidans, and expressed the genes in escherichia coli. his-trx and hi ...200919319598
enhanced biofiltration using cell attachment promotors.h2s polluted airstreams were treated in two biotrickling filter columns packed with polyurethane (pu) foam cubes, one with cubes coated with a solution of 25 mg/l of polyethyleneimine (pei, coated reactor) and the other containing just plain pu cubes (uncoated reactor) at empty bed residence times (ebrt) ranging from 6 to 60 s. and inlet h2s concentrations ranging from 30 to 235 ppm, (overall loads of up to 44 gh2s/m3bed/h), with overall removal efficiencies (re) in the range of 90-100% over 125 ...200919320156
ferrous iron oxidation and rusticyanin in halotolerant, acidophilic 'thiobacillus prosperus'.the halotolerant acidophile 'thiobacillus prosperus' was shown to require chloride for growth. with ferrous iron as substrate, growth occurred at a rate similar to that of the well-studied acidophile acidithiobacillus ferrooxidans. previously, the salt (nacl) requirement of 't. prosperus' was not clear and its growth on ferrous iron was described as poor. a subtractive hybridization of cdnas from ferrous-iron-grown and sulfur-grown 't. prosperus' strain v6 led to identification of a cluster of g ...200919332831
[response of genes for synthesizing the magnetic of acidithiobacillus ferrooxidans to different concentration of fe2+ stress].acidithiobacillus ferrooxidans is able to synthesize intra-cellular electron-dense magnetite, which formed by bcm method in acidithiobacillus ferrooxidans. the whole genome of the type strain acidithiobacillus ferrooxidans atcc 23270 was analyzed by bioinformatics and some homolog genes of functional ones in magnetotactic bacteria were available. this study analyzed the different concentration of fe2+ stress response of mpsa, maga, thy and mamb gene by using real-time pcr analysis. temporal gene ...200919441229
comparative genomic analysis of acidithiobacillus ferrooxidans strains using the a. ferrooxidans atcc 23270 whole-genome oligonucleotide microarray.acidithiobacillus ferrooxidans is an important microorganism used in biomining operations for metal recovery. whole-genomic diversity analysis based on the oligonucleotide microarray was used to analyze the gene content of 12 strains of a. ferrooxidans purified from various mining areas in china. among the 3100 open reading frames (orfs) on the slides, 1235 orfs were absent in at least 1 strain of bacteria and 1385 orfs were conserved in all strains. the hybridization results showed that these s ...200919483787
hydrogen sulfide removal from air by acidithiobacillus thiooxidans in a trickle bed reactor.a strain of acidithiobacillus thiooxidans immobilized in polyurethane foam was utilized for h(2)s removal in a bench-scale trickle-bed reactor, testing the limits of acidity and so(4) (2-) accumulation. the use of this acidophilic strain resulted in remarkable stability in the performance of the system. the reactor maintained a >98-99 % h(2)s removal efficiency for c of up to 66 ppmv and empty bed residence time <or=12-15 s. removal of >98 % h(2)s was achieved under steady-state conditions, over ...200919937213
a novel process to treat spent petroleum catalyst using sulfur-oxidizing lithotrophs.a novel process was developed using sulfur-oxidizing bacteria to extract metal values like ni, v and mo from spent petroleum catalyst. bacteria were grown in elemental sulfur media for five day and after filtering, the filtrate was used for leaching purpose. effect of different parameters such as contact time, particle size, pulp density and lixiviant composition were studied to find out the extent of metal leaching during the leaching process. xrd analysis proved the existence of v in oxide for ...200920183517
[recent research progress on the biomining bacteria of acidithiobacillus caldus--a review].acidithiobacillus caldus (a. caldus) is one of the predominant biomining bacteria, which shows application prospect in biological metallurgy. it can enhance the biomining efficiency together with iron oxidation bacteria in mixed biomining system. based on the published papers and our study on this bacterium, we described the research progress on it from four aspects, including the biomining mechanism, arsenic-resistant mechanism, genome study and genetic reconstruction. furthermore, we discussed ...200920112666
oxidation of elemental sulfur, tetrathionate and ferrous iron by the psychrotolerant acidithiobacillus strain ss3.mesophilic iron and sulfur-oxidizing acidophiles are readily found in acid mine drainage sites and bioleaching operations, but relatively little is known about their activities at suboptimal temperatures and in cold environments. the purpose of this work was to characterize the oxidation of elemental sulfur (s(0)), tetrathionate (s4o6(2-)) and ferrous iron (fe2+) by the psychrotolerant acidithiobacillus strain ss3. the rates of elemental sulfur and tetrathionate oxidation had temperature optima ...200919782750
dynamic of active microorganisms inhabiting a bioleaching industrial heap of low-grade copper sulfide ore monitored by real-time pcr and oligonucleotide prokaryotic acidophile microarray.the bioleaching of metal sulfide has developed into a very important industrial process and understanding the microbial dynamic is key to advancing commercial bioleaching operations. here we report the first quantitative description of the dynamic of active communities in an industrial bioleaching heap. acidithiobacillus ferrooxidans was the most abundant during the first part of the leaching cycle, while the abundance of leptospirillum ferriphilum and ferroplasma acidiphilum increased with age ...200921255296
the rus operon genes are differentially regulated when acidithiobacillus ferrooxidans lr is kept in contact with metal sulfides.acidithiobacillus ferrooxidans is a gram-negative bacterium that obtains energy from the oxidation of ferrous iron or reduced sulfur compounds. in this bacterium, the proteins encoded by the rus operon are involved in electron transfer from fe(ii) to o(2), and the first two proteins in this pathway also participate in the electron transfer pathway from fe(ii) to nad(p). in this work we analyzed the expression, by real-time pcr, of the eight genes from the rus operon when a. ferrooxidans lr was g ...200818665419
quantitative microbial community analysis of three different sulfidic mine tailing dumps generating acid mine drainage.the microbial communities of three different sulfidic and acidic mine waste tailing dumps located in botswana, germany, and sweden were quantitatively analyzed using quantitative real-time pcr (q-pcr), fluorescence in situ hybridization (fish), catalyzed reporter deposition-fish (card-fish), sybr green ii direct counting, and the most probable number (mpn) cultivation technique. depth profiles of cell numbers showed that the compositions of the microbial communities are greatly different at the ...200818586975
biosynthesis of nanocrystal akaganéite from fecl2 solution oxidized by acidithiobacillus ferrooxidans cells.akaganéite (beta-feooh) is a major iron oxyhydroxide component in some soils, marine concretions, and acid mine drainage environments. recently, synthetic beta-feooh has been found to be a promising absorbent in the treatment of metal-contaminated water. it has been recognized in previous study that akaganéite could be formed via fecl2 chemical oxidation under specific conditions. here we report a novel and simple method for akaganéite bioformation from fecl2 solution oxidized by acidithiobacill ...200818589982
insights into two high homogenous genes involved in copper homeostasis in acidithiobacillus ferrooxidans.acidithiobacillus ferrooxidans, an important microorganism in bioleaching industry, has been sequenced recently, and from the annotated information, there are four genes involved in copper homeostasis. sequence analysis showed that two of them, afe0329 and afe0663, were high homologous (94.43% identity). with the polymerase chain reaction-restriction fragment length polymorphism (pcr-rflp) cloning approach, the differential gene expression of these two high homologous genes in a genome was succe ...200818618174
a new iron-oxidizing/o2-reducing supercomplex spanning both inner and outer membranes, isolated from the extreme acidophile acidithiobacillus ferrooxidans.the iron respiratory chain of the acidophilic bacterium acidithiobacillus ferrooxidans involves various metalloenzymes. here we demonstrate that the oxygen reduction pathway from ferrous iron (named downhill pathway) is organized as a supercomplex constituted of proteins located in the outer and inner membranes as well as in the periplasm. for the first time, the outer membrane-bound cytochrome c cyc2 was purified, and we showed that it is responsible for iron oxidation and determined that its r ...200818632666
micro-raman analysis and afm imaging of acidithiobacillus ferrooxidans biofilm grown on uranium ore.acidithiobacillus ferrooxidans biofilm grown on uranium ore substrate was analyzed by a micro-raman spectrometer and an atomic force microscope (afm). the bacterium employed for this study, a. ferrooxidans bm1, was isolated from a uranium mine (jaduguda, india). micro-raman analysis revealed the different constituents of molecular fragments present in microbial cells and in secreted extracellular polymeric substances (epss). afm images clearly revealed bacterial cells surrounded by eps. from ram ...200818640267
in vitro assembly of [fe4s4] cluster in high potential iron-sulfur protein from acidithiobacillus ferrooxidans.high-potential iron-sulfur protein (hipip) has been proposed to be involved in the iron respiratory electron transport chain in acidithiobacillus ferrooxidans, which contains an [fe(4)s(4)] cluster. we report here the assembly of an [fe(4)s(4)] cluster in hipip from a. ferrooxidans atcc 23270 in vitro in the presence of fe(2+) and sulfide. the spectra and matrix-assisted laser desorption ionization-time of flight mass spectrometry results of holohipip confirmed that the iron-sulfur cluster was c ...200818574631
optimization of fe2 +/solids content ratio for a novel sludge heavy metal bioleaching process.a novel bioleaching process, preincubation bioleaching (pb) has been recently developed in our laboratory for decontamination of heavy-metal-laden sewage sludge by removing the toxic low molecular weight organic acids using an isolated degradative yeast species. the objective of the present study was to optimize fe2+ /solids content ratio required for removing heavy metals from sewage sludge by using this novel process at high solids content. results from the present study showed that regardless ...200818309225
expression, purification and characterization of the sulfite reductase hemo-subunit, sir-hp, from acidithiobacillus ferrooxidans.sulfite reductase (sir) is a large and soluble enzyme which catalyzes the transfer of six electrons from nadph to sulfite to produce sulfide. the sulfite reductase flavoprotein (sir-fp) contains both fad and fmn, and the sulfite reductase hemoprotein (sir-hp) contains an iron-sulfur cluster coupled to a siroheme. the enzyme is arranged so that the redox cofactors in the fad-fmn-fe(4)s(4)-heme sequence make an electron pathway between nadph and sulfite. here we report the cloning, expression, and ...200818317695
selection of leptospirillum ferrooxidans srpcbl and development for enhanced ferric regeneration in stirred tank and airlift column reactor.presence of leptospirillum ferrooxidans plays significant role in ferric sulphate generation during bioleaching process. thus, an attempt was made to select l. ferrooxidans from the polymetallic concentrate leachate and further developed it for enhanced ferric iron regeneration from the leachate in shake flask, stirred tank and column reactor. when ferric to ferrous iron ratio in the shake flask reached to 20:1, l. ferrooxidans out competed acidithiobacillus ferrooxidans and accounted for more t ...200818325759
characterization of arsenic resistant and arsenopyrite oxidizing acidithiobacillus ferrooxidans from hutti gold leachate and effluents.four arsenic resistant ferrous oxidizers were isolated from hutti gold mine ltd. (hgml) samples. characterization of these isolates was done using conventional microbiological, biochemical and molecular methods. the ferrous oxidation rates with these isolates were 16, 48, 34 and 34 mg l(-1)h(-1) and 15, 47, 34 and 32 mg l(-1)h(-1) in absence and presence of 20 mm of arsenite (as3+) respectively. except isolate hgm 8, other three isolates showed 2.9-6.3% inhibition due to the presence of 20 mm ar ...200818367394
microbial iron management mechanisms in extremely acidic environments: comparative genomics evidence for diversity and versatility.iron is an essential nutrient but can be toxic at high intracellular concentrations and organisms have evolved tightly regulated mechanisms for iron uptake and homeostasis. information on iron management mechanisms is available for organisms living at circumneutral ph. however, very little is known about how acidophilic bacteria, especially those used for industrial copper bioleaching, cope with environmental iron loads that can be 1018 times the concentration found in ph neutral environments. t ...200819025650
gene expression of the arsenic resistance operon in chromobacterium violaceum atcc 12472.chromobacterium violaceum atcc 12472 presents an arsrcb-type operon, which is involved in arsenic resistance. the regulating protein of this resistance system (arsr) does not have the small conserved site (elcvdcl) to link to the metalloid, as observed in escherichia coli, and is thus considered to be an atypical arsr protein, like that observed in acidithiobacillus ferrooxidans. in the present study, the gene expression profile of the ars operon under induction at different concentrations of ar ...200818388983
isolation and characterization of acidithiobacillus ferrooxidans strain d3-2 active in copper bioleaching from a copper mine in chile.acidithiobacillus ferrooxidans strain d3-2, which has a high copper bioleaching activity, was isolated from a low-grade sulfide ore dump in chile. the amounts of cu(2+) solubilized from 1% chalcopyrite (cufes(2)) concentrate medium (ph 2.5) by a. ferrooxidans strains d3-2, d3-6, and atcc 23270 and 33020 were 1360, 1080, 650, and 600 mg x l(-1) x 30 d(-1). the iron oxidase activities of d3-2, d3-6, and atcc 23270 were 11.7, 13.2, and 27.9 microl o(2) uptake x mg protein(-1) x min(-1). in contrast ...200818391470
comparative genomic analysis of carbon and nitrogen assimilation mechanisms in three indigenous bioleaching bacteria: predictions and validations.carbon and nitrogen fixation are essential pathways for autotrophic bacteria living in extreme environments. these bacteria can use carbon dioxide directly from the air as their sole carbon source and can use different sources of nitrogen such as ammonia, nitrate, nitrite, or even nitrogen from the air. to have a better understanding of how these processes occur and to determine how we can make them more efficient, a comparative genomic analysis of three bioleaching bacteria isolated from mine s ...200819055775
an effective method of dna extraction for bioleaching bacteria from acid mine drainage.an effective and versatile method for microorganism lysis and direct extraction of dna from bioleaching bacteria was developed using pure cultures and an acid mine drainage (amd) sediment sample. in the described method, microorganisms are treated at three different incubation temperatures: boiling water incubation for 6-10 min, followed by 60 +/- 5 degrees c for 30 min, then 72 degrees c for 30 min. the extracted dna is purified using a phenol/chloroform/alcohol mixture and precipitated in abso ...200818481056
acidithiobacillus ferrooxidans metabolism: from genome sequence to industrial applications.acidithiobacillus ferrooxidans is a major participant in consortia of microorganisms used for the industrial recovery of copper (bioleaching or biomining). it is a chemolithoautrophic, gamma-proteobacterium using energy from the oxidation of iron- and sulfur-containing minerals for growth. it thrives at extremely low ph (ph 1-2) and fixes both carbon and nitrogen from the atmosphere. it solubilizes copper and other metals from rocks and plays an important role in nutrient and metal biogeochemica ...200819077236
microbiological and geochemical dynamics in simulated-heap leaching of a polymetallic sulfide ore.the evolution of microbial populations involved in simulated-heap leaching of a polymetallic black schist sulfide ore (from the recently-commissioned talvivaara mine, finland) was monitored in aerated packed bed column reactors over a period of 40 weeks. the influence of ore particle size (2-6.5 mm and 6.5-12 mm) on changes in composition of the bioleaching microflora and mineral leaching dynamics in columns was investigated and compared to fine-grain (<2 microm) ore that was bioprocessed in sha ...200818496880
Refresh
firstprev
123456
nextlast
Displaying items 101 - 200 of 590