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1.
Available cultures of Thiobacillus ferrooxidans were found to be contaminated with bacteria very similar to Thiobacillus acidophilus. The experiments described were performed with a homogeneous culture of Thiobacillus ferrooxidans.Pyrite (FeS 2) was oxidized by Thiobacillus ferrooxidans grown on iron (Fe 2+), elemental sulphur (S o) or FeS 2.Evidence for the direct utilization of the sulphur moiety of pyrite by Thiobacillus ferrooxidans was derived from the following observations: a. Known inhibitors of Fe 2+ and S o oxidation, NaN 3 and NEM, respectively, partially abolished FeS 2 oxidation. b. A b-type cytochrome was detectable in FeS 2-and S o-grown cells but not in Fe 2+-grown cells. c. FeS 2 and S o reduced b-type cytochromes in whole cells grown on S o. d. CO 2 fixation at pH 4.0 per mole of oxygen consumed was the highest with S o, lowest with Fe 2+ and medium with FeS 2 as substrate. e. Bacterial Fe 2+ oxidation was found to be negligible at pH 5.0 whereas both FeS 2 and S o oxidation was still appreciable above this pH. f. Separation of pyrite and bacteria by means of a dialysis bag caused a pronounced drop of the oxidation rate which was similar to the reduction of pyrite oxidation by NEM; indirect oxidation of the sulphur moiety by Fe 3+ was not affected by separation of pyrite and bacteria.Bacterial oxidation and utilization of the sulphur moiety of pyrite were relatively more important with increasing pH. 相似文献
2.
Rate equations and kinetic parameters were obtained for various reactions involved in the bacterial oxidation of pyrite. The rate constants were 3.5 μM Fe 2+ per min per FeS 2 percent pulp density for the spontaneous pyrite dissolution, 10 μM Fe 2+ per min per mM Fe 3+ for the indirect leaching with Fe 3+, 90 μM O 2 per min per mg of wet cells per ml for the Thiobacillus ferrooxidans oxidation of washed pyrite, and 250 μM O 2 per min per mg of wet cells per ml for the T. ferrooxidans oxidation of unwashed pyrite. The Km values for pyrite concentration were similar and were 1.9, 2.5, and 2.75% pulp density for indirect leaching, washed pyrite oxidation by T. ferrooxidans, and unwashed pyrite oxidation by T. ferrooxidans, respectively. The last reaction was competitively inhibited by increasing concentrations of cells, with a Ki value of 0.13 mg of wet cells per ml. T. ferrooxidans cells also increased the rate of Fe 2+ production from Fe 3+ plus pyrite. 相似文献
3.
Summary A method for enumeration of viable numbers of Thiobacillus ferrooxidans using membrane filters on ferrous-iron agar is presented. Factors affecting colony production were the concentration and brand of agar, pH of the medium, and type of membrane filter. The results suggest that inhibition of T. ferrooxidans by agar is a result of the acid hydrolysis of agar, the main product of which is d-galactose. Colony development was suppressed by aged medium, by acid-hydrolysed agar and by 0.1% galactose. Sartorius and Millipore membrane filters were suitable for the experiments, whereas Oxoid MF-50 membranes virtually suppressed the production of colonies. The method was employed to follow growth of T. ferrooxidans in pH 1.3 medium. The viable cell numbers were correlated with 14CO 2-fixation and ferrous iron oxidation. Generation time was 6 h 22 min with a yield of 2.2×10 12 organisms/g atom Fe 2+ oxidized. Growth of T. neapolitanus on thiosulphate medium was not affected by agar-type or membrane filters and yield of the organism was 1.5×10 13 organisms/g molecule Na 2S 2O 3 oxidized. 相似文献
4.
Ferrous ion oxidation by Thiobacillus ferrooxidans was completely inhibited by 10 m M each of thiosulfate, sulfite, metabisulfite, bisulfite, and tetrathionate. The inhibition was enhanced in a low pH medium (pH 1.5 versus pH 2.5). Oxygen uptake measurements with Fe 2+ as the electron donor confirmed the toxicity of thiosulfate, but also indicated its dependency on the concentration of Fe 2+. Cytochrome spectra of intact cells of T. ferrooxidans showed that metabisulfite, and thiosulfate to a lesser extent, directly reduced electron transport components, in contrast to no direct reduction of cytochromes by tetrathionate and sulfite. 相似文献
5.
The oxidation of ferrous iron (Fe 2+) to ferric iron (Fe 3+) with dioxygen (O 2) by various strains of Thiobacillus ferrooxidans was studied by measuring the rate of O 2 consumption at various Fe 2+ concentrations and cell concentrations. The apparent Km values for Fe 2+ remained constant at different cell concentrations of laboratory strains ATCC 13661 and ATCC 19859 but increased with increasing cell concentrations of mine isolates SM-4 and SM-5. The latter results are explained by the competitive inhibition of the Fe 2+-binding site of a cell by other cells in the reaction mixture. Possible mechanisms involving cell surface properties are discussed. 相似文献
6.
Plasmid profiles were studied in five Acidithiobacillus ferrooxidans strains of various origin cultivated on a medium with Fe 2+, as well as adapted to such oxidation substrates as S 0, FeS 2, and sulfide concentrate. The method used revealed plasmids in all A. ferrooxidans strains grown on a medium with Fe 2+. One plasmid was found in strain TFL-2; two plasmids, in strains TFO, TFBk, and TFV-1; and three plasmids were detected in strain TFN-d. The adaptation of strain TFN-d to sulfide concentrate and the adaptation of strain TFV-1 to S 0, FeS 2, or sulfide concentrate resulted in a change in the number of plasmids occurring in cells. In cells of strain TFN-d adapted to sulfide concentrate, the number of plasmids decreased from three to two. The number of plasmids in cells of strain TFV-1 adapted to different substrates varied from three to six depending on the energy source present in the medium: three plasmids were found after growth on FeS 2, four after growth on S 0, and six after growth on sulfide concentrate. The possible role of plasmids in the adaptation of A. ferrooxidans to new energy substrates and in the regulation of the intensity of their oxidation is discussed. 相似文献
7.
An iron-sulfur cluster assembly protein, IscU, is encoded by the operon iscSUA in Acidithiobacillus ferrooxidans. The gene of IscU was cloned and expressed in Escherichia coli. The protein was purified by one-step affinity chromatography to homogeneity. The protein was in apo-form, the [Fe 2S 2] cluster could be assembled in apoIscU with Fe 2+ and sulfide in vitro, and in the presence of IscA and IscS, the IscU could utilize l-cysteine and Fe 2+ to synthesize [Fe 2S 2] cluster in the protein. Site-directed mutagenesis for the protein revealed that Cys37, Asp39, Cys63 and Cys106 were involved
in ligating with the [Fe 2S 2] cluster. 相似文献
8.
Thiobacillus ferrooxidans MAL4-1, an isolate from Malanjkhand copper mines, India, was adapted to grow in the presence of high concentration (30 gL −1) of Cu 2+, resulting in a 15-fold increase in its tolerance to Cu 2+. While wild-type T. ferrooxidans MAL4-1 contained multiple plasmids, cultures adapted to Cu 2+ concentrations of 20 gL −1 or more showed a drastic reduction in the copy number of the plasmids. The reduction for three of the plasmids was estimated
to be over 50-fold. Examination of the plasmid profiles of the strains adapted to high concentration of SO 4
2− anion (as Na 2SO 4 or ZnSO 4) indicated that the reduction in plasmid copy number is not owing to SO 4
2− anion, but is specific for Cu 2+. The effect of mercury on the plasmids was similar to that of copper. Deadaptation of the Cu 2+- or Hg 2+-adapted T. ferrooxidans resulted in restoration of the plasmids to the original level within the first passage. The fact that the plasmid copy number,
in general, is drastically reduced in Cu 2+-adapted T. ferrooxidans suggests that resistance to copper is chromosome mediated. This is the first report of a selective negative influence of
copper ions on the copy number of plasmids in T. ferrooxidans. 相似文献
9.
Summary The kinetics of oxidation of aqueous acidic ferrous sulphate by Thiobacillus ferrooxidans has been studied in a batch reactor. The contribution of cell wall envelopes to the oxidation rate has been shown to be negligible. A model which accounts for the oxidation of Fe 2 +, death of bacteria due to Fe 3 + poisoning, existence of an optimal pH and precipitation of Fe 3 + has been proposed. The model is able to predict the concentration of Fe 2 + and pH quite satisfactorily. The predictions of Fe 3 + are not so accurate because of simplifying assumptions made about its precipitation.
Offprint requests to: R. Kumar 相似文献
10.
The widely distributed Acidithiobacillus ferrooxidans (A. ferrooxidans)
lives in extremely acidic conditions by fixing CO2 and nitrogen, and by obtaining energy from Fe2+ oxidation with either downhill or uphill electron transfer pathway and from reduced sulfur oxidation. A. ferrooxidans exists as different genomovars and its genome size is 2.89–4.18 Mb. The chemotactic movement of A. ferrooxidans is regulated by quorum sensing. A. ferrooxidans shows weak magnetotaxis due to formation of 15–70 nm magnetite magnetosomes with surface functional groups. The room- and low-temperature magnetic features of A. ferrooxidans are different from other magnetotactic bacteria. A. ferrooxidans has potential for removing sulfur from solids and gases, metals recycling from metal-bearing ores, electric wastes and sludge, biochemical production synthesizing, and metal workpiece machining. 相似文献
11.
Eight strains of Thiobacillus ferrooxidans (laboratory strains Tf-1 [= ATCC 13661] and Tf-2 [= ATCC 19859] and mine isolates SM-1, SM-2, SM-3, SM-4, SM-5, and SM-8) and three strains of Thiobacillus thiooxidans (laboratory strain Tt [= ATCC 8085] and mine isolates SM-6 and SM-7) were grown on ferrous iron (Fe 2+), elemental sulfur (S 0), or sulfide ore (Fe, Cu, and Zn). The cells were studied for their aerobic Fe 2+ - and S 0-oxidizing activities (O 2 consumption) and anaerobic S 0-oxidizing activity with ferric iron (Fe 3+) (Fe 2+ formation). Fe 2+-grown T. ferrooxidans cells oxidized S 0 aerobically at a rate of 2 to 4% of the Fe 2+ oxidation rate. The rate of anaerobic S 0 oxidation with Fe 3+ was equal to the aerobic oxidation rate in SM-1, SM-3, SM-4, and SM-5, but was only one-half or less that in Tf-1, Tf-2, SM-2, and SM-8. Transition from growth on Fe 2+ to that on S 0 produced cells with relatively undiminished Fe 2+ oxidation activities and increased S 0 oxidation (both aerobic and anaerobic) activities in Tf-2, SM-4, and SM-5, whereas it produced cells with dramatically reduced Fe 2+ oxidation and anaerobic S 0 oxidation activities in Tf-1, SM-1, SM-2, SM-3, and SM-8. Growth on ore 1 of metal-leaching Fe 2+-grown strains and on ore 2 of all Fe 2+-grown strains resulted in very high yields of cells with high Fe 2+ and S 0 oxidation (both aerobic and anaerobic) activities with similar ratios of various activities. Sulfur-grown Tf-2, SM-1, SM-4, SM-6, SM-7, and SM-8 cultures leached metals from ore 3, and Tf-2 and SM-4 cells recovered showed activity ratios similar to those of other ore-grown cells. It is concluded that all the T. ferrooxidans strains studied have the ability to produce cells with Fe 2+ and S 0 oxidation and Fe 3+ reduction activities, but their levels are influenced by growth substrates and strain differences. 相似文献
12.
Massive pyrite was shown to produce soluble iron, hydrogen, and sulfate ions on exposure to air and water. The rate of this process was directly proportional to the surface area of the mineral; it was unaffected by a drop in the pH and the presence of the ferrous and sulfate ions formed. Cupic ion had no effect but ferric ion accelerated pyrite degradation until all the ferric ion was consumed, in accordance with FeS 2 + 2Fe 3+ —>‐3Fe 2+ + 2S°. Thiobacillus ferrooxidans increased pyrite degradation considerably; the presence of Thiobacillus thiooxidans had no influence on pyrite degradation. 相似文献
13.
In Thiobacillus ferrooxidans AP19-3, elemental sulfur is oxidized by the cooperation of three enzymes, namely, hydrogen sulfide: ferric ion oxidoreductase (SFORase), sulfite: ferric ion oxidoreductase, and iron oxidase. Sulfite ions are one of the products when elemental sulfur is oxidized by SFORase. Under the conditions in which sulfite ions are accumulated in the cells, use of sulfur as an energy source by this strain was strongly inhibited. So the mechanism of inhibition by sulfite ions in T. ferrooxidans AP19-3 was studied. The activities of SFORase and iron oxidase were completely inhibited by 0.8 m m and 1.5 m m NaHSO 3, respectively. 14CO 2 uptake into washed intact cells was also completely inhibited by 1m m NaHSO 3 when ferrous ion or elemental sulfur was used as an energy source. However, the activities of ribulose-1,5-bisphosphate carboxylase, phosphoribulokinase, and ribosephosphate isomerase measured with a cell-free extract were not inhibited by NaHSO 3 at 1 m m, indicating that sulfite ions didn’t inhibit key enzymes of the Calvin cycle. Since the activity of CO 2 uptake into washed intact cells was absolutely dependent on Fe 2 + - or S0-oxidation, mechanism of inhibition of sulfur use by sulfite ions is proposed as follows: sulfite ions inhibit SFORase and iron oxidase, as a result T. ferrooxidans AP19-3 can not obtain a carbon source for CO 2 fixation and stops cell growth on sulfur-salts medium. 相似文献
14.
The properties of a ferric ion-reducing system which catalyzes the reduction of ferric ion with elemental sulfur was investigated with a pure strain of Thiobacillus ferrooxidans. In anaerobic conditions, washed intact cells of the strain reduced 6 mol of Fe 3+ with 1 mol of elemental sulfur to give 6 mol of Fe 2+, 1 mol of sulfate, and a small amount of sulfite. In aerobic conditions, the 6 mol of Fe 2+ produced was immediately reoxidized by the iron oxidase of the cell, with a consumption of 1.5 mol of oxygen. As a result, Fe 2+ production was never observed under aerobic conditions. However, in the presence of 5 mM cyanide, which completely inhibits the iron oxidase of the cell, an amount of Fe 2+ production comparable to that formed under anaerobic conditions was observed under aerobic conditions. The ferric ion-reducing system had a pH optimum between 2.0 and 3.8, and the activity was completely destroyed by 10 min of incubation at 60°C. A short treatment of the strain with 0.5% phenol completely destroyed the ferric ion-reducing system of the cell. However, this treatment did not affect the iron oxidase of the cell. Since a concomitant complete loss of the activity of sulfur oxidation by molecular oxygen was observed in 0.5% phenol-treated cells, it was concluded that the ferric ion-reducing system plays an important role in the sulfur oxidation activity of this strain, and a new sulfur-oxidizing route is proposed for T. ferrooxidans. 相似文献
15.
Optimum pH, temperature and pulp density for microbiological leaching of museum-grade stibnite mineral has been investigated
using a stibnite-adapted strain of Thiobacillus ferrooxidans. Optimum conditions were found to be pH 1.75, 35 C and 12 g solid substrate per 100 ml of basal salts medium as the initial
dose. The energy of activation was determined to be 16.8 kcal per mole, and the temperature coefficient 2.2. The highest total
dissolved-antimony concentration, [Sb t] = [Sb +3] + [Sb +5] + [SbO +] + [SbO 2
+], was about 1400 mg/litre, due to relatively low solubility of (SbO) 2SO 4 and (SbO 2) 2SO 4. 相似文献
16.
Summary Experiments on the leaching of copper from chalcopyrite mineral by the bacterium Thiobacillus ferrooxidans show that, in the presence of adequate amounts of sulphide, iron-grown bacteria preferentially oxidise sulphur in the ore (through direct attachment) rather than ferrous sulphate in solution. At 20% pulp density, the leaching initially takes place by a predominantly direct mechanism. The cell density in the liquid phase increases, but the Fe 2+ is not oxidised. However, in the later stages when less solid substrate is available and the cell density becomes very high, the bacteria start oxidising Fe 2+ in the liquid phase, thus contributing to the indirect mechanism of leaching. Contrary to expectations, the rate of leaching increased with increasing particle size in spite of the decreasing specific surface area. This has been found to be due to increasing attachment efficiency with increase in particle size.
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17.
Restriction profiles of chromosomal DNA were studied in different Acidithiobacillus
ferrooxidans strains grown on medium with Fe 2+ and further adapted to another oxidation substrate (S 0, FeS 2, or sulfide ore concentrates). The restriction endonuclease XbaI digested the chromosomal DNA from different strains into different numbers of fragments of various sizes. Adaptation of two strains (TFBk and TFN-d) to new oxidation substrates resulted in structural changes in XbaI-restriction patterns of their chromosomal DNA. Such changes in the DNA restriction patterns occurred in strain TFBk after the adaptation to precyanidated gravitational pyrite-arsenopyrite concentrate (no. 1) from the Nezhdaninskoe deposit or to copper-containing ore from the Udokanskoe deposit and also in strain TFN-d adapted to untreated pyrite-arsenopyrite concentrate (no. 2) from the Nezhdaninskoe deposit. No changes in the number or size of the XbaI-restriction patterns of chromosomal DNA were revealed in either strain TFBk cultivated on media with pyrite from the Angren and Tulun deposits or in strains TFN-d and TFO grown on media with S 0 and pyrite. Neither were changes observed in the XbaI-restriction patterns of the DNA from strain TFV-1, isolated from the copper ore of the Volkovskoe deposit, when Fe 2+ was substituted with alternative substrates—S 0, pyrite or concentrate no. 2 from the ore of the Nezhdaninskoe deposit. In strain TFO, no differences in the XbaI-restriction patterns of the chromosomal DNA were revealed between the culture grown on medium containing concentrate no. 2 or the concentrate of surface-lying ore from the Olimpiadinskoe deposit and the culture grown on medium with Fe 2+. When strain TFO was cultivated on the ore concentrate from deeper horizons of the Olimpiadinskoe deposit, which are characterized by lower oxidation degrees and high antimony content, mutant TFO-2 differing from the parent strain in the chromosomal DNA structure was isolated. The correlation between the lability of the chromosomal DNA structure in A. ferrooxidans strains and the physical and chemical peculiarities of the isolation substrate and habitat is discussed. 相似文献
18.
Microbiological leaching of synthetic cobaltous sulfide (CoS) was investigated with a pure strain of Thiobacillus ferroxidans. The strain could not grow on CoS-salts medium in the absence of ferrous ions (Fe 2+). However, in CoS-salts medium supplemented with 18 mM Fe 2+, the strain utilized both Fe 2+ and the sulfur moiety in CoS for growth, resulting in an enhanced solubilization of Co 2+. Cell growth on sulfur-salts medium was strongly inhibited by Co 2+, and this inhibition was completely protected by Fe 2+. Cobalt-resistant cells, obtained by subculturing the strain in medium supplemented with both Fe 2+ and Co 2+, brought a marked decrease in the amount of Fe 2+ absolutely required for cell growth on CoS-salts medium. As one mechanism of protection by Fe 2+, it is proposed that the strain utilizes one part of Fe 2+ externally added to CoS-salts medium to synthesize the cobalt-resistant system. Since a similar protective effect by Fe 2+ was also observed for cell inhibition by stannous, nickel, zinc, silver, and mercuric ions, a new role of Fe 2+ in bacterial leaching in T. ferrooxidans is proposed. 相似文献
19.
Waste rubber has posed challenging environmental and disposal problems across the world. This study focused on the microbial reclaiming of ground tyre rubber (GTR) by Acidithiobacillus ferrooxidans YT-1 cultured in media with variable Fe 2+ concentrations. The Acidithiobacillus ferrooxidans YT-1 strain with the ability of oxidizing sulfur and reclaiming waste rubber was isolated and identified. Toxicity tests of different rubber and additives in tyre rubber compounds to microorganisms was quantitatively investigated. After desulfurization, there were many small colonies on the surface of the desulfurizated GTR (DGTR), due to surface degradation by A. ferrooxidans YT-1. The amount of small colonies increased and sulfur content decreased with the increase of Fe 2+ concentrations in the media, implying that Fe 2+ concentration had a great influence on the degradation ability of A. ferrooxidans YT-1. A medium with a high Fe 2+ concentration was good for growth of A. ferrooxidans YT-1. Compared with styrene butadiene rubber (SBR)/GTR blends, the tensile strength and elongation at the break of the SBR/DGTR blends were significantly improved. The scanning electron microscope (SEM) photographs of the fracture surface further indicated a good coherency between DGTR and the SBR matrix. These results revealed that A. ferrooxidans YT-1 cultured in a medium with a high Fe 2+ concentration could improve the reclaiming efficiency of waste rubber. 相似文献
20.
The growth capability of Trichoderma harzianum Rifaii Tl was tested on Malt Extract and Czapeks Dox agar containing different concentrations of Cu 2+, Zn 2+, Mn 2+, Fe 2+ and Ca 2+. The T. harzianum Tl isolate was observed to produce mycelia and spores in various mineral-containing media. It showed the lowest tolerance
to Ca 2+ and the highest tolerance to Fe 2+. Solubilization capability of T. harzianum Tl for some insoluble minerals via acidification of medium has been tested on MnO 2, CuO, Fe 2O 3 and metallic Zn. T. harzianum Tl was able to solubilize MnO 2 and metallic Zn in a liquid medium. 相似文献
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