Iron and Sulfur Oxidation byThiobacillus Ferrooxidansand Tolerance to Copper and Zinc Ions (original) (raw)
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Studies on multi-metal ion tolerance of Thiobacillus ferrooxidans
Minerals Engineering, 1997
The influence of different concentrations of base metal ions, such as Cu 2+, Zn 2+ and Fe 3+, when present either alone or in different possible binary and ternary combinationa in a 9K medium, on the ferrous ion oxidation ability of Thiobacillus ferrooxidans was studied. Levels and degree of toxicity of these ions have been quantified in terms of toxicity index (TI). Copper and zinc tolerant strains of the bacteria were developed through .,wrial subculturing and their activity tested in the presence of the above metal ions in comparison with the behavior of wild unadapted cells under similar conditions. Copper tolerant strains (25 g/L Cu 2+) were found to be more efficient in the bioleaching of both copper and zinc concentrates than wild unadapted strains, while zinc tolerant strains (,40 g/L Zn 2+) exhibited better leaching efficiency only in the bioleaching of sphalerite concentrates. The significance and relevance of multi-metal ion tolerance in ThiobaciUus ferrooxidans has been highlighted with respect to bioleaching of sulphide mineral concentrates.
Resistance to heavy metals in different strains of Thiobacillus ferrooxidans
World Journal of Microbiology and …, 1997
Ten different isolates of Thiobacillus ferrooxidans were studied with regard to their degree of resistance to the metals copper, nickel, uranium, and thorium. Inhibitory concentrations for a particular metal were those which showed a statistically-signi®cant decrease in the amount of ferrous iron oxidized by the bacterium compared to an untreated control. The different isolates had different susceptibilities to the metals tested, and none of the metals had a stimulatory effect. Uranium and thorium were 20 to 40 times more toxic to ferrous iron oxidation than either copper or nickel.
THE TOLERANCE OF THIOBACILLUS FERROOXIDANS BACTERIA TO DIFFERENT CONCENTRATIONS OF FERROUS SULPHATE
A special importance for using bacteria of the genus Thiobacillus in the biosolubilization processes of heavy metals from acid mine tailings is represented by the resistance of these microorganisms to high concentrations of metal ions. Due to the toxic increased concentrations of metal ions the study of the tolerance of chemolithotrophic acidophilic bacteria potentially involved becomes necessary in biotechnological applications. Therefore, the increasing efficiency of the bioleaching processes implies the stability of the tolerance of chemolithotrophic acidophilic bacteria to heavy metals and also the selecting of strains aand populations with an increased resistance. In this context, in the present paper was pursued the study of tolerance to high concentrations of ferric iron (10-20g/l Fe 2+ ) of the bacteria of the genus Thiobacillus. At the concentrations of 10 and 12g/l Fe 2+ the bacterial populations had an intense metabolical activity, oxidating the whole amount of Fe 2+ in 6 days and at the concentrations of 14, 16g/l Fe 2+ the iron in the medium was oxidated in a longer period of time.
Oxidation of ferrous iron and elemental sulfur by Thiobacillus ferrooxidans
Applied and …, 1988
The oxidation of ferrous iron and elemental sulfur by Thiobacillus ferrooxidans that was absorbed and unabsorbed onto the surface of sulfur prills was studied. Unadsorbed sulfur-grown cells oxidized ferrous iron at a rate that was 3 to 7 times slower than that of ferrous iron-grown cells, but sulfur-grown cells were able to reach the oxidation rate of the ferrous iron-adapted cells after only 1.5 generations in a medium containing ferrous iron. Bacteria that were adsorbed to sulfur prills oxidized ferrous iron at a rate similar to that of unadsorbed sulfur-grown bacteria. They also showed the enhancement of ferrous iron oxidation activity in the presence of ferrous iron, even though sulfur continued to be available to the bacteria in this case. An increase in the level of rusticyanin together with the enhancement of the ferrous iron oxidation rate were observed in both sulfur-adsorbed and unadsorbed cells. On the other hand, sulfur oxidation by the adsorbed bacteria was not affected by the presence of ferrous iron in the medium. When bacteria that were adsorbed to sulfur prills were grown at a higher pH (ca. 2.5) in the presence of ferrous iron, they rapidly lost both ferrous iron and sulfur oxidation capacities and became inactive, apparently because of the deposition of a jarosite-like precipitate onto the surface to which they were attached.
Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, 2000
Respirometric experiments demonstrated that the oxygen uptake by Thiobacillus ferrooxidans strain LR was not inhibited in the presence of 200 mM copper. Copper-treated and untreated cells from this T. ferrooxidans strain were used in growth experiments in the presence of cadmium, copper, nickel and zinc. Growth in the presence of copper was improved by the copper-treated cells. However, no growth was observed for these cells, within 190 h of culture, when cadmium, nickel and zinc were added to the media. Changes in the total protein synthesis pattern were detected by two-dimensional polyacrylamide gel electrophoresis for T. ferrooxidans LR cells grown in the presence of different heavy metals. Specific proteins were induced by copper (16, 28 and 42 kDa) and cadmium (66 kDa), whereas proteins that had their synthesis repressed were observed for all the heavy metals tested. Protein induction was also observed in the cytosolic and membrane fractions from T. ferrooxidans LR cells grown in the presence of copper. The level of protein phosphorylation was increased in the presence of this metal.
Applied and Environmental Microbiology
It was found that the de novo synthesis of not only sulfur:ferric ion oxidoreductase (ferric ion-reducing system) but also iron oxidase was absolutely required when Thiobacillus ferrooxidans AP19-3 was grown on sulfur-salts medium. The results strongly suggest that iron oxidase is involved in sulfur oxidation. This bacterium could not grow on sulfur-salts medium under anaerobic conditions with Fe3+ as a terminal electron acceptor, suggesting that energy conservation by electron transfer between elemental sulfur and Fe3+ is not available for this bacterium.
Journal of Biotechnology, 1994
Effect of ultraviolet exposure on silver tolerance and growth of Thiobacillus ferrooxidans (ore-isolate) were investigated. Ultraviolet exposure of 30 s was found to influence the ferrous oxidation activity. Ultraviolet-induced silver tolerance as high as 0.414 mM Ag was developed with complete (100%) ferrous oxidation within 163 h. Ultraviolet reexposure of the above culture enhanced ferrous oxidation by about 1.5-fold at 0.276 mM Ag concentration.
Copper ion removal by Thiobacillus ferrooxidans biomass
Biotechnology letters, 1998
Thiobacillus ferrooxidans removed copper ions at pH 1.4 with a specific uptake capacity of 0.7 g Cu 2ϩ g -1 dry weight. A 0.6 M copper ion tolerant T. ferrooxidans was isolated after successive subcultures on ferrous sulphate oxidation without loss of production, 52 mg protein (mol Fe 2ϩ oxidised) -1 . This adaptation lead to a decrease in copper ion uptake to 0.09 g Cu 2ϩ g -1 dry weight.
The chemolithotrophic bacterium Thiobacillus ferrooxidans
FEMS Microbiology Reviews, 1994
The iron-oxidizing bacterium Thiobacillus ferrooxMans is the most important microorganism in mineral leaching. It plays the dominant role in bioextractive processes because of its ability to oxidize both iron and reduced sulfur compounds. 7~ ferrooxidans is also an important microorganism in acid rock/mine drainage, a serious environmental problem In this article, the current status of this bacterium is described with particular emphasis on the biomining indust~'.
Arch Microbiol, 1973
1. Oxidation of ferrous iron by Thiobacillus ]errooxidans proceeded at the same rates in media grossly deficient in potassium as in media with 4.56 ml~ K + added. 2. Iron oxidation in "potassium-free" medium was markedly inhibited by the addition of 10-s M K + or I~a + (as sulphates), compared with normal or accelerated oxidation at lower or higher concentrations. 3. Chlorides of sodium or potassium were inhibitory under conditions where the sulphates were not; the concentrations of chlorides required to inhibit development depended on the total potassium content of the medium. 4. Thallium and rubidium were growth inhibitory at 10-4 M in the "potassium-free" medium, but were not toxic at 10-3 M in the normal medium. 5. Inhibition of growth by 2 mM uranyl sulphate was partially relieved by 200 mM K+, Na +, Li + or Nttt+ added to the normal medium as, sutphates. 6. Increased H2SO ~ concentration increased uranium toxicity without affecting the normal growth rates. 7. The results are discussed in relation to the possible presence in T./errooxidans of two K+-transport systems of different reaction to external K+-concentration, and the possible effects of uranium on membrane-dependent processes.