THE TAXONOMIC AND PHYSIOLOGIC DIVERSITY OF THE ACIDOPHILIC CHEMOLITHOTROPHIC BACTERIA OF THE GENUS THIOBACILLUS USED IN ORES SOLUBILIZATION PROCESSES (original) (raw)
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THE STUDY OF ACIDOPHILIC HETEROTROPHIC BACTERIA TOLERANCE TO HIGH CONCENTRATIONS OF METALLIC IONS
The development of biotechnological processes, based mainly on the activity of the acidophilic microorganisms proved their efficiency in recovering metals from sulphuric ores and mining drains and in bioremediation of the polluted environment with residual inorganic substances, like the heavy metals ions and their compounds. A special importance in using the heterotrophic acidophilic microorganisms in metal biosorption and bioaccumulation processes from industrial residual waters (especially the acid mining drains) is represented by the resistance of these microorganisms to higher concentrations of metallic ions existent in those media. The comparative analyses regarding the influence of the metallic ions (Cu 2+ and Zn 2+ ) on the growth of the Acidiphilium sp. populations, isolated from the two mining sites, demonstrated the higher resistance of the Acidiphilium sp. populations to higher concentrations of metallic ions,
Institute of Biology Bucharest, Romanian Academy, 2005
The increasing pollution of the environment raised the interest towards the resistance of microorganisms to metals and the potential of using microorganisms, not only in ore leaching and detoxifying of the environments polluted with heavy metals. The sulphur wastes deposited in dumps with high concentrations of metallic ions have the capacity of generating acid and toxic waters. A special importance in using bacteria of the genus Thiobacillus in the metal solubilization processes from the acid mine draining is represented by adapting of these microorganisms to higher concentrations of metallic ions existent in those environments. High percentages of soluble pyrite were obtained using the P5 population of Thiobacillus ferrooxidans, which made the pyrite soluble in percentages of 87-92, which confirms its higher tolerance to Fe 3+. The lowest percentages of solubilized pyrite (9.06-25.50%) were got in the presence of the Thiobacillus ferrooxidans B9 strain, this fact being correlated with the higher sensitivity of this strain to the presence of ferric iron in the environment.
The most efficient biotechnological processes for the recovery/removal of metal ions from industrial effluents include biosorption and bioaccumulation of heavy metals by acidophilic heterotrophic bacteria of the genus Acidiphilium. Enzymes activated by different metal ions have an exacerbation of catalytic function in their presence due to the formation of enzyme-metal complexes more active or due to the formation of enzyme-metal complexes, due to the formation of substrate-complexes or accumulation of these ions. In case of metalloenzymes, metal ion is bound and incorporated into higher order structures of protein providing an active catalytic structured and/or functional role. Acidophilic heterotrophic bacteria tested have been represented by populations of Acidiphilium species. In all experiments performed, the hydrolytic activity of Acidiphilium population isolated from Ro ia Poieni led to sharp decrease of starch in culture medium. In experiments testing of the hydrolytic activity at different concentrations of starch it was observed a more accentuated hydrolysis to its initial concentration of 0.2% in culture medium. Also, the presence of NaCl and CaSO 4 concentration of 0.1% in organic medium with starch stimulates the development of acidophilic heterotrophic bacteria belonging to genus Acidiphilium, as well as their extracellular amylolitic activity.
Journal of Microbiology, Biotechnology and Food Sciences, 2019
A chemolithotrophic bacterium was isolated from sulfur hot spring. According to phenotypic traits and 16-23S rDNA intergenic spacer region analysis, the isolate was identified and named as Acidithiobacillus sp. MR39, which was a gram-negative, rod-shape and non-motile bacterium. The strain was able to grow in a synthetic liquid medium supplemented with the mineral ore as the source of energy. The optimum conditions were found to be within initial pH range of 2.0-2.5, at 34±1˚C and with shaking at 120 rpm. The bacterium had a remarkable potential for mineralization of 88% iron, 75% copper, 59% zinc, 59% nickel and 40% cobalt upon their growth in the liquid media. After adapting the bacterial cells to copper ions in 100 mM for 5-day incubation, biorecovery of Cu increased about 10% comparing to unadapted cells that are able to dissolve approximately 15% of total cu of mineral concentrate. Considering the finding in this study, the strain MR39 offers a great prospect for in situ extraction of metals from various ores along with other indigenous bacteria that can grow under ambient conditions.
Romanian Biotechnological Letters, 2011
Bacteria that live in acidic environments are very important for industrial biotechnology. The physiological, biochemical and ecological studies, including the isolation of new acidophilic heterotrophic bacteria, will allow a better understanding of their signification for biodiversity and bioremediation. The aim of the present paper was to study the biosorption of heavy metallic ions by 8 strains and 3 populations of aerobe heterotrophic bacteria. They presented a maximum activity of acidophilic heterotrophic populations at acidity and temperature values close to the physico-chemical properties of habitats from which they were taken. The use of silicagel, zeolite and molecular sieve was proved efficient in the immobilization of neutrophilic and acidophilic heterotrophic bacteria by accentually decreasing of the optical density of cultures. Also, higher percentages biosorption of several metallic ions were obtained using populations of acidophilic bacteria compared with purified strains, which confirms the adaptation of populations to higher concentrations of Cu 2+ (68%), Zn 2+ (80%) and Ni 2+ (84%). In the experiments of the chromium removal from industrial waste water by the acidophilic heterotrophic bacterial strains an extraction of the hexavalent chrome of 86.78 -99.95% was noticed. The same experiments evidenced the fact that Cr 3+ and Cr 6+ were removed in bigger percentages (73.33% and 94.07%) after 48 hours contact between neutrophilic bacterial population and industrial waste water.
Rev. Roum. Biol., Veget. Biol., Bucarest, 2001
The growth and multiplication of acidophilic bacteria are the results of a series of coordinated metabolic reactions, which can take place only in certain acidic conditions. The influence of acidity, in various experimental conditions, on the growth and activity of acidophilic bacteria, isolated from the mines situated in two different areas of the country (Baia-Tulcea dept. and Roşia Poieni-Alba dept.) are studied in this work. The experiments prove a strong relationship between the acidity of the medium and the behavior of the acidophilic heterotrophic bacteria. Heterotrophic bacteria, in optimal developmental conditionsat pH 2.5 and temperatures 28 0 Cmay have an active contribution to the processes of biosorbtion of metallic ions that have polluted different environments.
Oltenia Jornal for Studies in Natural Sciences, 2010
The structural and physiological characterization of the species from acidophilic microbial communities may lead to the discovery of new species of acidophilic heterotrophic bacteria. These bacteria play an important role in bioremediation processes, due to their oxidative activity in environments polluted with metallic ions. The experiments prove the highest oxidative activity was found at 28°C and pH 2.5, meaning that these would be the best conditions in the natural environment for maximum activity of the genus Acidiphilium. The decrease of the pH to 2.0, as well as its increase to 3.5 determined the reduction of the oxidative activity to 25% from the values obtained at an optimum pH.
Comparative Study of Biosorption of Metallic Cations by Different Bacteria
SOUTHERN BRAZILIAN JOURNAL OF CHEMISTRY, 1998
Certain species of microorganisms have been found to accumulate surprisingly large quantities of important metals, involved in the toxicity provoked by human activities (Cd, Pb, Hg) and metals of economic values (Ag, Au). Microbiological methods are applied to large-scale recovery or removal of metallic ions from aqueous solutions. These applications involved the removal of heavy metals from sewage sludge, industrial effluents, and mine or wastewaters. This process has been developed using immobilized extracellular or cellular ligands or more simple chemical models based upon them. The uptake of metal ions on the cell surface and their translocations into the cell are well-known natural processes. These adsorption processes could be expressed using Langmuir isotherms. Fe2+ and Mn2+ appeared to .be the most effective cations for adsorption by Bacillus subtilis, Pseudomonas aeruginosa, even by Saccharomyces cerevisiae, while the Zn2+ cation, in spite of a great value of maximum adsorp...
The aim of this study was to investigate the effect of bacterial strains on the bioleaching of Cr, Cu, Pb, and Zn from contaminated sediment samples taken from a stationary point in Izmir Inner Bay. Single and mixed cultures of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans were used separately to achieve metal solubilization in suspension. Of the three trials tested, single culture of A. thiooxidans decreased the pH to 0.7, resulting in the highest metal solubilization ratios. Solubilization efficiencies of Cr, Cu, and Zn were high (N 80%) with A. thiooxidans but Pb could be solubilized to a ratio of 63%. The efficiency of metal solubilization from contaminated sediment in decreasing order is: Zn N Cu N Cr N Pb. In order to check for the mass balance, metals remaining in the residual sediment were also determined. The effect of bioleaching on sequentially extracted (chemically distributed) metals was investigated in addition to the metal solubilization efficiencies. For most of the trials, it is observed that, the stable forms of heavy metals were transferred and accumulated in more soluble forms during bioleaching and they directly solubilized in the water when they were finally transferred to the exchangeable and/or reducible form.
Proceedings of the Institute of Biology, Romanian Academy, Bucharest, 2002
The study of the research regarding the acidophilic procaryote microorganisms (eubacteria and archaea) is very new because of the importance of these microorganisms in biotechnology and in the depollution of the environment. The growth and activity of bacteria in the acidic biotopes depend greatly on the ecological conditions of the environment. Through their activity the acidophilic bacteria determine changes of the environment pH and of the oxido-reduction potential and during their metabolism, they can elaborate different useful substances, which have complex oxidizing or reductive properties. The acidity influences in a different way the life and activity of the different types of microorganisms present in low pH media. In this context, this paper presents the effects of acidity in static and continuous agitation conditions on the growth and activity of the acidophilic chemolithotrophic sulphur-oxidizing bacteria, isolated from the acidic mining effluents from two mines: Baia and Valea Şesei.