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Suzuki, Isamu, Douglas Lee, Byron Mackay, Lesia Harahuc, and Jae Key Oh. "Effect of Various Ions, pH, and Osmotic Pressure on Oxidation of Elemental Sulfur by Thiobacillus thiooxidans." Applied and Environmental Microbiology 65, no. 11 (1999): 5163–68. http://dx.doi.org/10.1128/aem.65.11.5163-5168.1999.
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ABSTRACT The oxidation of elemental sulfur by Thiobacillus thiooxidans was studied at pH 2.3, 4.5, and 7.0 in the presence of different concentrations of various anions (sulfate, phosphate, chloride, nitrate, and fluoride) and cations (potassium, sodium, lithium, rubidium, and cesium). The results agree with the expected response of this acidophilic bacterium to charge neutralization of colloids by ions, pH-dependent membrane permeability of ions, and osmotic pressure.
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Oppon, Joseph C., Robert J. Sarnovsky, Nancy L. Craig, and Douglas E. Rawlings. "A Tn7-Like Transposon Is Present in theglmUS Region of the Obligately Chemoautolithotrophic Bacterium Thiobacillus ferrooxidans." Journal of Bacteriology 180, no. 11 (1998): 3007–12. http://dx.doi.org/10.1128/jb.180.11.3007-3012.1998.
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ABSTRACT The region downstream of the Thiobacillus ferrooxidansATCC 33020 atp operon was examined, and the genes encodingN-acetylglucosamine-1-uridyltransferase (glmU) and glucosamine synthetase (glmS) were found. ThisatpEFHAGDC-glmUS gene order is identical to that ofEscherichia coli. The T. ferrooxidans glmS gene was shown to complement E. coli glmS mutants for growth on minimal medium lacking glucosamine. A Tn7-like transposon, Tn5468, was found inserted into the region immediately downstream of the glmS gene in a manner similar to the site-specific insertion of transposon Tn7 within the termination region of the E. coli glmS gene. Tn5468 was sequenced, and Tn7-like terminal repeat sequences as well as several open reading frames which are related to the Tn7 transposition genes tnsA,tnsB, tnsC, and tnsD were found. Tn5468 is the closest relative of Tn7 to have been characterized to date. Southern blot hybridization indicated that a similar or identical transposon was present in three T. ferrooxidans strains isolated from different parts of the world but not in two Thiobacillus thiooxidans strains or aLeptospirillum ferrooxidans strain. Since T. ferrooxidans is an obligately acidophilic autotroph and E. coli is a heterotroph, ancestors of the Tn7-like transposons must have been active in a variety of physiologically different bacteria so that their descendants are now found in bacteria that occupy very different ecological niches.
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Oksana, Shkromada, Ivchenko Viktoriia, Chivanov Vadym, et al. "Defining patterns in the influence exerted by the interelated biochemical corrosion on concrete building structures under the conditions of a chemical enterprise." Eastern-European Journal of Enterprise Technologies 2, no. 6 (110) (2021): 52–60. https://doi.org/10.15587/1729-4061.2021.226587.
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The effect of microbial and chemical corrosion on concrete structures operated in the conditions of chemical enterprises has been established that makes it possible to reliably predict the timing of their decommissioning in order to prevent industrial disasters. Even though the construction complies with all building codes, concrete structures eventually undergo chemical and biological corrosion. The innovation proposed in this study implies investigating the depth and degree of damage to concrete at the microscopic level by the method of raster electron microscopy. In addition, the TPD-MS method has been suggested for determining the quantitative and qualitative state of the carbonate components of concrete and sulfur compounds. This study has found that in concrete samples from the titanium dioxide production plant, the amount of carbon dioxide release is twice less than in control samples at t=600 °C while the level of sulfur dioxide, on the contrary, increases. This is due to the ability of thionic bacteria to accumulate sulfate acid that destroys the cementing component in concrete. The reported results confirm the impact of products of the activity of Acidithiobacillus thiooxidans microorganisms on corrosion processes in concrete. In addition, when using the TPD-MS method, it was established in the storage room of the finished product that heating the control sample of concrete leads to a release of the significant amount of СО<sub>2</sub> at t=580–600 °C. However, the experimental samples of concrete are almost lacking carbon compounds because the acid metabolites of microfungi interfere with its formation. Microscopic and REM studies revealed the localization of Acidithiobacillus thiooxidans and Aspergillus fumigatus in concrete. This study has established patterns related to the mechanism that forms chemical compounds in concrete and the metabolism of microorganisms
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Kyeoung-Suk, Cho, and Tadahiro Mori. "A newly isolated fungus participates in the corrosion of concrete sewer pipes." Water Science and Technology 31, no. 7 (1995): 263–71. http://dx.doi.org/10.2166/wst.1995.0242.
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The final microflora in the corrosion process of concrete sewer pipes was investigated. When the corroded sample was examined using several media, bacterial colonies were found only on acid media (pH 2.5); fungi were detected on neutral solid media (pH 6.5) as well as on acid media (pH 2.5). The acidophilic bacterial colonies were identified as Thiobacillus thiooxidans using a specific identification method for species of acidophilic thiobacilli. The dark green fungi that appeared on the isolation media showed similar morphological characteristics, even though the media used for isolation varied in pH and nutrient. The fungi showed tolerance against acid, although the optimum pH for their growth was neutral. The results showed that the severely corroded sewer pipe was inhabited by two kinds of microorganisms, Thiobacillus thiooxidans and the fungi. An isolated fungus, strain OMSOfl, could oxidize sulfide to thiosulfate. Thiosulfate can be utilized by T. thiooxidans as an energy source, and is converted to corrosive sulfate. Continued vigorous growth of T. thiooxidans presumably depends on a mutualistic relationship with the fungus. It is proposed that a close association between the two microorganisms accelerates the corrosion of concrete sewer pipes.
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Blais, J. F., J. C. Auclair, and R. D. Tyagi. "Cooperation between two Thiobacillus strains for heavy-metal removal from municipal sludge." Canadian Journal of Microbiology 38, no. 3 (1992): 181–87. http://dx.doi.org/10.1139/m92-031.
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A mixed culture of two fast-growing bacterial strains for heavy-metal solubilization of municipal sewage sludge has been developed. Strain VA-7 decreases the initial sludge pH (7–8.5) to a value between 4.0 and 4.5. Then, strain VA-4 begins growing and further reduces the pH to values below 2.0. The rapid decrease of sludge pH by a mixed culture through sulfur oxidation into sulfuric acid solubilizes the toxic metals (Cd 83–96%, Cr 16–54%, Cu 85–87%, Mn 91–94%, Ni 78–79%, Pb 28–46%, Zn 82–96%) to levels recommended for intensive use of residual sludge in agriculture. A study of the physiological and metabolic characteristics of these strains revealed that isolate VA-7 is a strain of Thiobacillus thioparus (ATCC 55127), while isolate VA-4 corresponds to a Thiobacillus thiooxidans (ATCC 55128). These bacterial strains possess distinctive physiological characteristics that allow them to easily grow and solubilize heavy metals in municipal sludge. Key words: heavy metals, sewage sludge, thiobacilli, bioleaching, elemental sulfur.
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Lizama, Hector M., and Isamu Suzuki. "Interaction of chalcopyrite and sphalerite with pyrite during leaching by Thiobacillus ferrooxidans and Thiobacillus thiooxidans." Canadian Journal of Microbiology 37, no. 4 (1991): 304–11. http://dx.doi.org/10.1139/m91-047.
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The interaction of chalcopyrite and sphalerite with pyrite during leaching by Thiobacillus ferrooxidans and Thiobacillus thiooxidans was studied in shake-flask leaching experiments and in respirometer experiments with resting cells. Two samples of pyrite (Nos. 1 and 2) were used. In shake-flask experiments in the absence of bacteria, the copper and zinc extraction rates increased in the presence of No. 1 pyrite from 1.6 to 10.2 and 13%, respectively, and in the presence of No. 2 pyrite from 1.6 to 3.5 and 5.8%, respectively. Thus the effect of pyrite was greater with sphalerite than with chalcopyrite and the No. 1 pyrite was more effective than the No. 2 pyrite. Thiobacillus ferrooxidans increased the leaching rates of Cu from chalcopyrite (from 1.6 to 11.1%), of Zn from sphalerite (from 1.6 to 36%), and of Fe from pyrite (from 7.3 to 29.9% (No. 1) and from 5.1 to 49.3% (No. 2)), although a period of adaptation was required for sphalerite leaching. Thiobacillus thiooxidans did not leach Cu form chalcopyrite, but increased leaching of Zn from sphalerite (from 1.6 to 8.3%) and some Fe from pyrite (from 7.3 to 9.5% (No. 1) and from 5.1 to 13.1% (No. 2)). In the chalcopyrite–pyrite mixture, Cu leaching was further stimulated by T. ferrooxidans (from 10.2 to 14.5% (No. 1) and from 3.5 to 12.2% (No. 2)) and by T. thiooxidans (from 3.5 to 5.8% (No. 2)). The Zn leaching from the sphalerite–pyrite combination increased further with T. ferrooxidans (from 13.0 to 61.7% (No. 1) and from 5.8 to 65.8% (No. 2)) and T. thiooxidans (from 13.0 to 22.4% (No. 1) and from 5.8 to 14.7% (No. 2)). The Fe solubilization from pyrite was inhibited by the presence of chalcopyrite or sphalerite with or without bacteria. Short-term respirometer studies generally supported the leaching results. Oxygen consumption was faster for chalcopyrite or sphalerite in the presence of pyrite. The effect was stronger for sphalerite, although the rapid pyrite oxidation by T. ferrooxidans was inhibited by the interaction. Chalcopyrite alone was oxidized by T. ferrooxidans but not by T. thiooxidans, while sphalerite alone was oxidized only by the latter. It is concluded that shake-flask leaching and Warburg respirometer experiments complement each other in elucidating the complex processes involved in bacterial metal leaching of sulfide ores. Key words: Thiobacillus, sulfide ores, oxidation, mineral leaching.
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Schippers, Axel, and Wolfgang Sand. "Bacterial Leaching of Metal Sulfides Proceeds by Two Indirect Mechanisms via Thiosulfate or via Polysulfides and Sulfur." Applied and Environmental Microbiology 65, no. 1 (1999): 319–21. http://dx.doi.org/10.1128/aem.65.1.319-321.1999.
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ABSTRACT The acid-insoluble metal sulfides FeS2, MoS2, and WS2 are chemically attacked by iron(III) hexahydrate ions, generating thiosulfate, which is oxidized to sulfuric acid. Other metal sulfides are attacked by iron(III) ions and by protons, resulting in the formation of elemental sulfur via intermediary polysulfides. Sulfur is biooxidized to sulfuric acid. This explains leaching of metal sulfides by Thiobacillus thiooxidans.
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Battaglia, F., D. Morin, and P. Ollivier. "Dissolution of cobaltiferous pyrite by Thiobacillus ferrooxidans and Thiobacillus thiooxidans: factors influencing bacterial leaching efficiency." Journal of Biotechnology 32, no. 1 (1994): 11–16. http://dx.doi.org/10.1016/0168-1656(94)90115-5.
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Zhang, Wei Wei, Chao Li, and Dong Wei Li. "Heavy Metals Leaching Experiment from the Pyritic Tailings by the T.F and T.T Bacterias." Advanced Materials Research 414 (December 2011): 111–16. http://dx.doi.org/10.4028/www.scientific.net/amr.414.111.
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The produced and extraction process of pyritic would generate a large amount of pyritic mineral processing solid waste. This kind of waste can lead to land occupation, and contaminate the local water, air and soil. Therefore, in this paper, Thiobacillus ferrooxidans and Thiobacillus thiooxidans are used to deal with the pyritic mineral processing solid waste. The particles, catalysts and bioleaching products between microorganism and pyritic mineral processing solid wast were studied. It is indicated that the microorganism growth and the heavy metals leaching efficiency involve biological and chemical interactions. The experimental results suggested that the T.t was best to bioleach the pyritic mineral processing solid waste, and the efficiency of T.f was worse than that of T.t. The leaching effect of mixed bacterias of T.t and T.f fell in between, the leaching rate would decrease when the pulp density increased. The micro-morphology of bacteria was observed by SEM detector, the single cellular dimension of bioleaching bactreia was about (1~2) μm × (0.2~0.5) μm.
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Hendrix, James W., Cathy Stevens Hunt, and Dale M. Maronek. "Relationship between the ectomycorrhizal fungus Pisolithus tinctorius associated with loblolly pine and acid-generating Thiobacillus spp. on an acidic strip mine site." Canadian Journal of Microbiology 31, no. 9 (1985): 878–79. http://dx.doi.org/10.1139/m85-164.
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Loblolly pine seedlings were transplanted onto a pyritic coal mine site in a commercial reclamation effort. After 5 years, trees which became naturally infected with Pisolithus tinctorius, or other ectomycorrhizal fungi which produced sporocarps, were twice the height and stem diameter of trees not associated with sporocarps. The hypothesis that P. tinctorius promotes superior growth of its host by inhibiting the growth or activity of Thiobacillus ferrooxidans and T. thiooxidans, which catalyze production of sulfuric acid from pyrite, was examined. Soil pH was lower in the root zones of trees associated with P. tinctorius than with trees not associated with P. tinctorius, and sulfate was higher. Differences were not found in ferric or ferrous ions or in populations of the two bacterial species. Apparently P. tinctorius benefits its hosts by mechanisms other than inhibition of Thiobacillus spp.
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Bacelar-Nicolau, Paula, and D. Barrie Johnson. "Leaching of Pyrite by Acidophilic Heterotrophic Iron-Oxidizing Bacteria in Pure and Mixed Cultures." Applied and Environmental Microbiology 65, no. 2 (1999): 585–90. http://dx.doi.org/10.1128/aem.65.2.585-590.1999.
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ABSTRACT Seven strains of heterotrophic iron-oxidizing acidophilic bacteria were examined to determine their abilities to promote oxidative dissolution of pyrite (FeS2) when they were grown in pure cultures and in mixed cultures with sulfur-oxidizingThiobacillus spp. Only one of the isolates (strain T-24) oxidized pyrite when it was grown in pyrite-basal salts medium. However, when pyrite-containing cultures were supplemented with 0.02% (wt/vol) yeast extract, most of the isolates oxidized pyrite, and one (strain T-24) promoted rates of mineral dissolution similar to the rates observed with the iron-oxidizing autotroph Thiobacillus ferrooxidans. Pyrite oxidation by another isolate (strain T-21) occurred in cultures containing between 0.005 and 0.05% (wt/vol) yeast extract but was completely inhibited in cultures containing 0.5% yeast extract. Ferrous iron was also needed for mineral dissolution by the iron-oxidizing heterotrophs, indicating that these organisms oxidize pyrite via the “indirect” mechanism. Mixed cultures of three isolates (strains T-21, T-23, and T-24) and the sulfur-oxidizing autotroph Thiobacillus thiooxidans promoted pyrite dissolution; since neither strains T-21 and T-23 nor T. thiooxidans could oxidize this mineral in yeast extract-free media, this was a novel example of bacterial synergism. Mixed cultures of strains T-21 and T-23 and the sulfur-oxidizing mixotrophThiobacillus acidophilus also oxidized pyrite but to a lesser extent than did mixed cultures containing T. thiooxidans. Pyrite leaching by strain T-23 grown in an organic compound-rich medium and incubated either shaken or unshaken was also assessed. The potential environmental significance of iron-oxidizing heterotrophs in accelerating pyrite oxidation is discussed.
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Okabe, Satoshi, Mitsunori Odagiri, Tsukasa Ito, and Hisashi Satoh. "Succession of Sulfur-Oxidizing Bacteria in the Microbial Community on Corroding Concrete in Sewer Systems." Applied and Environmental Microbiology 73, no. 3 (2006): 971–80. http://dx.doi.org/10.1128/aem.02054-06.
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ABSTRACT Microbially induced concrete corrosion (MICC) in sewer systems has been a serious problem for a long time. A better understanding of the succession of microbial community members responsible for the production of sulfuric acid is essential for the efficient control of MICC. In this study, the succession of sulfur-oxidizing bacteria (SOB) in the bacterial community on corroding concrete in a sewer system in situ was investigated over 1 year by culture-independent 16S rRNA gene-based molecular techniques. Results revealed that at least six phylotypes of SOB species were involved in the MICC process, and the predominant SOB species shifted in the following order: Thiothrix sp., Thiobacillus plumbophilus, Thiomonas intermedia, Halothiobacillus neapolitanus, Acidiphilium acidophilum, and Acidithiobacillus thiooxidans. A. thiooxidans, a hyperacidophilic SOB, was the most dominant (accounting for 70% of EUB338-mixed probe-hybridized cells) in the heavily corroded concrete after 1 year. This succession of SOB species could be dependent on the pH of the concrete surface as well as on trophic properties (e.g., autotrophic or mixotrophic) and on the ability of the SOB to utilize different sulfur compounds (e.g., H2S, S0, and S2O3 2−). In addition, diverse heterotrophic bacterial species (e.g., halo-tolerant, neutrophilic, and acidophilic bacteria) were associated with these SOB. The microbial succession of these microorganisms was involved in the colonization of the concrete and the production of sulfuric acid. Furthermore, the vertical distribution of microbial community members revealed that A. thiooxidans was the most dominant throughout the heavily corroded concrete (gypsum) layer and that A. thiooxidans was most abundant at the highest surface (1.5-mm) layer and decreased logarithmically with depth because of oxygen and H2S transport limitations. This suggested that the production of sulfuric acid by A. thiooxidans occurred mainly on the concrete surface and the sulfuric acid produced penetrated through the corroded concrete layer and reacted with the sound concrete below.
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Lizama, Hector M., and Isamu Suzuki. "Bacterial leaching of a sulfide ore by Thiobacillus ferrooxidans and Thiobacillus thiooxidans part II: Column leaching studies." Hydrometallurgy 22, no. 3 (1989): 301–10. http://dx.doi.org/10.1016/0304-386x(89)90027-3.
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Kenzhaliyev, Bagdaulet, Aigul Koizhanova, Gulnar Abdykirova, et al. "The The pre-bio-oxidation and its effect on the leaching process of low-grade copper ore in percolation columns." Acta Metallurgica Slovaca 31, no. 2 (2025): 129–33. https://doi.org/10.36547/ams.31.2.2214.
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The results of laboratory studies intended to extract copper from substandard copper raw materials in percolators are presented in this work. The results of chemical elemental analysis, X-ray phase analysis and chemical phase analysis for the copper and iron forms in the ore are also presented herein. The efficiency of sulfuric acid and bacterial leaching in percolation columns was compared. When standard sulfuric acid leaching was used, copper extraction into the solution was 49.85%, whereas in bacterial oxidation (by chemolithotrophic bacteria - Thiobacillus thiooxidans, oxidizing sulfur and iron compounds) - 74.81% during 60 days of the experiment. The redox potential values are presented for standard sulfuric acid and bacterial leaching of copper ore, which correlate with copper yield. It was found as a result of the research that the use of bacterial technology provides deeper processing of copper ore due to the oxidation of copper sulfide minerals.
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Kurosawa, Hiroshi, Shuichi Endo, Takahiro Hirano, Kazuo Nakamura, and Yoshifumi Amano. "Stabilization of freeze-dried Thiobacillus thiooxidans cells as a bacterial deodorant for removal of hydrogen sulfide." Journal of Fermentation and Bioengineering 83, no. 2 (1997): 213–15. http://dx.doi.org/10.1016/s0922-338x(97)83587-8.
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Brombacher, Christoph, Reinhard Bachofen, and Helmut Brandl. "Development of a Laboratory-Scale Leaching Plant for Metal Extraction from Fly Ash by ThiobacillusStrains." Applied and Environmental Microbiology 64, no. 4 (1998): 1237–41. http://dx.doi.org/10.1128/aem.64.4.1237-1241.1998.
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ABSTRACT Semicontinuous biohydrometallurgical processing of fly ash from municipal waste incineration was performed in a laboratory-scale leaching plant (LSLP) by using a mixed culture of Thiobacillus thiooxidans and Thiobacillus ferrooxidans. The LSLP consisted of three serially connected reaction vessels, reservoirs for a fly ash suspension and a bacterial stock culture, and a vacuum filter unit. The LSLP was operated with an ash concentration of 50 g liter−1, and the mean residence time was 6 days (2 days in each reaction vessel). The leaching efficiencies (expressed as percentages of the amounts applied) obtained for the economically most interesting metal, Zn, were up to 81%, and the leaching efficiencies for Al were up to 52%. Highly toxic Cd was completely solubilized (100%), and the leaching efficiencies for Cu, Ni, and Cr were 89, 64, and 12%, respectively. The role of T. ferrooxidans in metal mobilization was examined in a series of shake flask experiments. The release of copper present in the fly ash as chalcocite (Cu2S) or cuprite (Cu2O) was dependent on the metabolic activity of T. ferrooxidans, whereas other metals, such as Al, Cd, Cr, Ni, and Zn, were solubilized by biotically formed sulfuric acid. Chemical leaching with 5 N H2SO4 resulted in significantly increased solubilization only for Zn. The LSLP developed in this study is a promising first step toward a pilot plant with a high capacity to detoxify fly ash for reuse for construction purposes and economical recovery of valuable metals.
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Manga, S.S, S.B Oyeleke, A.D. Ibrahim, A.A. Aliero, and A.I Bagudo. "INFLUENCE OF BACTERIA ASSOCIATED WITH CORROSION OF METALS." Continental J. Microbiology 6, no. 1 (2012): 19–25. https://doi.org/10.5281/zenodo.824035.
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The physicochemical characteristics of the soil beneath and adjacent to corroded petrol tanks were examined. The result revealed that the moisture content of the soil beneath the tanks was higher (3.2%) than the adjacent soil (0.4%). There was no significant difference in the temperature of the soil beneath and the adjacent one. The pH of the soil beneath the tanks was acidic (5.9). The organic matter of the adjacent soil was higher (1.8%) than the soil beneath the tanks. Nitrate and sulphate contents of the adjacent soil were higher (1.36 and 153.5mg/kg) than soil beneath the tanks which was 0.7 and 87.2mg/kg respectively. The bacteria isolated from scrapings of the tanks included <em>Desulfovibrio vulgaris, Desulfotomaculum nigrificans</em>, <em>Desulfovibrio desulfuricans</em>, <em>Thiobacillus thiooxidans</em>, <em>Pseudomonas aeruginosa, Listeria monocytogenes, Bacillus cereus, Clostridium perfringes, Bacillus firmus, Staphylococcus cohnii, Bacillus laterosporus and Micrcococcus sedentarius.</em> <em>P. aeruginosa </em>was the most frequently observed (12.5%)<em>, while the least was B. laterosporus </em>(4.5%<em>). </em>The corroding ability of bacteria isolated was also examined and the result revealed that bacteria isolated have showed the corroding ability on metal strips and the average percentage weight loss of metal strips was 3.8%, thus indicating that these bacteria have contributed in the deterioration of the petrol tanks studied. The corrosion of storage petrol tanks could lead to seepages of petroleum products in the area, contaminating soil surface and ground water sources which could result in destruction of crops and aquaculture which consequently affect the ecosystem. The use of metals/plastic that can resist corrosion especially alloys to construct storage fuel tanks should be encouraged.
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"Improving heavy metal removal efficiency from steel sludge: Application of the coupled ultrasonic-bioleaching treatment." Global NEST: the international Journal, November 28, 2023. http://dx.doi.org/10.30955/gnj.005417.
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<p>This study assessed the efficiency of Fe, Al, Ni and Sr removal from the steel sludge using the coupled bioleaching with Thiobacillus thiooxidans and ultrasonic waves. Growth conditions were optimized using the surface response method. The bacterium was adapted successively to three heavy metal-containing solutions with different concentrations of 100, 200, and 300 mg/ml. Samples were exposed to ultrasonic waves at frequencies of 30, 60 and 90 kHz and durations of 20, 30 and 40 min for two weeks. The highest Fe removal efficiency of 98.45% was obtained using the T. thiooxidation, wave frequency of 30 kHz for 40 min, and pulp density of 100 mg/ml. The maximum removal efficiency was found to be 99.74% for Al under a wave frequency of 90 kHz for 20 min and a pulp density of 300 mg/ml, approximately 100% for Ni under a wave frequency of 30 kHz for 20 min and a pulp density of 300 mg/ml, and 98.45% for Sr under a wave frequency of 90 kHz for 20 min and a pulp density of 300 mg/mL. Results showed that the removal efficiency of Ni and Al bioleaching improved significantly (P &lt;0.05) under the ultrasonic irradiation while the removal efficiency of Fe and Sr remained statistically unchanged (P&gt; 0.05) with and without the application of ultrasonic waves.</p>
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Soleimani, Younes, Mohammad-Reza Mohammadi, Mahin Schaffie, Reza Zabihi, and Mohammad Ranjbar. "An experimental study of the effects of bacteria on asphaltene adsorption and wettability alteration of dolomite and quartz." Scientific Reports 13, no. 1 (2023). http://dx.doi.org/10.1038/s41598-023-48680-7.
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AbstractThe adsorption of asphaltene on the rock surface and the changes in its wettability are very relevant issues in flow assurance and oil recovery studies, and for carbonate reservoirs, they are even more important. During microbial enhanced oil recovery (MEOR) processes, wettability alteration is considered a crucial mechanism leading to improved oil recovery. Therefore, it is essential to understand the mechanisms of surface wettability changes by bacteria and biosurfactants and find new and reliable methods to prevent asphaltene adsorption. Hence, the main aim of this research was to investigate the effect of a mixture of thiobacillus thiooxidans and thiobacillus ferooxidans microorganisms with an optimum effective temperature of around 30 °C (referred to as mesophilic bacteria), as well as a mixture of two moderate thermophiles Sulfobacillus thermosulfidooxidans for operating temperatures around 50 °C (referred to as moderately thermophilic bacteria) on the adsorption of asphaltene samples isolated from two different crude oils onto main reservoir minerals (i.e., quartz and dolomite). The results indicated that after two weeks of mineral aging in moderate thermophilic bacteria, the adsorption of asphaltene on both minerals increased between 180 and 290%. Fourier-transform infrared spectroscopy (FTIR) analysis for quartz and dolomite samples demonstrated that after aging in bacterial solution, bonds related to the adsorption of bacterial cells and biosurfactant production appear, which are the main factors of change in wettability. Alteration in wettability towards hydrophilicity expands hydrogen bonds on the surface, thus improving asphaltene adsorption due to polar interaction. Asphaltene 1 changed the contact angle of dolomite from 53.85° to 90.51° and asphaltene 2 from 53.85° to 100.41°. However, both strains of bacteria caused a strong water-wetting effect on the dolomite rock samples. The influence of moderate thermophilic bacteria on surface wettability is more significant than that of mesophilic bacteria, which may be caused by the high protein content of these bacteria, which expands hydrogen bonding with the surface. Adsorption of asphaltenes on dolomite rocks previously aged with bacteria showed that the wetted rock samples retained their water-wet state. This study highlights the dual impact of the used microorganisms. On one hand, they significantly reduce contact angles and shift wettability towards a strongly water-wet condition, a crucial positive factor for MEOR. On the other hand, these microorganisms can elevate the adsorption of asphaltenes on reservoir rock minerals, posing a potential challenge in the form of formation damage, particularly in low-permeability reservoirs.