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Journal articles on the topic 'Metal-reducing microorganisms'
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1
Kashefi, Kazem, Jason M. Tor, Kelly P. Nevin, and Derek R. Lovley. "Reductive Precipitation of Gold by Dissimilatory Fe(III)-Reducing Bacteria andArchaea." Applied and Environmental Microbiology 67, no. 7 (July 1, 2001): 3275–79. http://dx.doi.org/10.1128/aem.67.7.3275-3279.2001.
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ABSTRACT Studies with a diversity of hyperthermophilic and mesophilic dissimilatory Fe(III)-reducing Bacteria andArchaea demonstrated that some of these organisms are capable of precipitating gold by reducing Au(III) to Au(0) with hydrogen as the electron donor. These studies suggest that models for the formation of gold deposits in both hydrothermal and cooler environments should consider the possibility that dissimilatory metal-reducing microorganisms can reductively precipitate gold from solution.
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Beech, Iwona B., and Christine C. Gaylarde. "Recent advances in the study of biocorrosion: an overview." Revista de Microbiologia 30, no. 3 (July 1999): 117–90. http://dx.doi.org/10.1590/s0001-37141999000300001.
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Biocorrosion processes at metal surfaces are associated with microorganisms, or the products of their metabolic activities including enzymes, exopolymers, organic and inorganic acids, as well as volatile compounds such as ammonia or hydrogen sulfide. These can affect cathodic and/or anodic reactions, thus altering electrochemistry at the biofilm/metal interface. Various mechanisms of biocorrosion, reflecting the variety of physiological activities carried out by different types of microorganisms, are identified and recent insights into these mechanisms reviewed. Many modern investigations have centered on the microbially-influenced corrosion of ferrous and copper alloys and particular microorganisms of interest have been the sulfate-reducing bacteria and metal (especially manganese)-depositing bacteria. The importance of microbial consortia and the role of extracellular polymeric substances in biocorrosion are emphasized. The contribution to the study of biocorrosion of modern analytical techniques, such as atomic force microscopy, Auger electron, X-ray photoelectron and Mössbauer spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy and microsensors, is discussed.
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Kalashnikova, O. B., A. V. Kashevskii, N. S. Vardanyan, D. Erdenechimeg, G. O. Zhdanova, I. A. Topchy, O. N. Ponamoreva, O. F. Vyatchina, and D. I. Stom. "Acidophilic chemolithotrophic microorganisms: prospects for use in biohydrometallurgy and microbial fuel cells." Proceedings of Universities. Applied Chemistry and Biotechnology 11, no. 1 (April 6, 2021): 34–52. http://dx.doi.org/10.21285/2227-2925-2021-11-1-34-52.
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Acidophilic chemolithotrophic microorganisms are used in biohydrometallurgy for the extraction of metals from sulphide ores. Some types of microorganisms belonging to this group are capable of generating electricity under certain conditions. This circumstance determined a recent upsurge of research interest in their use in biofuel cells. Under a constant supply of the substrate to the bioelectrochemical system, acidophilic chemolithotrophic microorganisms are capable of producing electricity for a prolonged period of time. The use of extremophiles in microbial fuel cells is of particular interest, since these microorganisms can serve as bioelectrocatalysts at extreme pH, salinity and temperature, while the vast majority of microorganisms are unable to survive under these conditions. Therefore, selection of optimal conditions and approaches to controlling the work of acidophilic chemolithotrophic microorganisms in such fuel cells is of particular importance. On this basis, a technology for the simulteneous bioleaching of metals from poor ores and the generation of electricity can be developed. Biofuel cells operating at low pH values using acidophilic chemolithotrophic microorganisms are yet to be investigated. The number of studies on acidophilic electroactive microorganisms is very limited. In this regard, the purpose of this review was to consider the prospects for the use of acidophilic chemolithotrophic microorganisms as bioagents in microbial fuel cells. The reviewed publications demonstrate that chemolithotrophic microorganisms can act as both anodic (metal-reducing, sulphur-oxidizing microorganisms) and cathodic (metal-oxidizing prokaryotes, sulfate reducers) highly efficient bioagents capable of using mining wastes as substrates.
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Roh, Y., H. Vali, T. J. Phelps, and J. W. Moon. "Extracellular Synthesis of Magnetite and Metal-Substituted Magnetite Nanoparticles." Journal of Nanoscience and Nanotechnology 6, no. 11 (November 1, 2006): 3517–20. http://dx.doi.org/10.1166/jnn.2006.17973.
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We have developed a novel microbial process that exploits the ability of Fe(III)-reducing microorganisms to produce copious amounts of extracellular magentites and metal-substituted magnetite nanoparticles. The Fe(III)-reducing bacteria (Theroanaerobacter ethanolicus and Shewanella sp.) have the ability to reduce Fe(III) and various metals in aqueous media and form various sized magnetite and metal-substituted magnetite nano-crystals. The Fe(III)-reducing bacteria formed metal-substituted magnetites using iron oxide plus metals (e.g., Co, Cr, Mn, Ni) under conditions of relatively low temperature (<70 °C), ambient pressure, and pH values near neutral to slightly basic (pH = 6.5 to 9). Precise biological control over activation and regulation of the biosolid-state processes can produce magnetite particles of well-defined size (typically tens of nanometers) and crystallographic morphology, containing selected dopant metals into the magnetite (Fe3−yXyO4) structure (where X = Co, Cr, Mn, Ni). Magnetite yields of up to 20 g/L per day have been observed in 20-L vessels. Water-based ferrofluids were formed with the nanometer sized, magnetite, and metal-substituted biomagnetite particles.
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Schippers, Axel, and Dagmar Kock. "Geomicrobiology of Sulfidic Mine Dumps: A Short Review." Advanced Materials Research 71-73 (May 2009): 37–41. http://dx.doi.org/10.4028/www.scientific.net/amr.71-73.37.
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The geomicrobiology of sulfidic mine dumps is reviewed. More than 30 microbiological studies of sulfidic mine dumps have been published. Mainly culturing approaches such as most probable number (MPN) or agar plates were used to study the microbial communities. More recently, molecular biological techniques such as FISH, CARD-FISH, Q-PCR, T-RFLP, DGGE, or cloning have been applied to quantify microorganisms and to investigate the microbial diversity. Aerobic Fe(II)- and sulfur compound oxidizing microorganisms oxidize pyrite, pyrrhotite and other metal sulfides and play an important role in the formation of acid mine drainage (AMD). Anaerobic microorganisms such as Fe(III)-reducing microorganisms dissolve Fe(III)(hydr)oxides and may thereby release adsorbed or precipitated metals. Sulfate-reducing microorganisms precipitate and immobilize metals. In addition to the microbial communities several biogeochemical processes have been analyzed in mine dumps. Pyrite or pyrrhotite oxidation rates have been measured by different techniques: Column experiments, humidity cells, microcalorimetry, or oxygen consumption measurements. Analyses of stable isotopes of iron, oxygen and sulfur have yielded valuable information on biogeochemical reactions. The microbiology and the biogeochemical processes in sulfidic mine dumps have to be understood for control and prevention of AMD generation and to provide different possibilities for remediation concepts. Today, remediation measures, e.g. under water storage of the waste or covering of the dumps, focus on the inhibition of pyrite oxidation to keep the toxic compounds inside the mine waste dumps. As an alternative to the inhibition of pyrite oxidation, metals which also have economic value could be extracted from mine dumps by the application of different metal extraction technologies including bioleaching.
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D, Thirumurugan, Ibrahim Adamu Karfi, Vijayakumar R, and Nithya Tg. "AN ALTERNATIVE APPROACH ON BIOREMEDIATION OF HEAVY METALS IN TANNERY EFFLUENTS WASTE USING STREPTOMYCES SP." Asian Journal of Pharmaceutical and Clinical Research 10, no. 10 (September 1, 2017): 323. http://dx.doi.org/10.22159/ajpcr.2017.v10i10.19480.
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Objective: The present study is conducted to investigate the abilities of microorganisms to degrade heavy metals in industrial tannery effluent sample.Methods: Tannery effluent sample was collected from effluent treatment plant and analyzed for physicochemical parameters. The potential microbes were isolated and identified by morphological and biochemical characterization. The sample was analyzed before and after to assess the heavy metal reducing the ability of the microorganism and the respective percentage of reduction were studied using X-ray fluorescence spectrometry.Results: The samples were initially found to be highly contaminated with chromium, nickel, and cadmium. Out of three potential isolates, the isolate Streptomyces sp. was found to exhibit a better reduction against chromium (25.7%), cadmium (14.6%), and nickel (23.1%) in 50 ppm at longer incubation period. Comparatively, the reduction abilities of all the three isolates against all the three heavy metals increased with the increase in the incubation period but decreased with the increase in initial metal ion concentration except in the case of Streptomyces sp. against nickel where the reducing ability increased with the increase in metal concentration.Conclusion: Apparently, the present study revealed that Streptomyces sp. had a better remediation potential than the indigenous Pseudomonas sp. and Aspergillus sp. Ultimately, the finding of this research has shown that the Streptomyces sp. can be used as a potent bioremediation agent for treating tannery and industrial effluent in an eco-friendly process.
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Jiang, Zhou, Meimei Shi, and Liang Shi. "Degradation of organic contaminants and steel corrosion by the dissimilatory metal-reducing microorganisms Shewanella and Geobacter spp." International Biodeterioration & Biodegradation 147 (February 2020): 104842. http://dx.doi.org/10.1016/j.ibiod.2019.104842.
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Bordoloi, Manobjyoti, Ranjan K. Sahoo, Kashyap J. Tamuli, Surovi Saikia, and Partha P. Dutta. "Plant Extracts Promoted Preparation of Silver and Gold Nanoparticles: A Systematic Review." Nano 15, no. 02 (February 2020): 2030001. http://dx.doi.org/10.1142/s1793292020300017.
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Eco-friendly synthesis of metal nanoparticles has accrued utmost interest by researchers in the last decade for their distinct properties making them applicable in different fields of science and technology. With regard to its low cost, low environmental effect, zero contamination and higher reducing potential, their synthesis by green chemistry procedure is an emerging area in nanobiotechnology. Plant-based nanoparticles produced are more stable, with high rate of synthesis and are suitable for large scale biosynthesis as compared to the use of microorganisms which require stringent control on cell cultures. Plant-based nanoparticles have advantages over other methods due to presence of biomolecules acting both as capping and reducing agents by increasing the rate of reduction and stabilization of nanoparticles. Furthermore, secondary metabolites present in plants are used for reducing metal ions in single step reaction. In this review paper, we have cited 265 research articles and have outlined 106 plant extract assisted gold and silver nanoparticles. The present review highlights the achievements of metal nanoparticle synthesis, especially silver and gold nanoparticles from plant extracts, along with factors liable for the synthesis of metal nanoparticles. It also focuses on the dye degrading properties and various biological activities of metal nanoparticles, their antimicrobial mechanism of action and the physicochemical properties that influence the biological effects of metallic nanoparticles. Biological activities of metal nanoparticles were also described, including the effect of physicochemical properties of metal nanoparticles on biological activities.
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Qi, Bei Meng, Bei Jia Wang, Chen Guang Wu, and Yi Xing Yuan. "The Disinfection Efficacy of Chlorine on Sulfate-Reducing Bacteria and Iron Bacteria in Water Supply Systems." Applied Mechanics and Materials 316-317 (April 2013): 657–60. http://dx.doi.org/10.4028/www.scientific.net/amm.316-317.657.
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Sulfate reducing bacteria (SRB) and iron reducing bacteria (IRB) that widely exist in water supply networks are the main microorganisms leading to metal corrosion in pipelines. Chlorine is widely used in drinking water supply systems. The concentration of chlorine with SRB declined rapidly after 10 mins and reached 0 mg/L finally whereas it decreased more slowly with IRB. If the concentration of chlorine is lower than 0.2mg/L, IRB cannot be sterilized. It indicates that at the end of water pipes where the concentration of chlorine is required to be 0.05mg/L, chlorine is not effective since the concentration is below the minimum requirement of removing IRB
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Bahaj, A. S., P. A. B. James, and F. D. Moeschler. "Wastewater treatment by bio-magnetic separation: a comparison of iron oxide and iron sulphide biomass recovery." Water Science and Technology 38, no. 6 (September 1, 1998): 311–17. http://dx.doi.org/10.2166/wst.1998.0266.
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Many microorganisms have an affinity to accumulate metal ions onto their surfaces, which results in metal loading of the biomass. Microbial biomineralisation of iron produces a biomass, which is often highly magnetic and can be separated from water systems by the application of a magnetic field. This paper reports on the magnetic separation of biomass containing microbial iron oxide (Fe3O4, present within magnetotactic bacteria) and iron sulphide (Fe1-XS, precipitated extracellularly by sulphate reducing bacteria) in a single wire cell. Since such bacteria can be separated magnetically, their affinity to heavy metal or organic material accumulation renders them useful for the removal of pollutants from wastewater. The relative merits of each bacterium to magnetic separation techniques in terms of applied magnetic field and processing conditions are discussed.
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Yakasai, Hafeez Muhammad, Mohd Fadhil Rahman, Motharasan Manogaran, Nur Adeela Yasid, Mohd Arif Syed, Nor Aripin Shamaan, and Mohd Yunus Shukor. "Microbiological Reduction of Molybdenum to Molybdenum Blue as a Sustainable Remediation Tool for Molybdenum: A Comprehensive Review." International Journal of Environmental Research and Public Health 18, no. 11 (May 27, 2021): 5731. http://dx.doi.org/10.3390/ijerph18115731.
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Molybdenum (Mo) microbial bioreduction is a phenomenon that is beginning to be recognized globally as a tool for the remediation of molybdenum toxicity. Molybdenum toxicity continues to be demonstrated in many animal models of spermatogenesis and oogenesis, particularly those of ruminants. The phenomenon has been reported for more than 100 years without a clear understanding of the reduction mechanism, indicating a clear gap in the scientific knowledge. This knowledge is not just fundamentally important—it is specifically important in applications for bioremediation measures and the sustainable recovery of metal from industrial or mine effluent. To date, about 52 molybdenum-reducing bacteria have been isolated globally. An increasing number of reports have also been published regarding the assimilation of other xenobiotics. This phenomenon is likely to be observed in current and future events in which the remediation of xenobiotics requires microorganisms capable of degrading or transforming multi-xenobiotics. This review aimed to comprehensively catalogue all of the characterizations of molybdenum-reducing microorganisms to date and identify future opportunities and improvements.
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Cooper, Rebecca E., Carl-Eric Wegner, Stefan Kügler, Remington X. Poulin, Nico Ueberschaar, Jens D. Wurlitzer, Daniel Stettin, Thomas Wichard, Georg Pohnert, and Kirsten Küsel. "Iron is not everything: unexpected complex metabolic responses between iron-cycling microorganisms." ISME Journal 14, no. 11 (July 20, 2020): 2675–90. http://dx.doi.org/10.1038/s41396-020-0718-z.
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Abstract Coexistence of microaerophilic Fe(II)-oxidizers and anaerobic Fe(III)-reducers in environments with fluctuating redox conditions is a prime example of mutualism, in which both partners benefit from the sustained Fe-pool. Consequently, the Fe-cycling machineries (i.e., metal-reducing or –oxidizing pathways) should be most affected during co-cultivation. However, contrasting growth requirements impeded systematic elucidation of their interactions. To disentangle underlying interaction mechanisms, we established a suboxic co-culture system of Sideroxydans sp. CL21 and Shewanella oneidensis. We showed that addition of the partner’s cell-free supernatant enhanced both growth and Fe(II)-oxidizing or Fe(III)-reducing activity of each partner. Metabolites of the exometabolome of Sideroxydans sp. CL21 are generally upregulated if stimulated with the partner´s spent medium, while S. oneidensis exhibits a mixed metabolic response in accordance with a balanced response to the partner. Surprisingly, RNA-seq analysis revealed genes involved in Fe-cycling were not differentially expressed during co-cultivation. Instead, the most differentially upregulated genes included those encoding for biopolymer production, lipoprotein transport, putrescine biosynthesis, and amino acid degradation suggesting a regulated inter-species biofilm formation. Furthermore, the upregulation of hydrogenases in Sideroxydans sp. CL21 points to competition for H2 as electron donor. Our findings reveal that a complex metabolic and transcriptomic response, but not accelerated formation of Fe-end products, drive interactions of Fe-cycling microorganisms.
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Bilyy, O., I. Kotsyumbas, I. Kushnir, T. Grechukh, S. Hnatush, O. Maslovska, B. Gutyj, and V. Kushnir. "Light-scattering properties of microorganisms Desulfuromonas acetoxidans by influence of silver." Ukrainian Journal of Veterinary and Agricultural Sciences 4, no. 1 (March 1, 2021): 7–11. http://dx.doi.org/10.32718/ujvas4-1.02.
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The article deals with the concentration changes and relative content of bacterial cells of Desulfuromonas acetoxidans in the intervals of sizes 0.2–2.0 µm under the influence of nano silver particles. Correlation between these changes of light-scattering properties of bacterial cells and growth abilities of bacteria Desulfuromonas acetoxidans under inflence of silver nanoparticles and ions has been shown. The purpose of the work was to research the intensity of processes the change of indexes of the antioxidant system the cells of Desulfuromonas acetoxidans at influence of silver nanoparticles and silver nitrate. The influence of various concentrations of silver nanoparticles and silver nitrate on enzymatic activity of catalase and reduced glutathione synthesis by Desulfuromonas аcetoxidans cells under their cultivation with fumarate addition and with absence of sulphur has been determined. Specific catalase activity increased with enhancing of concentration and duration of bacterial cultivation under the addition of this salt. The highest specific catalase activity was determined on the second day of bacterial growth under the influence of all concentration range of investigated metal salt. The reduced glutathione content under silver nitrate and silver nanoparticles exposure varied depending on the cultivation time and metal concentration. The maximum reduced glutathione content has been observed. The result of catalase activity changes and glutathione content changes of sulfur-reducing D. acetoxidans bacteria cell-free extracts and has been investigated under the influence of different concentrations of Ag nanoparticles during four days of cultivation has been investigated.
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Miller, Robert B., Kenton Lawson, Anwar Sadek, Chelsea N. Monty, and John M. Senko. "Uniform and Pitting Corrosion of Carbon Steel byShewanella oneidensisMR-1 under Nitrate-Reducing Conditions." Applied and Environmental Microbiology 84, no. 12 (April 13, 2018): e00790-18. http://dx.doi.org/10.1128/aem.00790-18.
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ABSTRACTDespite observations of steel corrosion in nitrate-reducing environments, processes of nitrate-dependent microbially influenced corrosion (MIC) remain poorly understood and difficult to identify. We evaluated carbon steel corrosion byShewanella oneidensisMR-1 under nitrate-reducing conditions using a split-chamber/zero-resistance ammetry (ZRA) technique. This approach entails the deployment of two metal (carbon steel 1018 in this case) electrodes into separate chambers of an electrochemical split-chamber unit, where the microbiology or chemistry of the chambers can be manipulated. This approach mimics the conditions of heterogeneous metal coverage that can lead to uniform and pitting corrosion. The current between working electrode 1 (WE1) and WE2 can be used to determine rates, mechanisms, and, we now show, extents of corrosion. WhenS. oneidensiswas incubated in the WE1 chamber with lactate under nitrate-reducing conditions, nitrite transiently accumulated, and electron transfer from WE2 to WE1 occurred as long as nitrite was present. Nitrite in the WE1 chamber (withoutS. oneidensis) induced electron transfer in the same direction, indicating that nitrite cathodically protected WE1 and accelerated the corrosion of WE2. WhenS. oneidensiswas incubated in the WE1 chamber without an electron donor, nitrate reduction proceeded, and electron transfer from WE2 to WE1 also occurred, indicating that the microorganism could use the carbon steel electrode as an electron donor for nitrate reduction. Our results indicate that under nitrate-reducing conditions, uniform and pitting carbon steel corrosion can occur due to nitrite accumulation and the use of steel-Fe(0) as an electron donor, but conditions of sustained nitrite accumulation can lead to more-aggressive corrosive conditions.IMPORTANCEMicrobially influenced corrosion (MIC) causes damage to metals and metal alloys that is estimated to cost over $100 million/year in the United States for prevention, mitigation, and repair. While MIC occurs in a variety of settings and by a variety of organisms, the mechanisms by which microorganisms cause this damage remain unclear. Steel pipe and equipment may be exposed to nitrate, especially in oil and gas production, where this compound is used for corrosion and “souring” control. In this paper, we show uniform and pitting MIC under nitrate-reducing conditions and that a major mechanism by which it occurs is via the heterogeneous cathodic protection of metal surfaces by nitrite as well as by the microbial oxidation of steel-Fe(0).
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North, Nadia N., Sherry L. Dollhopf, Lainie Petrie, Jonathan D. Istok, David L. Balkwill, and Joel E. Kostka. "Change in Bacterial Community Structure during In Situ Biostimulation of Subsurface Sediment Cocontaminated with Uranium and Nitrate." Applied and Environmental Microbiology 70, no. 8 (August 2004): 4911–20. http://dx.doi.org/10.1128/aem.70.8.4911-4920.2004.
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ABSTRACT Previous studies have demonstrated that metal-reducing microorganisms can effectively promote the precipitation and removal of uranium from contaminated groundwater. Microbial communities were stimulated in the acidic subsurface by pH neutralization and addition of an electron donor to wells. In single-well push-pull tests at a number of treated sites, nitrate, Fe(III), and uranium were extensively reduced and electron donors (glucose, ethanol) were consumed. Examination of sediment chemistry in cores sampled immediately adjacent to treated wells 3.5 months after treatment revealed that sediment pH increased substantially (by 1 to 2 pH units) while nitrate was largely depleted. A large diversity of 16S rRNA gene sequences were retrieved from subsurface sediments, including species from the α, β, δ, and γ subdivisions of the class Proteobacteria, as well as low- and high-G+C gram-positive species. Following in situ biostimulation of microbial communities within contaminated sediments, sequences related to previously cultured metal-reducing δ-Proteobacteria increased from 5% to nearly 40% of the clone libraries. Quantitative PCR revealed that Geobacter-type 16S rRNA gene sequences increased in biostimulated sediments by 1 to 2 orders of magnitude at two of the four sites tested. Evidence from the quantitative PCR analysis corroborated information obtained from 16S rRNA gene clone libraries, indicating that members of the δ-Proteobacteria subdivision, including Anaeromyxobacter dehalogenans-related and Geobacter-related sequences, are important metal-reducing organisms in acidic subsurface sediments. This study provides the first cultivation-independent analysis of the change in metal-reducing microbial communities in subsurface sediments during an in situ bioremediation experiment.
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Natarajan, K. A. "Microbial Aspects of Acid Generation and Bioremediation with Relevance to Indian Mining." Advanced Materials Research 71-73 (May 2009): 645–48. http://dx.doi.org/10.4028/www.scientific.net/amr.71-73.645.
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The role of Acidithiobacillus group of bacteria in acid generation and heavy metal dissolution was studied with relevance to some Indian mines. Microorganisms implicated in acid generation such as Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans were isolated from abandoned mines, waste rocks and tailing dumps. Arsenite oxidizing Thiomonas and Bacillus group of bacteria were isolated and their ability to oxidize As (III) to As (V) established. Mine isolated Sulfate reducing bacteria were used to remove dissolved copper, zinc, iron and arsenic from solutions.
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Hnatush, S. O., O. M. Moroz, G. V. Yavorska, and B. M. Borsukevych. "Sulfidogenic and metal reducing activities of Desulfuromonas genus bacteria under the influence of copper chloride." Biosystems Diversity 26, no. 3 (August 20, 2018): 218–26. http://dx.doi.org/10.15421/011833.
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The selection of strains isolated from technogenically altered ecotopes and resistant to contamination, capable of metabolizing a wide range of pollutants is a task highly relevant for creation of new methods for environmental purification. Sulphur-reducing bacteria of the Desulfuromonas genus carry out dissimilatory reduction not only of S0 but also oxidized forms of metals. Intensity of anaerobic respiration of microorganisms in polluted environments is determined by level of their adaptation to stress factors, in particular, copper (II) compounds. The aim of this work was to investigate the influence of copper (II) chloride on H2S production by Desulfuromonas sp. strains isolated by us from Yavorivske Lake, to determine the efficiency of Cu2+ precipitation by hydrogen sulfide, to analyse the possibility of usage by bacteria of CuCl2 as an electron acceptor of anaerobic respiration and to study the influence of Cu2+ on usage by these microorganisms of ferric (III) citrate, potassium dichromate or manganese (IV) oxide as electron acceptors. Bacteria were grown under anaerobic conditions in Kravtsov-Sorokin medium. To study the influence of Cu2+ on production by bacteria of H2S, their cells were incubated with CuCl2 (0.5–4.0 mM), washed and cultivated in a medium with S0. To determine the level of Cu2+ binding by H2S, produced by bacteria, cells were grown in a medium with CuCl2 (0.5–4.0 mM) and S0. To investigate the ability of bacteria to use copper (II) ions as electron acceptors, they were cultivated in a medium with CuCl2 (1.74–10.41 mM). To study the influence of Cu2+ on usage by bacteria of metal compounds as electron acceptors, their cells were incubated with CuCl2 (0.5–4.0 mM), washed and cultivated in media with C6H5O7Fe, K2Cr2O7 or MnO2 (1.74–10.41 mM). Biomass was determined by the turbidimetric method. In the cultural liquid the content of H2S was determined quantitatively by the spectrophotometric method, qualitatively – presence of Cu2+. Content of CuS in the growth medium was determined by weight method. Desulfuromonas sp. bacteria was revealed to be resistant to 2.0–2.5 mM copper (II) ions. Under the influence of 3.0–4.0 mM CuCl2 in the incubation mixture, sulfidogenic activity of bacteria decreased more than twice. The efficiency of Cu2+ binding in form of CuS by H2S produced by bacteria reached 97.3–100.0% at presence in the medium with S0 of up to 1.5 mM CuCl2. Bacteria used CuCl2 (1.74–10.41 mM) as an electron acceptor in the process of anaerobic respiration. The addition of 2.5–3.0 mM CuCl2 to the incubation mixture caused inhibition of metal reducing activity of cells, growth of all strains in media with 1.74–10.41 mM ferric (III) citrate, potassium dichromate or manganese (IV) oxide as electron acceptors decreased by 2.6 times. Almost complete precipitation up to 1.5 mM copper (II) ions in form of CuS by H2S produced by bacteria and ability to reduce up to 10.41 mM CuCl2, C6H5O7Fe, K2Cr2O7 or MnO2 in the process of anaerobic respiration indicates a high adaptation of the bacteria strains investigated by us to stress factors, in particular, the influence of CuCl2. We have proved the possibility of using Desulfuromonas sp. in biotechnologies for purification of environments with complex contamination from copper (II) compounds.
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Parada, Pilar, Pedro Morales, Roberto Collao, Roberto A. Bobadilla-Fazzini, and Ricardo Badilla. "Biomass Production and Inoculation of Industrial Bioleaching Processes." Advanced Materials Research 825 (October 2013): 296–300. http://dx.doi.org/10.4028/www.scientific.net/amr.825.296.
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Microbial activity inleaching processes accounts for 4% of today’s copper produced in the world. Factorsrelated with lesser overall metal recoveries, no recovery of precious metalsand molybdenum in comparison with conventional concentration/smelting &refining technologies and the high prices of metals inhibit the use of bioleachingat a larger scale. In order to increase bioleaching rates and overall metal recoveries,continuous inoculation of the ore with a leaching solution containing specific adaptedconsortium of microorganisms, allows an early expression of microbial activity,reducing 2-3 fold the time required by ore native bearing microflora to grow.This leaching solution concentrated in microorganisms can be produced by meansof bioreactors operated in continuous regime. Unfortunately biomining microorganisms have a very low duplication timewhen comparing to common microbes like E.colior B. subtilis, that forces the useof huge volume bioreactors in the case of conventional bioreactors, to ensurethe growth of microorganisms have sufficient residence time. To overcome thisproblem, we have designed a very efficient air-lift bioreactor (Patent Registration No. CL 48319), that can be used at industrial operations for the production ofsolutions with a high concentration of biomining microorganisms, for theinoculation of bioleaching heaps, with lesser residence time in comparison toconventional bioreactors. Ourbioreactor has an internal recirculation for producing sulfide-ore bioleachingsolutions, with a phase-separating and solids-recirculation system, without theneed to impel the suspension containing the solids towards the bioreactor withpumps, using diatomaceous earth, ferric precipitates and/or elemental sulfur asa solid support to immobilize iron and/or sulfur-oxidizing microorganisms. Dependingon the source of energy supplied for the growth of the microorganisms, thebioreactor can produce either a solution concentrated in ferric ions andiron-oxidizing bacteria or sulfur oxidizing bacteria. In order to validate ourbioreactor design at industrial scale, a trial was carried out in an air-liftbioreactor of 35 m3 nominal capacity, which is part of a biomassplant located in Radomiro Tomic Division of CODELCO. In this article, theresults of the test proving the advantages and satisfactory design of ourbioreactor for producing continuously iron-oxidizing bacteria and sulfuroxidizing bacteria for inoculation and irrigation of heaps and dumps are shown.
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Guerrero Correa, Matías, Fernanda B. Martínez, Cristian Patiño Vidal, Camilo Streitt, Juan Escrig, and Carol Lopez de Dicastillo. "Antimicrobial metal-based nanoparticles: a review on their synthesis, types and antimicrobial action." Beilstein Journal of Nanotechnology 11 (September 25, 2020): 1450–69. http://dx.doi.org/10.3762/bjnano.11.129.
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The investigation of novel nanoparticles with antimicrobial activity has grown in recent years due to the increased incidence of nosocomial infections occurring during hospitalization and food poisoning derived from foodborne pathogens. Antimicrobial agents are necessary in various fields in which biological contamination occurs. For example, in food packaging they are used to control food contamination by microbes, in the medical field the microbial agents are important for reducing the risk of contamination in invasive and routine interventions, and in the textile industry, they can limit the growth of microorganisms due to sweat. The combination of nanotechnology with materials that have an intrinsic antimicrobial activity can result in the development of novel antimicrobial substances. Specifically, metal-based nanoparticles have attracted much interest due to their broad effectiveness against pathogenic microorganisms due to their high surface area and high reactivity. The aim of this review was to explore the state-of-the-art in metal-based nanoparticles, focusing on their synthesis methods, types, and their antimicrobial action. Different techniques used to synthesize metal-based nanoparticles were discussed, including chemical and physical methods and “green synthesis” methods that are free of chemical agents. Although the most studied nanoparticles with antimicrobial properties are metallic or metal-oxide nanoparticles, other types of nanoparticles, such as superparamagnetic iron-oxide nanoparticles and silica-releasing systems also exhibit antimicrobial properties. Finally, since the quantification and understanding of the antimicrobial action of metal-based nanoparticles are key topics, several methods for evaluating in vitro antimicrobial activity and the most common antimicrobial mechanisms (e.g., cell damage and changes in the expression of metabolic genes) were discussed in this review.
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Podobas, Ewa Izabela, and Agnieszka Rożek. "Effect of copper upon the actions of sulphate-reducing bacteria isolated from soil contaminated by crude oil and heavy metals / Wpływ miedzi na aktywność bakterii redukujących siarczany wyizolowanych z gleby zanieczyszczonej ropą naftową i metalami ciężkimi." Ochrona Srodowiska i Zasobów Naturalnych 26, no. 4 (December 1, 2015): 20–25. http://dx.doi.org/10.1515/oszn-2015-0028.
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Abstract In the present study, copper tolerance by a mixed culture of sulphate-reducing bacteria (SRB) were evaluated. These sulphidogenic microbial communities were isolated from soils polluted by crude oil, oil-derived products and heavy metals (from selected areas of crude oil mines in south-eastern Poland). Copper tolerance of SRB was tested in modified Postgate C medium with ethanol and lactate as the sole carbon source and copper chloride at concentrations ranging from 0 to 1500 mg/l. Bacterial growth and sulphate reduction were possible between 100 and 1500 mg/l of initial copper concentration. Active sulphate reduction - maximum of 53% was observed in the cultures. Molecular analysis indicated not only the presence of SRB but also other microorganisms that are capable of living in environments contaminated by heavy metals. The high environmental sulphide concentrations produced by SRB lead to the precipitation of any biogenic mineral phases such as metal sulphides. As a result, soluble metal ion concentrations in the microenvironment of SRB are, therefore, extremely low. This process allows SRB to grow in environments containing high levels of toxic metals. Studies on SRB tolerance to heavy metals are extremely important because of the possibility of using this group of microorganisms for the bioremediation and microbial revitalisation of areas contaminated by heavy metals.
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Kermer, René, Sabrina Hedrich, Beate Brett, Daniel Schrader, Konstantin Räuchle, Petra Schönherr, Axel Schippers, Susan Reichel, Franz Glombitza, and Eberhard Janneck. "Metal Recovery and Exploitation of Lignite Ashes by Combined Physicochemical and Biotechnological Approaches." Advanced Materials Research 1130 (November 2015): 296–99. http://dx.doi.org/10.4028/www.scientific.net/amr.1130.296.
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Ashes from lignite combustion for power generation contain strategic metals, metalloids and rare earth elements and may thus be a potential source of industrially demanded metals. The presented project focuses on the assessment and exploitation of this potential raw material. Lignite ash assessment showed that largest ash amounts for potential exploitation are available in the Lusatia district, Saxony. Mechanical ash pre-treatment in principle provided enriched fractions by different methods but still suffered from low yields of enriched fractions. Thermal ash processing showed multiple significant phase changes compared to original ash. Subsequent chemical leaching using HClaq resulted in high metal extraction. Alternatively, bioleaching was applied using acidophilic Fe (II) and S-oxidizing or Fe (III)-reducing microorganisms (MO) as well as heterotrophic MO. The results indicated likewise high and partly specific metal mobilizations. Industrial ash exploitation was accomplished by direct reaction with acids resulting in Al-Fe-solutions which potentially can be applied in water treatment.
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Dong, Yiran, Robert A. Sanford, Maxim I. Boyanov, Kenneth M. Kemner, Theodore M. Flynn, Edward J. O'Loughlin, Yun-juan Chang, et al. "Orenia metallireducens sp. nov. Strain Z6, a Novel Metal-Reducing Member of the Phylum Firmicutes from the Deep Subsurface." Applied and Environmental Microbiology 82, no. 21 (August 26, 2016): 6440–53. http://dx.doi.org/10.1128/aem.02382-16.
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ABSTRACTA novel halophilic and metal-reducing bacterium,Orenia metallireducensstrain Z6, was isolated from briny groundwater extracted from a 2.02 km-deep borehole in the Illinois Basin, IL. This organism shared 96% 16S rRNA gene similarity withOrenia marismortuibut demonstrated physiological properties previously unknown for this genus. In addition to exhibiting a fermentative metabolism typical of the genusOrenia, strain Z6 reduces various metal oxides [Fe(III), Mn(IV), Co(III), and Cr(VI)], using H2as the electron donor. Strain Z6 actively reduced ferrihydrite over broad ranges of pH (6 to 9.6), salinity (0.4 to 3.5 M NaCl), and temperature (20 to 60°C). At pH 6.5, strain Z6 also reduced more crystalline iron oxides, such as lepidocrocite (γ-FeOOH), goethite (α-FeOOH), and hematite (α-Fe2O3). Analysis of X-ray absorption fine structure (XAFS) following Fe(III) reduction by strain Z6 revealed spectra from ferrous secondary mineral phases consistent with the precipitation of vivianite [Fe3(PO4)2] and siderite (FeCO3). The draft genome assembled for strain Z6 is 3.47 Mb in size and contains 3,269 protein-coding genes. Unlike the well-understood iron-reducingShewanellaandGeobacterspecies, this organism lacks thec-type cytochromes for typical Fe(III) reduction. Strain Z6 represents the first bacterial species in the genusOrenia(orderHalanaerobiales) reported to reduce ferric iron minerals and other metal oxides. This microbe expands both the phylogenetic and physiological scopes of iron-reducing microorganisms known to inhabit the deep subsurface and suggests new mechanisms for microbial iron reduction. These distinctions from otherOreniaspp. support the designation of strain Z6 as a new species,Orenia metallireducenssp. nov.IMPORTANCEA novel iron-reducing species,Orenia metallireducenssp. nov., strain Z6, was isolated from groundwater collected from a geological formation located 2.02 km below land surface in the Illinois Basin, USA. Phylogenetic, physiologic, and genomic analyses of strain Z6 found it to have unique properties for iron reducers, including (i) active microbial iron-reducing capacity under broad ranges of temperatures (20 to 60°C), pHs (6 to 9.6), and salinities (0.4 to 3.5 M NaCl), (ii) lack ofc-type cytochromes typically affiliated with iron reduction inGeobacterandShewanellaspecies, and (iii) being the only member of theHalanaerobialescapable of reducing crystalline goethite and hematite. This study expands the scope of phylogenetic affiliations, metabolic capacities, and catalytic mechanisms for iron-reducing microbes.
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Miletto, M., K. H. Williams, A. L. N'Guessan, and D. R. Lovley. "Molecular Analysis of the Metabolic Rates of Discrete Subsurface Populations of Sulfate Reducers." Applied and Environmental Microbiology 77, no. 18 (July 15, 2011): 6502–9. http://dx.doi.org/10.1128/aem.00576-11.
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ABSTRACTElucidating thein situmetabolic activity of phylogenetically diverse populations of sulfate-reducing microorganisms that populate anoxic sedimentary environments is key to understanding subsurface ecology. Previous pure culture studies have demonstrated that the transcript abundance of dissimilatory (bi)sulfite reductase genes is correlated with the sulfate-reducing activity of individual cells. To evaluate whether expression of these genes was diagnostic for subsurface communities, dissimilatory (bi)sulfite reductase gene transcript abundance in phylogenetically distinct sulfate-reducing populations was quantified during a field experiment in which acetate was added to uranium-contaminated groundwater. Analysis ofdsrABsequences prior to the addition of acetate indicated thatDesulfobacteraceae,Desulfobulbaceae, andSyntrophaceae-related sulfate reducers were the most abundant. QuantifyingdsrBtranscripts of the individual populations suggested thatDesulfobacteraceaeinitially had higherdsrBtranscripts per cell thanDesulfobulbaceaeorSyntrophaceaepopulations and that the activity ofDesulfobacteraceaeincreased further when the metabolism of dissimilatory metal reducers competing for the added acetate declined. In contrast,dsrBtranscript abundance inDesulfobulbaceaeandSyntrophaceaeremained relatively constant, suggesting a lack of stimulation by added acetate. The indication of higher sulfate-reducing activity in theDesulfobacteraceaewas consistent with the finding thatDesulfobacteraceaebecame the predominant component of the sulfate-reducing community. Discontinuing acetate additions resulted in a decline indsrBtranscript abundance in theDesulfobacteraceae. These results suggest that monitoring transcripts of dissimilatory (bi)sulfite reductase genes in distinct populations of sulfate reducers can provide insight into the relative rates of metabolism of different components of the sulfate-reducing community and their ability to respond to environmental perturbations.
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Rathgeber, Christopher, Natalia Yurkova, Erko Stackebrandt, J. Thomas Beatty, and Vladimir Yurkov. "Isolation of Tellurite- and Selenite-Resistant Bacteria from Hydrothermal Vents of the Juan de Fuca Ridge in the Pacific Ocean." Applied and Environmental Microbiology 68, no. 9 (September 2002): 4613–22. http://dx.doi.org/10.1128/aem.68.9.4613-4622.2002.
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ABSTRACT Deep-ocean hydrothermal-vent environments are rich in heavy metals and metalloids and present excellent sites for the isolation of metal-resistant microorganisms. Both metalloid-oxide-resistant and metalloid-oxide-reducing bacteria were found. Tellurite- and selenite-reducing strains were isolated in high numbers from ocean water near hydrothermal vents, bacterial films, and sulfide-rich rocks. Growth of these isolates in media containing K2TeO3 or Na2SeO3 resulted in the accumulation of metallic tellurium or selenium. The MIC of K2TeO3 ranged from 1,500 to greater than 2,500 μg/ml, and the MIC of Na2SeO3 ranged from 6,000 to greater than 7,000 μg/ml for 10 strains. Phylogenetic analysis of 4 of these 10 strains revealed that they form a branch closely related to members of the genus Pseudoalteromonas, within the γ-3 subclass of the Proteobacteria. All 10 strains were found to be salt tolerant, pH tolerant, and thermotolerant. The metalloid resistance and morphological, physiological, and phylogenetic characteristics of newly isolated strains are described.
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Pleshakova, Ekaterina, Clement Ngun, Mikhail Reshetnikov, and Maxim Viktorovich Larionov. "Evaluation of the Ecological Potential of Microorganisms for Purifying Water with High Iron Content." Water 13, no. 7 (March 26, 2021): 901. http://dx.doi.org/10.3390/w13070901.
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The ability of a number of microorganisms isolated from highly magnetic soil of the city Mednogorsk to oxidize Fe (II) under conditions of periodic cultivation in a liquid medium was studied. Among the studied microorganisms, two microbial isolates with maximum growth characteristics and iron-oxidizing activity were selected and identified: Bacillus megaterium 69.3 and B. megaterium 69.5. Individual levels of metal resistance of the isolates were determined: maximum tolerated concentration (MTC) for Fe (II) of the isolates B. megaterium 69.3 and B. megaterium 69.5 was 1200 mg L−1, minimum inhibitory concentration (MIC) was 1800 mg L−1. Both microbial isolates actively oxidized Fe (II) by reducing its high concentration in the medium (1.19 g L−1) by 33 and 39% during 14 days of culturing. Total increase in the biomass of B. megaterium 69.3 and B. megaterium 69.5 after 14 days of culturing was 15.3 and 14.7 g L−1; the active parts of the biomass increased 8.7- and 6.9-fold compared to the inoculum dose, respectively. These microbial isolates could be used in future in the biotechnological process of water purification with increased/high levels of Fe (II).
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Calbo, Vicente, Octavio Javier Furlong, and Silvia Viviana Julián. "Metal Biocorrosion of a Water Well: A Case Study." KnE Engineering 3, no. 1 (February 11, 2018): 301. http://dx.doi.org/10.18502/keg.v3i1.1435.
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Recently, in the city of La Rioja, the Microbiologically-Induced Corrosion (MIC) phenomenon has been confirmed. The last studied case corresponds to the water well of the La Rioja Regional Faculty of the National Technological University (UTN), where the water well facilities showed signs of this phenomenon.These microorganisms catalyze the iron (and magnesium) oxidation reactions, solubilizing or solubilizing and precipitating the metal. Confirming the existence of the MIC phenomenon is essential to mitigate or solve the problem.The laboratory work consisted in processing pipe and pump samples extracted after the well ceased to be used, at three initial temperatures and with different culture media, trying to cultivate, reproduce, and isolate and identify the different species.Thus, through culture methodology, the existence of a mixed flora featuring iron bacteria and sulfate-reducing bacteria was confirmed.Complementary Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray Spectroscopy (EDS) spectroscopy scans allowed to visualize the bacteria, the damage to the analyzed material, and the morphology of the bioprecipitation.This little-known phenomenon causes significant economic losses and should therefore be taken into account in the execution as well as the maintenance of wells. Keywords: Metal Corrosion, Microbiologically Induced Corrosion, Water Well, Bacteria.
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Weijma, Jan, Paula Gonzàles-Contreras, and Cees N. J. Buisman. "Chemical vs. Biological Crystals, all the Same?" Solid State Phenomena 262 (August 2017): 559–62. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.559.
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Using microorganisms to mediate crystallisation of metals and minerals in open-culture bioreactors has potential to recover recyclable materials from dilute aqueous streams, but also to prevent their emission to the environment. Although this potential is already exploited in practice to some extent, biological crystallization for metal recovery is still largely a black box technology with limited understanding of the role of the microorganisms in the crystallization, and the differences with chemical crystallisation. Using biocrystallisation of scorodite (FeAsO4.2H2O) and sphalerite (ZnS) as examples we propose that the role of microorganisms strongly depends on established saturation state of the solution. For scorodite, microorganisms are used to exert control over the crystallization as their ferrous iron-oxidizing activity keeps the solution slightly oversaturated. Also, the oversaturation level is kept homogeneous because of continuous biological formation of the reactant ferrous iron throughout the solution. In continuous bioreactor experiments on which we reported previously, scorodite crystal sizes still increased after 72 days of bioreactor operation indicating that indeed crystal growth was favored over nucleation. On the other hand, in our experiments with zinc sulfide, crystallization proceeded in highly oversaturated solutions in a continuous sulfate reducing bioreactor fed with a zinc sulfate solution and H2/CO2 as electron donor and carbon source. The high oversaturation likely resulted in dominant primary nucleation in the bulk solution, with little or no control over crystal growth, even though agglomeration may still have occurred. This was exemplified by particle sizes which decreased in the bioreactor experiment and remained stable after already about 2 weeks of operation.
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Tortella, Gonzalo, Olga Rubilar, Paola Fincheira, Joana C. Pieretti, Paola Duran, Isabella M. Lourenço, and Amedea B. Seabra. "Bactericidal and Virucidal Activities of Biogenic Metal-Based Nanoparticles: Advances and Perspectives." Antibiotics 10, no. 7 (June 28, 2021): 783. http://dx.doi.org/10.3390/antibiotics10070783.
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Much progress has been achieved in the preparation and application of engineered nanoparticles (NPs) in the field of medicine, mainly for antibacterial and antiviral applications. In the war against bacteria and viruses, besides traditional antibiotics and antiviral drugs, metal-based nanoparticles, such as silver (AgNPs), copper (CuNPs), copper oxides (CuO-NPs), iron oxide (FeO-NPs), zinc oxide (ZnO-NPs), and titanium oxide (TiO2-NPs) have been used as potent antimicrobial agents. These nanoparticles can be synthesized by traditional methods, such as chemical and physical routes, or more recently by biogenic processes. A great variety of macro and microorganisms can be successfully used as reducing agents of metal salt precursors in the biogenic synthesis of metal-based NPs for antimicrobial activity. Depending on the nature of the biological agent, NPs with different sizes, aggregation states, morphology, surface coatings and charges can be obtained, leading to different antimicrobial effects. Considering the drug resistance to traditional therapies, the development of versatile nanomaterials with potent antimicrobial effects is under intensive investigation. In this sense, this review presents and discusses the recent progress in the preparation and application of metal-based nanoparticles biogenically synthesized for antibacterial and antivirus applications. The strength and limitations are critically discussed.
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Cotoras, Davor, Cristian Hurtado, and Pabla Viedma. "Integrated Sulfate Reduction and Biosorption Process for the Treatment of Mine Drainages." Solid State Phenomena 262 (August 2017): 582–86. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.582.
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Sulfate is a pollutant present in the mining waste water and acid mine drainage. High levels of sulfate can generate important environmental problems. One of the alternatives proposed for the treatment of water with high levels of sulfate is the use of sulfate-reducing microorganisms. This work describes the synergistic combination of a treatment system for the removal of metals by biosorption with the strain Bacillus sp. NRRL-B-30881 to reduce the inhibiting concentration of metals in waters, followed by a new process of sulfate removal that uses a halotolerant sulfate-reducing microbial consortium. The results show that the sulfate reducing consortium can be cultured and is able to reduce the sulfate concentration using cheaper complex organic substrates like spirulina, cellulose and industrial starch. The sulfate reducing consortium was cultured on a bioreactor with Celite R-635, as support material. Using this bioreactor it was possible to reduce the sulfate concentration in the culture medium in batch or semi-continuous operation. An acid mine drainage was pretreated by lime and treated by biosortion in order to increase the pH and reduce the heavy metals concentration. Subsequently the remaining sulfate was removed by the developed process. This integrated biological process represents a more economical alternative for the removal of metal by biosortion and the removal of sulfate using a sulfate reducing consortium.
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Nancucheo, Ivan, José A. P. Bitencourt, Prafulla K. Sahoo, Joner Oliveira Alves, José O. Siqueira, and Guilherme Oliveira. "Recent Developments for Remediating Acidic Mine Waters Using Sulfidogenic Bacteria." BioMed Research International 2017 (2017): 1–17. http://dx.doi.org/10.1155/2017/7256582.
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Acidic mine drainage (AMD) is regarded as a pollutant and considered as potential source of valuable metals. With diminishing metal resources and ever-increasing demand on industry, recovering AMD metals is a sustainable initiative, despite facing major challenges. AMD refers to effluents draining from abandoned mines and mine wastes usually highly acidic that contain a variety of dissolved metals (Fe, Mn, Cu, Ni, and Zn) in much greater concentration than what is found in natural water bodies. There are numerous remediation treatments including chemical (lime treatment) or biological methods (aerobic wetlands and compost bioreactors) used for metal precipitation and removal from AMD. However, controlled biomineralization and selective recovering of metals using sulfidogenic bacteria are advantageous, reducing costs and environmental risks of sludge disposal. The increased understanding of the microbiology of acid-tolerant sulfidogenic bacteria will lead to the development of novel approaches to AMD treatment. We present and discuss several important recent approaches using low sulfidogenic bioreactors to both remediate and selectively recover metal sulfides from AMD. This work also highlights the efficiency and drawbacks of these types of treatments for metal recovery and points to future research for enhancing the use of novel acidophilic and acid-tolerant sulfidogenic microorganisms in AMD treatment.
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Moonsri, Piyarut, Wilaiporn Pongpian, and Prayak Juantrong. "Electricity Production from Organic Wastes Fermentation by Microbial Fuel Cell Process." Applied Mechanics and Materials 855 (October 2016): 91–97. http://dx.doi.org/10.4028/www.scientific.net/amm.855.91.
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This research studied the electricity production from organic wastes fermentation by microbial fuel cell by using a single chamber microbial fuel cell (SCMFC). Two sizes (1 L and 10 L) of simple SCMFC were fabricated by using a cylindrical plastic tank which anode compartment and cathode compartment separated by plastic plate with hole and covered with cotton fabric. The anode electrode contacted with organic matter and microorganisms where anaerobic reaction occurred to generate electron and proton. The electrons transferred through an external circuit while the protons diffused through the solution to the cathode electrode for reducing oxygen to water. From the study of the effect of different electrode types (carbon graphite rod, zinc metal, and copper metal) to the electricity generation using the SCMFC size 1 L in fermentation with synthetic sweetness solution (22%Brix) and the effective microorganism (EM) for 36 hrs, it found that the fuel cell which used copper metal as electrode produced electricity increasing over the times and has more efficient than the other electrode types. The study of electricity generation from organic waste fermentation by using the SCMFC size 10 L and using copper metal as electrode, the results showed that the fermentation of pineapple waste produced the current density, potential density, and power density higher than the fermentation of bananas and the fermentation of food garbage with EM. An optimal period of time for the production of electricity from this microbial fuel cell is the first five days of fermentation that the cells has voltage »500 mV, the current density 25.52 mA m-2, potential density 104.69 V m-2 and power density 12.59 mW m-2, and then decline over time five days (120 hrs). Moreover the bio-liquid fertilizer and the residues from the fermentation can be further used in agricultural because of the nutrient content (N, P, K), organic carbon and organic material contents available.
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Obeid, Muhammad H., Jana Oertel, Marc Solioz, and Karim Fahmy. "Mechanism of Attenuation of Uranyl Toxicity by Glutathione in Lactococcus lactis." Applied and Environmental Microbiology 82, no. 12 (April 8, 2016): 3563–71. http://dx.doi.org/10.1128/aem.00538-16.
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ABSTRACTBoth prokaryotic and eukaryotic organisms possess mechanisms for the detoxification of heavy metals, and these mechanisms are found among distantly related species. We investigated the role of intracellular glutathione (GSH), which, in a large number of taxa, plays a role in protection against the toxicity of common heavy metals. Anaerobically grownLactococcus lactiscontaining an inducible GSH synthesis pathway was used as a model organism. Its physiological condition allowed study of putative GSH-dependent uranyl detoxification mechanisms without interference from additional reactive oxygen species. By microcalorimetric measurements of metabolic heat during cultivation, it was shown that intracellular GSH attenuates the toxicity of uranium at a concentration in the range of 10 to 150 μM. In this concentration range, no effect was observed with copper, which was used as a reference for redox metal toxicity. At higher copper concentrations, GSH aggravated metal toxicity. Isothermal titration calorimetry revealed the endothermic binding of U(VI) to the carboxyl group(s) of GSH rather than to the reducing thiol group involved in copper interactions. The data indicate that the primary detoxifying mechanism is the intracellular sequestration of carboxyl-coordinated U(VI) into an insoluble complex with GSH. The opposite effects on uranyl and on copper toxicity can be related to the difference in coordination chemistry of the respective metal-GSH complexes, which cause distinct growth phase-specific effects on enzyme-metal interactions.IMPORTANCEUnderstanding microbial metal resistance is of particular importance for bioremediation, where microorganisms are employed for the removal of heavy metals from the environment. This strategy is increasingly being considered for uranium. However, little is known about the molecular mechanisms of uranyl detoxification. Existing studies of different taxa show little systematics but hint at a role of glutathione (GSH). Previous work could not unequivocally demonstrate a GSH function in decreasing the presumed uranyl-induced oxidative stress, nor could a redox-independent detoxifying action of GSH be identified. Combining metabolic calorimetry with cell number-based assays and genetics analysis enables a novel and general approach to quantify toxicity and relate it to molecular mechanisms. The results show that GSH-expressing microorganisms appear advantageous for uranyl bioremediation.
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Edwards, Marcus J., Gaye F. White, Colin W. Lockwood, Matthew C. Lawes, Anne Martel, Gemma Harris, David J. Scott, David J. Richardson, Julea N. Butt, and Thomas A. Clarke. "Structural modeling of an outer membrane electron conduit from a metal-reducing bacterium suggests electron transfer via periplasmic redox partners." Journal of Biological Chemistry 293, no. 21 (April 10, 2018): 8103–12. http://dx.doi.org/10.1074/jbc.ra118.001850.
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Many subsurface microorganisms couple their metabolism to the reduction or oxidation of extracellular substrates. For example, anaerobic mineral-respiring bacteria can use external metal oxides as terminal electron acceptors during respiration. Porin–cytochrome complexes facilitate the movement of electrons generated through intracellular catabolic processes across the bacterial outer membrane to these terminal electron acceptors. In the mineral-reducing model bacterium Shewanella oneidensis MR-1, this complex is composed of two decaheme cytochromes (MtrA and MtrC) and an outer-membrane β-barrel (MtrB). However, the structures and mechanisms by which porin–cytochrome complexes transfer electrons are unknown. Here, we used small-angle neutron scattering (SANS) to study the molecular structure of the transmembrane complexes MtrAB and MtrCAB. Ab initio modeling of the scattering data yielded a molecular envelope with dimensions of ∼105 × 60 × 35 Å for MtrAB and ∼170 × 60 × 45 Å for MtrCAB. The shapes of these molecular envelopes suggested that MtrC interacts with the surface of MtrAB, extending ∼70 Å from the membrane surface and allowing the terminal hemes to interact with both MtrAB and an extracellular acceptor. The data also reveal that MtrA fully extends through the length of MtrB, with ∼30 Å being exposed into the periplasm. Proteoliposome models containing membrane-associated MtrCAB and internalized small tetraheme cytochrome (STC) indicate that MtrCAB could reduce Fe(III) citrate with STC as an electron donor, disclosing a direct interaction between MtrCAB and STC. Taken together, both structural and proteoliposome experiments support porin–cytochrome–mediated electron transfer via periplasmic cytochromes such as STC.
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Roane, T. M., K. L. Josephson, and I. L. Pepper. "Dual-Bioaugmentation Strategy To Enhance Remediation of Cocontaminated Soil." Applied and Environmental Microbiology 67, no. 7 (July 1, 2001): 3208–15. http://dx.doi.org/10.1128/aem.67.7.3208-3215.2001.
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ABSTRACT Although metals are thought to inhibit the ability of microorganisms to degrade organic pollutants, several microbial mechanisms of resistance to metal are known to exist. This study examined the potential of cadmium-resistant microorganisms to reduce soluble cadmium levels to enhance degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under conditions of cocontamination. Four cadmium-resistant soil microorganisms were examined in this study. Resistant up to a cadmium concentration of 275 μg ml−1, these isolates represented the common soil genera Arthrobacter, Bacillus, andPseudomonas. Isolates Pseudomonas sp. strain H1 and Bacillus sp. strain H9 had a plasmid-dependent intracellular mechanism of cadmium detoxification, reducing soluble cadmium levels by 36%. IsolatesArthrobacter strain D9 and Pseudomonasstrain I1a both produced an extracellular polymer layer that bound and reduced soluble cadmium levels by 22 and 11%, respectively. Although none of the cadmium-resistant isolates could degrade 2,4-D, results of dual-bioaugmentation studies conducted with both pure culture and laboratory soil microcosms showed that each of four cadmium-resistant isolates supported the degradation of 500-μg ml−1 2,4-D by the cadmium-sensitive 2,4-D degrader Ralstonia eutropha JMP134. Degradation occurred in the presence of up to 24 μg of cadmium ml−1 in pure culture and up to 60 μg of cadmium g−1 in amended soil microcosms. In a pilot field study conducted with 5-gallon soil bioreactors, the dual-bioaugmentation strategy was again evaluated. Here, the cadmium-resistant isolate Pseudomonas strain H1 enhanced degradation of 2,4-D in reactors inoculated with R. eutropha JMP134 in the presence of 60 μg of cadmium g−1. Overall, dual bioaugmentation appears to be a viable approach in the remediation of cocontaminated soils.
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Merkel, Alexander Y., Nikolay A. Chernyh, Nikolai V. Pimenov, Elizaveta A. Bonch-Osmolovskaya, and Alexander I. Slobodkin. "Diversity and Metabolic Potential of the Terrestrial Mud Volcano Microbial Community with a High Abundance of Archaea Mediating the Anaerobic Oxidation of Methane." Life 11, no. 9 (September 11, 2021): 953. http://dx.doi.org/10.3390/life11090953.
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Terrestrial mud volcanoes (TMVs) are important natural sources of methane emission. The microorganisms inhabiting these environments remain largely unknown. We studied the phylogenetic composition and metabolic potential of the prokaryotic communities of TMVs located in the Taman Peninsula, Russia, using a metagenomic approach. One of the examined sites harbored a unique community with a high abundance of anaerobic methane-oxidizing archaea belonging to ANME-3 group (39% of all 16S rRNA gene reads). The high number of ANME-3 archaea was confirmed by qPCR, while the process of anaerobic methane oxidation was demonstrated by radioisotopic experiments. We recovered metagenome-assembled genomes (MAGs) of archaeal and bacterial community members and analyzed their metabolic capabilities. The ANME-3 MAG contained a complete set of genes for methanogenesis as well as of ribosomal RNA and did not encode proteins involved in dissimilatory nitrate or sulfate reduction. The presence of multiheme c-type cytochromes suggests that ANME-3 can couple methane oxidation with the reduction of metal oxides or with the interspecies electron transfer to a bacterial partner. The bacterial members of the community were mainly represented by autotrophic, nitrate-reducing, sulfur-oxidizing bacteria, as well as by fermentative microorganisms. This study extends the current knowledge of the phylogenetic and metabolic diversity of prokaryotes in TMVs and provides a first insight into the genomic features of ANME-3 archaea.
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Chandran, Smitha. "MANAGING FORMER LANDFILL SITES A CASE STUDY OF ECORESTORATION FROM KOCHI, KERALA." Green Chemistry & Technology Letters 1, no. 01 (January 10, 2016): 82–85. http://dx.doi.org/10.18510/gctl.2015.1113.
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This paper describes the dramatic success in the eco-restoration of a heavy-metal contaminated open garbage dump at the Amrita Institute of Medical Sciences (AIMS), a 1450-bed super-specialty hospital located in Kochi, Kerala, India. Today, the hospital caters to over 10 lakh patients annually. Inspired by our Chancellor’s vision of zero-waste, the hospital undertook its journey with a view to also reducing massive greenhouse gas emissions that result from improper handling of waste. Today, the hospital manages its municipal solid waste on an industrial scale, composting some eight metric tonnes of organic waste daily.This case study outlines the path followed to achieve zero-waste. Alongside, the rehabilitation of a former dump site is described in detail at this very site are carried out all composting operations of AIMS. Within three years of the restoration activities, heavy metal concentrations in the contaminated soil reduced drastically.There was relatively low uptake of the heavy metals by the plants; however, they might have been crucially responsible for providing a favorable environment for soil restoring microorganisms in their rhizosphere. Observable habitat-restoration continues at the site, including the return of birds and insects and other wildlife, making this an ideal site for further research and demonstration for community awareness and education.
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Moroz, O. M., S. O. Hnatush, C. I. Bohoslavets, G. V. Yavorska, and N. V. Truchym. "Usage of ferrum (ІІІ) and manganese (IV) ions as electron acceptors by Desulfuromonas sp. bacteria." Biosystems Diversity 24, no. 1 (March 7, 2016): 87–95. http://dx.doi.org/10.15421/011610.
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The toxicity of metal ions to microorganisms, in particular at high concentrations, is one of the main impediments to their usage in remediation technologies. The purpose of this work is to analyze the possibility of usage by bacteria of the Desulfuromonas genus, isolated by us from Yavorivske Lake, of ferrum (ІІІ) and manganese (IV) ions at concentrations in the medium of 1,74–10,41 mM as electron acceptors of anaerobic respiration to assesss resistance of sulphur reducing bacteria strains to heavy metal compounds. Cells of Desulfuromonas acetoxidans ІМV V-7384, Desulfuromonas sp. Yavor-5 and Desulfuromonas sp. Yavor-7 were cultivated for 10 days at 30 °C under anaerobic conditions in Kravtsov-Sorokin’s medium without sulphate ions, sulphur, with cysteine as the sulphur source (0.2 g/l) and sodium lactate or citrate as the electron donor (17.86 g/l), in which were added sterile 1 M solutions of C6H5O7Fe and C4H4O4 (control) and also weights of MnO2 to their terminal concentrations 1.74, 3.47, 5.21, 6.94, 10.41 mM. Biomass was determined by the turbidimetric method. In the culture liquid the presence of Fe3+ and Mn4+ were qualitatively determined, and the content of Fe2+ in reaction with о-phenanthroline was determined quantitatively. It was established that sulphur reducing bacteria used with different intensity ferrum (ІІІ) and manganese (IV) ions as electron acceptors during the process of anaerobic respiration at concentrations of 1.74–10.41 mM C6H5O7Fe and MnO2 in the medium, which demonstrated the important role of the investigated microorganisms in reductive detoxication of natural and technogenic media from oxidized forms of transitional heavy metals. An insignificant difference in biomass accumulation during usage of 5.21–10.41 mM ferrum (ІІІ) ions and fumarate is caused by toxicity of the metal ions to cells since the high redox potential of the Fe(III)/Fe(ІІ) pair with increase in concentrations of electron acceptors in the medium did not lead to increase in the biomass accumulation level. The greatest biomass of the bacteria accumulated on the 8–10th days in the medium with the lowest concentration of C6H5O7Fe – 1.74 mM (up to 2.77 g/l), and the lowest biomass – with highest concentration – 10.41 mM (up to 2.41 g/l). After 10 days of cultivation the bacteria of all strains had fully used the ferrum (ІІІ) ions present in the medium. A biomass yield almost twice as low was revealed after manganese (IV) oxide was used by bacteria compared with its use of ferrum (ІІІ) citrate and fumarate at all studied concentrations of electron acceptors in the medium. The highest biomass of bacteria accumulated in the medium with the lowest MnO2 content – 1.74 mM (up to 1.35 g/l), and the lowest biomass in the medium with the highest content – 10.41 mM (up to 1.15 g/l). After 10 days of cultivation bacteria of all strains had not fully restored the manganese (IV) ions present in the medium. The greatest biomass compared with other strains after growth in medium with different C6H5O7Fe and MnO2 contents was accumulated by the strain Desulfuromonas sp. Yavor-7. Since sulphur reducing bacteria strains proved to be resistant to Fe3+ and Mn4+ high concentrations (up to10.41 mM) they can be successfully used in technologies of environmenal remediation from sulphur and heavy metal compounds.
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Singh, Kanhaiya Kumar, and R. C. Vaishya. "Bioremediation of Heavy Metal Using Consortia Developed from Municipal Wastewater Isolates." SAMRIDDHI : A Journal of Physical Sciences, Engineering and Technology 9, no. 01 (June 25, 2017): 57–66. http://dx.doi.org/10.18090/samriddhi.v9i01.8339.
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Nowadays heavy-metal pollution has become an environmental problem due to their toxic effects, and their invasion in to the food chain leads to serious environmental and health problems. Heavy Metal degradation through common physico-chemical techniques is very expensive and unsuitable in treating large contaminated area effectively. Bioremediation provides a promising means to reclaim such toxic substances in an economical and ecofriendly way. Bioremediation obtains microorganisms that capable to degrade toxic contaminants or have the ability to accumulate it in their cells. The present study was carried out to evaluate degradation capacity of consortia developed from municipal wastewater isolates. The activity of the isolates for hemolysis was studied on the Blood-Agar plates. The identification of isolates obtained through biochemical and morphological characteristics. Seven isolates and three defined consortia were tested for degradation of heavy metals (zinc, lead and chromium). Consortia 3 (R9 + S11 + T12) showed better degradation with 93.78% ability in reducing zinc when incubated for 72 hours and 86.16% when incubated for 24 hours. The lead reduction was found to be 84.33% by Consortia 1(A3 + B4) when incubated at 37°C for 72 hours incubation. The chromium was reduced by Consortia 2(C6 + D7) with 87.61% ability when incubated for 72 hours. The organisms had capacity to reduce the heavy metals depending on the factors like time and concentration of inoculum. As the time of incubation increases, more reduction was observed. This study gives us insight in to the inherent potential of the Consortia to bio remediate toxic heavy metals.
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Сhayka, O. M., T. B. Peretyatko, and A. A. Halushka. "Thermophilic sulfate-reducing bacteria Moorela thermoacetica Nadia-3, isolated from “Nadiia” pit spoil heap of Chervonohrad mining region." Studia Biologica 15, no. 2 (2021): 35–46. http://dx.doi.org/10.30970/sbi.1502.654.
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Introduction. Thermophilic sulfate-reducing bacteria attract attention of scientists as the potential agents of purification of wastewater polluted by sulfur and its compounds, heavy metal ions and organic compounds. These bacteria oxidize different organic substrates using metals with variable valency as electron acceptors and transform them into non-toxic or less toxic forms for living organisms. However, wastewater contains high concentrations of different toxic xenobiotics, particularly, metal ions that have negative influence on living organisms. For this reason, it is important to use resistant strains of microorganisms for the purification of wastewater. The aim of this work was to identify the thermophilic sulfur-reducing bacteria, isolated from “Nadiia” pit spoil heap of Chervonohrad mining region, and to study their properties. Materials and Methods. Thermophilic sulfur-reducing bacteria were isolated from the samples of rock of “Nadiia” pit heap at 50 cm depth. Bacteria were cultivated in TF medium under the anaerobic conditions in anaerostates. Cell biomass was measured turbidimetrically using the photoelectric colorimeter KFK-3 (λ = 340 nm, 3 mm cuvette). Hydrogen sulfide content was measured photoelectrocolorymetrically by the production of methylene blue. Organic acids content was measured by high performance liquid chromatography. Cr(VI), Fe(III), Мn(IV) and NO3– content was measured turbidimetrically. Results. Thermophilic sulfur-reducing bacteria were isolated from the rock of “Nadiia” pit heap of Chervonohrad mining region. They were identified as Moorela thermoacetica based on the morpho-physiological and biochemical properties and on the results of phylogenetic analysis. M. thermoacetica Nadia-3 grow in the synthetic TF medium, have the shape of elongated rods, are gram-positive, endospore-forming. They form light brown colonies. Optimal growth was observed at 50–55 °C, pH 6.5–7. The bacteria utilize glucose, starch, fructose, maltose, lactose, sodium lactate, arabinose, cellulose, maltose, glycerol, fumarate, and ethanol as carbon sources. The highest sulfidogenic activity of M. thermoacetica Nadia-3 was found in media with glycerol, lactose, and glucose. M. thermoacetica Nadia-3 reduce SO42-, S2O32-, Fe(III), NO3–, Cr(VI) compounds besides elemental sulfur. They accumulate biomass at K2Cr2O7 concentrations of 0.1–1 mM. Sulfur reduction is not the main way of energy accumulation. Conclusions. Thermophilic chromium-resistant sulfur-reducing bacteria M. thermoacetica Nadia-3, that produce hydrogen sulfide during the oxidation of different organic compounds, were isolated from the rock of “Nadiia” pit heap. They reduce Fe(III), Cr(VI), NO3–, SO42-, S2O32-, besides elemental sulfur.
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Dewi, Nur Kusuma, Ibnul Mubarok, and Ari Yuniastuti. "Biosorption of Heavy Metal Pollution by Enterobacter agglomerans." Biosaintifika: Journal of Biology & Biology Education 11, no. 2 (August 19, 2019): 289–95. http://dx.doi.org/10.15294/biosaintifika.v11i2.20471.
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Biosorption is a new waste treatment technology that can eliminate toxic heavy metals. Biosorption can be considered as an environmentally friendly alternative technology to treat industrial liquid waste that is economically proper to use. One of them is biosorption that utilizes the microorganisms’ absorption ability, especially bacteria that can absorb heavy metals in waters, such as Enterobacter agglomerans. This research aimed to determine the ability of E. agglomerans in reducing heavy metals pollution in local river. The research employed the measurement of the effect of lead (Pb) to E. agglomerans growth using Optical Density (OD) at wavelength 600 nm. The colony numbers were calculated using a standard curve. While the ability of E. agglomerans to reduce heavy metals concentration in liquid media was measured using AAS with a wavelength of 240 nm. The results showed that lead affected the growth of E. agglomerans. The OD value has a negative relationship with the concentration level of Pb. The ODs were decreased from 2.867 to 1.242, using Pb level from 0 ppm to 20 ppm. Therefore, it proved that E. agglomerans could reduce heavy metals concentration in local river in Central Java Province. This research was the first report on E. agglomerans activity on heavy metal in contaminated water. This result can be used as a reference for industrial sites near the river to treat their wastewater before discharging it to the river body to preserve its water purity.
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Methé, Barbara A., Jennifer Webster, Kelly Nevin, Jessica Butler, and Derek R. Lovley. "DNA Microarray Analysis of Nitrogen Fixation and Fe(III) Reduction in Geobacter sulfurreducens." Applied and Environmental Microbiology 71, no. 5 (May 2005): 2530–38. http://dx.doi.org/10.1128/aem.71.5.2530-2538.2005.
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ABSTRACT A DNA microarray representing the genome of Geobacter sulfurreducens was constructed for use in global gene expression profiling of cells under steady-state conditions with acetate as the electron donor and Fe(III) or fumarate as the electron acceptor. Reproducible differences in transcript levels were also observed in comparisons between cells grown with ammonia and those fixing atmospheric nitrogen. There was a high correlation between changes in transcript levels determined with microarray analyses and an evaluation of a subset of the genome with quantitative PCR. As expected, cells required to fix nitrogen had higher levels of transcripts of genes associated with nitrogen fixation, further demonstrating that the microarray approach could reliably detect important physiological changes. Cells grown with Fe(III) as the electron acceptor had higher levels of transcripts for omcB, a gene coding for an outer membrane c-type cytochrome that is essential for Fe(III) reduction. Several other c-type cytochrome genes also appeared to be up-regulated. An unexpected result was significantly higher levels of transcripts for genes which have a role in metal efflux, potentially suggesting the importance of maintaining metal homeostasis during release of soluble metals when reducing Fe(III). A substantial proportion (30%) of significantly expressed genes during Fe(III) reduction were genes of unknown function or hypothetical proteins, suggesting differences in Fe(III) reduction physiology among microorganisms which perform this metabolic process.
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Álvarez, María Luisa, Ana Méndez, Jorge Paz-Ferreiro, and Gabriel Gascó. "Effects of Manure Waste Biochars in Mining Soils." Applied Sciences 10, no. 10 (May 14, 2020): 3393. http://dx.doi.org/10.3390/app10103393.
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Land degradation by old mining activities is a concern worldwide. However, many known technologies are expensive and cannot be considered for mining soil restoration. Biochar amendment of mining soils is becoming an interesting alternative to traditional technologies due to an improvement in soil properties and metal mobility reduction. Biochar effects depend on soil and biochar properties, which in turn vary with pyrolysis conversion parameters and the feedstock used. The objective of this study is to evaluate the effect of four biochars prepared from poultry and rabbit manure at two pyrolysis temperatures (450 and 600 °C) in the trace metal mobility, CO2 emissions, and enzymatic activity of 10 mining soils located in three historical mining areas of Spain (Zarandas-Andalusia, Mijarojos-Cantabria, and Portman-Murcia). For this reason, soils were amended with biochars at a rate of 10% (w/w), and different treatments were incubated for 180 days. For acid soils of the Zarandas-Andalusia area, biochar addition reduced the mobility of Ni, Zn, Cd, Pb, and Cr, respectively, by 91%, 81%, 29%, 67%, and 70%. Nevertheless, biochars did not exhibit the same efficiency in the other two areas where alkaline soils were predominant. CO2 emissions generally increased in the treated soils. The application of biochars produced at 600 °C reduced CO2 emissions, in some cases by more than 28%, being an adequate strategy for C sequestration in soil. The results showed that application of manure biochars can be an effective technique to reduce the mobility of metals in multi-contaminated acid soils, while reducing metal toxicity for soil microorganisms.
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Manjula, N., K. Kaviyarasu, A. Ayeshamariam, G. Selvan, A. Diallo, G. Ramalingam, S. B. Mohamed, D. Letsholathebe, and M. Jayachandran. "Structural, Morphological and Methanol Sensing Properties of Jet Nebulizer Spray Pyrolysis Effect of TiO2 Doped SnO2 Thin Film for Removal of Heavy Metal Ions." Journal of Nanoelectronics and Optoelectronics 13, no. 10 (October 1, 2018): 1543–51. http://dx.doi.org/10.1166/jno.2018.2384.
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Lead (Pb) and mercury (Hg) are two highly toxic heavy metals which must be removed completely or reduced to very low levels in drinking water supplies. TiO2:SnO2 nanoparticles and thin films were exploited for this purpose. TiO2:SnO2 nanoparticles were prepared by using the sol–gel combustion synthesis technique. The synthesized particles obtained were used in the analysis of the heavy metals of (Pb and Hg). The same material was used to deposit TiO2:SnO2 thin films by employing the Jet Nebulizer Technique (JNT). The films were subsequently characterized and used as adsorbents in the removal of heavy metal residues from contaminated water samples. The developed TiO2:SnO2 absorbents were characterized by transmission electron microscopy. The crystallite size of the prepared samples varied from 27 nm to 33 nm. The shape of the response curve for a given temperature variation depends on the well agreement with previously reported values ranging from zero for clean air to high positive values for strong interaction with reducing gas molecules. The application of these materials in many water filters may be helping to filter the sediments and economically feasible technology to filter microorganisms biological zone to purify the water.
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Blackwood, Daniel. "An Electrochemist Perspective of Microbiologically Influenced Corrosion." Corrosion and Materials Degradation 1, no. 1 (August 9, 2018): 59–76. http://dx.doi.org/10.3390/cmd1010005.
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Microbiologically influenced corrosion (MIC) is a major concern in a wide range of industries, with claims that it contributes 20% of the total annual corrosion cost. The focus of this present work is to review critically the most recent proposals for MIC mechanisms, with particular emphasis on whether or not these make sense in terms of their electrochemistry. It is determined that, despite the long history of investigating MIC, we are still a long way from really understanding its fundamental mechanisms, especially in relation to non-sulphate reducing bacterial (SRB) anaerobes. Nevertheless, we do know that both the cathodic polarization theory and direct electron transfer from the metal into the cell are incorrect. Electrically conducting pili also do not appear to play a role in direct electron transfer, although these could still play a role in aiding the mass transport of redox mediators. However, it is not clear if the microorganisms are just altering the local chemistry or if they are participating directly in the electrochemical corrosion process, albeit via the generation of redox mediators. The review finishes with suggestions on what needs to be done to further our understanding of MIC.
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Ortiz-Bernad, Irene, Robert T. Anderson, Helen A. Vrionis, and Derek R. Lovley. "Vanadium Respiration by Geobacter metallireducens: Novel Strategy for In Situ Removal of Vanadium from Groundwater." Applied and Environmental Microbiology 70, no. 5 (May 2004): 3091–95. http://dx.doi.org/10.1128/aem.70.5.3091-3095.2004.
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ABSTRACT Vanadium can be an important contaminant in groundwaters impacted by mining activities. In order to determine if microorganisms of the Geobacteraceae, the predominant dissimilatory metal reducers in many subsurface environments, were capable of reducing vanadium(V), Geobacter metallireducens was inoculated into a medium in which acetate was the electron donor and vanadium(V) was the sole electron acceptor. Reduction of vanadium(V) resulted in the production of vanadium(IV), which subsequently precipitated. Reduction of vanadium(V) was associated with cell growth with a generation time of 15 h. No vanadium(V) was reduced and no precipitate was formed in heat-killed or abiotic controls. Acetate was the most effective of all the electron donors evaluated. When acetate was injected into the subsurface to enhance the growth and activity of Geobacteraceae in an aquifer contaminated with uranium and vanadium, vanadium was removed from the groundwater even more effectively than uranium. These studies demonstrate that G. metallireducens can grow via vanadium(V) respiration and that stimulating the activity of Geobacteraceae, and hence vanadium(V) reduction, can be an effective strategy for in situ immobilization of vanadium in contaminated subsurface environments.
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Nancucheo, Ivan, and D. Barrie Johnson. "Characteristics of an Iron-Reducing, Moderately Acidophilic Actinobacterium Isolated from Pyritic Mine Waste, and Its Potential Role in Mitigating Mineral Dissolution in Mineral Tailings Deposits." Microorganisms 8, no. 7 (July 2, 2020): 990. http://dx.doi.org/10.3390/microorganisms8070990.
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Reactive pyritic mine tailings can be populated by chemolithotrophic prokaryotes that enhance the solubilities of many metals, though iron-reducing heterotrophic microorganisms can inhibit the environmental risk posed by tailings by promoting processes that are the reverse of those carried out by pyrite-oxidising autotrophic bacteria. A strain (IT2) of Curtobacterium ammoniigenes, a bacterium not previously identified as being associated with acidic mine wastes, was isolated from pyritic mine tailings and partially characterized. Strain IT2 was able to reduce ferric iron under anaerobic conditions, but was not found to catalyse the oxidation of ferrous iron or elemental (zero-valent) sulfur, and was an obligate heterotrophic. It metabolized monosaccharides and required small amounts of yeast extract for growth. Isolate IT2 is a mesophilic bacterium, with a temperature growth optimum of 30 °C and is moderately acidophilic, growing optimally at pH 4.0 and between pH 2.7 and 5.0. The isolate tolerated elevated concentrations of many transition metals, and was able to grow in the cell-free spent medium of the acidophilic autotroph Acidithiobacillus ferrooxidans, supporting the hypothesis that it can proliferate in acidic mine tailings. Its potential role in mitigating the production of acidic, metal-rich drainage waters from mine wastes is discussed.
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Michaelidou, Urania, Annemiek ter Heijne, Gerrit Jan W. Euverink, Hubertus V. M. Hamelers, Alfons J. M. Stams, and Jeanine S. Geelhoed. "Microbial Communities and Electrochemical Performance of Titanium-Based Anodic Electrodes in a Microbial Fuel Cell." Applied and Environmental Microbiology 77, no. 3 (December 3, 2010): 1069–75. http://dx.doi.org/10.1128/aem.02912-09.
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ABSTRACTFour types of titanium (Ti)-based electrodes were tested in the same microbial fuel cell (MFC) anodic compartment. Their electrochemical performances and the dominant microbial communities of the electrode biofilms were compared. The electrodes were identical in shape, macroscopic surface area, and core material but differed in either surface coating (Pt- or Ta-coated metal composites) or surface texture (smooth or rough). The MFC was inoculated with electrochemically active, neutrophilic microorganisms that had been enriched in the anodic compartments of acetate-fed MFCs over a period of 4 years. The original inoculum consisted of bioreactor sludge samples amended withGeobacter sulfurreducensstrain PCA. Overall, the Pt- and Ta-coated Ti bioanodes (electrode-biofilm association) showed higher current production than the uncoated Ti bioanodes. Analyses of extracted DNA of the anodic liquid and the Pt- and Ta-coated Ti electrode biofilms indicated differences in the dominant bacterial communities. Biofilm formation on the uncoated electrodes was poor and insufficient for further analyses. Bioanode samples from the Pt- and Ta-coated Ti electrodes incubated with Fe(III) and acetate showed several Fe(III)-reducing bacteria, of which selected species were dominant, on the surface of the electrodes. In contrast, nitrate-enriched samples showed less diversity, and the enriched strains were not dominant on the electrode surface. Isolated Fe(III)-reducing strains were phylogenetically related, but not all identical, toGeobacter sulfurreducensstrain PCA. Other bacterial species were also detected in the system, such as aPropionicimonas-related species that was dominant in the anodic liquid andPseudomonas-,Clostridium-,Desulfovibrio-,Azospira-, andAeromonas-related species.
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Gebresilassie, Abera Beyene, and Adam Mekonnen Engida. "Synthesis, characterization and functional evaluation of gold nanoparticles prepared using Dovyalis abyssinica leaf extracts as reducing and surface capping agent." Ethiopian Journal of Science and Technology 14, no. 2 (June 30, 2021): 171–90. http://dx.doi.org/10.4314/ejst.v14i2.6.
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Green synthesis of nanoparticles using plants and microorganisms is biologically safe, cost effective, and environmentally friendly technology. Gold nanoparticles (Au NPs) were synthesized using aqueous extracts of leaves of Dovyalis abyssinica as reducing and surface capping agent and the catalytic activity, antibacterial action and antioxidant potential of the synthesized AU NPs were evaluated. Firstly, HAuCl4 was synthesized in the laboratory from metallic gold and hydrochloric acid using a predesigned method. Secondly, Au NPs was synthesized by mixing HAuCl4 and the plant extract at 45 oC with a digestion time of 1 h. The size of the nanoparticles was modulated by varying the ratio of the plant extract and HAuCl4 with known concentrations. The synthesized Au NPs showed strong absorption around 540 nm which lies in the characteristic absorption region of Au metal nanoparticles (520–580 nm). The X-ray diffraction spectrum of the synthesized Au NPs showed characteristic crystalline structures of gold. The scanning electron spectroscopy images of the synthesized Au NPS revealed the presence of mixed shapes predominantly of irregular shapes and a particle size analyzer displayed an average size of 63.13 nm. The fourier-transform infrared spectrum of Au NPS confirmed the presence of amine, carbonyl and hydroxyl functional groups as surface capping molecules. Although the synthesized Au NPs showed poor bacterial growth inhibition activity on two selected bacteria, it demonstrated excellent free radical scavenging activity against 2, 2-Diphenyl-2-picrylhydrazyl (DPPH) radical and good catalytic activity for degrading bromothymol blue and methyl red compounds. In contrast to the hexane and ethyl acetate extracts, the aqueous fraction was identified as powerful reducing fraction for the synthesis of Au NPs in this experiment.
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Estevez, María Belén, Sofía Raffaelli, Scott G. Mitchell, Ricardo Faccio, and Silvana Alborés. "Biofilm Eradication Using Biogenic Silver Nanoparticles." Molecules 25, no. 9 (April 26, 2020): 2023. http://dx.doi.org/10.3390/molecules25092023.
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Microorganisms offer an alternative green and scalable technology for the synthesis of value added products. Fungi secrete high quantities of bioactive substances, which play dual-functional roles as both reducing and stabilizing agents in the synthesis of colloidal metal nanoparticles such as silver nanoparticles, which display potent antimicrobial properties that can be harnessed for a number of industrial applications. The aim of this work was the production of silver nanoparticles using the extracellular cell free extracts of Phanerochaete chrysosporium, and to evaluate their activity as antimicrobial and antibiofilm agents. The 45–nm diameter silver nanoparticles synthesized using this methodology possessed a high negative surface charge close to −30 mV and showed colloidal stability from pH 3–9 and under conditions of high ionic strength ([NaCl] = 10–500 mM). A combination of environmental SEM, TEM, and confocal Raman microscopy was used to study the nanoparticle-E. coli interactions to gain a first insight into their antimicrobial mechanisms. Raman data demonstrate a significant decrease in the fatty acid content of E. coli cells, which suggests a loss of the cell membrane integrity after exposure to the PchNPs, which is also commensurate with ESEM and TEM images. Additionally, these biogenic PchNPs displayed biofilm disruption activity for the eradication of E. coli and C. albicans biofilms.
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Tumolo, Marina, Valeria Ancona, Domenico De Paola, Daniela Losacco, Claudia Campanale, Carmine Massarelli, and Vito Felice Uricchio. "Chromium Pollution in European Water, Sources, Health Risk, and Remediation Strategies: An Overview." International Journal of Environmental Research and Public Health 17, no. 15 (July 28, 2020): 5438. http://dx.doi.org/10.3390/ijerph17155438.
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Chromium is a potentially toxic metal occurring in water and groundwater as a result of natural and anthropogenic sources. Microbial interaction with mafic and ultramafic rocks together with geogenic processes release Cr (VI) in natural environment by chromite oxidation. Moreover, Cr (VI) pollution is largely related to several Cr (VI) industrial applications in the field of energy production, manufacturing of metals and chemicals, and subsequent waste and wastewater management. Chromium discharge in European Union (EU) waters is subjected to nationwide recommendations, which vary depending on the type of industry and receiving water body. Once in water, chromium mainly occurs in two oxidation states Cr (III) and Cr (VI) and related ion forms depending on pH values, redox potential, and presence of natural reducing agents. Public concerns with chromium are primarily related to hexavalent compounds owing to their toxic effects on humans, animals, plants, and microorganisms. Risks for human health range from skin irritation to DNA damages and cancer development, depending on dose, exposure level, and duration. Remediation strategies commonly used for Cr (VI) removal include physico-chemical and biological methods. This work critically presents their advantages and disadvantages, suggesting a site-specific and accurate evaluation for choosing the best available recovering technology.