The strategic situation of Sinai made it an urgent national target for the sustainable development. One of the important factors in such development is the exploration and the processing of uraniferous rock materials. Consequently, the Lower Carboniferous sedimentary rocks were chosen for the present study to test the uranium bioleaching capacity of fungal strains isolated from exposed sedimentary rocks in southwestern Sinai. Eight fungal species were isolated from three grades of uraniferous sedimentary rock samples in southwestern Sinai, Egypt and tested for their bioleaching activity. Aspergillus niger (A. niger) and Aspergillus terreus (A. terreus) were the only isolates which gave a high grade leaching efficiency of uranium from the studied uraniferous rocks. The most favorable factors for solubilization of uranium were 7 days incubation time, 3% ore concentration, solid/liquid ratio 1/3 and 30 °C incubation temperature. Both fungi produced organic acids (oxalic, citric, formic and ascorbic) in the culture filtrate which are the key compounds of bioleaching processes. Applying these conditions on one kilogram of Ag-3 sample (the lowest U grade), the A. niger strain gave high uranium leaching efficiency of 71.4%. The recovery test of U has been performed by proper precipitation to obtain a high quality uranium concentrate.
To extend the knowledge on the microbial diversity of manganese rich environments, we performed a clone library based study using metagenomic approach. Pyrosequencing based analysis of 16S rRNA genes were carried out on an Illumina platform to gain insights into the bacterial community inhabiting in a manganese mining site and the taxonomic profiles were correlated with the inherent capacities of these strains to solubilise manganese. The application of shot gun sequencing in this study yielded results which revealed the highest prevalence of Proteobacteria (42.47%), followed by Actinobacteria (23.99%) in the area of study. Cluster of orthologous group (COG) functional category has 85,066 predicted functions. Out of which 11% are involved in metabolism of amino acid, 9% are involved in production and conversion of energy while Keto Encyclopedia of Gene and Genomes (KEGG) functional category has 107,388 predicted functions, out of which 55% are involved in cellular metabolism, 15% are environmental and information processing and 12% are genetic information processing in nature. The isolated microbial consortia demonstrated visible growth in presence of high concentrations of Mn. Solubilisation studies resulted in 86% of manganese recovery after 20 days. The result presented in this study has important implications in understanding the microbial diversity in manganese contaminated mine tailings and their role in natural geochemical cycling of Mn.
A versatile ligninolytic peroxidase has been cloned from Pleurotus eryngii and its allelic variant MnPL2 expressed in Aspergillus nidulans, with properties similar to those of the mature enzyme from P. eryngii. These include the ability to oxidize Mn2+ and aromatic substrates, confirming that this is a new peroxidase type sharing catalytic properties of lignin peroxidase and manganese peroxidase.
The study of the microbial ecology in extreme acidic environments has provided an important foundation for the development of mineral biotechnology. The present investigation reports the isolation, identification and molecular characterization of indigenous Manganese (Mn) solubilizing acidophilic bacterial strains from mine water samples from Odisha, India. Four morphologically distinct bacterial strains showing visible growth on Mn-supplemented plates of varying pH were isolated and identified. Mn solubilizing ability of the isolates was tested by growing them on Mn-supplemented agar plates. The appearance of lightening around the growing colonies of all the isolates demonstrated their Mn solubilizing ability in the medium. 16 S rRNA sequencing was carried out and the bacterial isolates were taxonomically classified as Enterobacter sp. AMSB1, Bacillus cereus AMSB3, Bacillus nealsonii AMSB4 and Staphylococcus hominis AMSB5. The evolutionary timeline was studied by constructing Neighbor-Joining phylogenetic trees. The ability of acidophilic microorganisms to solubilize heavy metals is supported by five basic mechanisms which include: enzymatic conversion, metal effluxing, reduction in sensitivity of cellular targets, intra- or extracellular sequestration, and permeability barrier exclusion. Such ecological studies undoubtedly will provide insights into Mn biogeochemical processes occurring in leaching environments. The application of acidophilic microbiology in mineral bio recovery and benefication has a large future potential.
The requirement for manganese (Mn) has augmented extensively owing to the intense production of steel and the mounting paucity of natural deposits. The widespread mining, mineral processing, and further human activities have faced a severe consequence in the generation of massive quantity of manganese mining waste residues. The inappropriate supervision and unprocessed liberation of these wastes have resulted in the spread of Mn to the contiguous atmosphere, soil and groundwater pollution, and loads of severe ecological tribulations. Chronic and acute exposure of this metal pollutant leads to lethal consequences and is clinically categorized by the multiple symptoms of neurotoxicity including cognitive and psychiatric symptoms, Parkinson’s disease, manganism, motor system dysfunction, and other neurodegenerative diseases. The advancement of bioremediation technology focuses on accomplishing successful removal of these metal pollutants by increasing the effectiveness of microbes related to metal-solubilizing activities. This chapter describes a complete advance in the research on manganese environmental pollution, manganese compound-induced toxicity, and recent approaches for the microbial remediation of manganese pollutants.
Exposure to manganese (Mn) causes clinical signs and symptoms resembling, but not identical to, Parkinson’s disease. Since our last review on this subject in 2004, the past decade has been a thriving period in the history of Mn research. This report provides a comprehensive review on new knowledge gained in the Mn research field. Emerging data suggest that beyond traditionally recognized occupational manganism, Mn exposures and the ensuing toxicities occur in a variety of environmental settings, nutritional sources, contaminated foods, infant formulas, and water, soil, and air with natural or man-made contaminations. Upon fast absorption into the body via oral and inhalation exposures, Mn has a relatively short half-life in blood, yet fairly long half-lives in tissues. Recent data suggest Mn accumulates substantially in bone, with a half-life of about 8–9 years expected in human bones. Mn toxicity has been associated with dopaminergic dysfunction by recent neurochemical analyses and synchrotron X-ray fluorescent imaging studies. Evidence from humans indicates that individual factors such as age, gender, ethnicity, genetics, and pre-existing medical conditions can have profound impacts on Mn toxicities. In addition to body fluid-based biomarkers, new approaches in searching biomarkers of Mn exposure include Mn levels in toenails, non-invasive measurement of Mn in bone, and functional alteration assessments. Comments and recommendations are also provided with regard to the diagnosis of Mn intoxication and clinical intervention. Finally, several hot and promising research areas in the next decade are discussed.
In this manuscript, we report that a bacterial multicopper oxidase (MCO266) catalyzes Mn(II) oxidation on the cell surface, resulting in the surface deposition of Mn(III) and Mn(IV) oxides and the gradual formation of bulky oxide aggregates. These aggregates serve as nucleation centers for the formation of Mn oxide micronodules and Mn-rich sediments. A soil-borne Escherichia coli with high Mn(II)-oxidizing activity formed Mn(III)/Mn(IV) oxide deposit layers and aggregates under laboratory culture conditions. We engineered MCO266 onto the cell surfaces of both an activity-negative recipient and wild-type strains. The results confirmed that MCO266 governs Mn(II) oxidation and initiates the formation of deposits and aggregates. By contrast, a cell-free substrate, heat-killed strains, and intracellularly expressed or purified MCO266 failed to catalyze Mn(II) oxidation. However, purified MCO266 exhibited Mn(II)-oxidizing activity when combined with cell outer membrane component (COMC) fractions in vitro. We demonstrated that Mn(II) oxidation and aggregate formation occurred through an oxygen-dependent biotic transformation process that requires a certain minimum Mn(II) concentration. We propose an approximate electron transfer pathway in which MCO266 transfers only one electron to convert Mn(II) to Mn(III) and then cooperates with other COMC electron transporters to transfer the other electron required to oxidize Mn(III) to Mn(IV).
Microorganisms including fungi and bacteria have been reported to extract heavy metals from wastewater through bioaccumulation and biosorption. An attempt was, therefore, made to isolate bacteria and fungi from sites contaminated with heavy metals for
higher tolerance and removal from wastewater. Bacterial and fungal isolates were obtained from the samples collected from Karnal, Ambala and Yamunanagar districts of Haryana using enrichment culture technique. Bacterial and fungal isolates with tolerant up to 100 ppm concentration of heavy metals (Pb, Cd, Cr) were tested for their removal from liquid media containing 50 ppm concentration of Pb, Cd and Cr each. Five fungi (Penicillium chrysogenum,
Aspegillus nidulans, Aspergillus flavus, Rhizopus arrhizus, Trichoderma viride) were also included in this study. Fungi Aspergillus nidulans, Rhizopus arrhizus and Trichoderma viride
showed maximum uptake capacity of 25.67 mg/g for Pb, 13.15 mg/g for Cd and 2.55 mg/g of Cr, respectively. The maximum uptake capacity of tolerant bacterial isolates - BPb12 and
BPb16, BCd5 and BCr14 were observed to be ~ 45 mg/g for Pb, 2.12 mg/g for Cd and 3.29 mg/g for Cr, respectively. This indicated the potential of these identified fungi and bacteria as biosorbent for removal of high concentration metals from wastewater and industrial effluents.
Manufacturing of manganese (Mn) compounds, their industrial applications as well as mining overburden, has generated a potential environmental pollutant. Occupational exposure to elevated levels of Mn occurs during mining, welding, smelting and other industrial anthropogenic sources. Chronic and acute exposure of this metal pollutant leads to adverse consequences and is clinically categorized by various symptoms of neurotoxicity including cognitive, psychiatric symptoms, Parkinson's disease, extra pyramidal signs, manganism, dystonia, and motor system dysfunction. The aim of this review is to summarize the possible mechanism underlying Mn compounds-mediated neurotoxicity leading to neurodegenerative diseases. Our review endeavours to examine recent advances in research on Mn-related environmental pollution, Mn-induced poisoning, molecular mechanisms underlying Mn-induced neurotoxicity with case studies as well as current approaches employed for treatment and prevention of Mn exposure.
Manganese dioxide (MnO2) particles have a catalytic effect on removing Mn(II) from contaminated water. On the basis of this effect, a manganese removal process was proposed in this paper. For this purpose, the oxidation of Mn(II) was studied first in batch reactor and then in continuous reactor. The experimental conditionals for batch reactor were Mn(II): 3 mg/l, Mn(IV): 0–800 mg/l, pH: 9.6, temperature: 25 °C and for continuous system, the conditionals were kept the same except Mn(II) concentration. A quadratic equation was obtained as a function of Mn(IV) concentration to determine the catalytic reaction rate constant. It was experimentally demonstrated that there was no significant effect of Mn(IV) on the Mn(II) oxidation at Mn(IV) concentrations beyond 800 mg/l. Furthermore, reaction kinetics was derived from the data of batch experiments. Based upon the reaction kinetics, it has been theoretically demonstrated that the volume of aeration tank can be significantly reduced by keeping a high concentration of Mn(IV) in the reactor. Lastly, manganese oxidation was studied in a continuous flow lab scale system with and without MnO2 sludge recirculation. In this system, until Mn(IV) concentration had reached 300 mg/l, Mn(II) removal rate had increased linearly, but beyond this level increase had continued decreasingly. This study shows that, instead of using stronger oxidants in the drinking water treatment systems, recycling of MnO2 flocks provides important advantages like low investment cost, minimization of treatment area and, because of the lack of using oxidants, low operation cost.
The present study was done to check the bioleaching feasibility of brown shale for the recovery of copper (Cu), aluminum (Al), magnesium (Mg) and manganese (Mn) ions using Ganoderma lucidum. Different experimental parameters were optimized for the enhanced recovery of metals ions. Effect of different substrates like glucose, molasses, saw dust and cotton seed cake on the recovery of metals ions was investigated under shaking as well as non-shaking conditions. Significant difference in leaching of metal ions by G. lucidum was observed under shaking and non shaking conditions. Maximum leaching of Al (90.7%), Mg (96.46%), Mn (66.3%) and Cu (73.45%) was observed using glucose under shaking conditions with 5, 3, 4 and 3% pulp densities respectively. The results show that maximum solubilization up to 68.89, 77.03 and 38.37% was achieved for Cu, Al and Mg ions respectively using molasses as substrate, whereas, 57.74% recovery of Mn was achieved with saw dust. The recovery of metal ions indicated that this low grade discarded ore may be a potential source of metal ions in future.
In this work, the performance of a sequencing batch reactor (SBR) on aerobic granular sludge was studied for urban wastewater treatment. The system was inoculated with aerobic activated sludge collected from a wastewater treatment plant and, after 30 days of operation, the first granules observed had an average diameter of 0.1 mm. The biomass concentration reached a maximum value around 4 g VSS L -1 , and COD removal and nitrification efficiency achieved stable values of 90%. The predominant oxidizing ammonium bacteria in the granules were identified as Nitrosomonas spp.
The introduction of magnetic properties in adsorbent materials has the aim of improving solid-liquid separation processes. In this work, a magnetic composite was synthesized through the precipitation of manganese oxide in the presence of magnetite particles using O2 as an oxidant. The composite proved to be chemically and physically stablewithin a wide range of pH values. The composite characterization indicated that hausmannite (Mn3O4) represents the precipitated manganese phase and that magnetite undergoes no phase transformation during the synthesis. The composite and Mn3O4 particles were used to remove As(III) from aqueous solutions. The magnetic composite and Mn3O4 sample presented high and similar affinity for As(III), with maximum sorptive capacities of 14mgAsgsolid-1 (0.0048mmolAsm-2solid) and 20mgAsgsolid-1 (0.0049mmolAsm-2solid), respectively, at pH5.0. The combination of an active high surface area sorbent (Mn3O4) with a magnetic phase (Fe3O4) allows for efficient As(III) removal and solid/liquid separation.
Abstract Plants endure a variety of abiotic and biotic stresses, all of which cause major limitations to production. Among abiotic stressors, heavy metal contamination represents a global environmental problem endangering humans, animals, and plants. Exposure to heavy metals has been documented to induce changes in the expression of plant proteins. Proteins are macromolecules directly responsible for most biological processes in a living cell, while protein function is directly influenced by posttranslational modifications, which cannot be identified through genome studies. Therefore, it is necessary to conduct proteomic studies, which enable the elucidation of the presence and role of proteins under specific environmental conditions. This review attempts to present current knowledge on proteomic techniques developed with an aim to detect the response of plant to heavy metal stress. Significant contributions to a better understanding of the complex mechanisms of plant acclimation to metal stress are also discussed.
Bacterial manganese (Mn) oxidation plays an important role in the global biogeochemical cycling of Mn and other compounds, and the diversity and prevalence of Mn oxidizers have been well established. Despite many hypotheses of why these bacteria may oxidize Mn, the physiological reasons remain elusive. Intracellular Mn levels were determined for Pseudomonas putida GB-1 grown in the presence or absence of Mn by inductively coupled plasma mass spectrometry (ICP-MS). Mn oxidizing wild type P. putida GB-1 had higher intracellular Mn than non Mn oxidizing mutants grown under the same conditions. P. putida GB-1 had a 5 fold increase in intracellular Mn compared to the non Mn oxidizing mutant P. putida GB-1-007 and a 59 fold increase in intracellular Mn compared to P. putida GB-1 ∆2665 ∆2447. The intracellular Mn is primarily associated with the less than 3 kDa fraction, suggesting it is not bound to protein. Protein oxidation levels in Mn oxidizing and non oxidizing cultures were relatively similar, yet Mn oxidation did increase survival of P. putida GB-1 when oxidatively stressed. This study is the first to link Mn oxidation to Mn homeostasis and oxidative stress protection.
Plant growth-promoting rhizobacteria (PGPR) play an important role in the biodegradation of natural and xenobiotic organic compounds in soil. They can also alter heavy metal bioavailability and contribute to phytoremediation in the presence or absence of synthetic metal chelating agents. In this study, the inhibitory effect of Cd2+ and Ni2+ at different concentrations of Ca2+ and Mg2+, and the influence of the widely used chelator EDTA on growth of the PGPR Pseudomonas brassicacearum in a mineral salt medium with a mixture of four main plant exudates (glucose, fructose, citrate, succinate) was investigated. Therefore, the bacteriostatic effect of Cd2+, Ni2+ and EDTA on the maximum specific growth rate and the determination of EC50 values was used to quantify inhibitory impact. At high concentrations of Ca2+ (800 μmol L-1) and Mg2+ (1,250 μmol L-1), only a small inhibitory effect of Cd2+ and Ni2+ on growth of P. brassicacearum was observed (EC50 Cd2+, 18,849 ± 80 μmol L−1; EC50 Ni2+, 3,578 ± 1,002 μmol L−1). The inhibition was much greater at low concentrations of Ca2+ (25 μmol L−1) and Mg2+ (100 μmol L−1) (EC50 Cd2+, 85 ± 0.5 μmol L−1 and EC Ni2+, 62 ± 1.8 μmol L−1). For the chosen model system, a competitive effect of the ions Cd2+ and Ca2+ on the one hand and Ni2+ and Mg2+ on the other hand can be deduced. However, the toxicity of both, Cd2+ and Ni2+, could be significantly reduced by addition of EDTA, but if this chelating agent was added in stoichiometric excess to the cations, it also exhibited an inhibitory effect on growth of P. brassicacearum.
A kinetic model was developed to assess the influence of batch cultivation of Aspergillus niger on the bioleaching of iron from kaolin. A simple model was proposed using the logistic equation for growth, and the Luedeking–Piret equations for iron removal, acid formation and sucrose consumption. The performance of the model was compared against that obtained by the empirically experimental data. The model provides a reasonable description for each parameter during the growth phase. The experimental results also suggest that the product formation depends upon both the instantaneous biomass concentration, and growth rate.
Manganese(IV) oxides, believed to form primarily through microbial activities, are extremely important mineral phases in marine environments where they scavenge a variety of trace elements and thereby control their distributions. The presence of various ions common in seawater are known to influence Mn oxide mineralogy yet little is known about the effect of these ions on the kinetics of bacterial Mn(II) oxidation and Mn oxide formation. We examined factors affecting bacterial Mn(II) oxidation by spores of the marine Bacillus sp. strain SG-1 in natural and artificial seawater of varying ionic conditions. Ca²⁺ concentration dramatically affected Mn(II) oxidation, while Mg²⁺, Sr²⁺, K⁺, Na⁺ and NO3⁻ ions had no effect. The rate of Mn(II) oxidation at 10 mM Ca²⁺ (seawater composition) was four or five times that without Ca²⁺. The relationship between Ca²⁺ content and oxidation rate demonstrates that the equilibrium constant is small (on the order of 0.1) and the binding coefficient is 0.5. The pH optimum for Mn(II) oxidation changed depending on the amount of Ca²⁺ present, suggesting that Ca²⁺ exerts a direct effect on the enzyme perhaps as a stabilizing bridge between polypeptide components.
This paper concerns the recovery of zinc and manganese from alkaline and zinc-carbon spent batteries. The metals were dissolved by a reductive-acid leaching with sulphuric acid in the presence of oxalic acid as reductant. Leaching tests were realised according to a full factorial design, then simple regression equations for Mn, Zn and Fe extraction were determined from the experimental data as a function of pulp density, sulphuric acid concentration, temperature and oxalic acid concentration. The main effects and interactions were investigated by the analysis of variance (ANOVA). This analysis evidenced the best operating conditions of the reductive acid leaching: 70% of manganese and 100% of zinc were extracted after 5h, at 80°C with 20% of pulp density, 1.8M sulphuric acid concentration and 59.4gL−1 of oxalic acid. Both manganese and zinc extraction yields higher than 96% were obtained by using two sequential leaching steps.
This paper presents results of a feasibility study of recycling manganese furnace dust generated in production of ferromanganese and silicomanganese at Tasmanian Electrometallurgical Company, Australia. Dried man- ganese furnace dust contains about 20 wt% of carbon, in average 33.4 wt% of manganese and 1.3 wt% of zinc. Manganese in the dust is in the form of MnO, Mn 3 O 4 and MnCO 3 ; zinc is mainly in the form of ZnO and ZnSO 4 . Analysis of the zinc balance with dust recycling showed that to keep zinc intake at the acceptable level, it should be partly removed from the dust. In the reduction laboratory experiments, zinc oxide was reduced to zinc vapour by tar of the dust. Reduction of zinc oxide started at 800 o C and zinc removal rate increased with increasing temperature; removal of zinc was close to completion at 1100 o C. Optimal conditions for removing zinc from the dust include temperature in the range 1000-1150 o C, inert gas atmosphere and furnace dust frac- tion in the furnace dust-manganese ore mixture above 60%. In the sintering of manganese ore with addition of manganese dust in the sintering pot, zinc was reoxidised and deposited in the sinter bed. Removal of zinc in the sintering pot tests was in the range 4-17%. Up to 30% zinc removal was achieved from the bottom layer of the sinter bed. It can be concluded that zinc removal will be low during the processing of manganese fur- nace dust in the sinter plant. The zinc removal rate will be the highest when pelletised manganese furnace dust is added to the bottom layer of the sintering bed.
The present work investigates the formation of manganese ferrite of nanosize by oxidation of MnO- and FeO-containing slag.
A horizontal resistance furnace was used as an experimental setup. The experiment was conducted in the temperature range of
1573 K to 1673 K (1300 °C to 1400 °C) in an oxidizing atmosphere. The samples were quenched to the cold end of the furnace
and were analyzed by X-ray diffraction (XRD). The XRD patterns of the products showed the presence of two phases—manganese
ferrite and calcium silicate. The particle size of the manganese ferrite was estimated by the Scherrer formula to be in the
range of nanometers.
Manganese is oxidized by a wide variety of bacteria. The current state of knowledge on mechanisms and functions of Mn2+ oxidation in two strains of Pseudomonas putida, in Leptothrix discophora SS-1, and in Bacillus sp. strain SG-1 is reviewed. In all three species, proteins bearing resemblance to multicopper oxidases appear to be involved in the oxidation process. A short description of the classification of Cu centers is followed by a more detailed review of properties and postulated functions of some well-known multicopper oxidases. Finally, suggestions are made for future research to assess the potential role of multicopper oxidases in bacterial Mn2+ oxidation
The low-grade siliceous manganese ores from Bonai-Keonjhar belt, Orissa, India was mineralogically characterized and investigated for their possible upgradation. Different physical beneficiation techniques like gravity, magnetic separation etc. were employed and results reported. The results reveal that a feed having 26% Mn could be upgraded to more than 45% Mn by using a dry belt type magnetic separator with 69% recovery at 1.00 tesla magnetic intensity at finer sizes.
Manganese oxide minerals are among the strongest sorbents and oxidants in the environment. The formation of these minerals controls the fate of contaminants, the degradation of recalcitrant carbon, the cycling of nutrients and the activity of anaerobic-based metabolisms(1-3). Oxidation of soluble manganese( II) ions to manganese(III/IV) oxides has been primarily attributed to direct enzymatic oxidation by microorganisms. However, the physiological reason for this process remains unknown. Here we assess the ability of a common species of marine bacteria-Roseobacter sp. AzwK-3b-to oxidize manganese( II) in the presence of chemical and biological inhibitors. We show that Roseobacter AzwK-3b oxidizes manganese(II) by producing the strong and versatile redox reactant superoxide. The oxidation of manganese(II), and concomitant production of manganese oxides, was inhibited in both the light and dark in the presence of enzymes and metals that scavenge superoxide. Oxidation was also inhibited by various proteases, enzymes that break down bacterial proteins, confirming that the superoxide was bacterially generated. We conclude that bacteria can oxidize manganese(II) indirectly, through the enzymatic generation of extracellular superoxide radicals. We suggest that dark bacterial production of superoxide may be a driving force in metal cycling and mineralization in the environment.
Mineral resources have been counted as public assets with economic benefit since time immemor-ial. Due to the rising issue of decreasing mineral deposits, recovery of metals from several waste residues has become progressively more essential. Novel and efficient recycling processes have been on the rise globally. Manganese (Mn) as the fourth most industrially applicable metal generates an extensive quantity of metallic waste which not only leads to loss of precious metal but also results in environmental toxicity. Globally, around 7 million tons of high-grade ores are produced , whereas 8 million tons of Mn alloys are produced yearly. Therefore, it is of greater significance to recover and recycle Mn from various waste residues. Various physical and biological techniques have been developed for recycling Mn from waste residues. Traditional Mn extraction processes are costly and labor intensive in nature, on the contrary, bioleaching techniques using diverse microorganism's, form the basis of an efficient, eco-friendly, and economically sustainable process of metal recovery. The quick progress in current methodologies to counteract the fast consumption of innate mineral resources involves the proper utilization of unused waste residues containing industrially important metals like Mn. This review focuses to enumerate diverse features of Mn recovery, efficient methodologies, bioleaching of Mn, merits of Mn bioleaching, and applications of recycled Mn along with the futuristic applications. Manganese recovery by means of biol-eaching will play a major role in changing the present situation where innate assets are quickly diminishing and substitute for metal recovery methodologies are the demand of this time. ARTICLE HISTORY
A comprehensive study on fungus assisted bioleaching of manganese (Mn) was carried out to demonstrate Mn solubilization of collected low grade ore from mining deposits of Sanindipur, Odisha, India. A native fungal strain MSF 5 was isolated and identified as Aspergillus sp. by Inter Transcribed Spacer (ITS) sequencing. The identified strain revealed an elevated tolerance ability to Mn under varying optimizing conditions like initial pH (2, 3, 4, 5, 6, 7), carbon sources (dextrose, sucrose, fructose and glucose) and pulp density (2%, 3%, 4%, 5% and 6%). Bioleaching studies carried out under optimized conditions of 2% pulp density of Mn ore at pH 6, temperature 37 °C and carbon dosage (dextrose) resulted with 79% Mn recovery from the ore sample within 20 days. SEM-EDX characterization of the ore sample and leach residue was carried out and the micrographs demonstrated porous and coagulated precipitates scattered across the matrix. The corresponding approach of FTIR analysis regulating the Mn oxide formation shows a distinctive peak of mycelium cells with and without treated Mn, resulting with generalized vibrations like MnOx stretching and CH2 stretch. Thus, our investigation endeavors’ the considerate possible mechanism involved in fungal surface cells onto Mn ore illustrating an alteration in cellular Mn interaction.
In the natural environment, manganese is found as reduced soluble or adsorbed Mn(II) and insoluble Mn(lll) and Mn(IV) oxides. Mn oxidation has been reported in various microorganisms. Several possible pathways, indirect or direct, have been proposed. A wider variety of Mn‐reducing microorganisms, from highly aerobic to strictly anaerobic, has been described. The mechanisms of Mn reduction can be either an indirect process resulting from interactions with organic or inorganic compounds, or a direct enzymatic (electron‐transfer) reaction. The role of microorganisms in Mn cycle is now well demonstrated by various methods in superficial natural environments, and research has been initiated on subsurface sediments. Observations in vivo (Rh6ne valley) and under in vitro suggested that bacterial activities are the main processes that promote manganese evolution and migration in shallow aquifers. After the building of hydroelectric dams, the stream of the Rhône was modified, giving rise to mud deposition on the bank. In the mud, bacteria are stimulated by the high organic content and consume oxygen. The redox potential drops. The manganese oxides previously formed under aerobic conditions are reduced and soluble manganese (Mn(II)) migrates into the aquifer. If the subsurface sediments are coarse‐grained, the aquifer is well aerated, allowing the re‐oxidation of Mn(ll) by the oligotrophic attached bacteria in aquifer sediments. If the aquifer is confined, aeration is not sufficient for Mn‐reoxidafion. Mn(II) remains in a reduced state and migrates to the wells. Furthermore, the presence of organic matter in subsurface sediments results in the reduction of previously formed Mn oxides. Pseudo‐amorphous manganese oxides, which were probably recently formed by bacteria, are more readily reduced than old crystalline manganese oxides. Although the concentrations of soluble manganese found in groundwaters are not toxic, it still is a problem since its oxidation results in darkening of water and plugging of pipes in drinking or industrial water systems. Soluble manganese can be removed from water by biological processes involving manganese‐oxidizing bacteria, either in situ, or in sand filters after pumping. Various procedures are mentioned.
The present investigation reports the isolation, molecular identification and screening of Mn
solubilizing fungal strains from low grade Mn mine tailings. Six morphologically distinct Mn
solubilizing fungal strains were isolated on MnO2 supplemented agar plates with Mn concentration
of 0.1 % (w/v).The biochemical characterization of the isolated fungal strains was carried out. The
molecular identification by Internal Transcribed Spacer (ITS) sequencing identified the strains as
Aspergillus terreus, Aspergillus oryzae, Penicillium species, Penicillium species, Penicillium dalea,
and Penicillium species with GenBank accession numbers KP309809, KP309810, KP309811,
KP309812, KP309813 and KP309814 respectively. The ability of the isolated fungal strains to
tolerate and solubilize Mn was investigated by sub-culturing them on Mn supplemented plates with
concentration ranging from 0.1-0.5% (w/v). Mn solubilizing ability of the fungal isolates is possibly
due to the mycelia production of bio generated organic acids such as oxalic acid, citric acid, maleic
acid and gluconic acid as revealed by ion chromatography. Our investigation signifies the role of
fungi in biotransformation of insoluble Mn oxide.
Although an important micronutrient for many living organisms, manganese (Mn) can become a health and environmental problem at high concentrations. The element is usually found in wastewaters and drainages of different industrial sectors and its removal is notoriously difficult because of the high stability of the Mn (II) ion in aqueous solutions. The treatment of Mn-laden wastewaters may include microorganisms that catalyze Mn oxidation by either enzymatic or non-enzymatic pathways. In this context, this mini-review discusses the mechanisms by which fungi and bacteria promote Mn bioremediation.
Recovery and separation of cobalt and manganese from one of zinc plant residues (ZPR), namely hot filter cake (HFC) using a hydrometallurgical process was studied. The process is carried out in four steps as follows: (1) washing zinc, (2) reductive leaching with hydrogen peroxide, (3) cadmium cementation with zinc powder and (4) separation of cobalt from manganese with beta naphthol. In this research, the separation between manganese and cobalt from the HFC using N-N reagent was investigated. The influence of several parameters on the course of the reaction such as N-N quantity, pH, temperature and reaction time was also examined. The optimum separation conditions were found to be N-N quantity: 8 times of stoichiometric value, time: 30 min, temperature: 25 °C and pH = 1.5. Using the optimized conditions, the cobalt and manganese precipitation was nearly 99% and 0%, respectively. A kinetic study of manganese precipitation through N-N reagent has been carried out to assess the effect of kinetics parameters. The data obtained for the leaching kinetics indicated that the precipitation of manganese is an ash diffusion controlled reaction and the reaction activation energy is equal to 1.4kJ/mol.
Manganese (Mn) ranks twelfth among the most exuberant metal present in the earth's crust and finds its imperative application in the manufacturing steel, chemical, tannery, glass, and battery industries. Solubilisation of Mn can be performed by several bacterial strains which are useful in developing environmental friendly solutions for mining activities. The present investigation aims to isolate and characterize Mn solubilising bacteria from low grade ores from Sanindipur Manganese mine of Sundargh district in Odisha state of India. Four morphologically distinct bacterial strains showing visible growth on Mn supplemented plates were isolated. Mn solubilising ability of the bacterial strains was assessed by visualizing the lightening of the medium appearing around the growing colonies. Three isolates were gram negative and rod shaped while the remaining one was gram positive, coccobacilli. Molecular identification of the isolates was carried out by 16S rRNA sequencing and the bacterial isolates were taxonomically classified as Bacillus anthrasis MSB 2, Acinetobacter sp. MSB 5, Lysinibacillus sp. MSB 11, and Bacillus sp. MMR-1 using BLAST algorithm. The sequences were deposited in NCBI GenBank with the accession number KP635223, KP635224, KP635225 and JQ936966, respectively. Manganese solubilisation efficiency of 40, 96, 97.5 and 48.5% were achieved by MMR-1, MSB 2, MSB 5 and MSB 11 respectively. The efficiency of Mn solubilisation is suggested with the help of a pH variation study. The results are discussed in relation to the possible mechanisms involved in Manganese solubilisation efficiency of bacterial isolates.
Biomedical waste ash generated due to the incineration of biomedical waste contains large amounts of heavy metals and polycyclic aromatic hydrocarbons (PAHs), which is disposed of in regular landfills, and results in unfavorable amounts of hazardous materials seeping into the ground and may pollute surface water and groundwater. Therefore, it is essential to remove the toxicity of ash before disposal into landfills or reutilization. Environmental characteristic analysis of BMW ash showed increased hardness (1320 mg/L) and chloride (8500 mg/L) content in leachate compared to World Health Organization (WHO) and Environment Protection Agency (EPA) guidelines for drinking water (hardness, 300 mg/L; chloride, 250 mg/L). The alkalinity and pH of the ash leachate were 400 mg/L and 8.35, respectively. In this paper, study was carried out to investigate the metal tolerance level of bacterial isolates isolated from soil. The isolate Bacillus sp. KGMDI can tolerate up to 75 mg/L of metal concentration (Mn, Mo, Cr, Fe, Cu, and Zn) in enriched growth medium. This shows that the isolated culture is capable of growing in presence of high concentration of heavy metals and acts as potential biological tool to reduce the negative impact of BMW ash on the environment during landfilling.
Bacteriological investigations of the ferromanganese nodules collected from the Indian Ocean indicate that the microbial populations associated with the nodules are, in general, comparable to those of the Pacific and Atlantic Oceans. Both Mn(II)‐oxidizing and MnO2‐reducing psychrotrophic bacteria were present in the nodules. The maximum percentage of oxidizers was noticed on the surface of the nodules. The sediments harbored more inactive forms. Members of Vibrio, Enterobacteriaceae, Bacillus, Micrococcus, Sta‐phylococcus, Arthrobacter, and coryneforms were encountered in the present study. Most of the isolates were able to grow on a wide range of sodium chloride concentrations (0 to 10%). The isolates elaborated a number of hydrolytic enzymes, namely, amylase, gelatinase, lipase, and phosphatase. The dominance of the gram‐positive group is attributed to terrigenous influences. The present study clearly indicates that Indian Ocean nodules also harbor a variety of heterotrophic bacteria capable of mobilizing and immobilizing manganese.
Large amounts of silicomanganese slag are generated and discarded from the silicomanganese alloy smelting furnaces that treat ferromanganese slag to produce silicomanganese alloy, which contain 10–14 mass% Mn. It is thus important to find a possibility for recovering manganese from silicomanganese slag in terms of environmental and economic points of view. Upgrading of manganese from the silicomanganese slag for recycling the slag back to the silicomanganese furnaces must be necessary to decrease the slag volume which causes irregularities in their operation. In this study, a physical separation process for the upgrading of manganese from silicomanganese slag discarded has been suggested. The process first grinds silicomanganese slag between −500 μm and +75 μm, followed by the dry magnetic separation process to separate and concentrate manganese from the ground slag. Based on the results obtained, a manganese rich slag which contains over 20 mass% manganese was calculated to be separated and concentrated from silicomanganese slag under a magnetic field of about 6,000 Tesla using the proposed process. The manganese rich slag obtained should be used as a manganese resource for manufacturing silicomanganese alloy.
Laccases (benzenediol: oxygen oxidoreductase; EC 18.104.22.168), a multicopper oxidase enzyme, widely distributed in plants, fungi and bacteria have ability to catalyze oxidation of various phenolic and non-phenolic compounds as well as many environmental pollutants. The diversified functions of laccases, including the antagonistic ones such as their involvement in lignin biosynthesis (in plants) as well as lignin degradation (in fungi and bacteria), make them an interesting enzyme for study from the point of view of their structure, function and application. Important applications of laccases include delignification, pulp bleaching and bioremediation. The ability of laccases to polymerize natural phenols helps to develop new cosmetic pigments, hair dyeing materials, deodorants, toothpastes, mouthwashes and other useful products.
Citric acid was used to selectively extract cobalt from limonite-type laterite ores in the presence of ammonium bifluoride. The results show that ammonium bifluoride enhances the leaching of cobalt by citric acid, and 84.5% cobalt is extracted from a laterite ore containing 0.13% Co when leached at ambient temperature for 2 h with 30 g/L citric acid and 10 g/L ammonium bifluoride. Pyrolusite is reduced by citric acid during leaching, cobalt intergrown with which is liberated and subsequently chelated by the citric acid. The extraction of cobalt is enhanced in the presence of ammonium bifluoride because the matrix of silicate minerals is destroyed by ammonium bifluoride and the adsorbed cobalt is subsequently liberated.
Bioleaching processes for extraction of zinc from sphalerite are more environmentally friendly and consume less energy than conventional technologies but are as yet less economic. One necessary step towards arriving at a cost-effective sphalerite bioleaching process is the use of appropriate methodology for the optimization of pertinent factors in such processes. Previous studies on Zn bioleaching systems have reported a fairly wide range of values as the optimum level of relevant physicochemical parameters for Zn bioleaching processes. This is partly due to the different strains and Zn source type employed but another reason could be that important parameters in this process interact with each other. In order to shed more light on this matter, in the present work Response Surface Methodology was employed for the study and optimization of important factors in a sphalerite bioleaching process by Acidithiobacillus ferrooxidans using shaking bioreactors. The effect of change in the levels of temperature, pH, initial Fe(II) concentration and pulp density – in the range 30–36°C, 1.4–2.0, 3–11gL−1 and 4–6% wt/vol respectively – on the rate Zn bioleaching was studied using a Central Composite Design. The results showed a statistically significant effect of pH and pulp density – and to a lesser extent temperature and initial Fe(II) concentration – on the rate of bioleaching of Zn. A statistically significant interaction was found between pH and temperature, which means that the optimum values of these two parameters can only be correctly obtained through the use of factorial design of experiments. Additionally, the optimum level of temperature and pH was found to depend on the level of pulp density. This means that when employing shaking bioreactors for optimization of these parameters the level of pulp density should be carefully chosen. However, there was no statistically significant interaction between initial Fe(II) concentration and the other three factors studied.
Metal-oxidizing bacteria may play a key role in the submarine weathering of volcanic rocks and the formation of ferromanganese crusts. Putative fossil microbes encrusted in Mn oxide phases are commonly observed on volcanic glasses recovered from the deep ocean; however, no known Mn(II)-oxidizing bacteria have been directly identified or cultured from natural weathered basalts. To isolate epilithic Mn(II) oxidizing bacteria, we collected young, oxidized pillow basalts from the cold, outer portions of Loihi Seamount, and from nearby exposures of pillow basalts at South Point and Kealakekua Bay, HI. SEM imaging, EDS spectra and X-ray absorption spectroscopy data show that microbial biofilms and associated Mn oxides were abundant on the basalt surfaces. Using a series of seawater-based media that range from highly oligotrophic to organic-rich, we have obtained 26 mesophilic, heterotrophic Mn(II)-oxidizing isolates dominated by α- and γ-Proteobacteria, such as Sulfitobacter, Methylarcula and Pseudoalteromonas spp. Additional isolates include Microbulbifer, Alteromonas, Marinobacter, and Halomonas spp. None of the isolates, nor their closest relatives, were previously recognized as Mn(II) oxidizing bacteria. The physiological function of Mn(II) oxidation is clearly spread amongst many phylogenetically diverse organisms colonizing basalt surfaces. Our findings support a biological catalysis of Mn(II) oxidation during basalt-weathering, and suggest heterotrophic Mn(II) oxidizing bacteria may be ubiquitously associated with submarine glasses within epilithic and endolithic biofilms.
Manganese‐oxidizing microorganisms have been implicated in the deposition of manganese in dark manganiferric rock varnish coatings on desert rocks. For this study, a collection of bacteria able to oxidize manganese has been obtained from rock varnish samples from the Sonoran and Mojave Deserts. Two groups of organisms predominated among the isolates. One group was identified as Arthrobacter spp. based on their rod‐coccus transformations, cell shapes, postfission division stages, and physiological characteristics. Another major group consisted of gram‐positive cocci tentatively ascribed to the genus Micrococcus. In addition, single isolates of Bacillus sp., Planococcus sp., Streptococcus sp., and Hyphomonas sp. were identified as manganese‐oxidizing bacteria. Some isolates grew too poorly to be easily characterized and identified.
The leaching of copper, nickel and cobalt from polymetallic manganese nodules from the Indian Ocean was investigated using a fungus — Aspergillus niger. Parameters such as initial pH, pulp density, particle size and duration of leaching were optimized for the bio-recovery of metals. At an initial pH of 4.5, 35ºC temperature and 5% (w/v) pulp density, about 97% Cu, 98% Ni, 86% Co, 91% Mn and 36% Fe were dissolved in 30days time using adapted fungus — as against only 4.9% Cu, 8.2% Ni, 27% Co, 6.3% Mn and 7.1% Fe solubilized in control experiment. The results indicate that A. niger released organic acids such as oxalic and citric acids which in turn reduced the host metal oxides/hydroxides to their lower valence states, and thus dissolving the base metals following the indirect mechanism. A comparison of results obtained with chemical leaching of sea nodules using citric and oxalic acids and bio-leaching using A. niger show that the leaching of metals was more effective in presence of the fungus. The appearance of some lower oxide phases of manganese and iron in the leach residue identified by XRD phase analyses may account for unlocking of the host lattice leading to release and dissolution of metals during leaching.
Extraction of manganese from manganese dioxide ores was investigated using corncob as a reducing agent in dilute sulfuric acid medium. The effects of corncob amount, concentration of sulfuric acid, leaching temperature, reaction time and ore particle size were discussed. The leaching efficiency of manganese reached 92.8% while iron dissolved was 24.6% under the optimal condition which was determined for 10g of manganese dioxide ore as corncob amount of 3g, ore size of 75μm, sulfuric acid concentration of 1.9mol/L, leaching temperature of 85°C for 60min. In a word, the method provided a good leaching yield while making a productive use of corncob.
The mechanism and kinetics of bioleaching of chalcopyrite concentrate by the thermophilic archaea Acidianus brierleyi was studied in batch and continuous-flow stirred tank reactors (CSTR). In the batch reactor, the thermophile A. brierleyi solubilized chalcopyrite much faster at 65°C than did the mesophile, Thiobacillus ferrooxidans at 30°C. The chalcopyrite leaching with A. brierleyi was found to take place with a direct attack by adsorbed cells on the mineral surface, the chemical leaching with ferric iron being insignificant. Rate data collected in the batch reactor were analyzed to estimate kinetic and stoichiometric parameters for the growth of A. brierleyi on chalcopyrite. The batch model and the estimated parameter values were used to find optimum levels of initial cell concentration and initial mineral/liquid loading ratio. Simulations based on continuous reactor model and the parameter values were used to predict the leaching fraction as a function of the number of reactors connected in series.
It was demonstrated that simultaneous removal of ammonia and manganese could be accomplished by biological aerated filter (BAF) with low-cost lava as media. Long-term operation performance and impact factors were systematically studied. DGGE analysis demonstrated that ammonia oxidizing bacteria (AOB), manganese oxidizing bacteria (MOB) and simultaneous ammonia and manganese oxidizing bacteria (SAMOB) co-existed in the bio-film. Ammonia and manganese concentration profiles along the height of BAF column, including that in the influent and effluent, were investigated with varying hydraulic loadings, aeration intensities and feed ammonia concentrations. It was inferred that AOB and MOB may have different spatial distribution in vertical direction, and AOB and MOB may compete for oxygen capture or be present on different layers of the bio-films. Further work should focus on the distribution of AOB, MOB and SAMOB in the reactor and optimize it for more efficient mass transfer and better system performance.