Extraction of lithium from spodumene by bioleaching

A multiplex PCR assay specifically detecting Escherichia coli O157 : H7 was developed by employing primers amplifying a DNA sequence upstream of E. coli O157 : H7 eaeA gene and genes encoding Shiga-like toxins (SLT) I and II. Analysis of 151 bacterial strains revealed that all E. coli O157 : H7 strains were identified simultaneously with the SLT types and could be distinguished from E. coli O55 : H7 and E. coli 055 : NM, and other non-O157 SLT-producing E. coli strains. Primer design, reaction composition (in particular, primer quantity and ratios), and amplification profile were most important in development of this multiplex PCR. This assay can serve not only as a confirmation test but also potentially can be applied to detect the pathogen in food.     

Bioleaching of silicon in electrolytic manganese residue using single and mixed silicate bacteria

Bioprocess and Biosystems Engineering - Electrolytic manganese residue (EMR) is a type of industrial solid waste with a high silicon content. The silicon in EMR can be used as an essential nutrient...     

Extraction of manganese peroxidase produced by Lentinula edodes

Lentinula edodes, commonly called shiitake, is considered a choice edible mushroom with exotic taste and medicinal quality. L. edodes grows very well and produces a range of enzymes when cultivated on eucalyptus residues. Development of appropriate experimental procedures for recovery and determination of enzymes became a widely important cash crop. In this work, enzymes produced by L. edodes were extracted using different pH buffer and determined regarding peroxidases and proteases. Lignin peroxidase (LiP) was not detected in the extracts based on veratryl alcohol or azure B oxidation. Proteases were very low while Mn-peroxidases (MnP) predominated. The optimal pH for MnP recovery was 5.0, under agitation at 25 degrees C. The oxidation of phenol red decreased after dark-colored small compounds or ions were eliminated by dialysis. The extract of L. edodes contained components of high molecular weight, such as proteases or high polyphenol, that could be involved in the LiP inactivation. L. edodes sample previously submitted to dialysis was also joined to LiP of Phanerochaete chrysosporium and a total inhibition of LiP was observed.     

Copper removal from an industrial waste by bioleaching

Summary Copper contained in a solid industrial waste produced in a silicone manufacturing process was leached with spent iron medium from aThiobacillus ferrooxidans culture. Most effective leaching was observed in a continuously fed, dual reactor system. Spent iron medium was generated by growingT. ferrooxidans in 0.9 K iron medium at pH 1.5 in the first reactor, and was transferred to a second reactor in which it leached the copper from the waste. Leaching was effective at a pulp density of the waste material as high as 20%. In experiments run at a pulp density of 2.5%, the spent iron medium was most efficient in leaching copper when it was first diluted 100-fold with a mineral salts solution at pH 1.5. Removal of the copper from the waste appeared to involve its displacement by acid, dissolved mineral salts, and ferric iron. Potentials for practical application of this process are discussed.     

烟草废料中绿原酸的提取工艺研究

讨论了从烟草废料中提取绿原酸的优势和甲醇、乙醇、丙酮、水等不同溶剂经超声波辅助提取绿原酸的效果：研究结果表明,用体积分数40％的甲醇得到的浸提液中,绿原酸质量浓度为2．11mg／mL,比以水为溶剂时高出近50％.不同浓度的甲醇溶液中,体积分数50％的甲醇提取绿原酸的浓度最高。对树脂的吸附动力学分析表明,大孔树脂CN-101对烟草浸提液中绿原酸的吸附遵循Freundlich等温方程,吸附和解析分离所得的绿原酸收率为87．6％.在超声辅助条件下,利用甲醇等有机溶剂提取烟草中的绿原酸,进而用大孔树脂进行吸附分离的方法可行。     

Aerobic processes for bioleaching manganese and silver using microorganisms indigenous to mine tailings

World Journal of Microbiology and Biotechnology - Alcohol fermentation is a key process in wine, beer, alcoholic beverage production, bioethanol production by means of carbohydrate sources, and...     

Enzymic oxidation of manganese by cell-free extracts of bacteria from manganese concretions from soil

Kinetics of Mn²⁺-oxidation by cell-free extract of two new Mn²⁺-oxidizing bacteria isolated from soil concentrations show that this oxidation is enzymic. Isolation of the enzyme or system of enzymes involved was attempted. The activity of cell-free extract was examined after storage of cell-free extract at 4 °C and −18 °C, after fractionation by centrifugation and after fractionation with Sephadex gels.     

Extraction, isolation and NMR data of the tetraether lipid calditoglycerocaldarchaeol (GDNT) from Sulfolobus metallicus harvested from a bioleaching reactor

The successful extraction and isolation of the hydrolysed tetraether lipid calditoglycerocaldarchaeol (GDNT) from Sulfolobus metallicus, a key thermophilic bioleaching archaeon, is described. The archaeal biomass was recovered directly from a thermophilic (68 degrees C) bioleaching tank reactor used to extract nickel from a pentlandite mineral concentrate. The initial Soxhlet extraction method employed was scaled to a bench-scale extraction procedure suitable for the preparation of gram-scale quantities of GDNT. The GDNT so obtained was analysed by 1D- and 2D-NMR techniques, providing the first complete 13C and 2D-NMR data-set for GDNT, including that for the intact underivatised calditol moiety. The study demonstrates the feasibility of recovering high-quality GNDT from thermophilic archaeal-mediated bioleaching reactors. The recovery of these lipids at relatively low cost, as a by-product from bioleaching reactors used in the metals processing industry, has important implications for future tetraether lipid availability and costs.     

Bauxite residue sand has the capacity to rapidly decrease availability of added manganese

Bauxite residue sand, even though a poor substrate for plant growth because of very high pH, salinity and sodicity, is required to be revegetated. Manganese deficiency is observed in residue-grown plants because broadcast applications of manganese fertiliser to the surface of residue deposits have a low residual value. In a laboratory experiment, manganese (as MnSO₄) was added to fresh and 4-year-old residue sand and a sequential fractionation procedure performed at 0, 1, 4, 8 and 24 h and 6, 14, 21, 43, 73, 103 and 130 d. Extraction with DTPA estimated plant-available Mn, while sequential fractionation with various extractants yielded the following fractions: readily soluble [Ca(NO₃)₂]; weakly adsorbed [CaDTPA-B₄O₇]; carbonate-bound [HNO₃]; and oxide-bound [NH₂OHHCl]. Residual Mn was calculated as a difference between the sum of all these forms and total Mn in residue sand. Transformation of manganese from the initially dominant readily soluble form to the less-available forms was very rapid (< 24 h). A change to fertilisation strategies is required if better efficiency of manganese application and uptake is to be achieved for plants growing on bauxite residue.     

Tank bioleaching of copper from combined flotation concentrate and smelter dust

Bioleaching studies were conducted to evaluate the extraction of copper from combined flotation concentrate and smelter dust using two different dust-addition strategies, non-fractional (simultaneously with concentrate) and fractional (step-wise dust addition) in stirred tank reactors. The highest copper extraction obtained with the fractional dust addition was up to 94% while extraction using the non-fractional method leveled off at approximately 44%. Thus, an increased copper recovery of about 50% was achieved with the fractional dust-addition method. It seems that the main reason for increased copper recovery using fractional dust addition could be the control and prevention of chalcopyrite passivation (according to SEM/EDS, XRD, and quantitative mineralogy data). This leads to its improved dissolution.     

加压提取地榆根中黄酮成分的研究

研究加压提取地榆中黄酮的最佳提取工艺。探讨了乙醇浓度、料液比、粒径、提取压力、提取温度和提取时间6个因素对黄酮得率的影响,并通过正交试验优化,确定了加压提取地榆中黄酮的最佳条件。结果表明加压提取地榆中黄酮的最佳提取条件:浸提温度120℃,料液比为1∶20,提取溶剂为60%的乙醇,浸提时间为30min,浸提压力为5 kg/cm2,粒径为40目,在该条件下黄酮提取率可达17.35%。与回流提取法相比,加压浸提法可显著提高浸提率。     

Direct zinc sulphide bioleaching by Thiobacillus ferrooxidans and Thiobacillus thiooxidans

Summary Direct bioleaching (no iron(II) present) by Thiobacillus ferrooxidans mainly occurs on the surface of the very insoluble sulphides but is more important in solution when the sulphides are more soluble. In this case, Thiobacillus thiooxidans, normally not able to leach directly insoluble sulphides, has an effective leaching action.     

Synthesis and characterization manganese oxide nanobundles from decomposition of manganese oxalate

The present investigation reports, the synthesis of manganese oxide (α-Mn₂O₃) nanobundles using thermal decomposition and its physicochemical characterization. The α-Mn₂O₃ nanobundles have been prepared using manganese oxalate dihydrate powders as precursor in the presence of oleylamine and triphenylphosphine as solvent and capping agent. Transmission electron microscopy (TEM) analysis demonstrated Mn₂O₃ nanobundles compose of nanospheres with diameter 30 nm. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy. Manganese oxide nanocrystals have been prepared under different condition. The controlled experimental results showed that the use of oleylamine and triphenylphosphine as the solvent and capping agent in the chemical process played important role in the formation of the final products.     

Indirect bioleaching of covellite by Thiobacillus thiooxidans with an oxidant agent

Summary High copper extraction by the action of Thiobacillus thiooxidans (T.t.) on covellite in presence of iron(III) is explained by indirect mechanism, in which T.t. only oxidizes the layer of sulphur that covers the sulphide surface allowing sulphide oxidation by iron(III). In cultures on elemental sulphur with iron(III) T.t. is not able to use iron(III) as an acceptor of electrons in sulphur oxidation; iron(III) only oxidizes those intermediates which were generated in the aerobic oxidation of sulphur.     

Conversion of milled pine wood by manganese peroxidase from Phlebia radiata

Purified manganese peroxidase (MnP) from the white-rot basidiomycete Phlebia radiata was found to convert in vitro milled pine wood (MPW) suspended in an aqueous reaction solution containing Tween 20, Mn(2+), Mn-chelating organic acid (malonate), and a hydrogen peroxide-generating system (glucose-glucose oxidase). The enzymatic attack resulted in the polymerization of lower-molecular-mass, soluble wood components and in the partial depolymerization of the insoluble bulk of pine wood, as demonstrated by high-performance size exclusion chromatography (HPSEC). The surfactant Tween 80 containing unsaturated fatty acid residues promoted the disintegration of bulk MPW. HPSEC showed that the depolymerization yielded preferentially lignocellulose fragments with a predominant molecular mass of ca. 0.5 kDa. MnP from P. radiata (MnP3) turned out to be a stable enzyme remaining active for 2 days even at 37 degrees C with vigorous stirring, and 65 and 35% of the activity applied was retained in Tween 20 and Tween 80 reaction mixtures, respectively. In the course of reactions, major part of the Mn-chelator malonate was decomposed (85 to 87%), resulting in an increase of pH from 4.4 to >6.5. An aromatic nonphenolic lignin structure (beta-O-4 dimer), which is normally not attacked by MnP, was oxidizible in the presence of pine wood meal. This finding indicates that certain wood components may promote the degradative activities of MnP in a way similar to that promoted by Tween 80, unsaturated fatty acids, or thiols.     

Differential bioleaching of copper by mesophilic and moderately thermophilic acidophilic consortium enriched from same copper mine water sample

Three acidophilic enrichment consortium were developed from mine water sample of copper mine site at Khetri, India were compared for their copper leaching efficiency. Out of these one was mesophilic (35 degrees C) and two were moderately thermophilic (50 degrees C). Consortia were named as mesophilic acidophilic chemolithotrophic consortia (MACC), thermophilic acidophilic chemolithotrophic consortia (TACC), and Sulfobacillus acidophilic consortia (SAC). Copper extraction ability of both the thermophilic consortia (77-78% extraction) was almost double to that of mesophilic consortia (40% extraction) at 10% pulp density after 55 days. Both the thermophilic consortia were equally effective in leaching of other metals like Ni, Co, Zn, Mn. After 55 days, the percentage of extractions of copper by TACC was 76, 74, 67, 48 and 45 at 5%, 10%, 15%, 20% and 30% pulp density, respectively. Total number of bacteria was maximum at 5% pulp density which decreases with increase in pulp density. Sulfobacillus-like bacteria were seen in the Sulfobacillus enrichment cultures. Moderately thermophilic consortia proved to be better in leaching performance than the mesophilic counterpart.     

Effects of L-cysteine on Ni-Cu sulfide and marmatite bioleaching by Acidithiobacillus caldus

The effect of L-cysteine in different concentrations on the bioleaching of Ni-Cu sulfide and marmatite were studied with a moderately thermophilic, sulfur-oxidizing bacterium, strain of Acidithiobacillus caldus. X-ray diffraction (XRD) observations showed the change of bioleached solid residues and the effect of L-cysteine on the surface charges of minerals. It was found that adding certain amounts of L-cysteine to the leaching system of Ni-Cu sulfide largely enhanced the leaching rate, while L-cysteine inhibited the bioleaching of marmatite by A. caldus. The mechanism of L-cysteine interaction with mineral surfaces was studied by means of zeta potential determination and IR spectra.     

Microbial manganese reduction mediated by bacterial strains isolated from aquifer sediments

One hundred and five strains isolated from aquifer sediments andEscherichia coli ML30S were tested for their ability to reduce manganese oxides. Eighty-two strains, includingE. coli, reduced manganese. In most cases the bacterial activity decreased the pH and Eh below 6.75 and 350 mV, respectively, enhancing a spontaneous and nonspecific reduction of manganese. However, for 12 strains the reduction was specifically catalyzed by bacteria; the high pH and Eh values would not permit a spontaneous reduction of manganese. Some of the most active strains were identified as genera common in soils and waters, i.e.,Pseudomonas, Bacillus, Corynebacterium, andAcinetobacter. Two strains were studied in detail. One of the strains, identified asPseudomonas fluorescens, required contact between the cells and the manganese oxides for reduction to occur. The reduction was inhibited by 15 mM of sodium azide. The other strain, identified asAcinetobacter johnsonii, catalyzed manganese reduction by an inductive and dialyzable substance which was excreted by the bacteria. The mechanism involved has not been previously demonstrated.