Iron leaching from China clay with oxalic acid: effect of different physico-chemical parameters

China clay is an important mineral, which is used in the manufacture of ceramics and refractory, as also in other industries. Mined China clay contains iron oxides and silicates as impurity; if present in excess of a threshold level, the impurities affect the commercial value of the products. Currently available processes for lowering the iron content in China clay to the desired level ( < 0.8%) are energy- and cost-intensive, not sufficiently flexible, and may cause environmental pollution. An alternative approach for iron removal consists in the development of a biotechnological process which is expected to be cost-effective, less complex and eco-friendly. We reported earlier that several fungi, especially Aspergillus niger, and their culture filtrates could leach sufficient amount of iron from a China clay sample; oxalic acid was found to be the most active component of the culture filtrate (Trans. Indian Inst. Met. 55 (2002) 1). We now report the rates of iron leaching from another China clay sample by oxalic acid and by the culture filtrate of A. niger NCIM 548 that was found to be the most active strain in our previous study (Trans. Indian Inst. Met. 55 (2002) 1). The iron-leaching rates increased with temperature (T) and followed biphasic kinetics. The effect of oxalic acid concentration (C), pH (H), solids concentration or pulp density ( P), time and mode of agitation on the rate of iron leaching is described. The rate of leaching with oxalic acid (Rox) can be calculated theoretically from the following relationship: Roxf(C)0.76(T)1.76(H)0.80( P)0.20 under the specified set of conditions. Using the same concentration of oxalic acid in A. niger culture filtrate, the relationship of the rate differed; this may be due to the influence of other metabolites present in the culture filtrate on the rate

Microbial Extraction of Cobalt and Nickel from Lateritic Chromite Overburden using Aspergillus wentii

ABSTRACT Low-grade nickeliferous lateritic ore from Sukinda region of Orissa, India, was subjected to biohydrometallurgical treatment for the extraction of nickel and cobalt. The mineralogical studies reveal that nickel is entrapped in goethite matrix while cobalt is associated with the manganese phase. Aspergillus wentii NCIM 667, a citric acid producing fungal strain, was used for direct (one step and two step) and indirect (using culture filtrate) leaching of the metals under different conditions. The effect of varying pulp density (2%, 5%, 8%) and culture medium composition (viz. molasses and sucrose media) was investigated and the leaching conditions optimized. It was found that a maximum of 49.29% Ni and 35.18% Co could be recovered from the heat-treated lateritic chromite overburden by the culture filtrate bioleaching at 80°C with 2% pulp density

Potential therapeutic application of gold nanoparticles in B-chronic lymphocytic leukemia (BCLL): enhancing apoptosis

B-Chronic Lymphocytic Leukemia (CLL) is an incurable disease predominantly characterized by apoptosis resistance. We have previously described a VEGF signaling pathway that generates apoptosis resistance in CLL B cells. We found induction of significantly more apoptosis in CLL B cells by co-culture with an anti-VEGF antibody. To increase the efficacy of these agents in CLL therapy we have focused on the use of gold nanoparticles (GNP). Gold nanoparticles were chosen based on their biocompatibility, very high surface area, ease of characterization and surface functionalization. We attached VEGF antibody (AbVF) to the gold nanoparticles and determined their ability to kill CLL B cells. Gold nanoparticles and their nanoconjugates were characterized using UV-Visible spectroscopy (UV-Vis), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). All the patient samples studied (N = 7) responded to the gold-AbVF treatment with a dose dependent apoptosis of CLL B cells. The induction of apoptosis with gold-AbVF was significantly higher than the CLL cells exposed to only AbVF or GNP. The gold-AbVF treated cells showed significant down regulation of anti-apoptotic proteins and exhibited PARP cleavage. Gold-AbVF treated and GNP treated cells showed internalization of the nanoparticles in early and late endosomes and in multivesicular bodies. Non-coated gold nanoparticles alone were able to induce some levels of apoptosis in CLL B cells. This paper opens up new opportunities in the treatment of CLL-B using gold nanoparticles and integrates nanoscience with therapy in CLL. In future, potential opportunities exist to harness the optoelectronic properties of gold nanoparticles in the treatment of CLL

CSR, co-optation and resistance: the emergence of new agnostic relations between business and civil society

This article examines the theoretical implications of the changing relationships between NGOs and businesses that have emerged as a response to the evolving agenda around CSR and sustainable development. In particular, it focuses upon examining whether greater engagement from non-governmental organisations (NGOs) in this area reflects a process of appropriation and co-optation of protest by the business community. To examine this process, the article considers two forms of appropriation—appropriation of language and appropriation via participation—as a basis for discussion. While co-optation pressures are identified within both areas, the article argues that co-optation is identified almost as an inevitable outcome of engagement without significant consideration of the ability of movements to identify and respond to these processes. In identifying an alternative approach, the article utilises Mouffe’s framework of agonistic pluralism. Mouffe’s framework, it is argued, provides an understanding of the way in which agonistic relationships are emerging between NGOs and businesses while highlighting the continuance of conflict between parties struggling to influence the contested interpretations of responsible business

Mechanism of Cadmium Binding on the Cell Wall of an Acidophilic Bacterium

Under certain conditions bacteria can act as a good biosorbent for different toxic heavy metals. However, no study on this aspect has been reported in case of acidophilic, heterotrophic, Gram-negative Acidiphilium strains, which are mostly resistant to several heavy metals. FTIR, SEM, TEM along with sorption experiments using bacterial cells of Acidiphilium symbioticum H8 were conducted to establish the mechanism of Cd2+ ion sorption. The anionic functional groups present in the cell envelop were the components primarily responsible for the metal-binding capability of the bacterium. Sorption experiment further confirmed that 248.62 mg of cadmium was adsorbed per gram biomass at pH 6.0. The process can better be explained by Langmuir–Freundlich dual isotherm model. Blocking of the functional groups by chemical modification suggested that the binding of cadmium on the biomass occurs through electrostatic reaction and complex formation. Accumulation of cadmium on the cell envelop was supported by fine structure study

High-yielding Plasmid Extraction Method from Acidophilic Heterotrophic Bacteria of the Genus Acidiphilium

Plasmid yield from Acidiphilium strains always had been poor following various standard methods. We adopted some simple modiWcations in the alkaline lysis procedure to get a better yield of plasmid from these bacteria. An approximately 10- to 20-fold increase in the plasmid yield was achieved when harvested Acidiphilium cells were preincubated 16–20 h at pH 6 in nitrogen-free medium. Another independent approach showed that freezing (¡18 to ¡20 °C) of the harvested cells initially and at two subsequent steps in the alkaline lysis procedure of plasmid DNA extraction improved the yield further by 1.5- to 3-fold. The combination of these changes yielded at least 15-to 30-fold more plasmid from various Acidiphilium strains as compared with standard methods

Nucleotide Sequence Analysis of Cryptic Plasmid pAM5 from Acidiphilium Multivorum

Plasmid pAM5 of Acidiphilium multivorum JCM-8867 has been completely sequenced by initial cloning of HindIII–PstI fragments followed by primer walking. It has a size of 5161 bp and single site for several restriction enzymes as revealed by DNA sequencing. Sequence analysis predicts five putative open reading frames. ORF1 and ORF3 show significant identity with various plasmid encoded mobilization (Mob) and replication initiation (Rep) proteins, respectively. The putative Mob protein has several characteristics of the MOBQ family having the motifs with conserved amino acid residues. Upstream of the Mob ORF, there exists a 34 bp oriT region having a nic consensus sequence. The constructed plasmid pSK1 bearing pAM5 mob region can be mobilized to Escherichia coli in presence of conjugative plasmid pRK2013. The replication module comprises of several DnaA like boxes, several perfect direct and inverted repeats, a potential prokaryotic promoter and putative rep gene. The rep module is very similar to several theta replicating iteron family plasmids, suggesting pAM5 replication to follow the same course. Any phenotypic character determinant (e.g., metal resistance, antibiotic resistance etc.) gene is absent in pAM5, suggesting this plasmid to be cryptic in nature. However, a pAM5 derivative plasmid named pSK2, containing the putative pAM5 rep region, can replicate and be stably maintained in Acidiphilium, Acidocella, and E. coli strains; it can also carry foreign DNA fragments. Thus, pSK2 could serve as a cloning shuttle vector between these bacteria. It was observed that pAM5 Rep is essential for pSK2 to replicate in acidophiles. In its natural host, A. multivorum JCM-8867, pAM5 maintains a copy number of 50–60, and its derivative pSK2 maintains a comparatively, higher copy number in E. coli than in acidophiles

Research Journal of Pharmaceutical, Biological and Chemical Sciences &apos;Green&apos; Synthesis of Silver Nanoparticles by Using Grape (Vitis vinifera) Fruit Extract: Characterization of the Particles and Study of Antibacterial Activity

ABSTRACT The synthesis of metal nanoparticles is a growing area for research due to its potentiality in the application and development of advanced technologies. In general, nanoparticles are synthesized by using chemical methods which are not eco-friendly. Here, we have used a fast, convenient and environment-friendly method for the synthesis of silver nanoparticles by reducing silver nitrate with fruit extract of grape (Vitis vinifera). Characterization of the metallic nanoparticles was done by UV-Vis Spectroscopy, Dynamic Light Scattering (DLS) and Energy Dispersive X-ray Spectroscopy (EDX). The particle size and lattice image of the silver nanoparticles was studied by Transmission Electron Microscopy (TEM). The antibacterial activity of these nanoparticles was studied against Bacillus subtilis and Escherichia coli. Growth curves of bacteria in presence of silver nanoparticles showed inhibition of growth suggesting antibacterial property of the nanoparticles

Plasmid Curing from an Acidophilic Bacterium of the Genus Acidocella

Preservation of the acidophilic heterotroph, Acidocella sp. strain GS19h, at 4³C in stab culture eliminated all indigenous plasmids from this bacterium. Growth at 42³C initially caused changes in the plasmid profile followed by total elimination of plasmids after 10 cycles of growth. Concomitant to this loss of all plasmids, the cured derivatives became sensitive to CdSO4 and ZnSO4, and the MIC value of the salts dropped from 1 M for each in the case of parental strain to 2 mM and 5 mM, respectively, suggesting plasmid-mediated inheritance of metal resistance in this bacterium. The cured derivatives could not utilise lactose, indicating this metabolic activity to be plasmid-associated in this strain. ß 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved

Resistance to Cadmium and Zinc in Acidiphilium symbioticum KM2 Is Plasmid Mediated

The acidophilic heterotroph, Acidiphilium symbioticum KM2, is highly resistant to several metals and harbors three plasmids of 3.8, 7.1, and 56 kb in size. The bacterium becomes extremely sensitive to metals when it is cured of its plasmids. A mini-plasmid library was constructed by ligating the plasmid DNA fragments generated by MboI partial digestion into the BamHI site of pBluescriptII KS�. The Lac�Ampr transformants of Escherichia coli DH5�, isolated after transformation with the library, were counter-selected on Cu2�, Cd2�, Ni2�, and Zn2�-containing plates. Only Cd2�- and Zn2�-resistant colonies were developed, and, after screening, four types of recombinant plasmids designated as pNM201 (7.2 kb), pNM206 (3.4 kb), pNM208 (4.5 kb), and pNM215 (4.9 kb) were obtained. The DNA insert in pNM206 hybridized strongly with the 3.8-kb plasmid and weakly with the 7.1-kb plasmid of Acidiphilium symbioticum KM2. The DNA insert in pNM215 hybridized only with the 7.1-kb plasmid. These results strongly suggested that resistance to cadmium and zinc in A. symbioticum KM2 is mediated by these plasmids. The smallest insert of 422 bp in pNM206 conferring metal resistance in E. coli has no sequence similarity with the reported metal-resistant genes. All the putative ORFs are significantly rich (up to 37%) in basic amino acids, mainly arginine