Biosorption of heavy metals by Bacillus thuringiensis strain OSM29 originating from industrial effluent contaminated north Indian soil

AbstractThe study was navigated to examine the metal biosorbing ability of bacterial strain OSM29 recovered from rhizosphere of cauliflower grown in soil irrigated consistently with industrial effluents. The metal tolerant bacterial strain OSM29 was identified as Bacillus thuringiensis following 16S rRNA gene sequence analysis. In the presence of the varying concentrations (25–150mgl−1) of heavy metals, such as cadmium, chromium, copper, lead and nickel, the B. thuringiensis strain OSM29 showed an obvious metal removing potential. The effect of certain physico-chemical factors such as pH, initial metal concentration, and contact time on biosorption was also assessed. The optimum pH for nickel and chromium removal was 7, while for cadmium, copper and lead, it was 6. The optimal contact time was 30min. for each metal at 32±2°C by strain OSM29. The biosorption capacity of the strain OSM29 for the metallic ions was highest for Ni (94%) which was followed by Cu (91.8%), while the lowest sorption by bacterial biomass was recorded for Cd (87%) at 25mgl−1 initial metal ion concentration. The regression coefficients obtained for heavy metals from the Freundlich and Langmuir models were significant. The surface chemical functional groups of B. thuringiensis biomass identified by Fourier transform infrared (FTIR) were amino, carboxyl, hydroxyl, and carbonyl groups, which may be involved in the biosorption of heavy metals. The biosorption ability of B. thuringiensis OSM29 varied with metals and was pH and metal concentration dependent. The biosorption of each metal was fairly rapid which could be an advantage for large scale treatment of contaminated sites

Synthesis, spectroscopic studies of novel N-substituted phthalimides and evaluation of their antibacterial, antioxidant, DNA binding and molecular docking studies

A new series of N-substituted phthalimide derivatives were prepared by condensation of appropriate amount of n-amino tetrachlorophthalimide with respective aldehyde in glacial acetic acid. The structural investigation of the synthesized compounds was done by spectroscopic methods (UV-Vis., IR, 1H and 13C NMR) and elemental analysis. The antibacterial screening of these compounds was performed against Escherichia coli and Staphylococcus mutans. The synthesized compounds were evaluated for their antioxidant potential using 2,2-diphenyl-1-picrylhydrazyl (DPPH) as a scavenging agent. The interaction ability of most promising compounds (3a and 3b) with native calf thymus DNA (Ct-DNA) was also studied by means of UV-Vis., circular dichroism (CD), viscosity measurements and thermal studies. The intrinsic binding constants (Kb) of 3a and 3b with Ct-DNA obtained from UV-Vis. absorption studies were 8 × 104 and 1 × 105, respectively. Molecular docking of target compounds (3a and 3b) against DNA dodecamer d(CGCGAATTCGCG)2 has been carried out. The test compounds exhibited remarkable antibacterial, antioxidant and DNA binding activities.

Obliteration of bacterial growth and biofilm through ROS generation by facilely synthesized green silver nanoparticles.

Mangifera indica inflorescence aqueous extract was utilized for production of green AgNPs. Synthesized AgNPs were characterized by UV-vis spectrophotometry, XRD, TEM, FESEM and particles size analyzer. AgNPs showed minimum inhibitory concentrations (MICs) of 8 μg ml-1 and 16 μg ml-1 for Gram negative (K. pneumoniae, P. aeruginosa and E. coli) and Gram positive (S. mutans and S. aureus) strains, respectively which was relatively quite low compared to chemically synthesized silver nanoparticles. AgNPs inhibited 80% and 75% biofilms of E. coli and S. mutans respectively as observed quantitatively by crystal violet assay. Qualitative biofilm inhibition was observed using SEM and CLSM. AgNPs adsorbed catheter also resisted the growth of biofilm on its surface displaying its possible future applications. AgNPs interaction with bacteria lead to bacterial membrane damage as observed by SEM and TEM. The membrane damage was confirmed by detecting leakage of proteins and reducing sugars from treated bacterial cells. AgNPs generated ROS on interaction with bacterial cells and this ROS production can be one of the possible reasons for their action. AgNPs exhibited no toxic effect on the cell viability of HeLa cell line

Therapeutic Applications of Biogenic Silver Nanomaterial Synthesized from the Paper Flower of Bougainvillea glabra (Miami, Pink)

In this research, Bougainvillea glabra paper flower extract was used to quickly synthesize biogenic silver nanoparticles (BAgNPs) utilizing green chemistry. Using the flower extract as a biological reducing agent, silver nanoparticles were generated by the conversion of Ag+ cations to Ag0 ions. Data patterns obtained from physical techniques for characterizing BAgNPs, employing UV-visible, scattering electron microscope (SEM), transmission electron microscope (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), suggested that the nanoparticles have a spherical to oval form with size ranging from 10 to 50 nm. Spectroscopy and microscopic analysis were used to learn more about the antibacterial properties of the biologically produced BAgNPs from Bougainvillea glabra. Further, the potential mechanism of action of nanoparticles was investigated by studying their interactions in vitro with several bacterial strains and mammalian cancer cell systems. Finally, we can conclude that BAgNPs can be functionalized to dramatically inhibit bacterial growth and the growth of cancer cells in culture conditions, suggesting that biologically produced nanomaterials will provide new opportunities for a wide range of biomedical applications in the near future

TEM images of bacterial cells treated with AgNPs and their EDX spectra.

<p>TEM images of bacterial cells treated with AgNPs and their EDX spectra.</p

AgNPs antibiofilm activity against biofilms of <i>E</i>. <i>coli</i> and <i>S</i>. <i>mutans</i>.

<p>Error bars represent standard deviations of triplicate incubations.</p

Growth curves of bacteria under the influence of AgNPs.

<p>(a) <i>E</i>. <i>coli</i> (b) <i>S</i>. <i>mutans</i>.</p

MICs and MBCs values of chemically synthesized and biogenic AgNPs.

<p>MICs and MBCs values of chemically synthesized and biogenic AgNPs.</p

Cell line (HeLa) toxicity assessment of the AgNPs.

<p>Error bars represent standard deviations of triplicate incubations.</p

Mobilization of Nuclear Copper by Green Tea Polyphenol Epicatechin-3-Gallate and Subsequent Prooxidant Breakage of Cellular DNA: Implications for Cancer Chemotherapy

Epidemiological as well as experimental evidence exists in support of chemopreventive and anticancer properties of green tea and its constituents. The gallocatechin, epicatechin-3-gallate is a major polyphenol present in green tea, shown responsible for these effects. Plant-derived polyphenolic compounds are established natural antioxidants which are capable of catalyzing oxidative DNA degradation of cellular DNA, alone as well as in the presence of transition metal ions, such as copper. Here we present evidence to support that, similar to various other polyphenoic compounds, epicatechin-3-gallate also causes oxidative degradation of cellular DNA. Single cell alkaline gel electrophoresis (Comet assay) was used to assess DNA breakage in lymphocytes that were exposed to various concentrations of epicatechin-3-gallate. Inhibition of DNA breakage in the presence of scavengers of reactive oxygen species (ROS) suggested involvement of ROS generation. Addition of neocuproine (a cell membrane permeable Cu(I) chelator) inhibited DNA degradation, dose-dependently, in intact lymphocytes. In contrast, bathocuproine, which does not permeate cell membrane, was observed to be ineffective. We further show that epicatechin-3-gallate degrades DNA in cell nuclei, which can also be inhibited by neocuproine, suggesting mobilization of nuclear copper in this reaction as well. Our results are indicative of ROS generation, possibly through mobilization of endogenous copper ions, and support our long-standing hypothesis of a prooxidant activity of plant-derived polyphenols as a mechanism for their documented anticancer properties