Biosorption of Heavy Metals using Individual and Mixed Cultures of Pseudomonas Aeruginosa and Bacillus Subtilis

Biosorption can be an effective technique for the treatment of heavy metal bearing waste water resulting from humuns and industrial activities. Several gram positive and gram negative bacteria have the ability to remove the heavy metals and there by making water contaminant free. It has been reported that attenuated bacterial biomass have greater biosorption capability than viable cells. In the present study, the biosorption of heavy metals using individual and mixed culture of attenuated bacteria (gram positive and gram negative) like Bacillus subtilis and Pseudomonas aeruginosa and parameters affecting the biosorption of heavy metals; such as time, pH, biomass concentration and initial metal concentration have been investigated. The batch experiments have been carried out using individual and mixed bacterial culture and the biosorption parameters were optimized using univariate procedures. The present study shows that 90.4% of biosorption of Mercury was observed for mixed cultures of Pseudomonas aeruginosa and Bacillus subtilis and 99.3% and 78.5% biosorption for individual cultures respectively. The time taken for maximum sorption of Mercury was 60, 40 and 40 minutes for mixed cultures of Pseudomonas aeruginosa and Bacillus subtilis. The optimum biomass concentration was found to be 2, 0.5 and 2.5 mg/ml for mixed cultures, Pseudomonas aeruginosa and Bacillus subtilis. pH 5 was found to be optimum for all the three biomass (two individual cultures; one mixed culture) for Mercury biosorption. Optimum temperature was 32\,^{\circ}C for all the three systems used in the present work. Adsorption isotherms of all the three metals with mixed cultures were best fitted with Langmuir and Freundlich isotherm models having highest value of regression coefficients with R2 0.99 which is close to one. Two kinetic models namely pseudo first order equation and pseudo second order equation were also tested for the biosorption processes. The biosorption of Chromium (VI) shows that 77.6% for mixed cultures, 60.5 and 81.3 for Pseudomonas aeruginosa and Bacillus subtilis respectively. The optimum biomass concentration was found to be 1.5, 1.5 and 2 for mixed cultures (Pseudomonas aeruginosa and Bacillus subtilis) at32\,^{\circ}C and 3 pH. The equilibrium Arsenic biosorption were also conducted by using the same biomasses as mentioned above by achieving a sorption of 30%, 32% and 28% for mixed culture, Pseudomonas aeruginosa and Bacillus subtils)

Neutrophil-Derived MMP-8 Drives AMPK-Dependent Matrix Destruction in Human Pulmonary Tuberculosis.

Pulmonary cavities, the hallmark of tuberculosis (TB), are characterized by high mycobacterial load and perpetuate the spread of M. tuberculosis. The mechanism of matrix destruction resulting in cavitation is not well defined. Neutrophils are emerging as key mediators of TB immunopathology and their influx are associated with poor outcomes. We investigated neutrophil-dependent mechanisms involved in TB-associated matrix destruction using a cellular model, a cohort of 108 patients, and in separate patient lung biopsies. Neutrophil-derived NF-kB-dependent matrix metalloproteinase-8 (MMP-8) secretion was up-regulated in TB and caused matrix destruction both in vitro and in respiratory samples of TB patients. Collagen destruction induced by TB infection was abolished by doxycycline, a licensed MMP inhibitor. Neutrophil extracellular traps (NETs) contain MMP-8 and are increased in samples from TB patients. Neutrophils lined the circumference of human pulmonary TB cavities and sputum MMP-8 concentrations reflected TB radiological and clinical disease severity. AMPK, a central regulator of catabolism, drove neutrophil MMP-8 secretion and neutrophils from AMPK-deficient patients secrete lower MMP-8 concentrations. AMPK-expressing neutrophils are present in human TB lung biopsies with phospho-AMPK detected in nuclei. These data demonstrate that neutrophil-derived MMP-8 has a key role in the immunopathology of TB and is a potential target for host-directed therapy in this infectious disease

Development of ZnO Nanoflake Type Structures Using Silk Fibres as Template for Water Pollutants Remediation

We have fabricated ZnO nanoflake structures using degummed silk fibers as templates, via soaking and calcining the silk fibers bearing ZnO nanoparticles at 150 °C for 6 h. The obtained ZnO nanostructures were characterized using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and UV-vis and fluorescence spectroscopic analysis. The size (~500–700 nm) in length and thicknesses (~60 nm) of ZnO nanoflakes were produced. The catalysis performances of ZnO nanoflakes on silk fibers (ZnSk) via photo-degradation of naphthalene (93% in 256 min), as well as Rose Bengal dye removal (~1.7 mM g−1) through adsorption from aqueous solution, were practically observed. Further, ZnSk displayed superb antibacterial activity against the tested model gram-negative Escherichia coli bacterium. The produced ZnSk has huge scope to be used for real-world water contaminants remediation applications