Browsing by Author "Mamta Awasthi"

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Effect of nickel and cadmium on ammonium uptake kinetics of free and immobilized cells of Anacystis nidulans; [Wirkung von nickel und cadmium auf die kinetik der ammonium-aufnahme freier und immobilisierter zellen von Anacystis nidulans]
(2004) Mamta Awasthi; Lal Chand Rai
The stress effect of Ni and Cd on the ammonium uptake varied significantly (ANOVA test) in free and immobilized state of the test organism. The effect due to the interaction between different variables (cell state type, metal type and metal dose) was studied to depict the significant or non-significant variation in the ammonium uptake by free and immobilized cells in the presence of metal ions. Ammonium uptake exhibited a competitive mode of inhibition in the presence of Ni in both free and immobilized state of the organism. However, Cd exhibited non-competitive and competitive inhibition in free and immobilized cells, respectively. The study demonstrates that there is a considerable influence of metal ions on the ammonium uptake. Cd was found to be more toxic compared to Ni in both free and immobilized state. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Interactions between zinc and cadmium uptake by free and immobilized cells of Scenedesmus quadricauda (Turp.) Breb
(2006) Mamta Awasthi; Lal Chand Rai
Biological treatment of heavy metals is an effective technology for the treatment of low concentration industrial wastewater. The purpose of this study was to evaluate the zinc and cadmium removal capacities through absorption (active) and adsorption (passive) by free and alginate-immobilized cells of Scenedesmus quadricauda. Immobilized cells have high capacities for uptake of both the heavy metal tested and the kinetics under the conditions studied were relatively fast. About 90% of the biosorption (adsorption) occurred within 10 min and equilibrium was reached within 30 minutes in both free and immobilized cells. However, a different pattern was observed for absorption. Maximum absorption by immobilized cells was found to be around 6.6 mmol Zn2+ and 8.0 mmol Cd2+ per mg protein, these values being approximately 1.4 and 1.6 fold higher than those of the free cells. Statistical analysis (ANOVA) confirmed the superiority of immobilized cells for metal absorption but not for adsorption. Free cells were equally good for adsorption. The results obtained on the patterns of metal/metal interactions showed either antagonistic, or non-interaction type of behaviour for both adsorption and absorption. However, no synergistic type of behaviour was observed during treatment. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Physiological response of the cyanobacterium Anacystis nidulans to a magnetic field
(Marcel Dekker Inc., 1998) Subas Rai; U.P. Singh; Mamta Awasthi; Suman Pandey
Physiological responses of the cyanobacterium Anacystis nidulans to direct and indirect exposures to a 0.3-T permanent magnet for different lengths of time were studied. Direct and indirect exposures, different exposure periods, and different magnetic poles produced significantly different effects. We suggest that the magnetic field (MF) caused these biological effects by inducing changes in the structural chemistry of water. We believe that different water structures caused these effects by influencing the organism's nutrient uptake, and enzymatic activities, and the orientation of precursor biomolecules in the liquid crystalline phase during physiological synthesis.
Physiological response of the cyanobacterium Anacystis nidulans to a magnetic field
(1998) Subas Rai; U.P. Singh; Mamta Awasthi; Suman Pandey
Physiological responses of the cyanobacterium Anacystis nidulans to direct and indirect exposures to a 0.3-T permanent magnet for different lengths of time were studied. Direct and indirect exposures, different exposure periods, and different magnetic poles produced significantly different effects. We suggest that the magnetic field (MF) caused these biological effects by inducing changes in the structural chemistry of water. We believe that different water structures caused these effects by influencing the organism's nutrient uptake, and enzymatic activities, and the orientation of precursor biomolecules in the liquid crystalline phase during physiological synthesis.
Relevance of alkaline phosphatase activity of immobilized green algae and cyanobacteria for heavy metal toxicity monitoring
(2012) Mamta Awasthi
Harmful effects of contaminants on the ecosystem and humans cannot be assessed by standard chemical analyses of environmental samples, therefore toxicity tests using live organisms or cells represent a vital part of environmental monitoring. Biological methods based on microorganisms as test-species, have already successfully been applied to environmental toxicity/genotoxicity assessment. The enzyme activity is examined in presence of essential and non-essential heavy metals (Ni, Zn, Cd) in green algae and cyanobacteria. The activity is based on total p-nitrophenol formed in a known volume of culture suspension. The activity was deleteriously affected in a concentration dependent manner. The maximum Apase activity observed in immobilized state of A. nidulans was 14.6 n moles pNP μg protein-1 per 30 minutes in presence of noninhibitory level of Ni and Cd. The effect due to interaction between different variables (cell state type, metal type and metal dose) depicted a significant variation (P< 0.01, ANOVA) in the Apase activity of free and immobilized cells of S. quadricauda and A. nidulans. This study describes the alkaline phosphatase activity which may differ with metal type, cell type or metal dose of the solution. Immobilization may protect the cell enzyme activity against the toxicity of heavy metals. The study may help in designing biosensor when estimating heavy metals quantitatively.
Toxicity of nickel, zinc, and cadmium to nitrate uptake in free and immobilized cells of Scenedesmus quadricauda
(2005) Mamta Awasthi; Lal Chand Rai
We examined the influences of three trace metals on the accumulation of a major nutrient (NO3-) in Scenedesmus quadricauda. A comparative study on metal-nutrient interaction in free and immobilized states of algal cells was conducted. The effect due to interaction between different variables (cell state type, metal type, and metal dose) was studied to assess the variation in the nitrate uptake by free and immobilized cells. The results analyzed by ANOVA (three-way) (components: cell state type, metal type, and metal dose) confirmed that the inhibition of nitrate uptake by test metals was highly significant (P<0.001). Free and immobilized states of S. quadricauda responded differently (P<0.05, ANOVA) to the types of metal added. Uptake kinetics was studied by monitoring short-term uptake rates at different nutrient levels. Free and immobilized cells of the organism displayed noncompetitive modes of inhibition for Ni and Zn while a competitive mode of inhibition by Cd was observed in both free and immobilized states of the organism. © 2005 Elsevier Inc. All rights reserved.