Mechanism of zinc resistance in a plant growth promoting Pseudomonas fluorescens strain |
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Authors: | Anamika Upadhyay Sheela Srivastava |
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Institution: | 1. Department of Genetics, University of Delhi South Campus, New Delhi, 110021, India
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Abstract: | Bacterial systems have evolved a number of mechanisms, both active and passive, to manage toxic concentrations of heavy metals in their environment. The present study is aimed at describing the zinc resistance mechanism in a rhizospheric isolate, Pseudomonas fluorescens strain Psd. The strain was able to sustain an external Zn2+ concentration of up to 5 mM in the medium. The strategy for metal management by the strain was found to be extracellular biosorption with a possible role of exopolysaccharides in metal accumulation. The attainment of equilibrium in biosorption reaction was found to be dependent on initial Zn2+ concentration, with the reaction reaching equilibrium faster (50 min) at high initial Zn2+ concentration. Biosorption kinetics of the process was adjusted to pseudo-first order rate equation. With the help of Langmuir and Freundlich adsorption isotherms, it was established that Zn2+ biosorption by the bacterium is a thermodynamically favourable process. |
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