Response of Rhizobium leguminosarum to nickel stress |
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Authors: | Singh Shweta Kayastha Arvind M Asthana Ravi K Srivastava Punit K Singh SP |
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Institution: | (1) Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi –, 221 005, India;(2) Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi –, 221 005, India |
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Abstract: | Rhizobium leguminosarum strain P-5 biovar viciae was sensitive to Ni2+ (MIC, 75 M) and showed concentration-dependent Ni2+ uptake in a wide concentration range (50–500 M). Ni2+ uptake up to a certain threshold limit also increased thiol content (66 nmol mg–1 protein), proline content (10.85 nmol mg–1 protein) and urease specific activity (500 nmol min–1 mg–1 protein) maximum corresponding to 100 M Ni2+ as the external concentration or 151 nmol Ni2+ mg–1 protein as the intracellular buildup. Proline synthesis was stimulated most even at much lower Ni2+ concentration (25 M). Higher intracellular Ni2+ load neither favoured thiol nor proline biosynthesis nor urease activity. Ni2+ requirement of urease was ascertained by using EDTA-grown cells and the addition of bicarbonate (NaHCO3, 100 mM) to the crude extract. The induction of thiol or proline by Ni2+, therefore, reflects the possible strategies adopted by bacterial cells to overcome the environmental stress. |
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Keywords: | Ni proline Rhizobium thiol urease |
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