Authors: G Raghu V Balaji G Venkateswaran A Rodrigue P Maruthi Mohan
Publish Date: 2008/10/24
Volume: 81, Issue: 3, Pages: 571-578
Abstract
Removal of radioactive cobalt at trace levels ≈nM in the presence of large excess 106fold of corrosion product ions of complexed Fe Cr and Ni in spent chemical decontamination formulations simulated effluent of nuclear reactors is currently done by using synthetic organic ion exchangers A large volume of solid waste is generated due to the nonspecific nature of ion sorption Our earlier work using various fungi and bacteria with the aim of nuclear waste volume reduction realized up to 30 of Co removal with specific capacities calculated up to 1 μg/g in 6–24 h In the present study using engineered Escherichia coli expressing NiCoT genes from Rhodopseudomonas palustris CGA009 RP and Novosphingobium aromaticivorans F199 NA we report a significant increase in the specific capacity for Co removal 12 μg/g in 1h exposure to simulated effluent About 85 of Co removal was achieved in a twocycle treatment with the cloned bacteria Expression of NiCoT genes in the E coli knockout mutant of NiCoT efflux gene rcnA was more efficient as compared to expression in wildtype E coli MC4100 JM109 and BL21 DE3 hosts The viability of the E coli strains in the formulation as well as at different doses of gamma rays exposure and the effect of gamma dose on their cobalt removal capacity are determined The potential application scheme of the above process of bioremediation of cobalt from nuclear power reactor chemical decontamination effluents is discussedThe authors thank Dr Thomas Eitinger Humboldt University Germany for providing the plasmids pCH675RP pCH675NA and Dr S K Apte Bhabha Atomic Research Center Mumbai for reading the initial manuscript The research work was supported by grants from the Dept of Atomic Energy No 2004/37/17/BRNS IFCPAR 37091 and UGCSAP DRSI
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