title: Microbial reduction of [Co(III)-EDTA]⁻ by Bacillus licheniformis SPB-2 strain isolated from a solar salt pan.
abstract: Naturally stressed habitats are known to be repositories for novel microorganisms with potential bioremediation applications. In this study, we isolated a [Co(III)-EDTA](-) reducing bacterium Bacillus licheniformis SPB-2 from a solar salt pan that is exposed to constant cycles of hydration and desiccation in nature. [Co(III)-EDTA](-) generated during nuclear waste management process is difficult to remove from the waste due to its high stability and solubility. It is reduced form i.e. [Co(II)-EDTA](2-) is less stable though it is toxic. This study showed that B. licheniformis SPB-2 reduced 1mM [Co(III)-EDTA](-) in 14 days when grown in a batch mode. However, subsequent cycles showed an increase in the reduction activity, which was observed up to four cycles. Interestingly, the present study also showed that [Co(III)-EDTA](-) acted as an inducer for B. licheniformis SPB-2 spore germination. Vegetative cells germinated from the spores were found to be involved in [Co(III)-EDTA](-) reduction. More detailed investigations showed that after [Co(III)-EDTA](-) reduction, i.e. [Co(II)-EDTA](2-) complex was removed by B. licheniformis SPB-2 from the bulk liquid by adsorption phenomenon. The bacterium showed a D10 value (radiation dose required to kill 90% cells) of ∼250 Gray (Gy), which signifies the potential use of B. licheniformis SPB-2 for bioremediation of moderately active nuclear waste.
authors.affiliation: Departartment of Biotechnology, Pondicherry University, Puducherry, India.
authors.forename: Arunachalam
authors.initials: A
authors.lastname: Paraneeiswaran
authors.affiliation: Biofouling & Biofilm Processes Section, Water & Steam Chemistry Division, BARC Facilities, Kalpakkam 603102, India; Homi Bhabha National Institute, Mumbai 400094, India.
authors.forename: Sudhir K
authors.initials: SK
authors.lastname: Shukla
authors.affiliation: Departartment of Biotechnology, Pondicherry University, Puducherry, India.
authors.forename: K
authors.initials: K
authors.lastname: Prashanth
authors.affiliation: Biofouling & Biofilm Processes Section, Water & Steam Chemistry Division, BARC Facilities, Kalpakkam 603102, India; Homi Bhabha National Institute, Mumbai 400094, India. Electronic address: subbarao@igcar.gov.in.
authors.forename: T Subba
authors.initials: TS
authors.lastname: Rao
mesh_terms: D001407:Bacillus / Q000302:isolation & purification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D003037:Cobalt Radioisotopes / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry*; D010084:Oxidation-Reduction; D011850:Radioactive Waste; D012965:Sodium Chloride; D013171:Spores, Bacterial; D014871:Water Microbiology
chemical_list: D003037:Cobalt Radioisotopes; D011850:Radioactive Waste; D012965:Sodium Chloride; D004492:Edetic Acid
keywords: Bacillus licheniformis; Bioremediation; Cobalt; Heavy metal reduction; Nuclear waste; [Co(III)–EDTA](−)