Luminescent investigations of terbium(III) biosorption as a surrogate for heavy metals and radionuclides

• Published in: Molecular and cellular biochemistry 2009-07, Vol.327 (1-2), p.87-92
• Main Authors: Achyuthan, Komandoor E, Arango, Dulce C, Carles, Elizabeth L, Cutler, Christopher E, Meyer, Lauren A, Brozik, Susan M
• Format: Article
• Language: English
• Subjects: Bacteria; Biochemistry; Biodegradation, Environmental; Biomedical and Life Sciences; Bioremediation; Cardiology; E coli; Environmental Pollutants - chemistry; Environmental Pollutants - metabolism; Escherichia coli; Escherichia coli - metabolism; Heavy metals; Ion transport; Ions; Kinetics; Life Sciences; Luminescent Measurements; Medical Biochemistry; Metal ions; Metals; Metals, Heavy - chemistry; Metals, Heavy - metabolism; Oncology; Radioactive Pollutants - chemistry; Radioactive Pollutants - metabolism; Radioisotopes; Studies; Terbium; Terbium - chemistry; Terbium - metabolism
• ISSN: 0300-8177; 1573-4919
• DOI: 10.1007/s11010-009-0046-0

We describe a metal transport system for investigating the interfacial interactions between the anionic surface charge of a gram-negative bacterium (Escherichia coli) and a trivalent cationic metal, Tb³⁺. We believe this is the first description of the uptake kinetics, sub- and intracellular distribution, and temporal fate of Tb³⁺ ion in E. coli. We used the luminescence of the terbium-dipicolinic acid chelate to study metal ion transport. The bacteria had a high tolerance for the metal (IC₅₀ = 4 mM Tb³⁺). Metal ion transport was passive and metabolism independent. The uptake kinetics rapidly reached a maximum within 15 min, followed by a stasis for 60 min, and declining thereafter between 120 and 240 min, resulting in a biphasic curve. During this period, greater than one-third of the metal ion was sequestered within the cell. Our choice of a safe Biosafety Level I E. coli bacteria and the relatively non-toxic Tb³⁺ metal represents a model system for luminescent investigations of biosorption, for studying bacterial-water interfacial chemistry and for the bioremediation of heavy metals and radionuclides.