Characterization of Lanthanide Ions Binding Sites in the Cell Wall of Pseudomonas aeruginosa

Abstract

Earlier studies have shown that Pseudomonas aeruginosa can adsorb selectively La3+, Eu3+, and Yb3+ from aqueous solution. These bacterial cells may find promising applications for removal and separation of lanthanide ions from contaminated effluents. In this work, potentiometric titrations and time-resolved laser-induced fluorescence spectroscopy were used to determine the binding sites of the biomass and, consequently, to elucidate the underlying mechanisms involved in the biosorption of lanthanide ions. Around 90 ± 5% of the adsorbed lanthanum was easily desorbed with an EDTA 0.1 M solution. In most instances, lanthanides seemed to concentrate extracellularly. The diversity of potential metal-binding groups was revealed by potentiometric titrations of the biomass. The amount of strong and weaker acidic functional groups in the wet biomass was estimated at 0.24 ± 0.04 and 0.86 ± 0.02 mequiv/g, respectively. Time-resolved laser-induced fluorescence spectroscopy on europium-loaded P. aeruginosa biomass sug...