Bioremoval of Yttrium (III), Cerium (III), Europium (III), and Terbium (III) from Single and Quaternary Aqueous Solutions Using the Extremophile Galdieria sulphuraria (Galdieriaceae, Rhodophyta)

Abstract

The lanthanides are among the rare earth elements (REEs), which are indispensable constituents of modern technologies and are often challenging to acquire from natural resources. The demand for REEs is so high that there is a clear need to develop efficient and environmentally-friendly recycling methods. In the present study, living cells of the extremophile Galdieria sulphuraria were used to remove four REEs, Yttrium, Cerium, Europium, and Terbium, from single- and quaternary-metal aqueous solutions. Two different strains, SAG 107.79 and ACUF 427, were exposed to solutions buffered at pH 2.5, 3.5, 4.5, and 5.5. Our data demonstrated that the removal performances were strain and pH dependent for all metal ions. At lower pH, ACUF 427 outperformed SAG 107.79 considerably. By increasing the pH of the solutions, there was a significant surge in the aqueous removal performance of both strains. The same trend was highlighted using quaternary-metal solutions, even if the quantities of metal removed were significantly lower. The present study provided the first insight into the comparative removal capacity of the Galdieria sulphuraria strains. The choice of the appropriate operational conditions such as the pH of the metal solutions is an essential step in developing efficient, rapid, and straightforward biological methods for recycling REEs.

Galdieria sulphuraria ACUF427 Freeze-Dried Biomass as Novel Biosorbent for Rare Earth Elements

“…Terbium was the element most easily adsorbed by the G. sulphuraria ACUF427. These findings agree with the results shown in the previous work [22], according to which the same Galdieria strain in the same quaternary system preferred terbium (in the same way as europium) and the highest removal rate was obtained at pH 4.5. A comparison between bioaccumulation [22] and biosorption of the same algal strain with the same metal system, carried out in the present study, showed comparable performance between metabolically active and inactive algae, respectively.…”

“…Bioaccumulation is an active metabolic process which includes the interaction of metals with the cell surface (passive adsorption), followed by an active metabolism-dependent adsorption involving the transport of metal ions across the cell membrane into the cytoplasm, which is much slower than biosorption. A recent study on living cells of G. sulphuraria highlighted, particularly, that the adsorption of yttrium, cerium, europium, and terbium is pH-dependent [22].…”

Cyanidiales-Based Bioremediation of Heavy Metals

“…In a study completed by Iovinella et al [ 68 ], the removal of four rare earth elements (REEs): yttrium (Y), cerium (Ce), europium (Eu), and terbium (Tb) was achieved using two strains of Galdieria sulphuraria. SAG 107.79 and ACUF 427 were two strains subjected to metal solutions at pH levels ranging from 2.5 to 5.5.…”

“…The effect of pH was studied by Iovinella et al [ 68 ], for the removal of REEs: Y, Ce, Eu, and Te using two strains of Galdieria sulphuraria: SAG 107.79 and ACUF 427. The range of pH levels was 2.5 to 5.5.…”

Comparisons between Complete Genomes of the Eukaryotic Extremophile Galdieria sulphuraria Reveals Complex Nuclear Chromosomal Structures

“…In addition to using light as a fuel source, G. sulphuraria utilises a variety of complex carbon sources for growth [11]. Consequently, G. sulphuraria is of great interest for use in biotechnology for the degradation of lignocellulosic materials [12], as well as the remediation of rare earth metals [13] [14] and wastewater treatments [15].…”