Penidiella sp. strain T9 is an effective dysprosium accumulator, incorporating dysprosium as dysprosium phosphate compounds

Biotechnological approaches have gained significant attention as a means to recover rare earth elements from acidic mine drainage and industrial liquid wastes. We recently isolated an acidophilic fungus, Penidiella sp. strain T9, that accumulates dysprosium (Dy) from acidic model drainage during growth. To develop the potential accumulation ability of the strain T9, we elucidated the localization and the chemical structure of Dy following its biogenetic solidification by the strain T9. High-magnification scanning electron microscopic analysis showed that the strain T9 formed a precipitated Dy (T9-Dy) layer with 1.0 μm thickness over the cell surface, along with some intracellular nanometer-sized Dy particles. X-ray photoelectron spectrometry and X-ray absorption fine structure analyses showed that the chemical composition of T9-Dy over the T9 cell surface corresponded to DyPO₄. The L_III-edge spectrum observed with X-ray absorption near-edge structure indicated that Dy existed as Dy^3 + ions in T9-Dy. X-ray diffraction analysis did not yield a clear spectrum from T9-Dy. Therefore, we conclude that the strain T9 accumulates and incorporates Dy as an amorphous DyPO₄. Further, we found that phosphoric acid was involved in the Dy accumulation by the strain T9. In order to improve Dy accumulation yield by the strain T9, we have initiated follow-on studies to optimize culture conditions using phosphoric acid.