Rare earth element sequestration by Aspergillus oryzae biomass.
Environ Technol. 2020 Mar 05;:1-41
Authors: Boczonádi I, Jakab Á, Baranyai E, Tóth CN, Daróczi L, Csernoch L, Kis G, Antal M, Pusztahelyi T, Grawunder A, Merten D, Emri T, Fábián I, Kothe E, Pócsi I
The fungus Aspergillus oryzae could be shown to be a viable alternative for biosorption of valuable metals from solution. Fungal biomass can be obtained easily in high quantities as a waste of biofermentation processes, and used in a complex, multi-phase solution mimicking naturally occurring, mining-affected water samples. With test solution formulated after natural conditions, formation of secondary Al and Fe phases co-precipitating Ce was recorded in addition to specific biosorption of rare earth elements. Remarkably, the latter were removed from the solution despite the presence of high concentrations of interfering Fe and Al. The biomass was viable even after prolonged incubation in the metal solution, and minimal inhibitory concentrations for single metals were higher than those in the test solution. While precipitation/biosorption of Ce (maximal biosorption efficiency was 58.0 ± 22.3% after 6 h of incubation) coincided with the gross removal of Fe from the metal solution, Y (81.5 ± 11.3% efficiency, 24 h incubation) and Nd (87.4 ± 9.1% efficiency, 24 h incubation) were sequestered later, similarly to Ni and Zn. The biphasic binding pattern specific to single metals could be connected to dynamically changing pH and NH4+ concentrations, which were attributed to the physiological changes taking place in starving A. oryzae biomass. The metals were found extracellularly in minerals associated with the cell wall, and intracellularly precipitated in the vacuoles. The latter process was explained with intracellular metal detoxification resulting in metal resistance.Aspergillus oryzae mycelia captured Y and Nd from a complex, multi-phase test solution concomitantly with increasing pH and NH4+ ion concentrations. Changing fungal cell physiology in starving mycelia may help to develop new technologies to sequester precious rare earth elements including Y effectively, even in the presence of high concentrations of interfering metals like Fe and Al.
PMID: 32134365 [PubMed – as supplied by publisher]