Rare earth element sequestration by Aspergillus oryzae biomass

Area of Science:

• Biotechnology
• Environmental Science
• Mycology

Background:

• Fungal biomass, particularly from Aspergillus oryzae, is an abundant waste product from biofermentation.
• Mining-affected waters often contain valuable and interfering metal ions, posing environmental challenges.
• Biosorption offers a potential method for metal recovery and remediation.

Purpose of the Study:

• To evaluate Aspergillus oryzae biomass as a biosorbent for valuable metals from complex, multi-phase solutions.
• To investigate the biosorption efficiency and mechanisms of rare earth elements (REEs), nickel, and zinc in the presence of high aluminum and iron concentrations.
• To understand the physiological responses of A. oryzae biomass during metal sequestration.

Main Methods:

• Utilized Aspergillus oryzae fungal biomass as a biosorbent.
• Prepared complex metal solutions mimicking mining-affected water.
• Analyzed metal concentrations, pH, and ammonium levels over time.
• Examined metal localization within the fungal biomass using microscopy.

Main Results:

• A. oryzae biomass demonstrated effective biosorption of REEs (Ce, Y, Nd), Ni, and Zn, even with high Fe and Al levels.
• Biosorption efficiency reached 58% for Ce, 81.5% for Y, and 87.4% for Nd within 24 hours.
• A biphasic metal binding pattern was observed, linked to dynamic pH and NH4+ changes due to starving biomass.
• Metals were localized extracellularly in cell wall-associated minerals and intracellularly in vacuoles, indicating detoxification.

Conclusions:

• Aspergillus oryzae biomass is a viable and efficient biosorbent for valuable metals from challenging environmental matrices.
• The fungus exhibits resistance to high metal concentrations, suggesting potential for bioremediation applications.
• Understanding the biosorption mechanisms, including extracellular and intracellular sequestration, is crucial for optimizing metal recovery processes.