Selenite removal and reduction by growing Aspergillus sp. J2

Area of Science:

• Environmental microbiology
• Bioremediation
• Selenium biogeochemistry

Background:

• Selenium is an essential trace element, but excess can be toxic.
• Selenite [Se(IV)] is a common and mobile form of selenium in contaminated environments.
• Microbial selenium transformations are crucial for selenium remediation.

Purpose of the Study:

• To investigate the capability of Aspergillus sp. J2 for selenite [Se(IV)] removal and reduction.
• To characterize the mechanism of selenite transformation by the fungus.
• To assess the impact of selenite on fungal growth and morphology.

Main Methods:

• Cultivation of Aspergillus sp. J2 with selenite [Se(IV)].
• Monitoring of fungal growth parameters (lag phase, growth rate, biomass).
• Analysis of selenium transformation using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and X-ray Diffraction (XRD).

Main Results:

• Aspergillus sp. J2 efficiently removed and reduced selenite [Se(IV)] without significant impact on its growth or morphology.
• Selenium removal occurred rapidly between the 3rd and 4th day of fungal growth.
• Reduced amorphous elemental selenium [Se(0)] nanoparticles were primarily located on the surface of the mycelial cell walls.
• Macromolecules with amine groups on the cell wall likely play a role in Se(IV) interaction and removal.

Conclusions:

• Aspergillus sp. J2 demonstrates a high potential for bioremediating selenite-contaminated environments.
• The fungus reduces selenite to elemental selenium nanoparticles, sequestering it on its cell surface.
• Cell wall components, particularly amine-containing macromolecules, are involved in the selenite removal mechanism.