The ability of Phanerochaete chrysosporium to reduce the oxidized forms of selenium, selenate and selenite, and their effects on the growth, substrate consumption rate, and pellet morphology of the fungus were assessed. The effect of different operational parameters (pH, glucose, and selenium concentration) on the response of P. chrysosporium to selenium oxyanions was explored as well. This fungal species showed a high sensitivity to selenium, particularly selenite, which inhibited the fungal growth and substrate consumption when supplied at 10 mg L−1 in the growth medium, whereas selenate did not have such a strong influence on the fungus. Biological removal of selenite was achieved under semi-acidic conditions (pH 4.5) with about 40 % removal efficiency, whereas less than 10 % selenium removal was achieved for incubations with selenate. P. chrysosporium was found to be a selenium-reducing organism, capable of synthesizing elemental selenium from selenite but not from selenate. Analysis with transmission electron microscopy, electron energy loss spectroscopy, and a 3D reconstruction showed that elemental selenium was produced intracellularly as nanoparticles in the range of 30–400 nm. Furthermore, selenite influenced the pellet morphology of P. chrysosporium by reducing the size of the fungal pellets and inducing their compaction and smoothness.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors thank the EU for providing financial support through the Erasmus Mundus Joint Doctorate Programme ETeCoS3 (Environmental Technologies for Contaminated Solids, Soils and Sediments, grant agreement FPA no. 2010-0009). This work was partly supported by a Global Research Partnership-Collaborative Fellows Award (GRFP-CF-2011-13-P) from the King Abdullah University of Science and Technology. The authors thank Rachid Sougrad for his assistance with TEM 3D image reconstruction.