Issue 7, 2020

Chemical and structural characterization of SeIV biotransformations by Stenotrophomonas bentonitica into Se0 nanostructures and volatiles Se species

Abstract

The deep geological repository (DGR) system is widely accepted as the solution for the disposal of radioactive wastes in the future. This concept is based on several natural and engineered barriers such as bentonite clays, which will encase the metal containers holding the radioactive waste. Microorganisms living therein can influence the mobility of the radionuclides (e.g. selenium, uranium, etc.) present in such residues. In this work the bentonite isolate Stenotrophomonas bentonitica is shown to reduce selenite (SeIV) to elemental Se (Se0) nanostructures (amorphous and trigonal) and to volatile methylated Se−II species. Electron microscopy (HAADF-STEM) analysis of purified Se nanostructures supported the transformation process from amorphous to trigonal Se, proposed in previous studies. Infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) revealed the presence of amine rich organic matter, covering the nanostructures, suggesting the role of proteins in their synthesis and transformation. In addition, X-ray absorption spectroscopy (XAS) of SeNPs associated to the cells confirmed the formation of different Se0 structures (amorphous and crystalline). Finally, the reduction of SeIV to volatile methylated species (DMDSe and DMSeS) was detected using a gas chromatography-mass spectrometry (GC-MS) system. The oxidation state and molecular coordination of Se in the purified Se nanostructures as well as the volatile Se species, by means of microscopic, spectroscopic, and gas chromatographic techniques, indicated their lower mobility and chemo-toxicity. This study thus highlights the potential environmental significance of microbial processes for the mobility and toxicity of selenium in future repositories, which in turn contribute to their safe implementation.

Graphical abstract: Chemical and structural characterization of SeIV biotransformations by Stenotrophomonas bentonitica into Se0 nanostructures and volatiles Se species

Supplementary files

Article information

Article type
Paper
Submitted
14 May 2020
Accepted
06 Jun 2020
First published
18 Jun 2020
This article is Open Access
Creative Commons BY-NC license

Environ. Sci.: Nano, 2020,7, 2140-2155

Chemical and structural characterization of SeIV biotransformations by Stenotrophomonas bentonitica into Se0 nanostructures and volatiles Se species

M. A. Ruiz-Fresneda, A. S. Eswayah, M. Romero-González, P. H. E. Gardiner, P. L. Solari and M. L. Merroun, Environ. Sci.: Nano, 2020, 7, 2140 DOI: 10.1039/D0EN00507J

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements