Delineation of cellular stages and identification of key proteins for reduction and biotransformation of Se(IV) by Stenotrophomonas bentonitica BII-R7 Pinel Cabello, María Ruiz Fresneda, Miguel Ángel Merroun, Mohamed Larbi Selenium nanostructures Stenotrophomonas Microbial Se(IV) reduction Se(0) biotransformation Proteomics This work was supported by the grants obtained by M.P-C: (FPU 15/04284; "Formacion de Profesorado Universitario") and EST 18/00610 ("Ayudas a la movilidad para estancias breves y traslados temporales") from Spanish Ministry (Ministerio de Universidades) . Funding was also provided by grants CGL2014-59616-R; RTI2018.101548.B.I00 to M.L. M. Funding for open access charge: University of Granada/CBUA. The authors thank Concepcion Hernandez-Castillo and Maria del Mar Abad Ortega for their assistance with microscopy at the University of Granada ("Centro de Instrumentacion Cientifica") . We also thank Dr. Kenneth McCreath for editorial support. The widespread use of selenium (Se) in technological applications (e.g., solar cells and electronic devices) has led to an accumulation of this metalloid in the environment to toxic levels. The newly described bacterial strain Stenotrophomonas bentonitica BII-R7 has been demonstrated to reduce mobile Se(IV) to Se(0)-nanoparticles (Se(0) NPs) and volatile species. Amorphous Se-nanospheres are reported to aggregate to form crystalline nanostructures and trigonal selenium. We investigated the molecular mechanisms underlying the biotransformation of Se(IV) to less toxic forms using differential shotgun proteomics analysis of S. bentonitica BII-R7 grown with or without sodium selenite for three different time-points. Results showed an increase in the abundance of several proteins involved in Se(IV) reduction and stabilization of Se(0)NPs, such as glutathione reductase, in bacteria grown with Se(IV), in addition to many proteins with transport functions, including RND (resistance-nodulationdivision) systems, possibly facilitating Se uptake. Notably proteins involved in oxidative stress defense (e.g., catalase/peroxidase HPI) were also induced by Se exposure. Electron microscopy analyses confirmed the biotransformation of amorphous nanospheres to trigonal Se. Overall, our results highlight the potential of S. bentonitica in reducing the bioavailability of Se, which provides a basis both for the development of bioremediation strategies and the eco-friendly synthesis of biotechnological nanomaterials. 2021-10-05T06:51:40Z 2021-10-05T06:51:40Z 2021-05-24 journal article M. Pinel-Cabello... [et al.]. Delineation of cellular stages and identification of key proteins for reduction and biotransformation of Se(IV) by Stenotrophomonas bentonitica BII-R7, Journal of Hazardous Materials, Volume 418, 2021, 126150, ISSN 0304-3894, [https://doi.org/10.1016/j.jhazmat.2021.126150] http://hdl.handle.net/10481/70637 10.1016/j.jhazmat.2021.126150 eng http://creativecommons.org/licenses/by-nc-nd/3.0/es/ open access Atribución-NoComercial-SinDerivadas 3.0 España Elsevier