Exploitation of the strictly aerobic Rhodococcus aetherivorans BCP1 strain for the production of Selenium- and Tellurium-nanostructures

Tellurite (TeO32-) and selenite (SeO32-) are hazardous and toxic oxyanions for livingorganisms. However, microorganisms that tolerate and bioconvert these oxyanions to the lesstoxic and available form of elemental tellurium (Te0) and selenium (Se0) are seen as ideal candidates not only for bioremediation purposes, but also as novel cell factories to produce valuable metalloid-nanostructures. Here, Rhodococcus aetherivorans BCP1\u2019s tolerance and consumption of both TeO32- and SeO32- have been investigated, along with the production and characterization of metalloid-nanomaterials in the form of Se/Te-nanorods and Se-nanoparticles. BCP1 displayed a Minimal Inhibitory Concentration towards TeO32- and/or SeO32- of 11.2 and 500 mM, respectively, in rich medium under oxic conditions. Generally, pre-adapted BCP1 cells bioconverted a higher amount of oxyanions, regardless the initial concentrations of TeO3 2- (0.4 or 2 mM) and/or SeO32- (0.5 or 2 mM). Transmission Electron Microscopy and Energy-Dispersive X-Ray Spectroscopy showed stable and non-aggregated metalloid-nanomaterials surrounded by an organic coating, whose ability to self-assemble in the nanoscale was assessed through Dynamic Light Scattering. Finally, Zeta potential analyses revealed negative surface charges for both metalloid-nanomaterials and organic coating. We hypothesize that the biogenic Se/T