Simultaneous bioreduction of tellurite and selenite by Yarrowia lipolytica, Trichosporon cutaneum, and their co-culture along with characterization of biosynthesized Te-Se nanoparticles

Abstract

Background: Natural and anthropogenic activities, such as weathering of rocks and industrial processes, result in the release of toxic oxyanions such as selenium (Se) and tellurium (Te) into the environment. Due to the high toxicity of these compounds, their removal from the environment is vital.

Results: In this study, two yeast strains, Yarrowia lipolytica and Trichosporon cutaneum, were selected as the superior strains for the bioremediation of tellurium and selenium. The reduction analyses showed that exposure to selenite induced more detrimental effects on the strains compared to tellurite. In addition, co-reduction of pollutants displayed almost the same results in selenite reduction and more than ~ 20% higher tellurite reduction in 50 h, which shows that selenite triggered higher tellurite reduction in both strains. The selenite and tellurite kinetics of removal were consistent with the first-order model because of their inhibitory behavior. The result of several characterization experiments, such as FE-SEM (Field emission scanning electron microscopy), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), and dispersive X-ray (EDX) on Te-Se nanoparticles (NPs) revealed that the separated Te-Se NPs were needle-like, spherical, and amorphous, consisted of Te-Se NPs ranging from 25 to 171 nm in size, and their surface was covered with different biomolecules.

Conclusions: Remarkably, this work shows, for the first time, the simultaneous bioreduction of tellurite and selenite and the production of Te-Se NPs using yeast strains, indicating their potential in this area, which may be applied to the nanotechnology industry and environmental remediation.

Keywords: Bioremediation; Co-contamination; Kinetics; Metalloid oxyanions; Te–Se nanoparticles; Yeast.

Fig. 1

Evaluation of the capabilities of 12 different yeast strains in 1 mM tellurite (a), 1 mM selenite (b), and 0.5 mM tellurite/selenite (c) reduction based on color intensity after 48 h. Each flask represents a different yeast strain, which are marked by numbers and letters

Fig. 2

a–c The growth rate and reduction yield of Y. lipolytica and T. cutaneum, respectively, in tellurite (1 mM), selenite (1 mM), and tellurite (1 mM)/ selenite (1 mM) mixture; d the first-order removal model of tellurite and selenite in separate and mixture cultures. Values are mean ± SD of three replicates

Fig. 3

DLS analysis of Y. lipolytica (a) and T.cutaneum (b) of biosynthesized Te–Se NPs

Fig. 4

FE-SEM images of Y.lipolytica (a–c) and T.cutaneum (d–f) of the extracted Te–Se NPs, and EDX analyses of Y. lipolytica (g) and T. cutaneum (h)

Fig. 5

XRD patterns of Y.lipolytica (a) and T.cutaneum (b) of biosynthesized Te–Se NPs

Fig. 6

FTIR analyses of Y.lipolytica (a) and T.cutaneum (b) of biosynthesized Te–Se NPs