Simultaneous bioremediation of phenol and tellurite by Lysinibacillus sp. EBL303 and characterization of biosynthesized Te nanoparticles

Abstract

Aromatic compounds and metalloid oxyanions are abundant in the environment due to natural resources and industrial wastes. The high toxicity of phenol and tellurite poses a significant threat to all forms of life. A halotolerant bacterium was isolated and identified as Lysinibacillus sp. EBL303. The remediation analysis shows that 500 mg/L phenol and 0.5 mM tellurite can be remediated entirely in separate cultures within 74 and 56 h, respectively. In addition, co-remediation of pollutants resulted in the same phenol degradation and 27% less tellurite reduction within 98 h. Since phenol and tellurite exhibited inhibitory behavior, their removal kinetics fitted well with the first-order model. In the characterization of biosynthesized tellurium nanoparticles (TeNPs), transmission electron microscopy, dynamic light scattering, FE-SEM, and dispersive X-ray (EDX) showed that the separated intracellular TeNPs were spherical and consisted of only tellurium with 22-148 nm in size. Additionally, investigations using X-ray diffraction and Fourier-transform infrared spectroscopy revealed proteins and lipids covering the surface of these amorphous TeNPs. Remarkably, this study is the first report to demonstrate the simultaneous bioremediation of phenol and tellurite and the biosynthesis of TeNPs, indicating the potential of Lysinibacillus sp. EBL303 in this matter, which can be applied to environmental remediation and the nanotechnology industry.

Figure 1

SEM micrograph of strain EBL303 (a) and Phylogenetic tree of Lysinibacillus sp. EBL303 (b) and its related sequences from the NCBI database.

Figure 2

The proposed mechanism for degradation of phenol coupled with reduction of tellurite to TeNPs by Lysinibacillus sp. EBL303 (created by Adobe Illustrator 2022, https://www.adobe.com/products/illustrator.html).

Figure 3

(a–c) the growth rate and remediation yield of Lysinibacillus sp. EBL303, respectively, in phenol (500 mg/L), tellurite (0.5 mM), and phenol (500 mg/l)/tellurite (0.5 mM) mixture; (d) the first-order removal model of phenol and tellurite in separate and mixture. Values are mean ± SD of three replicates.

Figure 4

TEM micrograph (a), DLS analysis (b), FE-SEM image (c), and EDX spectrum (d) of the extracted TeNPs synthesized by Lysinibacillus sp. EBL303.

Figure 5

XRD pattern (a) and FTIR analyses (b) of biosynthesized TeNPs.