Microbial biosynthesis of selenium nanoparticles using probiotic strain and its characterization.

The present study investigates the sustainable biosynthesis of selenium nanoparticles utilizing different probiotic strains namely Lactobacillus delbrueckii sub. sp. bulgaricus, Lactobacillus rhamnosus, Streptococcus thermophiles and mixed culture. The synthesis and analysis were concentrated on using multiple analytical techniques, including thermogravimetric analysis-differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, dynamic light scattering, and energy-dispersive X-ray spectroscopy. Major functional groups were identified by FTIR analysis that include conjugated ketones (C=O stretching) at 1648.82 cm⁻¹ to 1688.54 cm⁻¹, halo compounds (C–Br stretching) at 448.85 cm⁻¹ to 879.54 cm⁻¹, and fluoro compounds (C–F stretching) at 668.10 cm⁻¹ to 1065.89 cm⁻¹. Based on strain-specific measurements using SEM and TEM, the size of the nanoparticles ranged from 16 nm to 68.96 nm in diameter. Both extracellular and intracellular synthesis of the particles were identified. Significant amount of selenium were found using EDX analysis, with Lactobacillus rhamnosus and mix culture having the highest and the lowest concentrations at 97.50% and 90.58% by weight, respectively. Zeta potential measurements, indicating high colloidal stability, ranged from − 27.9 mV to − 23.1 mV and demonstrated that the nanoparticles synthesized by Lactobacillus rhamnosus was most stable among all. The synthesized nanoparticles were purely amorphous, according to XRD patterns. The TGA–DSC measurement showed that the nanoparticles exhibit varied levels of weight loss at different phases while being thermally stable. Lactobacillus rhamnosus showed maximum viability that is 8.67 log CFU/g and the least was seen in mix culture that is 7.22 log CFU/g. With applications in food fortification and biomedicine, this study highlights the potential of using probiotic strains for the synthesis of selenium nanoparticles. It also highlights an innovative approach that combines the fields of nanotechnology as well as biotechnology for sustainable and biocompatible solutions in the field of Food Science and Technology. [ABSTRACT FROM AUTHOR]