Biosynthesis and characterization of selenium nanoparticles by Se-tolerant Lactiplantibacillus plantarum

Selenium nanoparticles synthesized by Lactobacillus (LacSeNPs) are considered the safer form of selenium supplementation. This study synthesised a new LacSeNPs by a selenium-tolerant strain Lactiplanibacillus plantarum BSe, and investigate its characteristics, antibacterial activity, and cytotoxicity. The results showed that L. plantarum BSe could grow at Se(Ⅳ) concentrations of 100 mmol·L-1, and achieving a conversion level of 76.32% of selenium into LacSeNPs. Electron microscopy, FT-IR and X-ray photoelectron spectroscopic data indicated that only elemental Se existed in LacSeNPs and was encapsulated by proteins and polysaccharides, and the atomic proportion was Se (24.83%), accompanied with C (67.03%), N (3.12%), O (4.24%) and S (0.78%). LacSeNPs showed strong inhibition to Escherichia coli and Staphylococcus aureus. Furthermore, at equivalent selenium concentrations, LacSeNPs exhibits lower cytotoxicity compared to selenite. The findings of this study demonstrate that Lactiplanibacillus plantarum BSe is an excellent LacSeNPs synthesis bacterium and has potential application value in the production of SeNPs food additives.