Biosynthesis of Selenium Nanoparticles by Ligilactobacillus salivarius DACN818: Characterization and Mechanism

The biosynthesis of selenium nanoparticles (SeNPs) from selenite is a green and safe strategy, but their mechanisms in lactic acid bacteria (LAB) remain unclear. In this study, DACN818 was isolated from traditional homemade Paocai and identified via whole-genome analysis as Ligilactobacillus salivarius. It had a high conversion rate (≥70% within 24 h) of sodium selenite at a concentration of 2000 μg/mL (11.56 mM), exhibiting improved performance over currently reported LAB. Characterization by SEM-EDS, XRD, XPS, Raman, and FTIR spectroscopic techniques revealed that the synthesized SeNPs were predominantly amorphous and coated with polysaccharides and proteins. Transcriptome and metabolome analyses indicated that the conversion process involves sulfur/glutathione metabolism, the phosphotransferase system, amino acid degradation and energy metabolism, and genes such as manX, scrA, fruA, cadC, and yfeX, rather than genes encoding ABC transporter permeases, were implicated, providing a theoretical basis for its application in the green synthesis of SeNPs.