Highly Efficient Biotransformation and Production of Selenium Nanoparticles and Polysaccharides Using Potential Probiotic Bacillus subtilis T5.

Selenium is an essential microelement required for human health. The biotransformation of selenium nanoparticles has attracted increasing attention in recent years. However, little of the literature has investigated the comprehensive evaluation of the strains for practical application and the effect on the functional properties in the existence of Se. The present study showed the selenite reduction strain T5 (up to 200 mM), which could produce high yields of selenium polysaccharides and selenium nanoparticles in an economical and feasible manner. Biosynthesized selenium nanoparticles by T5 were characterized systematically using UV-vis spectroscopy, FTIR, Zeta Potential, DLS, and SEM techniques. The biosynthesized SeNPs exhibited high stability with small particle sizes. T5 also possessed a tolerance to acidic pH and bile salts, high aggregation, negative hemolytic, and superior antioxidant activity, which showed excellent probiotic potential and can be recommended as a potential candidate for the selenium biopharmaceuticals industry. Remarkably, T5 showed that the activity of α-amylase was enhanced with selenite treatment to 8.12 U/mL, 2.72-fold more than the control. The genus was first reported to produce both selenium polysaccharides with extremely high Se-content (2.302 g/kg) and significantly enhance the activity to promote α-amylase with selenium treatment. Overall, T5 showed potential as a bio-factory for the biosynthesized SeNPs and organ selenium (selenium polysaccharide), providing an appealing perspective for the biopharmaceutical industry.