Biosynthesis of Selenium Nanoparticles (via Bacillus subtilis BSN313), and Their Isolation, Characterization, and Bioactivities

Abstract

Among the trace elements, selenium (Se) has great demand as a health supplement. Compared to its other forms, selenium nanoparticles have minor toxicity, superior reactivity, and excellent bioavailability. The present study was conducted to produce selenium nanoparticles (SeNPs) via a biosynthetic approach using probiotic <i>Bacillus subtilis</i> BSN313 in an economical and easy manner. The BSN313 exhibited a gradual increase in Se reduction and production of SeNPs up to 5-200 µg/mL of its environmental Se. However, the capability was decreased beyond that concentration. The capacity for extracellular SeNP production was evidenced by the emergence of red color, then confirmed by a microscopic approach. Produced SeNPs were purified, freeze-dried, and subsequently characterized systematically using UV-Vis spectroscopy, FTIR, Zetasizer, SEM-EDS, and TEM techniques. SEM-EDS analysis proved the presence of selenium as the foremost constituent of SeNPs. With an average particle size of 530 nm, SeNPs were shown to have a -26.9 (mV) zeta potential and -2.11 µm cm/Vs electrophoretic mobility in water. SeNPs produced during both the 24 and 48 h incubation periods showed good antioxidant activity in terms of DPPH and ABST scavenging action at a concentration of 150 µg/mL with no significant differences (<i>p</i> > 0.05). Moreover, 200 µg/mL of SeNPs showed antibacterial reactivity against <i>Escherichia coli</i> ATCC 8739, <i>Staphylococcus aureus</i> ATCC 9027, and <i>Pseudomonas aeruginosa</i> ATCC 25923. In the future, this work will be helpful to produce biogenic SeNPs using probiotic <i>Bacillus subtilis</i> BSN313 as biofactories, with the potential for safe use in biomedical and nutritional applications.