Selenium Nanoparticles Biosynthesized by Pantoea agglomerans and Their Effects on Cellular and Physiological Parameters in the Rainbow Trout Oncorhynchus mykiss

Simple Summary Nanoparticles (Nps), new biotechnological tools, possess unique physical and chemical properties and are increasingly being used in several fields, such as manufacture, medicine and veterinary medicine. In this work, we evaluated the effects of selenium (Se) nanoparticles stabilized with L-Cysteine (Se(0)Nps/L-Cys) as a nutritional supplement, to modulate immunological, oxidative status, and productive parameters in O. mykiss. The results demonstrated that Se(0)Nps/L-Cys showed less toxicity and higher antioxidant activity than Se(0)Nps and Na2SeO3. The Se(0)Nps/L-Cys, as a dietary supplement, had a significantly better effect on both immunological and physiological parameters, causing improvements at the productive level of O. mykiss when compared with Se(0)Nps and Na2SeO3. We concluded that Se(0)Nps sythetised by P. agglomerans, used as dietary supplement, is an environmentally friendly and promising alternative for nutritional supplementation for O. mykiss. The applications of nanoparticles (Nps) as food additives, health enhancers, and antimicrobials in animal production are increasing. The aim of this study was to evaluate the effect of selenium (Se) nanoparticles (Se(0)Nps) stabilized with L-cysteine (Se(0)Nps/L-Cys), as a nutritional supplement, on immunological, oxidative status, and productive parameters in O. mykiss. TEM and SEM-EDS showed the accumulation of spherical Se(0)Nps entirely composed by elemental selenium (Se-0) as intracellular and extracellular deposits in Pantoea agglomerans UC-32 strain. The in vitro antioxidant capacity of Se(0)Nps/L-Cys was significant more efficient ROS scavengers than Se(0)Nps and Na2SeO3. We also evaluate the effect of Se(0)Nps/L-Cys on cell viability and oxidative stress in RTgill-W1, RTS-11, or T-PHKM Oncorhynchus mykiss cell lines. Se(0)Nps/L-Cys showed less toxic and high antioxidant activity than Se(0)Nps and Na2SeO3. Finally, the dietary Se(0)Nps/L-Cys had a significant better effect on both plasma lysozyme and respiratory burst activity (innate immune response), on tissular Gpx activity (oxidative status), and on well-being (productive parameter) of O. mykiss when it is compared to Se(0)Nps and Na2SeO3. Se(0)Nps/L-Cys is a promising alternative for nutritional supplement for O. mykiss with better performance than Na2SeO3 and Se(0)Nps, ease to implementation, and reduced environmental impact.