Preparation and Characteristics of Selenium Nanoparticles Synthesized by Limosilactobacillus reuteri CICC 6118 and Their Protective Effects on Intestinal Injury in Early-Weaned Piglets.

In this study, biogenic selenium nanoparticles (SeNPs) were synthesized through biotransformation of Na2SeO3 by the porcine-derived strain Limosilactobacillus reuteri CICC 6118 (L. reuteri CICC 6118) and subsequently characterized. Their protective effects were evaluated in early-weaned piglets challenged with enterotoxigenic Escherichia coli K88 (ETEC K88). L. reuteri CICC 6118 synthesized SeNPs with diameters of approximately 70-190 nm and achieved a Na2SeO3 conversion efficiency of 97%. The purified SeNPs exhibited antioxidant activity and reduced bacterial culture turbidity in preliminary assays. In ETEC K88-challenged piglets, dietary SeNPs supplied at the same supplemental selenium concentration as Na2SeO3 improved growth performance, reduced diarrhea incidence, enhanced colonic barrier integrity, and attenuated inflammatory and oxidative responses. SeNPs also increased antioxidant enzyme activities, selenoprotein-related gene expression, and colonic short-chain fatty acid concentrations. These findings support L. reuteri CICC 6118-derived SeNPs as a functional selenium source for alleviating ETEC K88-induced intestinal injury under the dietary conditions tested.