Improving selenium accumulation in broilers using Escherichia coil Nissle 1917 with surface-displayed selenite reductase SerV01

Selenium levels have a critical impact on livestock and poultry, and selenium nanoparticles (SeNPs) have shown significant efficiency in the supplementation. This study identified a high-efficiency selenite reductase, SerV01, in Staphylococcus aureus LZ-01, which can convert Se₂O₃^2- to SeNPs. Subsequently, SerV01 was applied into the intestine of the broilers by using the surface display-engineered E. coli Nissle 1917 (EcN). The results showed that, the engineered bacteria (EcN-IS) significantly increased the selenium content by 0.87 mg/kg⁻¹, 0.52 mg/kg⁻¹, and 6.10 mg/L⁻¹ in the liver, breast muscle, and serum, respectively. With SeNPs + EcN-IS treatment, glutathione peroxidase and thioredoxin reductase reached 0.7536 ± 0.03176 U/μL⁻¹ protein and 2.463 ± 0.1685 U/μL⁻¹ protein, respectively. With the modified probiotics, the proportion of beneficial intestinal flora increased, with Lactobacillus and Propionibacterium accounting for 75.85% and 0.19%. This technology provides a novel idea to facilitate the exploitation of selenium in broiler diets and improve antioxidant capability.