Lactobacillus delbrueckii subsp. bulgaricus 1.0207 Exopolysaccharides Attenuate Hydrogen Peroxide-Induced Oxidative Stress Damage in IPEC-J2 Cells through the Keap1/Nrf2 Pathway

<i>Lactobacillus delbrueckii</i> subsp. <i>bulgaricus</i> (<i>L. bulgaricus</i>) is one of the most commonly employed <i>Lactobacillus</i> in the food industry. Exopolysaccharides (EPS) of <i>Lactobacillus</i>, which are known to exhibit probiotic properties, are secondary metabolites produced during the growth of <i>Lactobacillus</i>. This study identified the structure of the EPS produced by <i>L. bulgaricus</i> 1.0207 and investigated the mitigation of <i>L. bulgaricus</i> 1.0207 EPS on H₂O₂-induced oxidative stress in IPEC-J2 cells. <i>L. bulgaricus</i> 1.0207 EPS consisted of glucose and galactose and possessed a molecular weight of 4.06 × 10⁴ Da. <i>L. bulgaricus</i> 1.0207 EPS exhibited notable scavenging capacity against DPPH, hydroxyl radicals, superoxide anions, and ABTS radicals. Additionally, <i>L. bulgaricus</i> 1.0207 EPS enhanced cell proliferation, reduced intracellular reactive oxygen species (ROS) accumulation, increased activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and total antioxidant capacity (T-AOC) elevated the relative expression of CAT, SOD, HO-1, NQO1, ZO-1, and Occludin genes. Moreover, <i>L. bulgaricus</i> 1.0207 EPS improved the expression of Nrf2, <i>p</i>Nrf2, <i>p</i>Nrf2/Nrf2, and Bcl-2 proteins, while decreasing the expression of Keap1, Caspase3, and Bax proteins, with the best effect at a concentration of 100 μg/mL. <i>L. bulgaricus</i> 1.0207 EPS mitigated H₂O₂-induced oxidative stress injury in IPEC-J2 cells by activating the Keap1/Nrf2 pathway. Meanwhile, <i>L. bulgaricus</i> 1.0207 EPS exhibited the potential to decrease apoptosis and restore the integrity of the gut barrier. The findings establish a theoretical foundation for the development and application of <i>L.bulgaricus</i> 1.0207 and its EPS.