Effects of Lactiplantibacillus plantarum A458 on Lactose Intolerance in Mice: Associations with Gut Microbiota and Redox Balance

Lactose intolerance (LI) is a common gastrointestinal disorder caused by reduced intestinal lactase activity, resulting in lactose maldigestion and digestive symptoms, including diarrhea, bloating, and abdominal pain. Supplementation with β-galactosidase-producing probiotics is a potential strategy to improve lactose metabolism and reduce symptoms. In this study, we evaluated the probiotic properties and LI-alleviating efficacy of Lactiplantibacillus (L.) plantarum A458 through integrated in vitro and in vivo analyses. The strain displayed robust survival under simulated gastric and bile environments, maintaining high viability at acidic pH (2.0) and in 0.3–0.5% bile salts. It also demonstrated active fermentation capacity, producing high levels of lactic acid, and showed strong adhesion to Caco-2 cells while effectively inhibiting the invasion of Listeria monocytogenes. In a mouse model of LI, oral administration of L. plantarum A458 reduced systemic inflammation, as evidenced by decreased serum levels of IL-1β, TNF-α, IL-6, and IFN-γ. Additionally, L. plantarum A458 improved hepatic antioxidant defenses by elevating SOD activity and reducing lipid peroxidation and redox imbalance, as indicated by decreased MDA levels and increased GSH/GSSG ratio. Notably, L. plantarum A458 increased jejunal lactase activity. Moreover, 16S rRNA sequencing suggested that L. plantarum A458 modulated the gut microbial community, with higher relative abundance of beneficial taxa and lower relative abundance of potentially pathogenic microbes. Collectively, these findings suggest that L. plantarum A458 shows potential as a probiotic candidate for managing LI, associated with increased lactase activity, reduced inflammation and oxidative stress, and modulated gut microbiota.