Structural and Metabolic Remodeling of Mixed Lactic Acid Bacteria-Fermented Wheat Germ and Its In Vitro and In Vivo Digestive Stability

Fermentation utilizing a combination of lactic acid bacteria (LAB) is known to enhance the nutritional value of wheat germ extract via the production of functional bioactive compounds. In this work, fermentation via compound LAB significantly enhanced the antioxidant activity of wheat germ extract. Compared to the unfermented group (CON), the in vitro antioxidant indices of Lactobacillus fermented wheat embryo extract were increased significantly: DPPH·+/ABTS·+ clearance (67.87 ± 3.48%/71.44 ± 5.90%), FRAP value (1.33 ± 0.02 μmol Trolox/10 mg), and active substance content including GSH (78.04 ± 1.43 μmol/g), total phenols (0.53 ± 0.01 mg GAE/10 mg), and total flavonoids (0.032 ± 0.01 mg/10 mg). Moreover, the antioxidant activity and substances of lactic acid bacteria-fermented wheat embryo extract were improved after gastrointestinal digestion compared with CON. In the erastin-induced Drosophila oxidative stress model, LFWGC intervention significantly improved behavioral performance (12.6 ± 3.78 s of tube climbing and 101.2 ± 7.98 jumps) and increased in vivo antioxidant levels: DPPH·+·+ clearance by 31.75 ± 0.62%, ABTS·+ clearance by 50.11 ± 0.82%, FRAP to 0.89 ± 0.03 μmol Trolox/10 mg, and GSH (116.30 ± 1.95 μmol/g), total phenols (0.117 ± 0.01 mg GAE/mg), and total flavonoids (0.027 ± 0.002 mg/g). Mechanistically, LFWGC enriched the intestinal flora with Levilactobacillus and Pseudomonas by restoring Tsf1 protein function, upregulating the expression of the TSF1 and GPX4 genes, and activating the pentose phosphate and a-lanine–aspartate-glutamate metabolic pathways, thereby synergistically enhancing the antioxidant defense system. LAB fermentation effectively enhanced the antioxidant capacity of wheat germ extract, providing a theoretical foundation for the development of functional foods.