Genetic potential of Limosilactobacillus fermentum 5.1.2 produces metabolite compounds with antioxidant activity

Limosilactobacillus fermentum 5.1.2, a tempeh-derived probiotic candidate, was investigated through an integrated genome-to-cell approach to evaluate its antioxidant capacity. Whole-genome analysis using GhostKOALA (KEGG) and antiSMASH 7.0 identified a terpene precursor biosynthetic gene cluster and key genes involved in terpenoid backbone (idi, GGPS) and terpenoid-quinone biosynthesis (menA, menB, menC, menE, ubiE). LC-QTOF-MS of the cell-free supernatant extract putatively identified terpenoid and terpenoid-quinone metabolites, including linalyl propionate, geranylbenzoquinone, geranylhydroquinone, theasapogenol A, and momordol. This is consistent with the predicted biosynthetic pathways. The cell-free supernatant exhibited strong DPPH radical-scavenging activity (84.85-88.99% inhibition), while the extract showed antioxidant activity against DPPH and ABTS+ radicals with IC₅₀ values of 660.5647 ± 35.67 µg/mL and 333.886 ± 13.13 µg/mL, respectively. Extract conferred cellular protection to Schizosaccharomyces pombe under H₂O₂-induced oxidative stress, comparable to calorie-restriction and ascorbic acid controls. These findings establish L. fermentum 5.1.2 as a multifunctional probiotic candidate with genomically supported antioxidant capacity.