Probiotic potential of Levilactobacillus brevis EG040 isolated from dongchimi and CRISPR-Cas based genome editing for enhanced γ-aminobutyric acid secretion

Résumé fourni par la source

Levilactobacillus brevis EG040, a high γ-aminobutyric acid (GABA)–producing strain, was isolated from dongchimi, a traditional Korean radish-water kimchi. EG040 showed high acid and bile tolerance in simulated digestive fluids and adhered strongly to Caco-2 intestinal epithelial cells, indicating intestinal colonization potential. Safety assessments revealed no hemolysis or clinically relevant antibiotic resistance in vitro, and genomics confirmed absence of significant antibiotic resistance and virulence factors. The genome also harbored health-promoting metabolites biosynthetic clusters including polyketide and lanthipeptide suggesting potential immunomodulatory and antimicrobial activities. COG profiling outlined functional capacity emphasizing translational capacity and stress-adaptive metabolism. Whole-genome phylogeny indicated EG040 is distinct from other L. brevis , supporting its novelty. CRISPR-Cas editing targeted norG and gadR and was confirmed by PCR and sequencing. RT-qPCR showed gadR overexpression upregulated GABA-biosynthetic genes. norG deletion reduced GABA by 97.3 % and impaired growth, whereas gadR overexpression increased GABA by 37.9 % and improved survival in simulated gastric solution by 19 %. These findings support EG040's probiotic potential and distinct genomic and functional features. Furthermore, the development of a GABA-overproducing strain through gadR overexpression provides foundational insights for developing live biotherapeutic products (LBPs) targeting metabolic syndrome.

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