Harnessing Enterococcus faecium WFD-128 from yogurt fermentation: Unveiling probiotic attributes and targeted inhibition of Shigella sonnei diarrheal pathogenesis.

Diarrhea is a leading cause of mortality among children under five, with few effective interventions beyond oral rehydration, antibiotics, and zinc supplementation. This study aimed to identify and evaluate the probiotic and anti-diarrheal potential of Enterococcus faecium WFD-128, isolated from fermented yogurt, through in vitro, in silico, and in vivo approaches. The bacterium showed notable antibacterial activity, with inhibition zones measuring 21 mm and 19 mm against Shigella flexneri and Shigella sonnei, respectively. Additionally, it exhibited anti-biofilm effectiveness of 82 % and 80 % against these pathogens. It exhibited resistance to Amoxicillin, intermediate sensitivity to Ampicillin and Chloramphenicol, and tolerance to bile salts over 3-48h, and to acidic pH levels ranging from 2 to 8. Gas Chromatography-Mass Spectrometry (GC-MS) identified 68 volatile compounds, of which [1,1'-Bicyclohexyl]-4-carboxylic acid, 4'-propyl-, 4-fluorophenyl ester (-8.5) and Cholest-4-en-26-oic acid, 3-oxo-, methyl ester (-7.9) showed strong binding affinities to the diarrheal protein T3SS of Shigella sonnei (PDB: 6WRY) in molecular docking studies. These compounds exhibited favorable pharmaceutical properties in ADMET analysis, further supported by molecular dynamics simulations. In vivo experiments with albino mice validated the bacterium's therapeutic potential. Histopathological analysis revealed significant recovery of diarrhea-affected organs, including the kidney, liver, intestine, and spleen, following treatment with E. faecium. This aligns with in vitro and in silico findings, demonstrating the bacterium's therapeutic effectiveness. This study highlights the promise of E. faecium as a probiotic-based treatment against bacteria-induced diarrhea, offering a strong foundation for the development of innovative anti-diarrheal therapeutics.