Assessment of four Poly Antibiotic-resistant Bacterial Strains of Bacillusclausii (TIL 19T, TIL 21C, TIL 28S, TIL 30R) and their Probiotic Attributes: Implicationsfor Safety and Therapeutic Viability

Abstract

Objective: This study evaluated the probiotic potential and safety of four poly-antibiotic-resistant strains of Bacillus clausii (TIL 19T, TIL 21C, TIL 28S, and TIL 30R), a spore-forming bacterium known for supporting gastrointestinal health. Results: The strains demonstrated several desirable probiotic characteristics, including tolerance to gastrointestinal conditions such as bile salts, lysozyme, and intestinal transit stress, along with strong auto-aggregation and co-aggregation abilities. Acid, bile, transit, and lysozyme tolerance assays demonstrated strong gastrointestinal survival abilities in all the four strains. TIL 19T and TIL 30R displayed high survival rates in lysozyme-rich environments, and TIL 28S and TIL 30R showed strong co-aggregation with E. coli, indicating potential
pathogen inhibition. The strains also adhered effectively to intestinal cell models, produced digestive enzymes and exopolysaccharides, reduced cholesterol levels, and exhibited antimicrobial properties. Safety assessments further supported their probiotic candidacy. The strains were heat resistant, capable of moderate biofilm formation, and did not produce harmful compounds such as biogenic amines, or DNase. Cytotoxicity testing on Vero cells revealed high cell viability, suggesting a favourable safety profile. Conclusion: Collectively, these findings indicate that the investigated Bacillus clausii (Shouchella clausii) strains possess strong probiotic and therapeutic potential, making them promising candidates for future applications in functional foods and gastrointestinal health promotion.