Development and Evaluation of Antioxidant Postbiotics from Bacillus amyloliquefaciens C-1 to Alleviate DSS-Induced Colitis

Bacillus amyloliquefaciens has been recognized as a next-generation probiotic with a qualified presumption of safety (QPS) status by the European Food Safety Authority (EFSA), indicating its promising application potential in postbiotic development. This study aimed to investigate the probiotic characteristics of B. amyloliquefaciens strain C-1, isolated from ready-to-eat fruit salads. Strain C-1 demonstrated robust tolerance to various adverse environments, maintaining 102.6% viability at pH 6.0 for 3 h and surviving in 10.0% NaCl, although it exhibited poor tolerance to high concentrations of bile salts. The strain showed sensitivity to most antibiotics, possessed strong auto-aggregating, hydrophobic properties and adhesion capacity, besides it can adhere to pathogenic microorganisms and inhibit the growth of pathogenic bacteria. Furthermore, genotypic and phenotypic experiments revealed that C-1 lacked virulence factors and pathogenicity islands, was non-hemolytic and non-cytotoxic, and displayed a favorable biosafety profile, making it a safe candidate for potential probiotic development. Based on these properties, five types of postbiotics were developed from C-1 fermentation through filtrate sterilization, thermal inactivation and ultrasonic cell disruption. The cell-free supernatant-type postbiotic (CFS) exhibited the most pronounced antioxidant and bacteriostatic activities. These postbiotics effectively alleviated intestinal damage in DSS-induced colitis in zebrafish, reduced acidic mucin, and decreased the expression of IL-1β, IL-6, and TNF-α. The most significant effect was observed at a concentration of 0.1% CFS. In summary, the active ingredient of C-1, primarily located in the fermentation supernatant, is heat-sensitive and is anticipated to be developed into a safe and effective postbiotic for preventing the development of colitis.