Fermentation medium optimization of Clostridium butyricum and degradation of aflatoxin B1 by fermentation products

Abstract:

[Background] Clostridium butyricum is a new generation of obligate anaerobic spore-producing probiotics with strong tolerance to heat, acid, and stress, demonstrating a great application value and development prospect. [Objective] To optimize the fermentation medium of C. butyricum and study the activities of the fermentation broth in terms of inhibiting Aspergillus flavus and degrading aflatoxin B₁ (AFB₁). [Methods] Response surface methodology was employed to optimize the fermentation medium. The oxford cup assay was employed to examine the inhibitory activity of C. butyricum fermentation broth on A. flavus and enzyme-linked immunosorbent assay to determine the AFB₁-degrading ability of the fermentation broth. [Results] The optimized fermentation medium was composed of 18.1 g/L glucose, 29.7 g/L soya peptone, 3.8 g/L K₂HPO₄· 3H₂O, 2.0 g/L NaCl, 4.0 g/L NaAc, 1.2 g/L MgSO₄· 7H₂O, and 0.3 g/L l-cystine hydrochloride. After optimization, the biomass of C. butyricum reached 2.28×10⁹ cells/mL, which was 2.54 times of that (8.99×10⁸ cells/mL) before optimization. The fermentation broth of C. butyricum exerted a significant inhibitory effect on A. flavus, and the concentrated supernatant degraded 68.65% of AFB₁ within 72 h. The results indicated that the active components degrading AFB₁ in the supernatant were the extracellular enzymes produced by C. butyricum.[Conclusion] The biomass of C. butyricum was significantly increased by fermentation medium optimization, and the fermentation broth of C. butyricum inhibited A. flavus and degraded AFB₁. The findings provide scientific evidence for the industrial production of C. butyricum and the development and application of microecological preparations.