Notice of RetractionOptimization of Medium and Fermentation Conditions for the Antagonistic Bacillus subtilis BS501a Strain Using Response Surface Methodology

Notice of Retraction

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To improve the antagonistic metabolites production of Bacillus subtilis BS501a in a cheap medium and efficient fermentation condition, the optimal carbon and nitrogen source were screened from raw materials and response surface methodology (RSM) was used to optimize culture medium and fermentation condition. In RSM, a Plackett-Burman (PB) design was used to find significant factors affecting antagonistic metabolites production, a central composition design (CCD) was used to optimize the significant factors screened from PB design and the results of CCD were analyzed by RSM. The results showed that the optimal carbon and nitrogen source were soybean meal and peanut cake; that soybean meal, peanut cake and KH₂PO₄ were the significant factors, and that the optimal fermentation medium formula was (% w/v): soybean meal 3.2, peanut cake 1.21, yeast extract 0.5, KH₂PO₄ 0.07, KH₂PO₄ 0.2, MgSO₄·7H₂O 0.05, MnSO₄·H₂O 0.01, FeSO₄·7H₂O 0.01, CaCl₂ 0.15, and the optimal fermentation condition was: initial medium pH of 7.2, inoculums volume 5%, cultivation temperature 37°C, liquid volume in flask 100mL/500mL. The hypha growing inhibition rate of B. subtilis BS501a filtered fermentation supernatant under the optimal medium and fermentation condition was 91.6%. There was a 1.27-fold increase of the activity of the FFS compared to 72.3% of that in the medium - rior to optimization and 1.06-fold increase compared to 85.8% of that in the initial medium.