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Abstract In order to obtain the antagonistic bacteria and the optimum fermentation conditions of tobacco anthracnose, the bacteria in the rhizospheric soil, roots, stems, and leaves of tobacco were isolated. Accordingly, the antagonistic bacteria of tobacco anthracnose were screened by the method of solid and liquid medium and their antagonistic activity was determined, as well as identified by 16S rRNA analysis. The single factor experiment of shake flask fermentation and the response surface method based on Box-Behnken design were used to optimize the fermentation conditions of the best antagonistic bacteria. The results showed that there were 31 strains with antagonistic effects against tobacco anthracnose, and 10 strains with inhibition rate greater than 30%. The strain with the highest inhibition rate was C-4, and the inhibition rate was 72.14%. Sequence analysis initially identified it belonged to the genus Bacillus. The optimal fermentation conditions for Bacillus C-4 were as follows: inoculum volume 4%, initial pH 7.1, culture temperature 25.5 ℃, liquid volume 84.5 mL, shaker speed 180 r/min, and culture time 48 h. It was verified that under the optimal conditions, the OD600 value of the fermentation broth was 1.859, which was 1.62 times of that before optimization, and the inhibition rate was increased by 8.4%. This study provides an available strain resource for the development of microbial inoculant for the control of tobacco anthracnose. It is effective to optimize fermentation conditions of antagonistic bacteria of tobacco by using the response surface method.
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