Abstract:

In order to increase the production of antimicrobial metabolites against Alternaria alternate by an antagonistic
endophytic strain L (Bacillus amyloliquefaciens), a novel experimental design and analysis approach, uniform design combined
with support vector regression (UD-SVR), was proposed to optimize culture medium components and fermenter conditions. Three
rounds of mixed level experiments of nine variables showed that the optimal culture medium consisted of starch 0.5%, glucose 2%,
yeast extract 0.4%, CaCl2 1.3% and KH2PO4 0.1% at pH 7.0, and the optimal fermentation conditions were 1% of inoculum amount,
30 ℃ and 36 h. The antimicrobial activity of a 10-fold dilution of the fermentation broth obtained under the optimized conditions was
57.39%, a 20.53% increase in comparison with the value from benchmark experiments. In conclusion, UD-SVR is more efficient than
the reference models and has more promising potential for wide applications in experimental design and optimization.

Key words: optimization, uniform design combined with support vector regression, Bacillus amyloliquefaciens, inhibitory activity