Optimization of fermentation process of antagonistic Bacillus subtilis BS24 using Plackett-Burman design and response surface methodology

摘要

B. subtilis BS24 is a potential broad-spectrum biocontrol strain against plant pathogenic fungi such as Alternaria alternata f. sp. mali, Marssonina coronaria (Ell. et Davis) Davis, Phyllosticta pirina, Bolyosphoma berengeriana, Fusarium o.xysporium f. sp. melonis, Glanerella cingulata and Alternaria solani. Response surface methodology was employed to optimize the fermentation process of antagonistic Bacillus subtilis BS24. The most influential factors influencing fermentation process (/><0.01), asidentified by Plackett-Burman design with 12 variables, were soybean flour, rotate speed and inoculum concentration. Steepest Ascent Path was undertaken to determine the optimal regions of these three significant factors. Central composite design and response surface analysis were adopted to further investigate the mutual interactions between these variables. Close agreement between experimental and predicted values was found. After optimization, the fermentation process was shown as follows, corn flour15 g/L, soybean flour 21.6 g/L, yeast extract 3 g/L, sucrose 5 g/L, urea 3 g/L, MnS04 0.1 g/L, MgS04 0.1 g/L, K,HP04 2 g/L, pH 7.0, 300 r/min and 7.8% of inoculation. The viable count under optimal process was 15.08x 10' cfu/mL, which increased by 75.35% compared with initial count 8.6x 10' cfa/mL.