Medium optimization of antifungal metabolites produced by Bacillus globisporus A95 using response surface methodology

Bacillus globisporus A95, a novel strain isolated from tea rhizosphere soil, showed broad-spectrum antifungal activity. Statistical optimization of the medium was applied to enhance the antifungal metabolites production. The Plackett-Burman Design revealed that soybean meal and CaCO₃ significantly affected the active substances production. A 2⁴-Central composite design was used for response surface methodology (RSM) to further optimize the fermentation medium. The optimized medium containing (g/l): corn meal, 20.00; maltose, 20.00; soybean meal, 29.45; (NH₄)₂SO₄, 1.00; CaCO₃, 3.78 resulted in a 105.48% increase in titer level (8054.87μg/ml), as compared to initial level (3916.65μg/ml) after 72h of fermentation.