Statistical optimization of medium components for the production of biosurfactant by Bacillus licheniformis K51

The nutritional medium requirement for biosurfactant production by Bacillus licheniformis K51 was optimized. The important medium components, identified by the initial screening method of Plackett-Burman, were H₃PO₄, CaCl₂, H₃BO₃, and Na-EDTA. Box-Behnken response surface methodology was applied to further optimize biosurfactant production. The optimal concentrations for higher production of biosurfactants were (g/l): glucose, 1.1; NaNO₃, 4.4; MgSO₄.7H₂O, 0.8; KCl, 0.4; CaCl₂, 0.27; H₃PO₄, 1.0 ml/l; and trace elements (mg/l): H₃BO₃, 0.25; CuSO₄, 0.6; MnSO₄, 2.2; Na₂MoO₄, 0.5; ZnSO₄, 6.0; FeSO₄, 8.0; CoCl₂, 1.0; and Na-EDTA, 30.0. Using this statistical optimization method, the relative biosurfactant yield as critical micelle dilution (CMD) was increased from 10× to 105×, which is ten times higher than the non-optimized rich medium.