Bacillus subtilis SPB1 biosurfactant: Production optimization and insecticidal activity against the carob moth Ectomyelois ceratoniae

•Bacillus subtilis SPB1 lipopeptide production under solid state fermentation.•Solid state fermentation for B. subtilis lipopeptide production.•Economic biosurfactant production.•Insecticidal activity of produced biosurfactant against the Lepidoptera Ectomyelois ceratoniae Zeller, the moth pest of stored dates in Tunisia.•E. ceratoniae mortality by SPB1 biosurfactant.

Bacillus subtilis SPB1 was shown to produce a lipopeptide biosurfactant. The insecticidal activity of this biosurfactant was evaluated against Ectomyelois ceratoniae Zeller, a moth pest of stored dates in Tunisia. The LC50 and LC90 values after six days of contact were 152 μg/g and 641 μg/g, respectively. To promote an economical production of this highly effective bioinsecticide, statistical experimental designs and response surface methodology were employed to optimize the concentrations of agro-industrial residues and humidity, for lipopeptide biosurfactant production by B. subtilis SPB1 under solid state fermentation. The optimal medium leading to a production yield near to 28 mg of crude lipopeptide preparation per g of wet solid material was composed of a mixture of 4.34 g of tuna fish flour and 5.66 g of potato waste flour with a moisture content of 76%.