Optimization of biosurfactant lipopeptide production from Bacillus subtilis S499 by Plackett-Burman design

Bacillus subtilis S499 is well-known for its ability to produce two familie s of surfactant lipopeptides: Iturin A and Surfactin S1. Fermentation optim ization for this strain was performed to amplify the surfactant production. Ten active variables were analyzed by two successive Plackett-Burman desig ns, consisting respectively of 12 and 16 experiments to give an optimized m edium. The amount of biosurfactant lipopeptides in the supernatant of a cul ture carried out in this optimized medium was about five times higher than that obtained in nonoptimized rich medium. The analysis of the surfactant m olecules produced in such optimized conditions has revealed the presence of a third family of lipopeptides: the fengycins. The time-dependent production of these three families of molecules in biore actors showed that surfactin S1 is produced during the exponential phase an d iturin A and fengycins during the stationary phase.