African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5233

Full Length Research Paper

Statistical optimization of low-cost medium for economical production of Bacillus subtilis biosurfactant, a biocontrol agent for the olive moth Prays oleae

  Dhouha Ghribi1,2*, Ines Mnif1,2, Hanen Boukedi3, Radhouane Kammoun2 and Semia Ellouze-Chaabouni1
  1Unité Enzymes et Bioconversion, National School of Engineers of Sfax, Tunisia. 2Higher Institute of Biotechnology of Sfax, Tunisia. 3Laboratory of Biopesticides, Centre of Biotechnology of Sfax, Tunisia.
Email: [email protected]

  •  Accepted: 11 November 2011
  •  Published: 23 November 2011



Biosurfactants are currently not a feasible alternative to chemically synthesized surfactants as a result of their potentially high production costs. In this work, Bacillus subtilis SPB1 biosurfactant was shown to be efficient in the biocontrol of the olive mothPrays oleae. Its production was improved by optimizing the medium components using inexpensive substrates. The effect of orange peels, soya bean and diluted sea water on SPB1 biosurfactant production was studied and was adjusted using central composite design. The experimental results were fitted to a second-order polynomial model that yielded a determination coefficient of R2=0.932. The optimal medium for biosurfactant production was found to be composed only by orange peels (15.5 g/L), soya bean (10 g/L) and diluted sea water (30%). The predicted and observed response were 4.3 g/L (with desirability = 0. 21) and 4.45 g/L, respectively. In comparison to original level production, two fold increases had been obtained.


Key words: Bacillus subtilis, biosurfactant, central composite design, optimization, Prays oleae.