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Keywords:

  • biosurfactants;
  • batch fermentation;
  • nitrogen limitation;
  • glycolipids;
  • rhamnolipids;
  • growth-limiting conditions

Abstract

Studies on the biosurfactants produced by Pseudomonas aeruginosa CFTR-6 revealed that they consisted of glycolipids R-1 and R-2. A time course study of fermentation indicated that the appearance of glycolipids in the fermentation broth coincided with the exhaustion of nitrogen and the commencement of the stationary phase with respect to biomass. The effect of variation of the media components such as carbon, nitrogen, phosphate and metal ions has been investigated. The following values were found to be optimum for biosurfactant production: glucose, 20 g dm−3; carbon to nitrogen ratio, 38; phosphate, 30 mmol dm−3; MgSO4.7H2O, 100 mg dm−3. Addition of iron to the medium significantly diminished the glycolipid yield.