The composition, structure, and pro

The composition, structure, and properties of a variety of surfactants produced by bacteria, yeasts, and fungi have been
described. Among the best-studied biosurfactants are the rhamnolipids of Pseudomonas aeruginosa. Most extracellular
surface-active compounds are synthesized by microorganisms growing on poorly soluble substrates, principally nalkanes. Biosurfactant production is often associated with the capacity of microorganisms to utilize hydrocarbons as substrates. Koch et al. have isolated a mutant of P. aeruginosa PG201 which had lost its capacity to grow on hexadecane because it failed to secrete its extracellular rhamnolipids. It has been suggested that biosurfactant growth-stimulating activity is more specific for the hydrophobic substrate used to produce it and is restricted mainly to the producing organism itself.