Microorganisms showed a high capacity
of synthesizing a wide range of surface-active compounds, generally called
biosurfactants. These compounds are mainly classified according to their
molecular weight, physico-chemical properties and mode of action.Many surfactants
including rhamnolipids alter the surface properties of liquids, even when
present in small quantities. Like other surfactants, rhamnolipids present a
lyophilic group and a lyophobic group which facilitate the orientation of the
surfactant to reduce the liquid surface free energy and increase surface
viscosity.
Some chemical surfactants
decontaminated and maintain membrane performance as well as membrane integrity under mild operation
conditions. Undefined cleaning activity together
with its low biodegradability and high cost most possibly determine the much
less frequent use of chemical surfactants in the industrial applications.
Rhamnolipids are potent natural
glycolipid biosurfactants often biosynthesized by Pseudomonas aeruginosa
strains through the fermentation process, with cheaper agro-based substrates
and waste materials. They can be good substituents for chemical surfactants, in
different industrial fields. Rhamnolipids are classified as mono-rhamnolipids
and di-rhamnolipids, depending on one or two rhamnose sugars linked to a dimer
of β-hydroxyacids (primarily β-hydroxydecanoate) which can rise up to three
hydroxyl fatty acids containing 8– 14 carbons.
