Glycolipid and Lipopeptide Biosurfactants: Structural Classes and Characterization—Rhamnolipids as a Model

In recent years, biosurfactants (BS) produced by various bacteria, fungi and yeast strains have attracted much interest because of their unique properties and potential applications in many industries ranging from bioremediation to agriculture and biomedical to cosmetics. Glycolipids are a popular group of BS that include rhamnolipids, sophorolipids, mannosylerythritol, trehalose lipids, xylolipids and cellobiose lipids. Lipopeptides e.g., surfactins, iturins and fengycins are of major biotechnological interest because of their antitumor, immunomodulatory, and antimicrobial activities effects. This review addresses the structural properties of glycolipids and lipopeptides, their main domains of application as well as the screening tests of BS production. Glycolipids are mostly composed of a carbohydrate moiety linked to a ß-hydroxy fatty acid chain with a glycosidic bond. The properties of glycolipids are related to the nature of the carbohydrate moiety and the length of the fatty acid chain. The lipopeptide structure is mainly composed of a linear or cyclic peptide linked to fatty acids of different chain lengths. The structural complexity of these compounds requires various analytical techniques for characterization and quantification. As an example, the analytical techniques used for the characterization of rhamnolipids are presented in this review. RLs are very promising BS with a wide range of applications in various fields, such as cosmetics, food science, pharmaceuticals, and environmental remediation.