Surface-Active Compounds from Microorganisms

Publisher Summary This chapter discusses the metabolites produced by microorganisms, which demonstrate surface activity. It focuses on systems in which the metabolite has been characterized and shown to be surface active. The examples of biosurfactant modification, usually by substrate manipulation are also reviewed. Biosurfactants are important because they present a broad range of surfactant types and properties than the available synthetic surfactants. Furthermore, they are usually biodegradable, which reduces the potential of pollution. The surfactants produced by microorganisms are usually lipids. Their surfactant properties result from a combination of polar and apolar moieties in a single molecule. The apolar or hydrophobic portion is normally a hydrocarbon. The polar or hydrophilic groups include a wide range of possibilities. A method used to determine the surface activity is to measure the surface tension of the whole broth or a dilution of the whole broth. The most commonly isolated microbial surfactants, or emulsifying agents, are glycolipids. Most of the trehalose lipids considered in the chapter have the same general structure of two α-branched β-hydroxy fatty acids esterified to a trehalose molecule.