Natural surfactants or biosurfactants are amphiphilic biological compounds, usually extracellular, produced by variety of microorganisms from various substances including waste materials. There is an increasing interest on this topic because of their unique properties such as low toxicity, functionality under extreme conditions, based on renewable substances and biologically degradable nature. The diversity of these molecules supports them for their potential application in the field of petroleum, medicine, agriculture, food, cosmetics etc. They are also effective in curtailing green-house effect by reducing the emission of CO 2 . They can be termed as 'green' because of their low toxicity, biodegradability and relative stability under a wide range of physicochemical environments.