ABSTRACT
Biosurfactants are amphiphilic molecules that are synthesized as secondary metabolites by many microorganisms, such as, bacteria, yeast and fungi. They reduce the surface and interfacial tension between two phases which can be either liquid-liquid or liquid-solid, respectively. They are high molecular weight biomolecules consisting of carbohydrates, proteins and lipid moieties and are synthesized from biological sources utilizing renewable sources as substrates. Hence they are non-toxic and safe for various applications. Depending on their chemical structure biosurfactants can be grouped into four types, namely, lipopeptides, phospholipids, glycolipids and polymeric biosurfactants. Among these biosurfactants, lipopeptides are the best-known biosurfactants. They are produced by many microbial species, the most prominent being Bacillus sp. Due to their amphiphilic nature they easily interact with phospholipid layer present in cell membrane of all prokaryotic and eukaryotic cells. This leads to creation of pores in the cell membrane leading to cell death. This mechanism of action of biosurfactants leads to their application as biomedical and therapeutic agents, in plant-pathogen control and environmental bioremediation. Even though bacterial species producing lipopeptides are fast-growing, the microbial production of lipopeptides offer disadvantage of low yield. Process optimization is a suitable solution to increase the production at reduced cost. This includes optimization of medium components (carbon, nitrogen and trace elements) and operational conditions. This chapter reviews different types of lipopeptides produced by various species of microorganisms and their mode of action corresponding to their broad range of application. It also provides insights into their production strategies, optimization of process parameters and the challenges in the industrial production of lipopeptides.
