Bioemulsifiers from marine microorganisms

This review highlights bioemulsifier-producing marine microorganisms, which are capable of producing unique metabolites having industrial applications. High molecular weight biosurfactants (bioemulsifiers) produce stable emulsions, which allow bacteria to adhere strongly to hydrophobic surfaces and then degrade large biological complexes. Bioemulsifiers are classified according to their hydrophile-lipophile balance (HLB); those having a low HLB are strong lipophiles and used as water-in-oil emulsifiers, whereas those having a high HLB are strong hydrophiles and used as oil-in-water emulsifiers. Acinetobacter calcoaceticus is the most promising marine microorganism used in diverse applications. In A. calcoaceticus RAG-1, emulsification is brought about by production of an extracellular, polymeric bioemulsifier termed emulsan. Tropical marine yeast, Yarrowia lipolytica NCIM 3589, produces emulsifier in the presence of alkanes or crude oil. Bioemulsifier potential is mainly dependent on its chemical nature and hence its activity can be enhanced by simple media modification or mutagenesis.