Emulsan

Emulsan is an extracellular emulsifying polymer produced by certain Acinetobacter species, most notably Acinetobacter calcoaceticus. It is a water-soluble biosurfactant that promotes the formation and stabilization of oil-in-water emulsions, earning attention for its high emulsification activity.

Chemically, emulsan is a high molecular weight, heterogeneous polymer composed of polysaccharide chains with lipid and protein components. The exact composition varies among producing strains. Its amphiphilic character arises from hydrophilic carbohydrate backbones coupled to hydrophobic lipid moieties, enabling adsorption at oil–water interfaces and the formation of protective interfacial films around droplets.

Production and isolation typically involve microbial cultivation on hydrocarbon substrates, followed by purification steps that recover the polymer from culture filtrates. Emulsan is noted for its strong emulsifying capabilities, often surpassing many other biosurfactants in certain systems.

Properties include stability over a broad range of conditions, with activity persisting under various pH levels and salinities. The polymer’s high molecular weight and interfacial activity contribute to the persistence of stable emulsions, even with challenging hydrocarbons.

Applications and research have focused on its potential for environmental and industrial use. Emulsan has been studied for oil spill remediation, enhanced oil recovery, and formulation of stable hydrocarbon emulsions in industrial processes. It has also been explored for cosmetic and pharmaceutical emulsions, though commercial adoption is limited by factors such as production scale, purification requirements, and regulatory considerations. Safety and toxicity data are not as comprehensive as for some synthetic emulsifiers, underscoring the need for site-specific evaluation in applications involving consumer exposure or environmental release.

History: Emulsan was identified in studies of emulsifying activity in Acinetobacter calcoaceticus during the late 1960s and 1970s and has since remained a subject of interest in biosurfactant research.