biosurfactants

Biosurfactants are surface-active compounds produced by microorganisms that reduce surface tension at liquid interfaces and stabilize emulsions. They are typically characterized by their biodegradability and relatively low toxicity compared with many synthetic surfactants.

Major classes include glycolipids (for example rhamnolipids from Pseudomonas species and sophorolipids from Candida spp.), lipopeptides (notably surfactin, fengycin, and iturin from Bacillus subtilis and related strains), and polymeric biosurfactants such as emulsan produced by Acinetobacter calcoaceticus. Phospholipids and neutral lipids also feature in discussions of biosurfactant activity. They are produced by bacteria, yeasts, and fungi during growth on diverse carbon sources, including hydrophobic compounds and industrial wastes.

Key properties include the reduction of surface and interfacial tension, the ability to emulsify immiscible liquids, and stability under a range of pH, salinity, and temperature. They are often biodegradable and display lower ecotoxicity than many synthetic surfactants, supporting use in environmentally sensitive applications.

Applications span environmental remediation (soil and water decontamination, oil spill response), enhanced oil recovery, detergents and cleaning products, cosmetics, pharmaceuticals, and agriculture as biopesticides or soil amendments. Production is typically achieved by microbial fermentation using renewable feedstocks; downstream processing can be costly due to product variability and the presence of impurities, which has limited large-scale adoption. Ongoing research seeks to reduce costs through strain improvement, process optimization, and the use of waste substrates.