Surface active properties and antimicrobial activities of mannosylerythritol lipids as biosurfactants produced by Candida antarctica

The interfacial and antimicrobial properties of two kinds of mannosylerythritol lipids (MEL-A and B), which were produced as biosurfactants from soybean oil by a yeast strain of Candida antarctica T-34, were investigated. MEL showed excellent surface and interfacial tension lowering actions and critical micelle concentrations (CMC). At CMCs, they reduced the surface tension and the interfacial tension against n-tetradecane to about 28 and 2 mN m −1, respectively. These interfacial properties are equivalent to those of other biosurfactants reported and ordinary glycolipid-type synthetic surfactants. MEL also exhibited antimicrobial activity particularly against Gram-positive bacteria, and their minimum inhibitory concentrations were significantly smaller than those of sucrose and sorbitan monoesters of fatty acids.