Characterization of a biosurfactant, mannosylerythritol lipid produced from Candida sp SY16

One yeast strain, SY16, was selected as a potential producer of a biosurfac tant, and identified as a Candida species. A biosurfactant produced from Ca ndida sp. SY16 was purified and confirmed to be a glycolipid. This glycolip id-type biosurfactant lowered the surface tension of water to 29 dyne/cm at critical micelle concentration of 10 mg/l (1.5 x 10(-5) M), and the minimu m interfacial tension was 0.1 dyne/cm against kerosene. Thin-layer and high -pressure liquid chromatography studies demonstrated that the glycolipid co ntained mannosylerythritol as a hydrophilic moiety. The hydrophilic sugar m oiety of the biosurfactant was determined to be beta-D-mannopyranosyl-(1 -- > 4)-O-meso-erythritol by nuclear magnetic resonance (NMR) and fast atom bo mbardment mass-spectroscopy analyses. The hydrophobic moiety, fatty acids, of the biosurfactant was determined to be hexanoic, dodecanoic, tetradecano ic, and tetradecenoic acid by gas chromatography-mass spectroscopy. The str ucture of the native biosurfactant was determined to be 6-O-acetyl-2,3-di-O -alkanoyl-beta-D-mannopyranosyl-(1 --> 4)-O-meso-erythritol by NMR analyses . We newly determined that an acetyl group was linked to the C-6 position o f the D-mannose unit in the hydrophilic sugar moiety.