Mannosylerythritol lipids (MELs) are glycolipid biosurfactants produced by various yeasts belonging to the genus Pseudozyma, which exhibit excellent surface activities as well as versatile biochemical activities. A study on P. tsukubaensis NBRC1940 as a mono-acetylated MEL (MEL-B) producer revealed that the yeast accumulated a novel glycolipid from castor oil at a yield of 22 g/L. Its main chemical structure was identified as 1-O-β-(2'-O-alka(e)noyl-3'-O-hydroxyalka(e)noyl-6'-O-acetyl-D-mannopyranosyl)-D-erythritol designated as "new MEL-B." The new MEL-B, comprising a hydroxy fatty acid had a reduced surface tension of 28.5 mN/m at a critical micelle concentration (CMC) of 2.2×10^-5 M in water. The observed CMC was 5-fold higher than that of conventional MEL-B. When conventional MEL-B was dispersed in water, it self-assembled to form the lamellar (L(α)) phase at a wide range of concentrations. In contrast, new MEL-B formed spherical oily droplets similar to the sponge (L3) phase, which is observed in aqueous solutions of di-acetylated MEL (MEL-A). The data suggest that the newly identified MEL-B is likely to have a different structure and interfacial properties compared to the conventional MELs, and could facilitate an increase in the application of glycolipid biosurfactants.
glycolipid, biosurfactant, mannosylerythritol lipid, Pseudozyma yeast, Hydroxy fatty acid
NCBI PubMed ID: 23728329Publication DOI: 10.5650/jos.62.381Journal NLM ID: 101175339Publisher: Tokyo: Japan Oil Chemists Society
Correspondence: Masaru_Kitagawa@toyobo.jp
Institutions: Research Institute for Innovations in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan, Toyobo Co., Ltd. Tsuruga Institute of Biotechnology, Tsuruga Fukui, Japan, Toyobo Co., Ltd. Biochemical Dept., Osaka, Japan
Methods: 13C NMR, 1H NMR, NMR-2D, GC-MS, TLC, MALDI-TOF MS, HPLC, extraction, CC, determination of surface tension, self-assembling assay
Found