1 research outputs found
Microbial Synthesis of Nonionic LongâChain Sophorolipid Emulsifiers Obtained from Fatty Alcohol and Mixed Lipid Feeding
Starmerella bombicola is known to produce subâterminally hydroxylated lactonic sophorolipids (SLs), while Candida kuoi synthesizes acidic open chain SLs with terminally hydroxylated fatty acids. Upon feeding glucose and fatty alcohols both strains form longâchain nonionic SLs. According to structure elucidation the SLs consist of a hydroxylated fatty acid esterified with fatty alcohol and linked via a glycoside bond to the diacetylated sophorose unit. Palmityl, stearyl, and oleyl alcohols lead to products with lipid chain lengths of C32 or C36. Oleyl alcohol is the preferred substrate leading to 45 g Lâ1 of the double unsaturated C36 SL with S. bombicola and 20 g Lâ1 with C. kuoi. Scale up from shake flask to 1.5 L fermentations is possible and 65 g Lâ1 longâchain SLs are obtained with S. bombicola within 7 days. Mixed feeding of oleic acid and a variety of fatty alcohols leads to new longâchain SLs. In the presence of oleic acid the yeasts do not oxidize the fatty alcohol and thus the production of biosurfactants with tailored chain length is possible. The longâchain SLs show good emulsification ability of water/paraffin oil mixtures at low energy input and reduced interfacial tension significantly.
Practical Applications: Sophorolipids are produced by fermentation on industrial scale focusing on cleaning and detergent applications. Mainly lactonic or anionic openâchain forms are used today. The new longâchain SLs presented in this manuscript are accessible with existing production technology and can be produced with high titers from costâefficient renewable raw materials. In contrast to the commercial products the longâchain SLs are more hydrophobic and exhibit a strong emulsification behavior. Therefore they have the potential to broaden the application range of SLs in future. They may be useful as novel emulsifiers for cosmetic creams and lotions, pharmaceutical ointments and food products or may find application in oil spill remediation