Production and Antimicrobial Character of Select Glycolipid Biosurfactants

Glycolipids are a broad class of molecules produced by select strains of both bacteria (e.g. rhamnolipids from Pseudomonas) and yeasts (e.g. sophorolipids generally produced from species of Candida). Sophorolipids are generally composed of a disaccharide (Glc-(β-1,2)-Glc) and a fatty acid tail with lengths varying from C16 to C22. The chemical structures of these molecules can be controlled based on the producing strain, the feedstock and the fermentation conditions used in their synthesis. Aside from being good biosurfactants, one valuable property of these molecules is their antimicrobial character. Results have shown that the sophorolipids produced from both Candida bombicola and Rhodotorula bogoriensis are capable of inhibiting bacterial growth and therefore have potential in both cosmetic/skin applications and in enhancing food safety. Specifically, work with Propionibacterium acnes (the acne-causing bacterial strain) showed a concentration-dependent response to sophorolipid application thus lending itself for use as a renewable, environmentally friendly acne-fighting agent without the drawbacks associated with current anti-acne medications. In addition, sophorolipids have been shown to work synergistically with other anti-microbial agents against E. coli O157:H7 inoculated onto leafy vegetables. These results show the possibility of a more widespread use of these microbial compounds in antimicrobial applications.