The soil bacterium Tsukamurella spec. DSM 44370 produces a mixture of oligosaccharide lipids when cultivated on sunflower oil. In contrast cultivation with calendula oil as carbon source afforded a different product composition with overproduction of 2,3-di-O-acyl-beta-D-glucopyranosyl-(1-2)-beta-D-galactopyranosyl-(1-6)-4,6-di-O-acyl-alpha-D-glucopyranosyl-(1-1)-alpha-D-glucopyranose (GL 3) that amounted to 60% of the whole product. GL 3 and its parent tetrahexose backbone G 3 were then modified enzymatically with the lipase Novozyme 435 from Candida antarctica by addition of one and two oleic acid molecules to GL 3 and four molecules to G 3. The new glycolipids were shown to exhibit interesting surface activities compared to commercially available products, decreasing the surface tension of water to 23 mN/m. In addition these products showed novel biological activities through the inhibition of the activation of Epstein-Barr virus early antigen. (c) 2006 Elsevier Ltd. All rights reserved.