Immobilized Staphylococcus xylosus lipase-catalysed synthesis of ricinoleic acid esters

Staphylococcus xylosus lipase 2 (SXL2) was immobilized by physical adsorption onto CaCO3. A high immobilization yield was obtained (82 +/- 3.7%) corresponding to the loading of 3250 +/- 150 IU/g of support. Thermal stability of the CaCO3-immobilized lipase was remarkably enhanced compared with that of the free one. Therefore, the immobilized SXL2 was stable at 80 degrees C after 60 min-incubation, while the free one was completely inactivated above 50 degrees C. The immobilized lipase was used to catalyse the enzymatic synthesis of ricinoleic acid estolides using two systems (in presence or absence of organic solvent). The effects of various reactions parameters such as the amount of lipase, the temperature and the molecular sieves were investigated. A conversion yield of about 65 +/- 4% was achieved in a solvent free system using 400 IU of immobilized SXL2 at 55 degrees C, in the presence of 1 g of molecular sieves. The structure of synthesised biopolymer was analyzed by LC-MS, FT-IR and C-13 NMR spectroscopy. (C) 2011 Elsevier B.V. All rights reserved.