Immobilization of Pseudomonas cepacia lipase in a phyllosilicate sol-gel matrix: effectiveness as a biocatalyst

A novel procedure is described for immobilizing a lipase from Pseudomonas c epacia (PS-30) within a phyllosilicate sol-gel matrix. The method is based on crosslinking a phyllosilicate clay with silicate polymers produced by th e controlled hydrolysis of tetramethyl orthosilicate (TMOS). The activity o f the phyllosilicate sol-gel-immobilized lipase was dependent upon the type of alkylammonium salt, inorganic catalyst and volume ratio of phyllosilica te clay to TMOS used. Lipase PS-30 immobilized in this way was more stable and had higher activity compared with the free lipase. Studies on the lipas e-catalysed esterification of lauric acid with octan-1-ol in iso-octane sho wed that under controlled water activity conditions the phyllosilicate sol- gel-immobilized lipase had better activity compared with other supported li pase preparations. In addition, the phyllosilicate sol-gel-immobilized lipa se was reusable for at least five esterification cycles without significant loss of activity.