Hydrolysis Behaviour of Lipase from Pseudomonas Cepacia Encapsulated in Silica Aerogels with Different Characteristics

Lipase from Pseudomonas Cepacia was encapsulated in silica aerogels dried by the supercritical method using CO2 Aerogels with a different balance of hydrophillic and hydrophobic functionalities were tested in a hydrolysis reaction performed in 1,4-dioxane. This solvent was chosen so that the organic substrate and the hydrolysis water were soluble in the reaction medium. The gels were expected to act somewhat like emulsion droplets, so as to provide an immediate solvent environment close to the enzyme, different from the general solvent environment in which the gel particles were dispersed and the substrates were soluble. For each type of gels, the porous texture was characterized by nitrogen adsorption isotherms. The results were analyzed in terms of gel network characteristics and their participation in the displacement of the kinetics and equilibrium. While the gel's chemistry and its preparation protocole are far from being optimized, it is shown that the gel composition can have an important influence on the biocatalyst activity. Depending on the characteristics of the gel, lipase-catalyzed hydrolysis can be performed in hydrophilic organic solvents which are known to be harmful to lipases.