Characterisation of the equilibrium behaviour of lipase PS (from Pseudomonas) and lipolase 100L (from Humicola) onto Accurel EP100.

The present work characterised the equilibrium behaviour of lipases from Pseudomonas and Humicola immobilised on polypropylene-based hydrophobic support Accurel EP100. The support capacity for both lipases was evaluated, and activities of immobilised lipases were assayed. Also, the stability of immobilised lipases was tested. Experimentally, the adsorption isotherm for each lipase was produced and the activity of immobilised lipase was assayed by esterification of oleic acid and octanol. Also, immobilised lipase activities, using different support particle sizes and masses, were assayed. The immobilised lipase stability was tested by a series of successive esterifications done on the same immobilised lipase sample. Analytically, the lipase adsorption isotherm was modelled by the Langmuir and Freundlich formulas. It was found that lipase PS exhibited the Freundlich behaviour, which suggests multilayer adsorption, while lipolase 100L reflected the Langmuir formula, i.e. formed a monolayer. Also, Accurel EP100 capacities for lipase PS and lipolase 100L were 4500 mg (1.35 x 10(5) LU) and 1200 mg (1.20 x 10(5) LU), respectively for each gram of support. It was also found that the activity of lipase PS initially increased with loading and then levelled off, while it continued to increase with loading of lipolase 100L. Moreover, lipase activity decreased with mean particle diameter increase. Stability studies showed that lipase PS guarded its activity to more than 60% for more than 8 runs. Lipolase 100L showed the same behaviour.