Activity and stability of Chromobacterium viscosum lipase in modified AOT reverse micelles

The modification of AOT/water/isooctane reverse micellar system by various additives was undertaken to enhance the activity and stability of Chromobacterium viscosum lipase. Polypropylene glycols (PPG, MW<700), polypropylene glycols triol (PPGT, MW=725), glycerol propoxylate (GP, MW=260) and polyethylene glycol (PEG, MW<1000) appreciably increased lipase activity. Low molecular weight polyethylene glycol, PEG 400, was found to be the most effective among them. Fourier transformed infrared spectroscopy (FTIR) analysis suggested that PEG 400 molecules participated in the redistribution of water inside the reverse micelles and strongly interacted with the head groups (SO3−) of anionic surfactant AOT. Deactivation kinetic at 25 °C indicated that the C. viscosum lipase entrapped in AOT/PEG 400 reverse micelles was very stable, retaining over 75% of its initial activity after 60 days, whereas half-life time in simple AOT reverse micelles was 38 days.