Purification of lipase derived from Burkholderia pseudomallei with alcohol/salt-based aqueous two-phase systems

Production of an acidic and thermostable lipase of the mesophilic fungus Penicillium simplicissimum by solid-state fermentation

Immobilization of Rhizopus oryzae lipase on silica aerogels by adsorption: Comparison with the free enzyme

Water-in-ionic liquid (w/IL) microemulsions formulated with non-ionic surfactants, (Tween 20 or Triton X-100) in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6), were used as media for lipase-catalyzed esterification reactions. The catalytic behavior and stability of lipases from Candida rugosa, Chromobacterium viscosum and Thermomyces lanuginosa in these novel microemulsions were investigated and compared to other microheterogeneous media used so far for enzyme-catalyzed reactions. The catalytic behavior of the enzymes depends strongly on the surfactant concentration and the water content. The dependence of the esterification activity of lipases on molar ratio of water to surfactant ( w o ) follows a bell-shaped profile, presenting a maximum at w o ≈ 5 . The operational stability of lipases in w/IL microemulsions, especially at high incubation temperature (50 °C), was significantly increased compared to that observed in other microheterogeneous media. The highest half-life times (>100 h) were obtained in w/IL microemulsions with low water content. Conformational studies via Fourier transform-infrared (FT-IR) and circular dichroism (CD) spectroscopy indicated that lipases entrapped in w/IL microemulsions in most cases retain their native structure or adapt a more rigid structure compared to other microheterogeneous media, which correlated well with the stability results. A simple procedure suitable for ester separation and enzyme reuse was developed. T. lanuginosa lipase retained 90% of activity after ten reaction cycles in w/IL microemulsions formulated with Tween 20.

Lipases in water-in-ionic liquid microemulsions: Structural and activity studies

Enormous interest in biocatalysis in non-aqueous phase has recently been triggered due to the merits of good enantioselectivity, reverse thermodynamic equilibrium, and no water-dependent side reactions. It has been demonstrated that enzyme has high activity and stability in non-aqueous media, and the variation of enzyme activity is attributed to its conformational modifications. This review comprehensively addresses the stability and activity of the intact enzymes in various non-aqueous systems, such as organic solvents, ionic liquids, sub-/super-critical fluids and their combined mixtures. It has been revealed that critical factors such as Log P, functional groups and the molecular structures of the solvents define the microenvironment surrounding the enzyme molecule and affect enzyme tertiary and secondary structure, influencing enzyme catalytic properties. Therefore, it is of high importance for biocatalysis in non-aqueous media to elucidate the links between the microenvironment surrounding enzyme surface and its stability and activity. In fact, a better understanding of the correlation between different non-aqueous environments and enzyme structure, stability and activity can contribute to identifying the most suitable reaction medium for a given biotransformation.

J.D Fontana

Papers

Activity and stability of a crude lipase from Penicillium aurantiogriseum in aqueous media and organic solvents