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ABSTRACT: A novel extracellular lipase with organic solvent tolerance was isolated from a local Pseudomonas species. The lipase gene was cloned and expressed in Escherichia coli as a heterologous host and purified by affinity chromatography. The activity of purified lipase was investigated in the presence of imidazolium-based ionic liquids (ILs) such as EMIM[Cl], BMIM[Cl], and HMIM[Cl]. It has been found that the activity of treated lipase with ILs was higher than untreated control in the hydrolysis reaction. Also, the results indicated that the enzymatic activity strongly depends on IL concentration in reaction media. The best concentration of the IL was 30%, 45%, and 50% (v/v) for HMIM[Cl], BMIM[Cl], and EMIM[Cl], respectively. Additionally, the enzyme exhibited excellent stability in the presence of 25% of n-hexane, toluene, acetone, and t-butanol. The optimum values of pH and temperature were determined 10 and 55 °C, respectively. The K (m) and V (max) values were calculated 0.4 mM and 1.92 U/ml, respectively, using p-nitrophenyl palmitate as substrate. With respect to the biochemical properties of the newly isolated lipase such as high-level stability and noticeable activity in the presence of organic solvents and ionic liquids, the newly isolated lipase seems to be a good candidate for environmental and industrial processes carried out in non-aqueous media.
Applied biochemistry and biotechnology 07/2011; 165(3-4):785-94. · 1.94 Impact Factor