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The main objective of this work was to identify novel lipases of industrial interest. In this paper, Aspergillus flavus lipase (AFL) was isolated from the traditional tannery of Fez city in Morocco; it kept its stability even in the presence of high concentrations of detergent from 0 to 10 mM sodium deoxycholate (NaDC). Bile salts showed no inhibitory effect on the lipolytic activity, whereas the calcium salts showed a stimulating action on the lipase activity. Unlike most of the lipases which were quickly denatured at the lipid/water interface, the accumulation of free fatty acids at the oil/water interface did not affect the activity of the enzyme which effectively hydrolyzed the emulsified olive oil even in the absence of bile salts. Furthermore, AFL was more active on long chain triacylglycerols than on short chain triacylglycerols. This study allowed us to prove that AFL had the interfacial activation phenomenon. A 3D structure model of AFL was built and we have concluded that the ratio hydrophobic surface/hydrophilic surface was 51% versus 50%; it could be responsible for a higher tolerance to the presence of free fatty acids at lipid/water interface.

Nonstop demand for greatly thermostable and thermoactive active lipase encourages the research for the new enzyme sources. In this study, a strain of Trichosporon coremiiforme was isolated from the traditional tannery in the city of Fez in Morocco, lipase production and their lipolytic activity was studied. Pure T. coremiiforme lipase (TCL) was obtained after ammonium sulfate fractionation, G-75 gel filtration and cation exchanger chromatography (Mono-S), having a molecular weight of 67 kDa. TCL presents a maximal activity at pH 8 and 50°C. After a 5 min treatment at 80°C, the enzyme maintained 50% of its activity, which is so far as is known. TCL previously characterized is found to be stable between pH 5 and 10 after 60 min incubation. TCL hydrolyses the long chains triacylglycerols more efficiently than the short ones. A specific activity of 1800 U/mg was measured on tributyrin or olive oil emulsion as substrate. This newly isolated lipase can be considered as a good candidature for industrial and biotechnological applications.

Aspergillus Niger lipase (ANL) was purified from a culture medium. Pure ANL was obtained after ammonium sulfate fractionation, Sephacryl S-200 gel filtration and cation exchange chromatography (Mono-Q). The pure lipase, which is not a glycoprotein, was presented as a monomer having a molecular mass of about 99 kDa. The lipase activity was maximal at pH 8 and at 39°C. ANL hydrolyses the long chains of triacylglycerols more efficiently than the short ones. A specific activity of 3779 U/mg was measured on olive oil as substrate at 39°C and at pH 8 in the presence of 4 mM NaTDC. ANL was inactivated when the enzyme was incubated at 75°C or at pH less than 4. Natural detergent (NaTDC), pH dependence of the catalytic activity of ANL was at pH 8, which confirm that ANL present one pH profile.