Catalytic Properties of Lipase Extracts from Aspergillus niger

Licia M. Pera¹*, Cintia M. Romero¹, Mario D. Baigori¹ and Guillermo R. Castro<sup>1,2

1</sup>PROIMI, Av. Belgrano y Pasaje Caseros, 4000 Tucumán, Argentina
²Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA

Article history:
Received November 3, 2005
Accepted March 5, 2006

Key words:
lipase, Aspergillus niger, substrate specificity, solvent tolerance, thermoresistance, enzyme stability, lipase screening

Summary:
Screening of lipolytic strains using Rhodamine-B/olive oil plate technique allowed the selection of Aspergillus niger MYA 135. Lipase production in submerged culture containing 2 % olive oil was enhanced by more than 50 % compared to basal cultural conditions. Optimal catalytic conditions for olive oil-induced lipase were pH=6.5 and 30–35 °C. These values were shifted to the acid region (4.0–6.5) and 35–37 °C when lipase extract was produced under basal conditions. Slight changes of the residual lipase activity against the pH were found. However, preincubation at either 37 or 40 °C caused an increase in the olive oil-inducible lipolytic activity. On the contrary, lipase residual activity decreases in the 30–55 °C range when it was produced in basal medium. Lipolytic extracts were almost not deactivated in presence of 50 % water-miscible organic solvents. However, water-immiscible aliphatic solvents reduced the lipase activity between 20 and 80 %.

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