Current studies about lipase production by solid-state fermentation involve the use of agro-industrial residues towards developing cost-effective systems directed to large-scale commercialization of enzyme-catalyzed processes. In this work, lipase production and partial characterization of the crude enzymatic extracts obtained by Penicillium verrucosum using soybean bran as substrate was investigated. Different inductors were evaluated and the results showed that there is no influence of this variable on the lipase production, while temperature and initial moisture were the main factors that affected enzyme production. The optimized cultivation temperature (27.5 degrees C) and initial moisture of substrate (55%) were determined using the response surface methodology. Kinetics of lipase production was followed at the optimized growth conditions. Optimum lipase yield was 40 U/g of dry bran. The crude enzymatic extract showed optimal activity in the range from 30 to 45 degrees C and in pH 7.0.
We studied the production of fatty acid ethyl esters from castor oil using n-hexane as solvent and two commercial lipases, Novozym 435 and Lipozyme IM, as catalysts. For this purpose, a Taguchi experimental design was adopted considering the following variables: temperature (35-65 degrees C), water (0-10 wt/wt%), and enzyme (5-20 wt/wt%) concentrations and oil-to-ethanol molar ratio (1:3 to 1:10). An empirical model was then built so as to assess the main and cross-variable effects on the reaction conversion and also to maximize biodiesel production for each enzyme. For the system containing Novozym 435 as catalyst the maximum conversion obtained was 81.4% at 65 degrees C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1:10. When the catalyst was Lipozyme IM, a conversion as high as 98% was obtained at 65 degrees C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1:3.
Microbial lipases constitute an important group of enzymes with high biotechnological potential, but their application is limited due to production costs. The present study aimed to evaluate the extraction conditions, concentration with ammonium sulfate, and the partial characterization of the enzyme extracts (in terms of the optimum temperature and pH and their stability at low temperatures). It was shown that the optimal extraction conditions were established at 37°C and pH of 7.0 and that the best conditions for precipitation with ammonium sulfate were with 60% saturation for 5 h. In the partial characterization of the concentrated extract, the optima conditions were obtained at 42°C and pH of 8.5. In a study carried out with the concentrated enzymatic extract, the hydrolytic activity was shown to be practically the same as the initial value after 91 days of storage at both 4 and −10°C.
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