Efeito das variáveis de processo na produção de lipase por fermentação submersa por Aspergillus niger C

Abstract

The interest in the production of lipases is associated with its biotechnological potential due to its catalytic action in hydrolysis reactions, esterification, transesterification and interesterification. These enzymes can be of animal, plant and microbial sources. Microbial have wide industrial application due to its stability, selectivity and specificity. In this context, the objective of this study was to investigate the lipase production by submerged fermentation in shake flasks using the strain Aspergillus niger C. Using a 25-1 fractional factorial design (FFD) some independent variables were evaluated in the lipase production process, such as: sucrose (10.0; 15.0; 20.0 g/L), ammonium sulphate (2.0; 4.0; 6.0 g/L), yeast extract (0.0; 1.0; 2.0 g/ L), soy oil (2.0; 4.0; 6.0 g/L) concentrations and pH (6.0; 7.0; 8.0). After the selection of the variables that significantly influenced the production, central composite rotational design 22 (CCRD) and response surface analysis was used, aiming to find the most favorable condition for the production of lipase. The dependent variable for both desing was the enzyme activity (U/mL). The statistical results obtained from the FFD indicated that soybean oil concentration and the pH were marginally significant (p <0.10) and better average activity (13.12 U mL-1) was obtained when it was used 15.0 g / L sucrose, 4.0 g / L ammonium sulphate, 1.0 g / L yeast extract and 4.0 g / L soybean oil, pH 7.0 at 72 h of fermentation. In CCRD the response surface methodology (RSM) suggests there a more favorable region for the synthesis of lipase by A. niger C in FS. In the pH range between 4.0 and 6.0 the best responses lipase activity are found in region soybean oil concentration above 4 g / L. After the establishment of the best condition in the CCRD 22, the kinetics of lipase production was carried out with the aim of establish the fermentation time that maximizes the production of lipase by A. niger C which was achieved within 72 hours (13.25 U / ml), but the highest productivity was 36 hours of fermentation (0.28 U / mL.h). Finally, the biochemical characterization of the enzyme found that the best reaction conditions lipase from A. niger C, with the substrate olive oil, were: 5 minutes of reaction at pH 5.0 to 6.0 and temperature 55 ° C. The observation of the aspects analyzed, the lipase production of A. niger C submerged fermentation in shake flasks presented important results indicate the viability of the process of the study continued, on another scale