Estudo da produção da enzima celulase a partir da matéria lignocelulósica bagaço do caju por fermentação semissólida utilizando o Aspergillus níger.

Abstract

The cashew peduncle is a lignocellulosic material that concentrates primarily in the Northeast and, after extracting the juice and obtaining the cashew nut. Its physicochemical composition varies according to the state of maturity, the size, the duration of the harvest and regional environmental variations. Cellulase enzymes are used to hydrolyze cellulose by generating directly fermentable carbon sources, such as glucose, to be used, for example, in bioethanol production. Thus, the objective of this work was the study of cellulase production through semi-solid fermentation, using the peduncle as substrate. dried cashew nuts and Aspergillus niger CCT 0916 as a metabolizing microorganism. To this end, we studied the influence of the variables: initial humidity and nitrogen source concentration, to determine the best process conditions. The fermentation temperature studied was 30 ° C for an estimated time of 72 h. The methodologies used for the experimental procedure were those already used by LEB (Laboratory of Biochemical Engineering). As a culture medium, two cashew tree stalk residues were used: washed residue and unwashed residue. The soluble solids content for the wash was 10.25% and 30.00% for the without wash. The values ​​found for the pH were 4.58 for the washed and 4.33 for the without washing. Moisture was 5.87% and 8.22%, for washing and washing without, respectively. The percentage of cellulose was 12.75 for the washed residue and 11.76 for the without washing. The AR content found for the washed cashew cake was 10.02%. During the Fermentation process, which was carried out for a period of 72 hours, samples were taken periodically and some parameters that characterize the process as medium humidity, pH, reducing sugars and cellulolytic activity were analyzed. The humidity did not change significantly during the process and the pH showed a tendency to fall during the 72 hours of fermentation. In terms of cellulase production using washed cashew nuts, the data reproducibility results in moisture conditions and nitrogen concentration were 55% and 0.75%, respectively, showed that, in general, the points are very reproductive, and the 30 hours of process The highest cellulase yield (0.10U / mL) was obtained. For the content of reducing sugars (AR) Under the same conditions, its profile tends to fall throughout the process, indicating that there was a probable consumption of the carbon source for enzyme production. The highest cellulolytic activity values ​​for the washed cashew peduncle residue were obtained in the experiments with 45% and 1.0% moisture and nitrogen, respectively and 55% and 1.1% moisture and nitrogen, respectively, being activity peaks of 0.15 U / mL for the first, and 0.14 U / mL for the second. The other experiments presented the highest cellulase production peaks in 30 hours of fermentation. Comparing the FSS process of the bagasse without washing with the bagasse washed under the conditions of highest activity for the washed, the unwashed cashew apple showed an activity peak of 0.19U / mL at 7 hours of fermentation.