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| Author(s): |
Thiago Machado Pasin
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2015-07-07 |
| Examining board members: |
Maria de Lourdes Teixeira de Moraes Polizeli;
Vivian Machado Benassi;
Joao Atilio Jorge
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| Advisor: | Maria de Lourdes Teixeira de Moraes Polizeli |
| Abstract | |
The genus Aspergillus has been highlighted in the production of enzymes for industrial application, standing out among these, amylases, capable of hydrolyzing the ?-glycosidic linkages of starch. Amylases are used in industrial processes for the production of ethanol, glucose and fructose syrup, in addition to textiles, detergents and paper. In this context, this work aimed the prospecting of filamentous fungi to produce amylase and the standardization of Aspergillus japonicus culture conditions. The optimization of reaction conditions for amylase produced by the fungus, purification, characterization and testing different concentrations of ions in pure enzyme activity, determining the carbohydrate content, the kinetic constants, analysis of the amino acids that comprise the purified glucoamylase and the application of crude amylase in the bleaching process of the recycled paper. The results of the screening of filamentous fungi that produced good levels of amylolytic enzymes showed two fungi with high production of amylase, which were identified as Aspergillus parasiticus and Aspergillus japonicus. The studies continued with A. japonicus as selected fungus. This strain showed the best enzyme production in the culture medium Khanna and maximum amilolytic production after 4 days of growth under static conditions obtaining an activity of 44.65 (± 0:49) U/ml. The optimum pH of the medium was 5.5 and the optimum temperature of 25°C. The best carbon sources for the enzyme production were potato starch and maltose, respectively, and the best food residue was orange peel and bagasse. After the characterization of fungal culture conditions, came the characterization of physical and chemical parameters of amylase. The temperature and optimum pH of enzyme assay were standardized being, respectively, 5.5 and 50°C. Amylase retained its activity around 90% at 30 to 50°C after one hour of incubation, approximately 95% of its activity in the pH range of 4.0 to 6.0 and 50% in pH range of 6.5 to 9.0 after an hour of incubation. Amylase hydrolysis products showed only the formation of glucose, in thin layer chromatography on silica, and it can be assumed that it is a glucoamylase, which was confirmed by subsequent experiments. The crude enzyme was subjected to elution through DEAE-cellulose and a glucoamylase showing a molecular weight of 72 kDa as determined by SDS-PAGE was purified. The optimum temperature of this purified glucoamylase was 65°C and the pH was 5.0. The enzyme also showed high stability at different temperatures and pH, as well as a large amount of products generated when used as a reaction substrate the amylopectin. Glucoamylase showed a high activation in the presence of 10 mM de MnCl2, KCl, Pb(C2H3O2)2.3H2O, and 2-mercaptoethanol and a Km value of 0.59 mg/mL, Vmax of 308.01 U/mg and Kcat of 369.58 (s-1). The amount of carbohydrates that compose the structure of crude and purified enzyme were measured at 15% and 5.5%, respectively. The pure enzyme had its amino acids identified by comparison with other genera and species of fungi producers of glucoamylase, the enzyme also showed identity with the existing starch binding domain in Neosartorya fischeri NRRL 181 fungus. When the crude glucoamylase was applied in biobleaching process of the recycled paper printed by the ink jet, the enzyme showed an average of 23.34% increase in relative brightness as compared to control, in the journal paper pulp has led to the enzyme an average of 23.89% increase in the relative brightness. The results presented here open the possibility of using these enzymes in pulp biobleaching pulp for the production and recycling of paper by industry. (AU) | |
| FAPESP's process: | 12/24948-0 - Prospecting filamentous fungi aiming the amylase production and application in paper recycling |
| Grantee: | Thiago Machado Pasin |
| Support Opportunities: | Scholarships in Brazil - Master |