Banca de QUALIFICAÇÃO: JULIA MARIA DE MEDEIROS DANTAS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : JULIA MARIA DE MEDEIROS DANTAS
DATA : 19/08/2019
HORA: 09:00
LOCAL: Sala do CATRE
TÍTULO:

Immobilization study of cellulase, b-glucosidase and chitosanase for chitosan hydrolysis

PALAVRAS-CHAVES:
PÁGINAS: 77
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Química
RESUMO:

Chitoligosaccharides (COS), the products of the chitosan hydrolysis, have a high added value. Therefore, it is of industrial interest the search more viable production ways of these oligomers, since the use of enzymes as the catalyst of the reaction is more advantageous than acids. However, the manipulation of enzymes is quite expensive, so it is necessary to implement strategies to reduce the costs of operations. Between them, the immobilization due to the improve of the thermal and pH stability, in addition to the recycling of the enzyme. Another way to lower the production cost of the QOS is based on the use of non-specific enzymes. Thus, in this study analyzed the immobilization of cellulase, β-glucosidase, and chitosanases for hydrolysis of chitosan by adsorption and cross-linking. Different immobilization conditions were tested on both techniques for each enzyme, in order to assess the best conditions for each strategy. For cellulase, the best condition of immobilization by adsorption was 25 U/g at pH 6.0 and for cross-linking was 25 U/g using 0.5% glutaraldehyde. The β-glucosidase obtained the best results of immobilization by adsorption using 50 U/g (pH 5.0) and 50 U/g using 1% glutaraldehyde for cross-linking. Concerning the chitosanase, the best results with the adsorption was 25 U/g (pH 5.0), and 25 U/g and 0.5% glutaraldehyde when the cross-linking technique was used. To determine the best strategy for each enzyme immobilization, thermal and pH stability and recycling tests were carried out. The results demonstrated that the best strategy for cellulase was cross-linking, since it favored the pH stability and during the recycles, around 40% for cross-linking against 20% for the adsorption. For the β-glucosidase, the best strategy was also the cross-linking, because despite having a better adsorption performance in thermal stability (60% by adsorption and 40% by cross-links), the effect of cross-links in the recycle was much more significant, showing only 5.75% of activity in the adsorption system compared to 14.75% of final activity of the cross-linking system. Finally, the chitosanase was really benefited by both strategies, but the adsorption presented a better performance than the cross-links in recycles, 65.00% initial activity featuring the end of test against 44.42% of the cross-linking system. Thus, all three enzymes presented themselves as viable alternatives to the hydrolysis of chitosan.

MEMBROS DA BANCA:
Externo à Instituição - CARLOS EDUARDO DE ARAÚJO PADILHA - UFRN
Presidente - 1346198 - EVERALDO SILVINO DOS SANTOS
Externa ao Programa - 011.694.104-99 - NATHALIA KELLY DE ARAUJO - UFRN
Externo à Instituição - PEDRO FERREIRA DE SOUZA FILHO