Detalhes bibliográficos
| Ano de defesa: |
2019 |
| Autor(a) principal: |
Pereira, Mariana Bisinotto
 |
| Orientador(a): |
Suarez, Carlos Alberto Galeano
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| Banca de defesa: |
Suarez, Carlos Alberto Galeano,
Rodrigues, Dasciana de Sousa,
Seolatto, Araceli Aparecida,
Mendes, Adriano Aguiar |
| Tipo de documento: |
Dissertação
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| Tipo de acesso: |
Acesso aberto |
| Idioma: |
por |
| Instituição de defesa: |
Universidade Federal de Goiás
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| Programa de Pós-Graduação: |
Programa de Pós-graduação em Engenharia Química (IQ)
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| Departamento: |
Instituto de Química - IQ (RG)
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| País: |
Brasil
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| Palavras-chave em Português: |
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| Palavras-chave em Inglês: |
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| Área do conhecimento CNPq: |
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| Link de acesso: |
http://repositorio.bc.ufg.br/tede/handle/tede/9346
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Resumo: |
In the present work, different strategies of cellulases immobilization were studied. The strategy that showed better cost-benefit was chosen for further optimization. The enzymatic cocktail employed in this study was the Cellic Ctec 3 produced by Novozymes. One of the main challenges was to immobilize in a non-selective way, the greatest possible number of the (at least) 17 enzymes present in the cocktail, since they have different molecular masses, types and number of functional groups on their surface. It’s worth mentioning that the absence of one of these enzymes may prevent the complete conversion of the cellulose into glucose. Cellulases immobilized by both cross-linking and covalent attachment on glutaraldehyde-activated chitosan gel as well as sequential immobilization of β-glycosidase (nucleus) and cellulases (periphery) had their performances evaluated in the hydrolysis of sugarcane bagasse pretreated by an Organosolv process. Cellulases immobilized by covalent attachment on glutaraldehyde activated chitosan gel presented the best results. A preliminary study was necessary to develop a methodology to obtain the sequential immobilized β- glycosidase, since the use of this methodology for hydrolysis of lignocellulosic materials represents a great scientific innovation. Reaction parameters such as chitosan concentration in gel preparation (0.5% to 2%), pH (7 to 10), immobilization time (10 to 120 minutes) and enzyme loading (40.2 to 1340 mg protein / g support) were evaluated. Cellulases immobilized at pH 9.0 for 30 minutes exhibited better hydrolysis performance when an enzyme loading of 134 milligrams per gram of support was used. Hydrolysates with a glucose content of 13.43 and 10.35 g / L were obtained when micro fibrillated avicel and pre-treated sugarcane bagasse were used as substrate, respectively. The immobilized cellulase lost 60% of its hydrolysis performance after 8 cycles of application using microfiber avicel as substrate. The loss was 75% after 6 cycles of application when sugarcane bagasse was used. The great hydrolysis performance associated with the successful reuse of the immobilized cellulases indicates that the improvement of both immobilization methodology and pretreatment of lignocellulosic biomass is able to generate cellulose with a high degree of purity, which will allow the development of a continuous system of enzymatic hydrolysis with retained enzyme in the reactor. |
