Title:	Desenvolvimento de complexos enzimáticos baseados em xilanases de Clostridium thermocellum
Authors:	Hamann, Pedro Ricardo Vieira
Orientador(es)::	Noronha, Eliane Ferreira
Assunto::	Clostridium thermocellum Xilanase Celulossoma Biomassa lignocelulósica
Issue Date:	17-Jul-2024
Data de defesa::	29-Jun-2021
Citation:	HAMANN, Pedro Ricardo Vieira. Desenvolvimento de complexos enzimáticos baseados em xilanases de Clostridium thermocellum. 2021. 164 f., il. Tese (Doutorado em Biologia Molecular) — Universidade de Brasília, Brasília, 2021.
Abstract:	Clostridum thermocellum is an anaerobic thermophilic bacterium that is specialized in degrading cellulosic materials through the secretion of enzymatic complexes, namely cellulosomes. The main feature that calls attention for cellulosomes as machinery for plant cell wall degradation is several hydrolytic activities along with cellulases, including xylanases and pectinases. Despite the great number of studies regarding the cellulosome assembly using cellulases, little is known about the advantage of organizing xylanases in enzymatic complexes and the effect of complexed xylanases in biotechnological applications. In the present study, the heterologous expression of xylanases XynZ and XynA was done, and the N-terminus portion of the scaffolding proteins CipA, containing two cohesin domains and a cellulose-binding module. For the enzyme XynA, a first study was conducted to evaluate the effect of phenolic compounds derived from lignocellulose on XynA’s xylanase activity. Among the evaluated compounds, tannic acid caused the highest activity decay when assays were conducted at 60°C. However, when XynA was exposed to phenolic compounds at a lower temperature (40ºC), activity loss could be reversible. Still, regarding XynA, this enzyme was used to assembly mini-xylanosomes with the N-terminus portion of scaffolding protein CipA. The formed enzymatic complex was used to hydrolyze chemically treated sugarcane bagasse and showed a better release of reducing sugar than the enzyme on its non-complexed state and same activity load. It was also observed that the scaffolding protein, when coupled with fungal enzymes in hydrolysis of lignocellulose, was capable of improving the D-glucose production. Regarding XynZ, this enzyme was also used to assemble mini-xylanosomes. The assembled complex displayed similar pH and temperature effect in xylanase activity compared to the free enzyme. However, was observed improvement in thermostability property for the mini-xylanosome. When applying the mini-xylansome to hydrolyze sisal fibers, was observed production of reducing sugar three times higher than those observed for non-complexed enzymes. Results shown in the present study attest that the assembly of xylanases into mini-xylanosomes can improve lignocellulose deconstruction.
metadata.dc.description.unidade:	Instituto de Ciências Biológicas (IB)
Description:	Tese (doutorado) — Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Biologia Celular, Programa de Pós-Graduação em Biologia Molecular, 2021.
metadata.dc.description.ppg:	Programa de Pós-Graduação em Biologia Molecular
Licença::	A concessão da licença deste item refere-se ao termo de autorização impresso assinado pelo autor com as seguintes condições: Na qualidade de titular dos direitos de autor da publicação, autorizo a Universidade de Brasília e o IBICT a disponibilizar por meio dos sites www.bce.unb.br, www.ibict.br, http://hercules.vtls.com/cgi-bin/ndltd/chameleon?lng=pt&skin=ndltd sem ressarcimento dos direitos autorais, de acordo com a Lei nº 9610/98, o texto integral da obra disponibilizada, conforme permissões assinaladas, para fins de leitura, impressão e/ou download, a título de divulgação da produção científica brasileira, a partir desta data.
Agência financiadora:	Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).
Appears in Collections:	Teses, dissertações e produtos pós-doutorado

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