Identificação de genes envolvidos na degradação de xilana por meio de abordagens genômica e metagenômica

• Ano de defesa: 2014
• Autor(a) principal: Schroeder, Luís Felipe
• Orientador(a): Barreto, Cristine Chaves , Quirino, Betania Ferraz
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Católica de Brasília
• Programa de Pós-Graduação: Programa Strictu Sensu em Ciências Genômicas e Biotecnologia
• Departamento: Escola de Saúde e Medicina
• País: Brasil
• Palavras-chave em Português: Biotecnologia; Genoma; Genética; Xilanase; Glicosil hidrolase; Etanol Celulósico; Rúmen de caprino; Acidobacteria; Metagenômica funcional; Genômica funcional
• Área do conhecimento CNPq: CIENCIAS BIOLOGICAS::GENETICA
• Link de acesso: https://bdtd.ucb.br:8443/jspui/handle/tede/1998

There are different process being developed for cellulosic ethanol production, with possible different pretreatments with varying temperatures and pH, in addition to several biomasses can be used as the source of fermentable sugars. Among the important enzymes for deconstruction of plant biomass, stand out xylanases. These enzymes are responsible for deconstruction of the hemicellulose present in the structure of the plant cell walls. There are several ways to accomplish the identification of these enzymes: purification from an isolated microorganism is one. In this study, genomic and metagenomic approaches were used to carry out the prospection of the genes responsible for coding these enzymes. Clones from two libraries were used for detection and evaluation of activity on solid medium, supplemented with xylan and acid pretreated sugarcane bagasse. Nineteen clones of a goat rumen metagenomic library and five clones from an AB60 bacterium genomic library, with 15,000 clones constructed in this study, were selected initially. Fourteen clones from the metagenomic library were completely sequenced and their ORFs were analyzed. Four clones from the genomic library were partially sequenced and one clone had its sequence completely determined and 104 ORFs were obtained for all clones completely or partially sequenced ORFs were analyzed. Eleven ORFs showed some similarity to genes of importance for the degradation of complex polysaccharides. Among the most important ORFs and most likely to be related to the detected activity, are genes coding for β-glucosidase, α-xylosidase and β-glucuronidase. Furthermore, also other ORFs with lower probability of relation with the activity or necessity to full sequencing of the clones for a few more conclusive analysis were identified. About 40% of the ORFs present in the rumen clones and 37.8% of the ORFs present in Acidobacteria clones showed similarity with hypothetical or uncharacterized proteins, which could be important in the activity detected. A β-glucuronidase gene detected in a clone from the goat rumen metagenomic library was synthesized, its sequence was optimized for expression in Escherichia coli. However, in the present work, it was not possible to sub-cloning, made expression and purification of this enzyme. Some ORFs detected can be used for future studies of expression and characterization in order to improve knowledge about biotechnological potential present in the rumen and acidobacteria AB60, besides the ecological role of these microorganisms in their environment.