Functional characterization of Trichoderma reesei xyloglucanase (CEL74A) in degradation of sugarcane bagasse

Author(s)

Douglas Christian Borges Lopes

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2018-10-17

Examining board members

Roberto do Nascimento Silva; Gilberto Ubida Leite Braga; Fernanda Zanolli Freitas

• Advisor: Roberto do Nascimento Silva; Renato Graciano de Paula

Abstract

The filamentous fungus Trichoderma reesei is one of the main fungi used for the large-scale production of enzymes due to their great capacity of production and secretion of holocellulases for application in saccharification processes of lignocellulosic plant biomass. Although T. reesei is used as one of the main producers of cellulases at industrial level, several processes and studies are carried out with the aim of improving the understanding of the whole plant biomass degradation mechanism, as well as increasing the efficiency of both the production and cellulase activity. In the present work the construction of a mutant lineage for the cel74a gene (coding for a xyloglucanase) and the functional characterization of CEL74A in the gene regulation of holocellulases during the cultivation of sugarcane bagasse were carried out. Our results showed that deletion of cel74a may be involved in the regulation of holocellulase expression during sugarcane bagasse cultivation. From the analysis of the gene expression profile, it was possible to observe the reduction in the expression of all tested cellulase genes (cel7a, cel7b and cel6a), although it did not affect the enzymatic activity, whereas the hemicellulases (xyn1 and xyn2) presented increase in both expression and enzymatic activity. In the ?cel74a strain, a reduction in glucose, xylose and galactose release was observed after xyloglucan hydrolysis. In addition, the activity of CEL74A was modulated in the presence of calcium and may be required for the more efficient performance of other enzymes involved in the degradation of xyloglucan. Thus, in T. reesei, CEL74A plays an important role both in the regulation of holocellulolytic genes and in the efficient degradation of sugarcane bagasse, contributing to the elucidation of mechanisms by which this fungus uses for the use of sugarcane bagasse as source of carbon (AU)

• FAPESP's process: 16/09708-4 - Expression of accessory enzymes polysaccharide mono-oxygenase and cellobiose dehydrogenase from Aspergillus nidulans in Trichoderma reesei and evaluation of the degradation efficiency of sugar cane bagasse
• Grantee: Douglas Christian Borges Lopes
• Support Opportunities: Scholarships in Brazil - Master