Enzymes that degrade polysaccharides: from obtaining to application as insecticide, fungicide and tissue recycling

• Grant number: 22/15172-0
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2023
• End date: November 30, 2025
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Organic Chemistry
• Principal Investigator: Dulce Helena Ferreira de Souza
• Grantee: Dulce Helena Ferreira de Souza
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Enzymes that hydrolyze glycosidic bonds and, therefore, degrade polysaccharides, are research targets aiming at biotechnological applications. Our research group has been dedicated to the study of metabolic pathways of polysaccharides, focusing mainly on the enzymes involved in the degradation of some classes of polysaccharides such as xylan, pectin, cellulose and chitin. In this project we propose the study of two classes of enzymes, cellulases and chitinases, with the objective of obtaining the enzymes and studying their possible biotechnological applications.Cellulases have been widely studied for applications in the paper, pharmaceutical and food industries, in the second-generation ethanol production industry and, more recently, as a potential use in the recycling of cotton fabric or mixed cotton-synthetic fiber. To our knowledge, these studies have been developed with commercial enzymes. We isolated and characterized two cellulases, an endoglucanase and a ²-glucosidase, from Lasiodiplodia theobromae, fungus that attacks several fruit plantations. In this project, we will evaluate the activities of these two cellulases in the hydrolysis of cellulose present in cotton fabric and mixed cotton-synthetic fiber. As cellulose is recalcitrant, there is a need for pre-treatment of the fabric, which can be chemical, thermal or mechanical. Thus, the study aims to find the best pre-treatment and hydrolysis conditions. The project also aims to test the concept of Circular Economy, using the glucose released in tissue hydrolysis as a substrate for fermentation by S. cerevisiae to obtain ethanol.Chitinases, enzymes that degrade chitin, have been studied as potential applications in the biocontrol of insects and fungi. In a previous project, leaf-cutting ant DNAs were cloned and two polypeptide chains constituted by chitinase catalytic domains and chitin-binding domain (CBM) were expressed in P. pastoris. These enzymes showed insecticidal and fungicidal activity. In this project, three recombinant enzymes will be obtained without CBMs and that do not have high sequential identity, which will be evaluated for their insecticidal and fungicidal activities, providing information on the role of CBM in these activities and on the different catalytic domains.The methodologies involved in the development of the project are domain of the research group and the expected results will contribute to the area of biotechnology. (AU)