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Effect of pretreated sugarcane bagasse lignin on the enzymatic hydrolysis of cellulose

Grant number: 12/09940-3
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): December 01, 2012
Effective date (End): April 30, 2015
Field of knowledge:Biological Sciences - Biochemistry - Enzymology
Principal researcher:Adriane Maria Ferreira Milagres
Grantee:Germano Andrade Siqueira
Home Institution: Escola de Engenharia de Lorena (EEL). Universidade de São Paulo (USP). Lorena , SP, Brazil
Associated research grant:08/56256-5 - Topochemistry, porosity and chemical composition determining successful enzymatic sacarification of sugarcane bagasse, AP.BIOEN.TEM

Abstract

Cellulose can be enzymatically converted to glucose. However, the lignocellulosic cell wall is recalcitrant, so that to reach satisfactory hydrolysis levels, chemical and physical pretreatments are required. Even with the development of many pretreatment technologies in the last decades, the cellulose digestion is hardly complete. A possible explanation is the presence of the residual lignin, which can limit the hydrolytical action of the enzymes. During these pretreatments, lignin is melted and can redeposit in different regions of the cell wall, changing the accessibility of the enzymes or causing unproductive binding. Some works had also shown that low molecular weight compounds released from lignin can competitively inhibit the cellulolytic enzymes, depending on their concentration. In this work plan, the study of these effects is proposed, using lignins and aromatic compounds released from sugarcane bagasses pretreated with diluted sulfuric acid, acid sulfite, sodium hydroxide and alkaline sulfite. The different pretreatment will be evaluated according to their lignin binding and inhibitory properties, depending on the physicochemical characteristics. The lignins will be used to impregnate the sugarcane rind, previously delignified with sodium chlorite / acetic acid, a selective method. This procedure will be done to simulate the lignin redeposition on the cell wall, reestablishing the original lignin content on the sugarcane rind. The topochemical distribution of lignin after impregnation will be measured by UV microspectrophotometry. The impregnated rind will be hydrolysed with commercial cellulases in order to evaluate the cellulose hydrolysis level and correlate with the lignin distribution on the cell wall. The surface area of these samples will be determined by the Simons' Stain technique and the cellulases adsorption will be measured by the ninhydrin assay. Solutions containing aromatic compounds will be prepared from the pretreated bagasses. These solutions will be used in the inhibition assays with the commercial enzymes, purified and combined. The inhibitory potential of these compounds will also be analyzed during the enzymatic hydrolysis of cellulose. With the obtained results, we intend to infer about how the lignins from different pretreatments affect the hydrolysis levels of cellulose from sugarcane bagasse. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
SIQUEIRA, GERMANO; ARANTES, VALDEIR; SADDLER, JACK N.; FERRAZ, ANDRE; MILAGRES, ADRIANE M. F. Limitation of cellulose accessibility and unproductive binding of cellulases by pretreated sugarcane bagasse lignin. BIOTECHNOLOGY FOR BIOFUELS, v. 10, JUL 11 2017. Web of Science Citations: 25.
Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
SIQUEIRA, Germano Andrade. Effect of the lignin from pretreated sugarcane bagasses in the enzymatic hydrolysis of the cellulose. 2015. Doctoral Thesis - Universidade de São Paulo (USP). Escola de Engenharia de Lorena Lorena.

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