Effects on Lignin Redistribution in Eucalyptus globulus Fibres Pre-Treated by Steam Explosion: A Microscale Study to Cellulose Accessibility.

Eduardo Troncoso-Ortega,Rosario Del P Castillo,Nicolás Schiappacasse,Patricia Castaño-Rivera,Pablo Reyes-Contreras,Regis Teixeira Mendonça,Carolina Parra

doi:10.3390/biom11040507

Eduardo Troncoso-Ortega, Rosario Del P Castillo + Show 5 more

Open Access

https://doi.org/10.3390/biom11040507

Copy DOI

Abstract

The objective of this study was to investigate structural changes and lignin redistribution in Eucalyptus globulus pre-treated by steam explosion under different degrees of severity (S0), in order to evaluate their effect on cellulose accessibility by enzymatic hydrolysis. Approximately 87.7% to 98.5% of original glucans were retained in the pre-treated material. Glucose yields after the enzymatic hydrolysis of pre-treated material improved from 19.4% to 85.1% when S0 was increased from 8.53 to 10.42. One of the main reasons for the increase in glucose yield was the redistribution of lignin as micro-particles were deposited on the surface and interior of the fibre cell wall. This information was confirmed by laser scanning confocal fluorescence and FT-IR imaging; these microscopic techniques show changes in the physical and chemical characteristics of pre-treated fibres. In addition, the results allowed the construction of an explanatory model for microscale understanding of the enzymatic accessibility mechanism in the pre-treated lignocellulose.

Highlights

IntroductionThe recalcitrance of lignocellulosic biomass (LCB) to enzymatic hydrolysis is due to the interaction of the macromolecular components (cellulose, hemicelluloses, and lignin), which generates a rigid, fibrillar structure
The recalcitrance of lignocellulosic biomass (LCB) to enzymatic hydrolysis is due to the interaction of the macromolecular components, which generates a rigid, fibrillar structure
The xylan content in the liquid phase increased due to acid hydrolysis that occurs in hydrothermal pre-treatments of hardwoods, where the initial content of acetyls in the raw material acts as a catalyst

Summary

Introduction

The recalcitrance of lignocellulosic biomass (LCB) to enzymatic hydrolysis is due to the interaction of the macromolecular components (cellulose, hemicelluloses, and lignin), which generates a rigid, fibrillar structure. For this reason, a pre-treatment process is necessary to break up the lignocellulosic matrix and increase its enzymatic digestibility in order to obtain monosaccharides and oligomers which will generate chemical building blocks or sugar to ferment to second-generation bioethanol [1,2,3]. Numerous methods have been developed for pre-treating LCB, including biological, physical, chemical, and physicochemical processes. SE has several attractive features when compared to other fractionation technologies: lower envi- 4.0/).

Objectives

Methods

Results

Conclusion