Stronger cellulose microfibril network structure through the expression of cellulose-binding modules in plant primary cell walls

Núria Butchosa,Qi Zhou,Vincent Bulone,Felicia Leijon

doi:10.1007/s10570-019-02285-4

Núria Butchosa, Qi Zhou + Show 2 more

Open Access

https://doi.org/10.1007/s10570-019-02285-4

Copy DOI

Abstract

Cellulose-binding modules (CBMs) are non-catalytic domains typically occurring in glycoside hydrolases. Their specific interaction with diverse polysaccharides assists hydrolysis by the catalytic subunits. In this work, we have exploited the interactions between a CBM from family 3 (CBM3) and cell wall polysaccharides to alter the structure and mechanical properties of cellulose microfibrils from BY-2 tobacco cell suspension cultures. A CBM3 from Clostridium thermocellum was overexpressed in the cells using Agrobacterium-mediated transformation. Water suspensions of cellulose microfibrils were prepared by the removal of the non-cellulosic components of the primary cell walls, followed by mild disintegration using sonication. The morphology of the microfibrils was characterized by transmission electron microscopy and atomic force microscopy. These cellulose microfibrils were further hydrolyzed with 64 wt% sulfuric acid to produce cellulose nanocrystals (CNCs). The average length of CNCs prepared from the CBM3-transformed cells was 201 nm, higher than that from the wild-type cells (122 nm). In addition, the mechanical properties and deformation mechanism of nanopapers prepared from suspensions of cellulose microfibrils were investigated. The nanopapers obtained from the CBM3-transformed cells exhibited enhanced tensile strength and work of fracture, 40% and 128% higher than those prepared from wild-type tobacco cells, respectively.Graphical abstract

Highlights

In plant primary cell walls, cellulose microfibrils (CMFs) act as a load bearing component embedded in a hydrated matrix of hemicelluloses and pectins (Brown 2004; Carpita and Gibeaut 1993; Somerville 2006)
The extracted cellulose particles prepared from the CBM from family 3 (CBM3) line (Fig. 1b) exhibited a higher aspect ratio compared to their counterparts from the wild type (WT) line (Fig. 1a), indicating BY-2 cells expressing CBM3 exhibited a significantly elongated shape with a smaller lateral size compared to WT cells
We have demonstrated that the structure and properties of cellulose microfibrils from plant cells can be modified by interfering with the biosynthesis of cellulose through the overexpression of Cellulose-binding modules (CBMs)

Summary

Introduction

In plant primary cell walls, cellulose microfibrils (CMFs) act as a load bearing component embedded in a hydrated matrix of hemicelluloses and pectins (Brown 2004; Carpita and Gibeaut 1993; Somerville 2006). 3.5 nm) have been successfully prepared from wood pulp fibers using chemical pretreatment and subsequent mechanical disintegration (Pei et al 2013; Saito et al 2006). In order to exploit improved preparation methods to decrease the internal damage in CNFs and lower the energy consumption required, an increased understanding of the mechanism involved in plant cell wall formation and its recalcitrance to degradation is essential. To make biomass less recalcitrant to processes for energy production, such as biofuel generation, the cell wall can be modified by altering its chemical composition or properties through genetic engineering (Albersheim et al 2010). The modification of the biosynthetic process of cellulose in plant cell walls has great potential to alter the structure of cellulose microfibrils and decrease their resistance against chemical and mechanical treatments. The impact of such genetic engineering approaches on the extraction of cellulose nanomaterials from biomass, including nanofibrils and nanocrystals, has not been addressed previously

Methods

Results

Conclusion