Wood hemicelluloses exert distinct biomechanical contributions to cellulose fibrillar networks

Abstract

Hemicelluloses, a family of heterogeneous polysaccharides with complex molecular structures, constitute a fundamental component of lignocellulosic biomass. However, the contribution of each hemicellulose type to the mechanical properties of secondary plant cell walls remains elusive. Here we homogeneously incorporate different combinations of extracted and purified hemicelluloses (xylans and glucomannans) from softwood and hardwood species into self-assembled networks during cellulose biosynthesis in a bacterial model, without altering the morphology and the crystallinity of the cellulose bundles. These composite hydrogels can be therefore envisioned as models of secondary plant cell walls prior to lignification. The incorporated hemicelluloses exhibit both a rigid phase having close interactions with cellulose, together with a flexible phase contributing to the multiscale architecture of the bacterial cellulose hydrogels. The wood hemicelluloses exhibit distinct biomechanical contributions, with glucomannans increasing the elastic modulus in compression, and xylans contributing to a dramatic increase of the elongation at break under tension. These diverging effects cannot be explained solely from the nature of their direct interactions with cellulose, but can be related to the distinct molecular structure of wood xylans and mannans, the multiphase architecture of the hydrogels and the aggregative effects amongst hemicellulose-coated fibrils. Our study contributes to understanding the specific roles of wood xylans and glucomannans in the biomechanical integrity of secondary cell walls in tension and compression and has significance for the development of lignocellulosic materials with controlled assembly and tailored mechanical properties.

Hard Carbon Anodes for Next‐Generation Li‐Ion Batteries: Review and Perspective

“…[ 129–131 ] In comparison, the content of cellulose in wood only accounts for 40–50% by atom ratio, along with 10–30% hemicellulose and 20–30% lignin. [ 132–135 ] Recently, Li et al. investigated the impact of pyrolysis temperature on the storage performance of Li + ions in pyrolytic‐polyvinylidene fluoride (PVDF)‐coated hard carbons derived from pure cellulose.…”

Two conifer GUX clades are responsible for distinct glucuronic acid patterns on xylan

“…The exact biological functions of conifer hemicelluloses are still debated. However, they are likely to mediate cross‐linking of different cell wall components and modulate the mechanical properties of the cell wall (Terrett & Dupree, 2019; Berglund et al ., 2020a,b; Martínez‐Abad et al ., 2020). Both in vitro binding assays (Whitney et al ., 1998; Berglund et al ., 2020a,b) and in planta analysis (Terashima et al ., 2009; Yu et al ., 2018; Terrett et al ., 2019) suggest that GGM can interact with cellulose microfibrils.…”

Molecular-Level Characterization of Changes in the Mechanical Properties of Wood in Response to Thermal Treatment

“…For the samples treated from 160 ℃ to 200 ℃, the intensities of the two split peaks decreased upon increasing the temperature, which indicated that the elastic-like response of cellulose and the stiffness of thermally-treated wood were decreased (Hofstetter et al, 2006; Åkerholm and Salmén 2003). The main reason for this was that the hemicelluloses, as the micro brilmatrix interface, crosslinked on the surface of the micro brils, which increased the stiffness of the cell wall (Berglund 2020). This was also demonstrated by the relationship between the hemicellulose content and elastic modulus of thermally-treated wood (Kačíková et al, 2013), but for the sample treated at 220 ℃, the intensities of the two split peaks increased, which indicated that the stiffness of the sample increased because the MFA decreased (Table 1).…”