Redesigning plant cell walls for the biomass-based bioeconomy

Carpita, Nicholas C.; McCann, Maureen C.

doi:10.1074/jbc.rev120.014561

Cited by 55 publications

(29 citation statements)

References 143 publications

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“…However, there is a tremendous amount of information still to be elucidated regarding the networks and interactions between cell wall components. This is especially true for the grasses, since digestibility/recalcitrance of the cell wall is a key feature determining their application in bioenergy, animal feed, and human health [50][51][52][53] . Previous work demonstrated that the presence of two-fold screw xylan, which requires an even pattern of substitution on its backbone, is critical for interactions with the cellulose microfibrils on the hydrophilic surface in plant cell walls 16,[30][31][32]34 .…”

Section: Discussionmentioning

confidence: 99%

A grass-specific cellulose–xylan interaction dominates in sorghum secondary cell walls

et al. 2020

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Sorghum (Sorghum bicolor L. Moench) is a promising source of lignocellulosic biomass for the production of renewable fuels and chemicals, as well as for forage. Understanding secondary cell wall architecture is key to understanding recalcitrance i.e. identifying features which prevent the efficient conversion of complex biomass to simple carbon units. Here, we use multi-dimensional magic angle spinning solid-state NMR to characterize the sorghum secondary cell wall. We show that xylan is mainly in a three-fold screw conformation due to dense arabinosyl substitutions, with close proximity to cellulose. We also show that sorghum secondary cell walls present a high ratio of amorphous to crystalline cellulose as compared to dicots. We propose a model of sorghum cell wall architecture which is dominated by interactions between three-fold screw xylan and amorphous cellulose. This work will aid the design of low-recalcitrance biomass crops, a requirement for a sustainable bioeconomy.

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Section: Discussionmentioning

confidence: 99%

A grass-specific cellulose–xylan interaction dominates in sorghum secondary cell walls

et al. 2020

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“…It can be enzymatically degraded by cellulases that release cellobiose, which is subsequently split into two glucose molecules that can be fermented into biofuels ( 2 ). However, the partially crystalline structure of cellulose and its interactions with other components of plant cell walls, such as lignin, make it resistant to enzymatic degradation ( 3 ). Optimizing cellulase-dependent degradation of lignocellulosic feedstocks has the potential to improve the cost effectiveness of biofuels; however, this requires a more complete understanding of the mechanisms of cellulose degradation by cellulases.…”

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confidence: 99%

Nanoscale dynamics of cellulose digestion by the cellobiohydrolase TrCel7A

Haviland

Nong²,

Kuntz³

et al. 2021

Journal of Biological Chemistry

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Understanding the mechanism by which cellulases from bacteria, fungi, and protozoans catalyze the digestion of lignocellulose is important for developing cost-effective strategies for bioethanol production. Cel7A from the fungus Trichoderma reesei is a model exoglucanase that degrades cellulose strands from their reducing ends by processively cleaving individual cellobiose units. Despite being one of the most studied cellulases, the binding and hydrolysis mechanisms of Cel7A are still debated. Here, we used single-molecule tracking to analyze the dynamics of 11,116 quantum dot-labeled Tr Cel7A molecules binding to and moving processively along immobilized cellulose. Individual enzyme molecules were localized with a spatial precision of a few nanometers and followed for hundreds of seconds. Most enzyme molecules bound to cellulose in a static state and dissociated without detectable movement, whereas a minority of molecules moved processively for an average distance of 39 nm at an average speed of 3.2 nm/s. These data were integrated into a three-state model in which Tr Cel7A molecules can bind from solution into either static or processive states and can reversibly switch between states before dissociating. From these results, we conclude that the rate-limiting step for cellulose degradation by Cel7A is the transition out of the static state, either by dissociation from the cellulose surface or by initiation of a processive run. Thus, accelerating the transition of Cel7A out of its static state is a potential avenue for improving cellulase efficiency.

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“…Peng [ 29 ] proposes the use of hemicellulose as a natural renewable raw material for the production of ethylene-vinyl alcohol, polyvinylidene chloride or hydrogel networks, which are fully biodegradable; however, hemicellulose needs to be chemically modified to reduce hydroxyl and carboxyl free groups and increase the polymer chain stability. “Lignin-first” biorefinery has been proposed by Carpita and McCann [ 30 ] in order to increase the value of lignin-derived compounds, removing first aromatic compounds, and then processing cellulose and other carbohydrates. This approach allows valorizing lignin, which constitutes up to 40% of plants, and which is mainly devoted to energy gain by transforming the biomass into epoxy resins [ 31 ], and also to providing cellulose nanofibers and nanocrystals [ 30 ], with great interest also in the composite industry.…”

Section: Polymer Compositesmentioning

confidence: 99%

“…“Lignin-first” biorefinery has been proposed by Carpita and McCann [ 30 ] in order to increase the value of lignin-derived compounds, removing first aromatic compounds, and then processing cellulose and other carbohydrates. This approach allows valorizing lignin, which constitutes up to 40% of plants, and which is mainly devoted to energy gain by transforming the biomass into epoxy resins [ 31 ], and also to providing cellulose nanofibers and nanocrystals [ 30 ], with great interest also in the composite industry. Lignin-based bioplastics for agricultural applications and food packaging have been compiled [ 32 ], also showing its potential as reinforcement.…”

Section: Polymer Compositesmentioning

confidence: 99%

Are Natural-Based Composites Sustainable?

et al. 2021

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This paper assesses the aspects related to sustainability of polymer composites, focusing on the two main components of a composite, the matrix and the reinforcement/filler. Most studies analyzed deals with the assessment of the composite performance, but not much attention has been paid to the life cycle assessment (LCA), biodegradation or recyclability of these materials, even in those papers containing the terms “sustainable” (or its derivate words), “green” or “eco”. Many papers claim about the sustainable or renewable character of natural fiber composites, although, again, analysis about recyclability, biodegradation or carbon footprint determination of these materials have not been studied in detail. More studies focusing on the assessment of these composites are needed in order to clarify their potential environmental benefits when compared to other types of composites, which include compounds not obtained from biological resources. LCA methodology has only been applied to some case studies, finding enhanced environmental behavior for natural fiber composites when compared to synthetic ones, also showing the potential benefits of using recycled carbon or glass fibers. Biodegradable composites are considered of lesser interest to recyclable ones, as they allow for a higher profitability of the resources. Finally, it is interesting to highlight the enormous potential of waste as raw material for composite production, both for the matrix and the filler/reinforcement; these have two main benefits: no resources are used for their growth (in the case of biological materials), and fewer residues need to be disposed.

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Redesigning plant cell walls for the biomass-based bioeconomy

Cited by 55 publications

References 143 publications

A grass-specific cellulose–xylan interaction dominates in sorghum secondary cell walls

A grass-specific cellulose–xylan interaction dominates in sorghum secondary cell walls

Nanoscale dynamics of cellulose digestion by the cellobiohydrolase TrCel7A

Are Natural-Based Composites Sustainable?

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