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Intake of 13C ssNMR at natural abundance and T2 LF-NMR, to understand spatial organization of plant macromolecular assemblies

Abstract : Over the last 15 years, research efforts have been dedicated to identifying the factors that influence lignocellulosic biomass (LB) enzymatic deconstruction to develop alternatives to fossil carbon resources [1]. Accessibility of LB is an important parameter influencing the biomass deconstruction and is guided by many factors contributing to recalcitrance which can be separated between factors related to the composition of the LB (hemicelluloses, lignin or hydroxycinnamic acids content) and structural factors (the chemical structure and interaction of cell wall polymers, cell wall porosity …) [2].. This study focused on the hot water pretreatment (HWP) of maize internodes during 20 or 40 minutes, which induces disruptions within the tight inter-polymers association mainly through the breakdown of inter- and intra-polymer bonds and a reorganization of the network. The chemical characterization showed that HWP modified the cell wall composition with a loss of hemicelluloses (up to 45% for HWP 40 min) and of ferulic acid cross-linking, associated with a lignin enrichment. Impact of HWP on cellulose supramolecular organization was highlighted with the 13C CPMAS sequence [3], showing an increase of cellulose crystallinity concomitant with an increase of.agregate dimension. This acquisition also shown that the lignin structure is altered, related through a decrease of β-O-4 bonds. The study of the kinetics of polarization transfer made it possible, by using a model using two proton reservoirs [4], to characterize, on the one hand, the increase in the molecular order (T1ρH), and on the other hand, the presence of a greater density of water molecules in the macromolecular assembly (THH). Low-field T2 measurement at two different hydration levels spotlights a modulation of the domains and promotes the creation of new domains where the water is more constrained and which can be associated with pore sizes between 5 and 15 nm. This increase of the porosity, seen by NMR and Simons’ staining, should favour the mobility of enzymes and thus facilitate their catalytic activity. The results obtained by the combined use of these different NMR modalities, associated with the results obtained using chemical analyzes, were synthesized in a diagram illustrating the evolution of interactions within the macromolecular assembly. This study highlights that the loss of hemicelluloses and changes in polymers structural features induced by HWP leads to a reorganization of the cell walls. These modifications induce an increase in the specific surface area and a water redistribution allowing an increase in the accessibility of cellulases and an enhancement of the hydrolysis yield [5].
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https://hal.inrae.fr/hal-03281359
Contributor : Gabriel Paes <>
Submitted on : Thursday, July 8, 2021 - 10:37:12 AM
Last modification on : Wednesday, September 15, 2021 - 7:58:02 PM

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  • HAL Id : hal-03281359, version 1

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Xavier Falourd, Amandine Leroy, Valérie Méchin, Guillon Fabienne, Gabriel Paës, et al.. Intake of 13C ssNMR at natural abundance and T2 LF-NMR, to understand spatial organization of plant macromolecular assemblies. EUROMAR, Jul 2021, Portoroz, Slovenia. ⟨hal-03281359⟩

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