Biomass accessibility analysis using electron tomography

Hinkle, Jacob; Ciesielski, Peter N.; Gruchalla, Kenny; Munch, Kristin; Donohoe, Bryon S.

doi:10.1186/s13068-015-0395-8

Cited by 15 publications

(8 citation statements)

References 41 publications

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“…Reconstruction of microfibril organization in cell walls has also been attempted by use of electron tomography of thin cross‐sections of cell walls (Xu et al ., ; Ciesielski et al ., ; Sarkar et al ., ; Hinkle et al ., ). This involves substantial labor and image processing, yet the results to date do not render microfibrils and their organizations within individual lamellae with the clarity evident in the AFM images of onion epidermal walls.…”

Section: Discussionmentioning

confidence: 97%

Disentangling loosening from softening: insights into primary cell wall structure

et al. 2019

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How cell wall elasticity, plasticity, and time-dependent extension (creep) relate to one another, to plant cell wall structure and to cell growth remain unsettled topics. To examine these issues without the complexities of living tissues, we treated cell-free strips of onion epidermal walls with various enzymes and other agents to assess which polysaccharides bear mechanical forces in-plane and out-of-plane of the cell wall. This information is critical for integrating concepts of wall structure, wall material properties, tissue mechanics and mechanisms of cell growth. With atomic force microscopy we also monitored real-time changes in the wall surface during treatments. Driselase, a potent cocktail of wall-degrading enzymes, removed cellulose microfibrils in superficial lamellae sequentially, layer-by-layer, and softened the wall (reduced its mechanical stiffness), yet did not induce wall loosening (creep). In contrast Cel12A, a bifunctional xyloglucanase/cellulase, induced creep with only subtle changes in wall appearance. Both Driselase and Cel12A increased the tensile compliance, but differently for elastic and plastic components. Homogalacturonan solubilization by pectate lyase and calcium chelation greatly increased the indentation compliance without changing tensile compliances. Acidic buffer induced rapid cell wall creep via endogenous a-expansins, with negligible effects on wall compliances. We conclude that these various wall properties are not tightly coupled and therefore reflect distinctive aspects of wall structure. Cross-lamellate networks of cellulose microfibrils influenced creep and tensile stiffness whereas homogalacturonan influenced indentation mechanics. This information is crucial for constructing realistic molecular models that define how wall mechanics and growth depend on primary cell wall structure.

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Section: Discussionmentioning

confidence: 97%

Disentangling loosening from softening: insights into primary cell wall structure

et al. 2019

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“…A strong case can be made that substrate characterization in biorefinery has emerged as a research field in its own right. Characterization of biorefinery resources has been examined by several state-of-the-art analytical techniques including Fourier transform infrared spectroscopy (FTIR) 2 , fluorescence spectroscopy 3 , HPLC 4 , gas chromatography-mass spectrometry (GC-MS) 5 , NMR spectroscopy 6 , gel permeation chromatography (GPC) 7 , scanning electron microscopy 8 , tunneling electron microscopy 9 , atomic force microscopy 10 , Raman spectrometry 11 , time-of-flight secondary ion mass spectrometry (ToF-SIMS) 12 , and small-angle neutron scattering 13 along with a host of wet-chemistry and biological assays.…”

Section: Introductionmentioning

confidence: 99%

Determination of hydroxyl groups in biorefinery resources via quantitative 31P NMR spectroscopy

et al. 2019

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The analysis of chemical structural characteristics of biorefinery product streams (such as lignin and tannin) has advanced substantially over the past decade, with traditional wet-chemical techniques being replaced or supplemented by NMR methodologies. Quantitative 31 P NMR spectroscopy is a promising technique for the analysis of hydroxyl groups because of its unique characterization capability and broad potential applicability across the biorefinery research community. This protocol describes procedures for (i) the preparation/solubilization of lignin and tannin, (ii) the phosphitylation of their hydroxyl groups, (iii) NMR acquisition details, and (iv) the ensuing data analyses and means to precisely calculate the content of the different types of hydroxyl groups. Compared with traditional wet-chemical techniques, the technique of quantitative 31 P NMR spectroscopy offers unique advantages in measuring hydroxyl groups in a single spectrum with high signal resolution. The method provides complete quantitative information about the hydroxyl groups with small amounts of sample (~30 mg) within a relatively short experimental time (~30-120 min).

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“…Classical techniques to estimate plant cell wall porosity such as solute exclusion [ 11 ] and Simon’s Stain method [ 12 ] only give an indirect indication of specific molecules accessibility to plant cell wall components according to their size. Electron tomography can be used to directly assess pores size but requires drying the samples which might induce possible collapsing of the pores [ 13 ]. Low-field nuclear magnetic resonance (NMR) spectroscopy was recently used to study the interactions and retention of water molecules by the plant cell wall constituents in pretreated spruce [ 14 , 15 ] and bagasse samples [ 16 ] showing positive correlation between water accessibility and biomass hydrolysis.…”

Section: Introductionmentioning

confidence: 99%

Multimodal analysis of pretreated biomass species highlights generic markers of lignocellulose recalcitrance

Herbaut

Zoghlami

Habrant

et al. 2018

Biotechnol Biofuels

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BackgroundBiomass recalcitrance to enzymatic hydrolysis has been assigned to several structural and chemical factors. However, their relative importance remains challenging to evaluate. Three representative biomass species (wheat straw, poplar and miscanthus) were submitted to four standard pretreatments (dilute acid, hot water, ionic liquid and sodium chlorite) in order to generate a set of contrasted samples. A large array of techniques, including wet chemistry analysis, porosity measurements using NMR spectroscopy, electron and fluorescence microscopy, were used in order to determine possible generic factors of biomass recalcitrance.ResultsThe pretreatment conditions selected allowed obtaining samples displaying different susceptibility to enzymatic hydrolysis (from 3 up to 98% of the initial glucose content released after 96 h of saccharification). Generic correlation coefficients were calculated between the measured chemical and structural features and the final saccharification rates. Increases in porosity displayed overall strong positive correlations with saccharification efficiency, but different porosity ranges were concerned depending on the considered biomass. Lignin-related factors displayed highly negative coefficients for all biomasses. Lignin content, which is likely involved in the correlations observed for porosity, was less detrimental to enzymatic hydrolysis than lignin composition. Lignin influence was highlighted by the strong negative correlation with fluorescence intensity which mainly originates from monolignols in mature tissues.ConclusionsOur results provide a better understanding of the factors responsible for biomass recalcitrance that can reasonably be considered as generic. The correlations with specific porosity ranges are biomass species-dependent, meaning that enzymes cocktails with fitted enzyme size are likely to be needed to optimise saccharification depending on the biomass origin. Lignin composition, which probably influences its structure, is the most important parameter to overcome to enhance enzymes access to the polysaccharides. Accordingly, fluorescence intensity was found to be a rapid and simple method to assess recalcitrance after pretreatment.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1053-8) contains supplementary material, which is available to authorised users.

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Biomass accessibility analysis using electron tomography

Cited by 15 publications

References 41 publications

Disentangling loosening from softening: insights into primary cell wall structure

Disentangling loosening from softening: insights into primary cell wall structure

Determination of hydroxyl groups in biorefinery resources via quantitative 31P NMR spectroscopy

Multimodal analysis of pretreated biomass species highlights generic markers of lignocellulose recalcitrance

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