Cellulose is not just cellulose: a review of dislocations as reactive sites in the enzymatic hydrolysis of cellulose microfibrils

Hidayat, Budi J.; Felby, Claus; Johansen, Katja Salomon; Thygesen, Lisbeth Garbrecht

doi:10.1007/s10570-012-9740-2

Cited by 55 publications

(46 citation statements)

References 79 publications

(103 reference statements)

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“…Although highly crystalline, the BC fiber contains a small fraction of heterogeneities [45,46]. These heterogeneities are preferentially degraded by cellulases, and their depletion is thought to be responsible for rate retardation of cellulose hydrolysis [47]. Thus, interpretation of the results of product inhibition is more straightforward if measured at a higher degree of substrate conversion.…”

Section: Resultsmentioning

confidence: 99%

Product inhibition of cellulases studied with 14C-labeled cellulose substrates

Teugjas

Väljamaë

2013

Biotechnol Biofuels

120

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BackgroundAs a green alternative for the production of transportation fuels, the enzymatic hydrolysis of lignocellulose and subsequent fermentation to ethanol are being intensively researched. To be economically feasible, the hydrolysis of lignocellulose must be conducted at a high concentration of solids, which results in high concentrations of hydrolysis end-products, cellobiose and glucose, making the relief of product inhibition of cellulases a major challenge in the process. However, little quantitative information on the product inhibition of individual cellulases acting on cellulose substrates is available because it is experimentally difficult to assess the hydrolysis of the heterogeneous polymeric substrate in the high background of added products.ResultsThe cellobiose and glucose inhibition of thermostable cellulases from Acremonium thermophilum, Thermoascus aurantiacus, and Chaetomium thermophilum acting on uniformly 14C-labeled bacterial cellulose and its derivatives, 14C-bacterial microcrystalline cellulose and 14C-amorphous cellulose, was studied. Cellulases from Trichoderma reesei were used for comparison. The enzymes most sensitive to cellobiose inhibition were glycoside hydrolase (GH) family 7 cellobiohydrolases (CBHs), followed by family 6 CBHs and endoglucanases (EGs). The strength of glucose inhibition followed the same order. The product inhibition of all enzymes was relieved at higher temperatures. The inhibition strength measured for GH7 CBHs with low molecular-weight model substrates did not correlate with that measured with 14C-cellulose substrates.ConclusionsGH7 CBHs are the primary targets for product inhibition of the synergistic hydrolysis of cellulose. The inhibition must be studied on cellulose substrates instead of on low molecular-weight model substrates when selecting enzymes for lignocellulose hydrolysis. The advantages of using higher temperatures are an increase in the catalytic efficiency of enzymes and the relief of product inhibition.

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Section: Resultsmentioning

confidence: 99%

Product inhibition of cellulases studied with 14C-labeled cellulose substrates

Teugjas

Väljamaë

2013

Biotechnol Biofuels

120

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“…Cellulose, a natural highly abundant macromolecule made up of glucose 1, 4-β-linked is a principle substrate for bioethanol conversion (Hidayat et al, 2012). Further, hemicellulose is also a convertible carbohydrate substrate to alcohol fuels (Saha, 2003).…”

Section: Resultsmentioning

confidence: 99%

Comparative feedstock analysis in Setaria viridis L. as a model for C4 bioenergy grasses and Panicoid crop species

Petti¹,

Shearer²,

Tateno³

et al. 2013

Front. Plant Sci.

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Second generation feedstocks for bioethanol will likely include a sizable proportion of perennial C4 grasses, principally in the Panicoideae clade. The Panicoideae contain agronomically important annual grasses including Zea mays L. (maize), Sorghum bicolor (L.) Moench (sorghum), and Saccharum officinarum L. (sugar cane) as well as promising second generation perennial feedstocks including Miscanthus×giganteus and Panicum virgatum L. (switchgrass). The underlying complexity of these polyploid grass genomes is a major limitation for their direct manipulation and thus driving a need for rapidly cycling comparative model. Setaria viridis (green millet) is a rapid cycling C4 panicoid grass with a relatively small and sequenced diploid genome and abundant seed production. Stable, transient, and protoplast transformation technologies have also been developed for Setaria viridis making it a potentially excellent model for other C4 bioenergy grasses. Here, the lignocellulosic feedstock composition, cellulose biosynthesis inhibitor response and saccharification dynamics of Setaria viridis are compared with the annual sorghum and maize and the perennial switchgrass bioenergy crops as a baseline study into the applicability for translational research. A genome-wide systematic investigation of the cellulose synthase-A genes was performed identifying eight candidate sequences. Two developmental stages; (a) metabolically active young tissue and (b) metabolically plateaued (mature) material are examined to compare biomass performance metrics.

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“…These cellulose nanomaterials are obtained by disintegrating cellulosic fibers in the plant cell wall through chemical or mechanochemical treatments. These materials may experience various stress conditions in industrial processes and in use that may alter the inner structure of the cellulose nanocrystals through dislocations (Hidayat et al 2012) and allomorphic transitions. Understanding the mechanical response of crystalline cellulose to various external Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10570-018-1860-x) contains supplementary material, which is available to authorized users.…”

Section: Introductionmentioning

confidence: 99%

Iα to Iβ mechano-conversion and amorphization in native cellulose simulated by crystal bending

et al. 2018

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The bending of rod-like native cellulose crystals with degree of polymerization 40 and 160 using molecular dynamics simulations resulted in a deformation-induced local amorphization at the kinking point and allomorphic interconversion between cellulose Ia and Ib in the unbent segments. The transformation mechanism involves a longitudinal chain slippage of the hydrogen-bonded sheets by the length of one anhydroglucose residue (* 0.5 nm), which alters the chain stacking from the monotonic (Ia) form to the alternating Ib one or vice versa. This mechanical deformation converts the Ia form progressively to the Ib form, as has been experimentally observed for ultrasonication of microfibrils. Ib is also able to partially convert to Ia-like organization but this conversion is only transitory. The qualitative agreement between the behavior of ultrasonicated microfibrils and in silico observed Ia ? Ib conversion suggests that shear deformation and chain slippage under bending deformation is a general process when cellulose fibrils experience lateral mechanical stress.

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Cellulose is not just cellulose: a review of dislocations as reactive sites in the enzymatic hydrolysis of cellulose microfibrils

Cited by 55 publications

References 79 publications

Product inhibition of cellulases studied with 14C-labeled cellulose substrates

Product inhibition of cellulases studied with 14C-labeled cellulose substrates

Comparative feedstock analysis in Setaria viridis L. as a model for C4 bioenergy grasses and Panicoid crop species

Iα to Iβ mechano-conversion and amorphization in native cellulose simulated by crystal bending

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