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Xylanolytic enzymes, with both endo-xylanase and arabinoxylan arabinofuranohydrolase (AXH) activities, are attractive for the economically feasible conversion of recalcitrant arabinoxylan. However, their characterization and utilization of these enzymes in biotechnological applications have been limited. Here, we characterize a novel bifunctional enzyme, rAbf43A, cloned from a bacterial consortium that exhibits AXH and endo-xylanase activities. Hydrolytic pattern analyses revealed that the AXH activity belongs to AXHd3 because it attacked only the C(O)-3-linked arabinofuranosyl residues of double-substituted xylopyranosyl units of arabinoxylan and arabinoxylan-derived oligosaccharides, which are usually resistant to hydrolysis. The enzyme rAbf43A also liberated a series of xylo-oligosaccharides (XOSs) from beechwood xylan, xylohexaose and xylopentaose, indicating that rAbf43A exhibited endo-xylanase activity. Homology modelling based on AlphaFold2 and site-directed mutagenesis identified three non-catalytic residues (H161, A270 and L505) located in the substrate-binding pocket essential for its dual-functionality, while the mutation of A117 located in the -1 subsite to the proline residue only affected its endo-xylanase activity. Additionally, rAbf43A showed significant synergistic action with the bifunctional xylanase/feruloyl esterase rXyn10A/Fae1A from the same bacterial consortium on insoluble wheat arabinoxylan and de-starched wheat bran degradation. When rXyn10A/Fae1A was added to the rAbf43A pre-hydrolyzed reactions, the amount of released reducing sugars, xylose and ferulic acid increased by 9.43% and 25.16%, 189.37% and 93.54%, 31.39% and 32.30%, respectively, in comparison with the sum of hydrolysis products released by each enzyme alone. The unique characteristics of rAbf43A position it as a promising candidate not only for designing high-performance enzyme cocktails but also for investigating the structure-function relationship of GH43 multifunctional enzymes., (© 2023 The Authors. Microbial Biotechnology published by Applied Microbiology International and John Wiley & Sons Ltd.)

Understanding of how the plant cell walls of different plant species respond to pretreatment can help improve saccharification in bioconversion processes. Here, we studied the chemical and structural modifications in lignin and hemicellulose in hydrothermally pretreated poplar and wheat straw using wet chemistry and 2D heteronuclear single quantum coherence nuclear magnetic resonance (NMR) and their effects on cellulose conversion. Increased pretreatment severity reduced the levels of β─O─4 linkages with concomitant relatively increased levels of β─5 and β─β structures in the NMR spectra. β─5 structures appeared at medium and high severities for wheat straw while only β─β structures were observed at all pretreatment severities for poplar. These structural differences accounted for the differences in cellulose conversion for these biomasses at different severities. Changes in the hemicellulose component include a complete removal of arabinosyl and 4-O-methyl glucuronosyl substituents at low and medium pretreatment severities while acetyl groups were found to be relatively resistant toward hydrothermal pretreatment. This illustrates the importance of these groups, rather than xylan content, in the detrimental role of xylan in cellulose saccharification and helps explain the higher poplar recalcitrance compared to wheat straw. The results point toward the need for both enzyme preparation development and pretreatment technologies to target specific plant species., (© 2021 American Institute of Chemical Engineers.)

In this study, zymographic analysis for xylanase and pectinase enzymes has been carried out using agrowaste residues, wheat bran and citrus peel as well as their extracts. Isozymic forms of xylanase as well as pectinase enzyme displayed comparable zymographic bands onto agar petriplates containing either commercial substrates (xylan and pectin), agrowaste-based substrates (wheat bran and citrus peel), or polysaccharides extracted from these agrowastes (crude xylan and pectin extracted from wheat bran and citrus peel, respectively), indicating the fact that agro residues and their extracts can be utilized as a substitute of cost-intensive commercial substrates, xylan and pectin for zymographic analysis. This is the first report revealing the zymographic analysis of xylano-pectinolytic enzymes using agro-based solid residues particles or polysaccharides extracted from agro-based residues., (© 2019 American Institute of Chemical Engineers.)

An extracellular esterase gene estK was identified in Pseudomonas putida mt-2 and overexpressed at high levels in Escherichia coli. The recombinant EstK enzyme was purified and characterized kinetically against p-nitrophenyl ester and other aryl-alkyl ester substrates and found to be selective for hydrolysis of acetyl ester substrates with high activity for p-nitrophenyl acetate (k cat 5.5 Sec -1 , K M 285 µM). Recombinant EstK was found to catalyze deacetylation of acetylated beech xylan, indicating a possible in vivo function for this enzyme, and partial deacetylation of a synthetic polymer (poly(vinylacetate)). EstK was found to catalyze enantioselective hydrolysis of racemic 1-phenylethyl acetate, generating 1R-phenylethanol with an enantiomeric excess of 80.4%., (© 2016 International Union of Biochemistry and Molecular Biology, Inc.)

The role of particle size in carbohydrate fractionation upon pretreatment and glucan yields upon enzymatic hydrolysis was investigated at two different temperatures, to examine the possibility of pretreating under milder conditions smaller particles, in order to satisfy pilot-scale operational constraints. Maize stover was knife-milled through 1-mm and 0.5-mm screens and pretreated by soaking in aqueous ammonia pretreatment at 60 or 110°C for 6 h. Pretreated solids were analyzed for composition and a material balance calculated for glucan, xylan, and lignin. At 60°C, milling resulted in greater delignification compared to unmilled biomass. Delignification was more uniform at 110°C. Pretreated solids were washed and cellulase hydrolysis carried out at 10% w/w solids loading, with low and high enzyme loadings. Liquid samples were drawn and concentration data developed through HPLC to calculate 48-h glucan and xylan hydrolytic yields. The differences in hydrolytic yield between milled and unmilled treatments were found to vary with pretreatment temperature and enzyme loading. The results show that while particle size impacts carbohydrate recovery and hydrolytic yield, it is less important in bioprocessing than pretreatment temperature and enzyme loading, possibly owing to the particles' morphology rather than the size., (© 2015 American Institute of Chemical Engineers.)

Xylanase II from Trichoderma reesei catalyzes the hydrolysis of glycosidic bonds in xylan. Crystallographic studies of this commercially important enzyme have been initiated to investigate its reaction mechanism, substrate binding and dependence on basic pH conditions. The wild-type protein was heterologously expressed in an Escherichia coli host using the defined medium and four active-site amino acids were replaced to abolish its activity (E177Q and E86Q) or to change its pH optimum (N44D and N44H). Cation-exchange and size-exclusion chromatography were used to obtain >90% protein purity. The ligand-free proteins and variant complexes containing substrate (xylohexaose) or product (xylotriose) were crystallized in several different space groups and diffracted to high resolutions (from 1.07 to 1.55 Å).

Sodium hydroxide and its derivatives are used as pulping reagents, wherein the spent NaOH is recovered in salt form and reused. In this study, use of low concentration NaOH (1-5%) in pretreatment of corn stover and hybrid poplar was investigated. It was done with the understanding that NaOH can be recovered. One of the main objectives in this study is to explore the potential of H(2)O(2) with NaOH for pretreatment of high lignin substrate such as hybrid poplar. Pretreatment time has not been optimized in this study but held constant at 24 h. Corn stover, after treatment with NaOH under moderate conditions, attains near quantitative glucan digestibility. On the other hand, hybrid poplar requires treatment at higher temperature and NaOH concentration to attain acceptable level of digestibility. Supplementation of hydrogen peroxide in the pretreatment significantly raises delignification and digestibility of hybrid poplar. It was also helpful in retaining the carbohydrates in the treated solids. Retention of hemicellulose after pretreatment provides a significant economic benefit as it eliminates the need for detoxifying hemicellulose sugars. As the residual xylan remaining after pretreatment is an impediment to enzymatic digestion of glucan, supplementation of xylanase has significantly increased the digestibility of glucan as well as xylan of the treated hybrid poplar., ((c) 2010 American Institute of Chemical Engineers)

Among four cellulolytic microorganisms examined, Cellulomonas biazotea NCIM-2550 can grow on various cellulosic substrates and produce reducing sugar. The activity of cellulases (endoglucanase, exoglucanase, and cellobiase), xylanase, amylase, and lignin class of enzymes produced by C. biazotea was mainly present extracellularly and the enzyme production was dependent on cellulosic substrates (carboxymethyl cellulose [CMC], sugarcane bagasse [SCB], and xylan) used for growth. Effects of physicochemical conditions on cellulolytic enzyme production were systematically investigated. Using MnCl(2) as a metal additive significantly induces the cellulase enzyme system, resulting in more reducing sugar production. The efficiency of fermentative conversion of the hydrolyzed SCB and xylan into clean H(2) energy was examined with seven H(2)-producing pure bacterial isolates. Only Clostridiumbutyricum CGS5 exhibited efficient H(2) production performance with the hydrolysate of SCB and xylan. The cumulative H(2) production and H(2) yield from using bagasse hydrolysate (initial reducing sugar concentration = 1.545 g/L) were approximately 72.61 mL/L and 2.13 mmol H(2)/g reducing sugar (or 1.91 mmol H(2)/g cellulose), respectively. Using xylan hydrolysate (initial reducing sugar concentration = 0.345 g/L) as substrate could also attain a cumulative H(2) production and H(2) yield of 87.02 mL/L and 5.03 mmol H(2)/g reducing sugar (or 4.01 mmol H(2)/g cellulose), respectively.

The pretreatment of cellulose using ionic liquids (ILs) has been shown to be an effective method for improving the enzymatic hydrolysis of cellulose; this technique affords a fast and complete saccharification of cellulose into reducing sugars (Dadi et al., Biotechnol Bioeng. 2006; 95:904-910; Liu and Chen, Chinese Sci Bull. 2006; 51:2432-2436; Zhao et al., J Biotechnol. 2009; 139:47-54). Motivated by these advances, this study examines the effect of IL-pretreatment on the enzymatic hydrolysis of purified xylan (as a model system of hemicellulose) and switchgrass (as a real lignocellulose). The IL-pretreatment resulted in no improvement in the hydrolysis of xylan. The likely reason is that pure xylan has a low degree of polymerization (DP), and is readily biodegraded even without any pretreatment. However, in real cellulosic materials (such as switchgrass), xylan is entrapped within the cellulosic matrix, and cannot be conveniently accessed by enzymes. Our data demonstrate that the IL-pretreatment of switchgrass significantly improved the enzymatic saccharification of both cellulose (96% D-glucose yield in 24 h) and xylan (63% D-xylose yield in 24 h). The compositional analysis of switchgrass suggests a lower lignin content after IL-pretreatment. In addition, the infrared spectrum of regenerated switchgrass indicates a lower substrate crystallinity, whereas the enzyme adsorption isotherm further implies that the regenerated substrate is more accessible to enzymes. This study has further confirmed that IL-pretreatment is an effective tool in enhancing the enzymatic hydrolysis of cellulosic biomass, and allowing a more complete saccharification.

There is a growing need to find alternatives to crude oil as the primary feed stock for the chemicals and fuel industry and ethanol has been demonstrated to be a viable alternative. Among the various feed stocks for producing ethanol, poplar (Populus nigra x Populus maximowiczii) is considered to have great potential as a biorefinery feedstock in the United States, due to their widespread availability and good productivity in several parts of the country. We have optimized AFEX pretreatment conditions (180 degrees C, 2:1 ammonia to biomass loading, 233% moisture, 30 minutes residence time) and by using various combinations of enzymes (commercical celluloses and xylanases) to achieve high glucan and xylan conversion (93 and 65%, respectively). We have also identified and quantified several important degradation products formed during AFEX using liquid chromatography followed by mass spectrometry (LC-MS/MS). As a part of degradation product analysis, we have also quantified oligosaccharides in the AFEX water wash extracts by acid hydrolysis. It is interesting to note that corn stover (C4 grass) can be pretreated effectively using mild AFEX pretreatment conditions, while on the other hand hardwood poplar requires much harsher AFEX conditions to obtain equivalent sugar yields upon enzymatic hydrolysis. Comparing corn stover and poplar, we conclude that pretreatment severity and enzymatic hydrolysis efficiency are dictated to a large extent by lignin carbohydrate complexes and arabinoxylan cross-linkages for AFEX., ((c) 2009 American Institute of Chemical Engineers Biotechnol.)

Arabinoxylan-oligosaccharides (AXOS) are a recently newly discovered class of candidate prebiotics as - depending on their structure - they are fermented in different regions of gastrointestinal tract. This can have an impact on the protein/carbohydrate fermentation balance in the large intestine and, thus, affect the generation of potentially toxic metabolites in the colon originating from proteolytic activity. In this study, we screened different AXOS preparations for their impact on the in vitro intestinal fermentation activity and microbial community structure. Short-term fermentation experiments with AXOS with an average degree of polymerization (avDP) of 29 allowed part of the oligosaccharides to reach the distal colon, and decreased the concentration of proteolytic markers, whereas AXOS with lower avDP were primarily fermented in the proximal colon. Additionally, prolonged supplementation of AXOS with avDP 29 to the Simulator of Human Intestinal Microbial Ecosystem (SHIME) reactor decreased levels of the toxic proteolytic markers phenol and p-cresol in the two distal colon compartments and increased concentrations of beneficial short-chain fatty acids (SCFA) in all colon vessels (25-48%). Denaturant gradient gel electrophoresis (DGGE) analysis indicated that AXOS supplementation only slightly modified the total microbial community, implying that the observed effects on fermentation markers are mainly caused by changes in fermentation activity. Finally, specific quantitative PCR (qPCR) analysis showed that AXOS supplementation significantly increased the amount of health-promoting lactobacilli as well as of Bacteroides-Prevotella and Clostridium coccoides-Eubacterium rectale groups. These data allow concluding that AXOS are promising candidates to modulate the microbial metabolism in the distal colon., (Journal compilation © 2008 Society for Applied Microbiology and Blackwell Publishing Ltd. No claim to original Belgium government works.)

The cellulosome of Clostridium thermocellum is a highly organized multi-enzyme complex of cellulases and hemicellulases involved in the hydrolysis of plant cell-wall polysaccharides. The bifunctional multi-modular xylanase Xyn10B is one of the hemicellulase components of the C. thermocellum cellulosome. The enzyme contains an internal glycoside hydrolase family 10 catalytic domain (GH10) and a C-terminal family 1 carbohydrate esterase domain (CE1). The N-terminal moiety of Xyn10B (residues 32-551), comprising a carbohydrate-binding module (CBM22-1) and the GH10 E337A mutant, was crystallized in complex with xylohexaose. The crystals belong to the trigonal space group P3(2)21 and contain a dimer in the asymmetric unit. The crystals diffracted to beyond 2.0 A resolution.

Arabinoxylan arabinofuranohydrolases (AXH) are alpha-L-arabinofuranosidases (EC 3.2.1.55) that specifically hydrolyse the glycosidic bond between arabinofuranosyl substituents and xylopyranosyl residues from arabinoxylan, hence their name. In this study, the crystallization and preliminary X-ray analysis of the AXH from Bacillus subtilis, a glycoside hydrolase belonging to family 43, is described. Purified recombinant AXH crystallized in the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 68.7, b = 73.7, c = 106.5 A. X-ray diffraction data were collected to a resolution of 1.55 A.

This study describes the identification of the key enzyme activities required in a "minimal" enzyme cocktail able to catalyze hydrolysis of water-soluble and water-insoluble wheat arabinoxylan and whole vinasse, a fermentation effluent resulting from industrial ethanol manufacture from wheat. The optimal arabinose-releasing and xylan-depolymerizing enzyme activities were identified from data obtained when selected, recombinant enzymes were systematically supplemented to the different arabinoxylan substrates in mixtures; this examination revealed three novel alpha-l-arabinofuranosidase activities: (i) one GH51 enzyme from Meripilus giganteus and (ii) one GH51 enzyme from Humicola insolens, both able to catalyze arabinose release from singly substituted xylose; and (iii) one GH43 enzyme from H. insolens able to catalyze the release of arabinose from doubly substituted xylose. Treatment of water-soluble and water-insoluble wheat arabinoxylan with an enzyme cocktail containing a 20%:20%:20%:40% mixture and a 25%:25%:25%:25% mixture, respectively, of the GH43 alpha-l-arabinofuranosidase from H. insolens (Abf II), the GH51 alpha-l-arabinofuranosidase from M. giganteus (Abf III), a GH10 endo-1,4-beta-xylanase from H. insolens (Xyl III), and a GH3 beta-xylosidase from Trichoderma reesei (beta-xyl) released 322 mg of arabinose and 512 mg of xylose per gram of water-soluble wheat arabinoxylan dry matter and 150 mg of arabinose and 266 mg of xylose per gram of water-insoluble wheat arabinoxylan dry matter after 24 h at pH 5, 50 degrees C. A 10%:40%:50% mixture of Abf II, Abf III, and beta-xyl released 56 mg of arabinose and 91 mg of xylose per gram of vinasse dry matter after 24 h at pH 5, 50 degrees C. The optimal dosages of the "minimal" enzyme cocktails were determined to be 0.4, 0.3, and 0.2 g enzyme protein per kilogram of substrate dry matter for the water-soluble wheat arabinoxylan, the water-insoluble wheat arabinoxylan, and the vinasse, respectively. These enzyme protein dosage levels were approximately 14, approximately 18, and approximately 27 times lower than the dosages used previously, when the same wheat arabinoxylan substrates were hydrolyzed with a combination of Ultraflo L and Celluclast 1.5 L, two commercially available enzyme preparations produced by H. insolens and T. reesei.

Acetone, butanol, and ethanol (ABE) were produced from corn fiber arabinoxylan (CFAX) and CFAX sugars (glucose, xylose, galactose, and arabinose) using Clostridium acetobutylicum P260. In mixed sugar (glucose, xylose, galactose, and arabinose) fermentation, the culture preferred glucose and arabinose over galactose and xylose. Under the experimental conditions, CFAX (60 g/L) was not fermented until either 5 g/L xylose or glucose plus xylanase enzyme were added to support initial growth and fermentation. In this system, C. acetobutylicum produced 9.60 g/L ABE from CFAX and xylose. This experiment resulted in a yield and productivity of 0.41 and 0.20 g/L x h, respectively. In the integrated hydrolysis, fermentation, and recovery process, 60 g/L CFAX and 5 g/L xylose produced 24.67 g/L ABE and resulted in a higher yield (0.44) and a higher productivity (0.47 g/L x h). CFAX was hydrolyzed by xylan-hydrolyzing enzymes, and ABE were recovered by gas stripping. This investigation demonstrated that integration of hydrolysis of CFAX, fermentation to ABE, and recovery of ABE in a single system is an economically attractive process. It is suggested that the culture be further developed to hydrolyze CFAX and utilize all xylan sugars simultaneously. This would further increase productivity of the reactor.

This study examined enzyme-catalyzed viscosity reduction and evaluated the effects of substrate dry matter concentration on enzymatic degradation of arabinoxylan in a fermentation residue, "vinasse", resulting from industrial ethanol manufacture on wheat. Enzymatic catalysis was accomplished with a 50:50 mixture of an enzyme preparation from Humicola insolens, Ultraflo L, and a cellulolytic enzyme preparation from Trichoderma reesei, Celluclast 1.5 L. This enzyme mixture was previously shown to exhibit a synergistic action on arabinoxylan degradation. The viscosity of vinasse decreased with increased enzyme dosage and treatment time at pH 5, 50 degrees C, 5 wt % vinasse dry matter. After 24 h of enzymatic treatment, 76-84%, 75-80%, and 43-47%, respectively, of the theoretically maximal arabinose, xylose, and glucose releases were achieved, indicating that the viscosity decrease was a result of enzyme-catalyzed hydrolysis of arabinoxylan, beta-glucan, and cellulose. In designed response surface experiments, the optimal enzyme reaction conditions with respect to pH and temperature of the vinasse, the vinasse supernatant (mainly soluble material), and the vinasse sediment (mainly insoluble substances) varied from pH 5.2-6.4 and 41-49 degrees C for arabinose release and from pH 4.9-5.3 and 42-46 degrees C for xylose release. Even though only limited hydrolysis of the arabinoxylan in the vinasse sediment fraction was obtained, the results indicated that the same enzyme activities acted on the arabinoxylan in the different vinasse fractions irrespective of the state of solubility of the substrate material. The levels of liberated arabinose and xylose increased with increased dry matter concentration during enzymatic hydrolysis in the vinasse and the vinasse supernatant, but at the same time, increased substrate dry matter concentrations gave corresponding linear decreases in the hydrolytic efficiency as evaluated from levels of monosaccharide release per weight unit dry matter. The study thus documents that enzymatic arabinoxylan hydrolysis of the vinasse significantly decreases the vinasse viscosity and that a compromise in the dry matter must be found if enzymatic efficiency must be balanced with monosaccharide yields.

Isothermal autohydrolysis treatments of brewery's spent grain were used as a method for hemicellulose solubilization and xylo-oligosaccharides production. The time course of the concentrations of residual hemicelluloses (made up of xylan and arabinan) and reaction products were determined in experiments carried out at temperatures in the range from 150 to 190 degrees C using liquid-to-solid ratios of 8 and 10 g/g. To model the experimental findings concerning to brewery's spent grain autohydrolysis several kinetic models based on sequential pseudo-homogeneous first-order reactions were tested. Xylan and arabinan were assumed to yield oligosaccharides, monosaccharides (xylose or arabinose), furfural, and other decomposition products in consecutive reaction steps. The models proposed provide a satisfactory interpretation of the hydrolytic conversion of xylan and arabinan. An additional model merging the two proposed models for xylan and arabinan degradation assuming that furfural was formed from both pentoses was developed and the results obtained are discussed. The dependence of the calculated kinetic coefficients on temperature was established using Arrhenius-type equations.

Enzymes such as family 11 xylanases are increasingly being used for industrial applications. Here, the cloning, structure determination and temperature-stability data of a family 11 xylanase, Xyn11X, from the alkali-tolerant Bacillus subtilis subspecies B230 are reported. This enzyme, which degrades xylan polymers, is being produced on an industrial scale for use in the paper-bleaching industry. Xyn11X adopts the canonical family 11 xylanase fold. It has a greater abundance of side chain to side chain hydrogen bonds compared with all other family 11 xylanase crystal structures. Means by which the thermostability of Xyn11X might be improved are suggested.

The glycoside hydrolase sequence-based classification reveals two families of enzymes which hydrolyse the beta-1,4-linked backbone of xylan, xylanases, termed families GH-10 and GH-11. Family GH-11 xylanases are intriguing in that catalysis is performed via a covalent intermediate adopting an unusual (2,5)B (boat) conformation, a conformation which also fulfils the stereochemical constraints of the oxocarbenium ion-like transition state. Here, the 1.9 A structure of a nucleophile, E94A, mutant of the Xyn11 from Bacillus agaradhaerens in complex with xylotriose is presented. Intriguingly, this complex also adopts the (2,5)B conformation in the -1 subsite, with the vacant space provided by the Glu-->Ala mutation allowing the sugar to adopt the alpha-configuration at C1. The structure of the covalent 2-deoxy-2-fluoroxylobiosyl-enzyme intermediate has been extended to atomic (1.1 A) resolution.

Feruloyl esterases cleave ferulic acid from arabinoxylan and pectin. Feruloyl groups are believed to crosslink the polysaccharide chain within the polymer and to link hemicellulose to lignin, which may play a role in controlling the growth of plants. The Clostridium thermocellum cellulosome xylanase Z feruloyl esterase was expressed in Escherichia coli, purified and crystallized. The crystals diffract to 2.4 A resolution and belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 43.14, b = 63.77, c = 79.57 A. Assuming one molecule per asymmetric unit, the Matthews coefficient is calculated to be 1.87 A(3) Da(-1), which corresponds to a solvent content of 34%.

In numerous plant cell walls, the cellulose microfibrils are arranged in a helicoidal pattern which has been considered as an analog to a cholesteric order. Here, we report on the spontaneous helicoidal organization which occurs in acellular conditions from aqueous suspensions of cellulose. The cellulosic mucilage of mature seeds of quince (Cydonia oblonga L) was studied both in situ (pre-release mucilage) and after water extraction and in in vitro re-assembly (prolonged high speed ultracentrifugation, further progressive dehydration and embedding in LR White methacrylate or hydrosoluble melamine resin). The cellulosic component was characterized by the use of cellobiohydrolase (CBH1) bound to colloidal gold, and the glucuronic acid residues of the xylan matrix were characterized by the use of cationised gold. Inside the seeds, the pre-release mucilage is mostly helicoidal, with the occurrence of more or less ordered domains, which indicate a fluid organization relevant to an actual liquid crystal state. Cytochemical tests revealed the tight association between cellulose and glucuronoxylans, the latter constituting a charged coat around each microfibril. Following the hydration of the seed, a cellulosic suspension was extracted in which microfibrils were totally dispersed. The progressive dehydration of the suspension gave rise to concentrated viscous drops. Ultrastructural observations revealed the occurrence of multidomain organization, from non-ordered to cholesteric-like regions, revealing that the mucilage is at the same time crystalline and liquid. This constitutes the first demonstration that liquid crystal type assemblies can arise from crystalline and biological cellulose in aqueous suspension. It strengthens the hypothesis that a transient liquid crystal state must occur during the cellulose ordering. The possible morphogenetic role of the glucuronoxylans in the cholesteric organization of the cellulose is discussed.