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Cellohexaose O-CHE
Product code: O-CHE

10 mg

Prices exclude VAT

Available for shipping

Content: 10 mg
Shipping Temperature: Ambient
Storage Temperature: Ambient
Physical Form: Powder
Stability: > 10 years under recommended storage conditions
CAS Number: 2478-35-5
Molecular Formula: C36H62O31
Molecular Weight: 990.9
Purity: > 95%
Substrate For (Enzyme): endo-Cellulase

High purity Cellohexaose for use in research, biochemical enzyme assays and in vitro diagnostic analysis.

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Megazyme publication

Versatile high resolution oligosaccharide microarrays for plant glycobiology and cell wall research.

Pedersen, H. L., Fangel, J. U., McCleary, B., Ruzanski, C., Rydahl, M. G., Ralet, M. C., Farkas, V., Von Schantz, L., Marcus, S. E., Andersen, M.C. F., Field, R., Ohlin, M., Knox, J. P., Clausen, M. H. & Willats, W. G. T. (2012). Journal of Biological Chemistry, 287(47), 39429-39438.

Microarrays are powerful tools for high throughput analysis, and hundreds or thousands of molecular interactions can be assessed simultaneously using very small amounts of analytes. Nucleotide microarrays are well established in plant research, but carbohydrate microarrays are much less established, and one reason for this is a lack of suitable glycans with which to populate arrays. Polysaccharide microarrays are relatively easy to produce because of the ease of immobilizing large polymers noncovalently onto a variety of microarray surfaces, but they lack analytical resolution because polysaccharides often contain multiple distinct carbohydrate substructures. Microarrays of defined oligosaccharides potentially overcome this problem but are harder to produce because oligosaccharides usually require coupling prior to immobilization. We have assembled a library of well characterized plant oligosaccharides produced either by partial hydrolysis from polysaccharides or by de novo chemical synthesis. Once coupled to protein, these neoglycoconjugates are versatile reagents that can be printed as microarrays onto a variety of slide types and membranes. We show that these microarrays are suitable for the high throughput characterization of the recognition capabilities of monoclonal antibodies, carbohydrate-binding modules, and other oligosaccharide-binding proteins of biological significance and also that they have potential for the characterization of carbohydrate-active enzymes.

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Four cellulose-active lytic polysaccharide monooxygenases from Cellulomonas species.

Li, J., Solhi, L., Goddard-Borger, E. D., Mathieu, Y., Wakarchuk, W. W., Withers, S. G. & Brumer, H. (2021). Biotechnology for Biofuels, 14(1), 1-19.

Background: The discovery of lytic polysaccharide monooxygenases (LPMOs) has fundamentally changed our understanding of microbial lignocellulose degradation. Cellulomonas bacteria have a rich history of study due to their ability to degrade recalcitrant cellulose, yet little is known about the predicted LPMOs that they encode from Auxiliary Activity Family 10 (AA10). Results: Here, we present the comprehensive biochemical characterization of three AA10 LPMOs from Cellulomonas flavigena (CflaLPMO10A, CflaLPMO10B, and CflaLPMO10C) and one LPMO from Cellulomonas fimi (CfiLPMO10). We demonstrate that these four enzymes oxidize insoluble cellulose with C1 regioselectivity and show a preference for substrates with high surface area. In addition, CflaLPMO10B, CflaLPMO10C, and CfiLPMO10 exhibit limited capacity to perform mixed C1/C4 regioselective oxidative cleavage. Thermostability analysis indicates that these LPMOs can refold spontaneously following denaturation dependent on the presence of copper coordination. Scanning and transmission electron microscopy revealed substrate-specific surface and structural morphological changes following LPMO action on Avicel and phosphoric acid-swollen cellulose (PASC). Further, we demonstrate that the LPMOs encoded by Cellulomonas flavigena exhibit synergy in cellulose degradation, which is due in part to decreased autoinactivation. Conclusions: Together, these results advance understanding of the cellulose utilization machinery of historically important Cellulomonas species beyond hydrolytic enzymes to include lytic cleavage. This work also contributes to the broader mapping of enzyme activity in Auxiliary Activity Family 10 and provides new biocatalysts for potential applications in biomass modification.

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Engineering of cellobiose phosphorylase for the defined synthesis of cellotriose.

Ubiparip, Z., Moreno, D. S., Beerens, K. & Desmet, T. (2020). Applied Microbiology and Biotechnology, 104(19), 8327-8337.

Cellodextrins are non-digestible oligosaccharides that have attracted interest from the food industry as potential prebiotics. They are typically produced through the partial hydrolysis of cellulose, resulting in a complex mixture of oligosaccharides with a varying degree of polymerisation (DP). Here, we explore the defined synthesis of cellotriose as product since this oligosaccharide is believed to be the most potent prebiotic in the mixture. To that end, the cellobiose phosphorylase (CBP) from Cellulomonas uda and the cellodextrin phosphorylase (CDP) from Clostridium cellulosi were evaluated as biocatalysts, starting from cellobiose and α-D-glucose 1-phosphate as acceptor and donor substrate, respectively. The CDP enzyme was shown to rapidly elongate the chains towards higher DPs, even after extensive mutagenesis. In contrast, an optimised variant of CBP was found to convert cellobiose to cellotriose with a molar yield of 73%. The share of cellotriose within the final soluble cellodextrin mixture (DP2-5) was 82%, resulting in a cellotriose product with the highest purity reported to date. Interestingly, the reaction could even be initiated from glucose as acceptor substrate, which should further decrease the production costs.

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Characterization of two GH5 endoglucanases from termite microbiome using synthetic metagenomics.

Guerrero, E. B., de Villegas, R. M. D., Soria, M. A., Santangelo, M. P., Campos, E. & Talia, P. M. (2020). Applied Microbiology and Biotechnology, 104(19), 8351-8366.

Here, we characterize two novel GH5 endoglucanases (GH5CelA and GH5CelB) from an uncultured bacterium identified in termite gut microbiomes. Both genes were codon-optimized, synthetized, cloned, and expressed as recombinant proteins in Escherichia coli for subsequent purification. Both enzymes showed activity on the pNPC and barley β-glucan substrates, whereas GH5CelB also showed low activity on carboxymethyl cellulose. The optimum conditions for both enzymes were an acid pH (5) and moderate temperature (35 to 50°C). The enzymes differed in the kinetic profiles and patterns of the generated hydrolysis products. A structural-based modeling analysis indicated that both enzymes possess a typical (β/α)8-barrel fold characteristic of GH5 family, with some differential features in the active site cleft. Also, GH5CelB presents a putative secondary binding site. Furthermore, adjacent to the active site of GH5CelA and GH5CelB, a whole subdomain rarely found in GH5 family may participate in substrate binding and thermal stability. Therefore, GH5CelA may be a good candidate for the production of cello-oligosaccharides of different degrees of polymerization applicable for feed and food industries, including prebiotics. On the other hand, GH5CelB could be useful in an enzymatic cocktail for the production of lignocellulosic bioethanol, because of the production of glucose as a hydrolysis product.

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Promoting and Impeding Effects of Lytic Polysaccharide Monooxygenases on Glycoside Hydrolase Activity.

Keller, M. B., Badino, S. F., Blossom, B. M., McBrayer, B., Borch, K. & Westh, P. (2020). ACS Sustainable Chemistry & Engineering, 8(37), 14117-14126.

Lytic polysaccharide monooxygenases (LPMOs) have attracted attention due to their ability to boost cellulolytic enzyme cocktails for application in biorefineries. However, the interplay between LPMOs and individual glycoside hydrolases remains poorly understood. We investigated how the activity of two cellobiohydrolases (Cel7A and Cel6A) and an endoglucanase (Cel7B) from Trichoderma reesei were affected by a C1-oxidizing LPMO from Thielavia terrestrit (TtAA9). We quantified products from a mixture of LPMO and glycoside hydrolase and estimated separate contributions of products by each of the enzymes. Hereby, we assessed if an observed synergy reflected a promotion of the activity of hydrolase, LPMO, or both. We consistently found that TtAA9 affected the investigated hydrolases differently. It strongly impeded the turnover of the reducing end cellobiohydrolase, TrCel7A, moderately promoted the turnover of the nonreducing end cellobiohydrolase TrCel6A, and promoted the turnover of the endoglucanase, TrCel7B up to 5-fold. The promoting effect on the endoglucanase increased with hydrolysis extent, indicating that the promoting effect became more important as the recalcitrance of the substrate increased. Experiments with mixtures containing multiple glycoside hydrolases suggested that the LPMO primarily promoted the activity of the endoglucanase, whereas promotion of TrCel6A was secondary.

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Degradative GH5 β-1, 3-1, 4-glucanase PpBglu5A for glucan in Paenibacillus polymyxa KF-1.

Yuan, Y., Zhang, X., Zhang, H., Wang, W., Zhao, X., Gao, J. & Zhou, Y. (2020). Process Biochemistry, 98, 183-192.

A novel β-1,3-1,4-glucanase in the glycoside hydrolase family 5 (GH5) has been identified in the secretome of Paenibacillus polymyxa KF-1. The recombinant GH5 enzyme PpBglu5A shows broad substrate specificity, with strong lichenase activity, medium β-1,3-glucanase activity, and minimal cellulase activity. Barley β-glucan, lichenan, curdlan, and carboxymethyl cellulose are hydrolyzed to varying degrees by PpBglu5A, with the highest catalytic activity being observed with barley β-glucan. Hydrolysates from barley β-glucan or lichenan are primarily glucan oligosaccharides with degrees of polymerization from 2 to 4. PpBglu5A also hydrolyzes oat bran into oligosaccharides mainly consisted of di-, tri-, and tetra- oligosaccharides that are useful in the preparation of gluco-oligosaccharides. In addition to hydrolytic activity, transglycosylation was also observed with PpBglu5A and cellotriose as substrate. An in vitro assay indicated that the recombinant PpBglu5A has antifungal activity and can inhibit the growth of Canidia albicans. These results suggest that PpBglu5A exhibits unique properties and may be useful as an antifungal agent.

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Identification of a unique 1, 4-β-D-glucan glucohydrolase of glycoside hydrolase family 9 from Cytophaga hutchinsonii.

Jiang, N., Ma, X. D., Fu, L. H., Li, C. X., Feng, J. X. & Duan, C. J. (2020). Applied Microbiology and Biotechnology, 104(16), 7051-7066.

Cytophaga hutchinsonii is an aerobic cellulolytic soil bacterium that rapidly digests crystalline cellulose. The predicted mechanism by which C. hutchinsonii digests cellulose differs from that of other known cellulolytic bacteria and fungi. The genome of C. hutchinsonii contains 22 glycoside hydrolase (GH) genes, which may be involved in cellulose degradation. One predicted GH with uncertain specificity, CHU_0961, is a modular enzyme with several modules. In this study, phylogenetic tree of the catalytic modules of the GH9 enzymes showed that CHU_0961 and its homologues formed a new group (group C) of GH9 enzymes. The catalytic module of CHU_0961 (CHU_0961B) was identified as a 1,4-β-D-glucan glucohydrolase (EC that has unique properties compared with known GH9 cellulases. CHU_0961B showed highest activity against barley glucan, but low activity against other polysaccharides. Interestingly, CHU_0961B showed similar activity against ρ-nitrophenyl β-D-cellobioside (ρ-NPC) and ρ-nitrophenyl β-D-glucopyranoside. CHU_0961B released glucose from the nonreducing end of cello-oligosaccharides, ρ-NPC, and barley glucan in a nonprocessive exo-type mode. CHU_0961B also showed same hydrolysis mode against deacetyl-chitooligosaccharides as against cello-oligosaccharides. The kcat/Km values for CHU_0961B against cello-oligosaccharides increased as the degree of polymerization increased, and its kcat/Km for cellohexose was 750 times higher than that for cellobiose. Site-directed mutagenesis showed that threonine 321 in CHU_0961 played a role in hydrolyzing cellobiose to glucose. CHU_0961 may act synergistically with other cellulases to convert cellulose to glucose on the bacterial cell surface. The end product, glucose, may initiate cellulose degradation to provide nutrients for bacterial proliferation in the early stage of C. hutchinsonii growth.

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Configuration of active site segments in lytic polysaccharide monooxygenases steers oxidative xyloglucan degradation.

Sun, P., Laurent, C. V., Scheiblbrandner, S., Frommhagen, M., Kouzounis, D., Sanders, M. G., van Berkel, W. J. H., Ludwig, R. & Kabel, M. A. (2020). Biotechnology for Biofuels, 13, 1-19.

This study investigated pilot-scale production of xylo-oligosaccharides (XOS) and fermentable sugars from Miscanthus using steam explosion (SE) pretreatment. SE conditions (200°C; 15 bar; 10 min) led to XOS yields up to 52 % (w/w of initial xylan) in the hydrolysate. Liquid chromatography-mass spectrometry demonstrated that the solubilised XOS contained bound acetyl- and hydroxycinnamate residues, physicochemical properties known for high prebiotic effects and anti-oxidant activity in nutraceutical foods. Enzymatic hydrolysis of XOS-rich hydrolysate with commercial endo-xylanases resulted in xylobiose yields of 380 to 500 g/kg of initial xylan in the biomass after only 4 h, equivalent to ~74 to 90 % conversion of XOS into xylobiose. Fermentable glucose yields from enzymatic hydrolysis of solid residues were 8 to 9-fold higher than for untreated material. In view of an integrated biorefinery, we demonstrate the potential for efficient utilisation of Miscanthus for the production of renewable sources, including biochemicals and biofuels.

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Identification and characterization of a hyperthermophilic GH9 cellulase from the Arctic Mid-Ocean Ridge vent field.

Stepnov, A. A., Fredriksen, L., Steen, I. H., Stokke, R. & Eijsink, V. G. (2019). PloS One, 14(9), e0222216.

A novel GH9 cellulase (AMOR_GH9A) was discovered by sequence-based mining of a unique metagenomic dataset collected at the Jan Mayen hydrothermal vent field. AMOR_GH9A comprises a signal peptide, a catalytic domain and a CBM3 cellulose-binding module. AMOR_GH9A is an exceptionally stable enzyme with a temperature optimum around 100°C and an apparent melting temperature of 105°C. The novel cellulase retains 64% of its activity after 4 hours of incubation at 95°C. The closest characterized homolog of AMOR_GH9A is TfCel9A, a processive endocellulase from the model thermophilic bacterium Thermobifida fusca (64.2% sequence identity). Direct comparison of AMOR_GH9A and TfCel9A revealed that AMOR_GH9A possesses higher activity on soluble and amorphous substrates (phosphoric acid swollen cellulose, konjac glucomannan) and has an ability to hydrolyse xylan that is lacking in TfCel9A.

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A lytic polysaccharide monooxygenase from Myceliophthora thermophila and its synergism with cellobiohydrolases in cellulose hydrolysis.

Zhou, H., Li, T., Yu, Z., Ju, J., Zhang, H., Tan, H., Li, K. & Yin, H. (2019). International Journal of Biological Macromolecules, 139, 570-576.

Lytic polysaccharide monooxygenases (LPMOs) have attracted vast attention because of their unique mechanism of oxidative degradation of carbohydrate polymers and the potential application in biorefineries. This study characterized a novel LPMO from Myceliophthora thermophila, denoted MtLPMO9L. The structure model of the enzyme indicated that it belongs to the C1-oxidizing LPMO, which has neither an extra helix in the L3 loop nor extra loop region in the L2 loop. This was confirmed subsequently by the enzymatic assays since MtLPMO9L only acts on cellulose and generates C1-oxidized cello-oligosaccharides. Moreover, synergetic experiments showed that MtLPMO9L significantly improves the efficiency of cellobiohydrolase (CBH) II. In contrast, the inhibitory rather than synergetic effect was observed when combining used MtLPMO9L and CBHI. Changing the incubation time and concentration ratio of MtLPMO9L and CBHI could attenuate the inhibitory effects. This discovery suggests a different synergy detail between MtLPMO9L and two CBHs, which implies that the composition of cellulase cocktails may need reconsideration.

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Lytic polysaccharide monooxygenases (LPMOs) facilitate cellulose nanofibrils production.

Moreau, C., Tapin-Lingua, S., Grisel, S., Gimbert, I., Le Gall, S., Meyer, V., Petit-Conil, M., Berrin, J, Cathala, B. & Villares, A. (2019). Biotechnology for Biofuels, 12(1), 1-13.

Background: Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that cleave polysaccharides through an oxidative mechanism. These enzymes are major contributors to the recycling of carbon in nature and are currently used in the biorefinery industry. LPMOs are commonly used in synergy with cellulases to enhance biomass deconstruction. However, there are few examples of the use of monocomponent LPMOs as a tool for cellulose fibrillation. In this work, we took advantage of the LPMO action to facilitate disruption of wood cellulose fibers as a strategy to produce nanofibrillated cellulose (NFC). Results: The fungal LPMO from AA9 family (PaLPMO9E) was used in this study as it displays high specificity toward cellulose and its recombinant production in bioreactor is easily upscalable. The treatment of birchwood fibers with PaLPMO9E resulted in the release of a mixture of C1-oxidized oligosaccharides without any apparent modification in fiber morphology and dimensions. The subsequent mechanical shearing disintegrated the LPMO-pretreated samples yielding nanoscale cellulose elements. Their gel-like aspect and nanometric dimensions demonstrated that LPMOs disrupt the cellulose structure and facilitate the production of NFC. Conclusions: This study demonstrates the potential use of LPMOs as a pretreatment in the NFC production process. LPMOs weaken fiber cohesion and facilitate fiber disruption while maintaining the crystallinity of cellulose.

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An actinobacteria lytic polysaccharide monooxygenase acts on both cellulose and xylan to boost biomass saccharification.

Corrêa, T. L. R., Júnior, A. T., Wolf, L. D., Buckeridge, M. S., dos Santos, L. V. & Murakami, M. T. (2019). Biotechnology for Biofuels, 12(1), 117.

Background: Lytic polysaccharide monooxygenases (LPMOs) opened a new horizon for biomass deconstruction. They use a redox mechanism not yet fully understood and the range of substrates initially envisaged to be the crystalline polysaccharides is steadily expanding to non-crystalline ones. Results: The enzyme KpLPMO10A from the actinomycete Kitasatospora papulosa was cloned and overexpressed in Escherichia coli cells in the functional form with native N-terminal. The enzyme can release oxidized species from chitin (C1-type oxidation) and cellulose (C1/C4-type oxidation) similarly to other AA10 members from clade II (subclade A). Interestingly, KpLPMO10A also cleaves isolated xylan (not complexed with cellulose, C4-type oxidation), a rare activity among LPMOs not described yet for the AA10 family. The synergistic effect of KpLPMO10A with Celluclast ® and an endo-β-1,4-xylanase also supports this finding. The crystallographic elucidation of KpLPMO10A at 1.6 Å resolution along with extensive structural analyses did not indicate any evident diference with other characterized AA10 LPMOs at the catalytic interface, tempting us to suggest that these enzymes might also be active on xylan or that the ability to attack both crystalline and non-crystalline substrates involves yet obscure mechanisms of substrate recognition and binding. Conclusions: This work expands the spectrum of substrates recognized by AA10 family, opening a new perspective for the understanding of the synergistic efect of these enzymes with canonical glycoside hydrolases to deconstruct ligno(hemi)cellulosic biomass.

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A novel thermostable GH10 xylanase with activities on a wide variety of cellulosic substrates from a xylanolytic Bacillus strain exhibiting significant synergy with commercial Celluclast 1.5 L in pretreated corn stover hydrolysis.

Wang, K., Cao, R., Wang, M., Lin, Q., Zhan, R., Xu, H. & Wang, S. (2019). Biotechnology for Biofuels, 12(1), 48.

Background: Cellulose and hemicellulose are the two largest components in lignocellulosic biomass. Enzymes with activities towards cellulose and xylan have attracted great interest in the bioconversion of lignocellulosic biomass, since they have potential in improving the hydrolytic performance and reducing the enzyme costs. Exploring glycoside hydrolases (GHs) with good thermostability and activities on xylan and cellulose would be beneficial to the industrial production of biofuels and bio-based chemicals. Results: A novel GH10 enzyme (XynA) identified from a xylanolytic strain Bacillus sp. KW1 was cloned and expressed. Its optimal pH and temperature were determined to be pH 6.0 and 65°C. Stability analyses revealed that XynA was stable over a broad pH range (pH 6.0-11.0) after being incubated at 25°C for 24 h. Moreover, XynA retained over 95% activity after heat treatment at 60°C for 60 h, and its half-lives at 65°C and 70°C were about 12 h and 1.5 h, respectively. More importantly, in terms of substrate specificity, XynA exhibits hydrolytic activities towards xylans, microcrystalline cellulose (filter paper and Avicel), carboxymethyl cellulose (CMC), cellobiose, p-nitrophenyl-β-D-cellobioside (pNPC), and p-nitrophenyl-β-D-glucopyranoside (pNPG). Furthermore, the addition of XynA into commercial cellulase in the hydrolysis of pretreated corn stover resulted in remarkable increases (the relative increases may up to 90%) in the release of reducing sugars. Finally, it is worth mentioning that XynA only shows high amino acid sequence identity (88%) with rXynAHJ14, a GH10 xylanase with no activity on CMC. The similarities with other characterized GH10 enzymes, including xylanases and bifunctional xylanase/cellulase enzymes, are no more than 30%. Conclusions: XynA is a novel thermostable GH10 xylanase with a wide substrate spectrum. It displays good stability in a broad range of pH and high temperatures, and exhibits activities towards xylans and a wide variety of cellulosic substrates, which are not found in other GH10 enzymes. The enzyme also has high capacity in saccharification of pretreated corn stover. These characteristics make XynA a good candidate not only for assisting cellulase in lignocellulosic biomass hydrolysis, but also for the research on structure-function relationship of bifunctional xylanase/cellulase.

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Thermodynamic signatures of substrate binding for three Thermobifida fusca cellulases with different modes of action.

Hamre, A. G., Kaupang, A., Payne, C. M., Väljamäe, P. & Sørlie, M. (2019). Biochemistry, 58(12), 1648-1659.

The enzymatic breakdown of recalcitrant polysaccharides is achieved by synergistic enzyme cocktails of glycoside hydrolases (GHs) and accessory enzymes. Many GHs are processive, meaning that they stay bound to the substrate between subsequent catalytic interactions. Cellulases are GHs that catalyze the hydrolysis of cellulose [β-1,4-linked glucose (Glc)]. Here, we have determined the relative subsite binding affinity for a glucose moiety as well as the thermodynamic signatures for (Glc)6 binding to three of the seven cellulases produced by the bacterium Thermobifida fusca. TfCel48A is exo-processive, TfCel9A endo-processive, and TfCel5A endo-nonprocessive. Initial hydrolysis of (Glc)5 and (Glc)6 was performed in H218O enabling the incorporation of an 18O atom at the new reducing end anomeric carbon. A matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of the products reveals the intensity ratios of otherwise identical 18O- and 16O-containing products to provide insight into how the substrate is placed during productive binding. The two processive cellulases have significant binding affinity in subsites where products dissociate during processive hydrolysis, aligned with a need to have a pushing potential to remove obstacles on the substrate. Moreover, we observed a correlation between processive ability and favorable binding free energy, as previously postulated. Upon ligand binding, the largest contribution to the binding free energy is desolvation for all three cellulases as determined by isothermal titration calorimetry. The two endo-active cellulases show a more favorable solvation entropy change compared to the exo-active cellulase, while the two processive cellulases have less favorable changes in binding enthalpy compared to the nonprocessive TfCel5A.

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Functional characterization and comparative analysis of two heterologous endoglucanases from diverging subfamilies of glycosyl hydrolase family 45.

Berto, G. L., Velasco, J., Ribeiro, C. T. C., Zanphorlin, L. M., Domingues, M. N., Murakami, M. T., Polikarpoy, I., Oliveira, L. C., Ferraz, A. & Segato, F. (2019). Enzyme and Microbial Technology, 120, 23-35.

Lignocellulosic materials are abundant, renewable and are emerging as valuable substrates for many industrial applications such as the production of second-generation biofuels, green chemicals and pharmaceuticals. However, the recalcitrance and the complexity of cell wall polysaccharides require multiple enzymes for their complete conversion to oligo- and monosaccharides. The endoglucanases from GH45 family are a small and relatively poorly studied group of enzymes with potential industrial application. The present study reports cloning, heterologous expression and functional characterization of two GH45 endoglucanases from mesophilic fungi Gloeophyllum trabeum (GtGH45) and thermophilic fungi Myceliophthora thermophila (MtGH45), which belong to subfamilies GH45C and GH45A, respectively. Both enzymes have optimal pH 5.0 and melting temperatures (Tm) of 66.0°C and 80.9°C, respectively, as estimated from circular dichroism experiments. The recombinant proteins also exhibited different mode of action when incubated with oligosaccharides ranging from cellotriose to cellohexaose, generating mainly cellobiose and cellotriose (MtGH45) or glucose and cellobiose (GtGH45). The MtGH45 did not show activity against oligosaccharides smaller than cellopentaose while the enzyme GtGH45 was able to depolymerize cellotriose, however with lower efficiency when compared to larger oligosaccharides. Furthermore, both GHs45 were stable up to 70°C for 24 h and useful to enhance initial glucan hydrolysis rates during saccharification of sugarcane pith by a mixture of cellulolytic enzymes. Recombinant GHs45 from diverging subfamilies stand out for differences in substrate specificity appearing as new tools for preparation of enzyme cocktails used in cellulose hydrolysis.

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A novel thermostable GH3 β-glucosidase from Talaromyce leycettanus with broad substrate specificity and significant soybean isoflavone glycosides-hydrolyzing capability.

Reichenbach, T., Li, X., Xia, W., Bai, Y., Ma, R., Yang, H., Luo, H. & Shi, P. (2018). BioMed Research International, 2018, 4794690.

A novel β-glucosidase gene (Bgl3B) of glycoside hydrolase (GH) family 3 was cloned from the thermophilic fungus Talaromyce leycettanus JM12802 and successfully expressed in Pichia pastoris. The deduced Bgl3B contains 860 amino acid residues with a calculated molecular mass of 91.2 kDa. The purified recombinant Bgl3B exhibited maximum activities at pH 4.5 and 65°C and remained stable at temperatures up to 60°C and pH 3.0-9.0, respectively. The enzyme exhibited broad substrate specificities, showing β-glucosidase, glucanase, cellobiase, xylanase, and isoflavone glycoside hydrolase activities, and its activities were stimulated by short-chain alcohols. The catalytic efficiencies of Bgl3B were 693 and 104/mM/s towards pNPG and cellobiose, respectively. Moreover, Bgl3B was highly effective in converting isoflavone glycosides to aglycones at 37°C within 10 min, with the hydrolysis rates of 95.1%, 76.0%, and 75.3% for daidzin, genistin, and glycitin, respectively. These superior properties make Bgl3B potential for applications in the food, animal feed, and biofuel industries.

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Functional characterization of a lytic polysaccharide monooxygenase from the thermophilic fungus Myceliophthora thermophila.

Kadowaki, M. A., Várnai, A., Jameson, J. K., Leite, A. E., Costa-Filho, A. J., Kumagai, P. S., Prade, R. A., Polikarpov, I. & Eijsink, V. G. (2018). PloS One, 13(8), e0202148.

Thermophilic fungi are a promising source of thermostable enzymes able to hydrolytically or oxidatively degrade plant cell wall components. Among these enzymes are lytic polysaccharide monooxygenases (LPMOs), enzymes capable of enhancing biomass hydrolysis through an oxidative mechanism. Myceliophthora thermophila (synonym Sporotrichum thermophile), an Ascomycete fungus, expresses and secretes over a dozen different LPMOs. In this study, we report the overexpression and biochemical study of a previously uncharacterized LPMO (MtLPMO9J) from M. thermophila M77 in Aspergillus nidulansMtLPMO9J is a single-domain LPMO and has 63% sequence similarity with the catalytic domain of NcLPMO9C from Neurospora crassa. Biochemical characterization of MtLPMO9J revealed that it performs C4-oxidation and is active against cellulose, soluble cello-oligosaccharides and xyloglucan. Moreover, biophysical studies showed that MtLPMO9J is structurally stable at pH above 5 and at temperatures up to 50°C. Importantly, LC-MS analysis of the peptides after tryptic digestion of the recombinantly produced protein revealed not only the correct processing of the signal peptide and methylation of the N-terminal histidine, but also partial autoxidation of the catalytic center. This shows that redox conditions need to be controlled, not only during LPMO reactions but also during protein production, to protect LPMOs from oxidative damage.

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A highly glucose-tolerant GH1 β-glucosidase with greater conversion rate of soybean isoflavones in monogastric animals.

Cao, H., Zhang, Y., Shi, P., Ma, R., Yang, H., Xia, W., Cui, Y., Luo, H., Bai, Y. & Yao, B. (2018). Journal of Industrial Microbiology & Biotechnology, 197, 1-10.

In the feed industry, β-glucosidase has been widely used in the conversion of inactive and bounded soybean isoflavones into active aglycones. However, the conversion is frequently inhibited by the high concentration of intestinal glucose in monogastric animals. In this study, a GH1 β-glucosidase (AsBG1) with high specific activity, thermostability and glucose tolerance (IC50 = 800 mM) was identified. It showed great glucose tolerance against substrates with hydrophobic aryl ligands (such as pNPG and soy isoflavones). Using soybean meal as the substrate, AsBG1 exhibited higher hydrolysis efficiency than the GH3 counterpart Bgl3A with or without the presence of glucose in the reaction system. Furthermore, it is the first time to find that the endogenous β-glucosidase of soybean meal, mostly belonging to GH3, plays a role in the hydrolysis of soybean isoflavones and is highly sensitive to glucose. These findings lead to a conclusion that the GH1 rather than GH3 β-glucosidase has prosperous application advantages in the conversion of soybean isoflavones in the feed industry.

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Determination of optimal biomass pretreatment strategies for biofuel production: investigation of relationships between surface-exposed polysaccharides and their enzymatic conversion using carbohydrate-binding modules. 

Khatri, V., Meddeb-Mouelhi, F., Adjallé, K., Barnabé, S. & Beauregard, M. (2018). Biotechnology for Biofuels, 11(1), 144.

Background: Pretreatment of lignocellulosic biomass (LCB) is a key step for its efficient bioconversion into ethanol. Determining the best pretreatment and its parameters requires monitoring its impacts on the biomass material. Here, we used fluorescent protein-tagged carbohydrate-binding modules method (FTCM)-depletion assay to study the relationship between surface-exposed polysaccharides and enzymatic hydrolysis of LCB. Results: Our results indicated that alkali extrusion pretreatment led to the highest hydrolysis rates for alfalfa stover, cattail stems and flax shives, despite its lower lignin removal efficiency compared to alkali pretreatment. Corn crop residues were more sensitive to alkali pretreatments, leading to higher hydrolysis rates. A clear relationship was consistently observed between total surface-exposed cellulose detected by the FTCM-depletion assay and biomass enzymatic hydrolysis. Comparison of bioconversion yield and total composition analysis (by NREL/TP-510-42618) of LCB prior to or after pretreatments did not show any close relationship. Lignin removal efficiency and total cellulose content (by NREL/TP-510-42618) led to an unreliable prediction of enzymatic polysaccharide hydrolysis. Conclusions: Fluorescent protein-tagged carbohydrate-binding modules method (FTCM)-depletion assay provided direct evidence that cellulose exposure is the key determinant of hydrolysis yield. The clear and robust relationships that were observed between the cellulose accessibility by FTCM probes and enzymatic hydrolysis rates change could be evolved into a powerful prediction tool that might help develop optimal biomass pretreatment strategies for biofuel production.

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Performance, egg quality, nutrient digestibility, and excreta microbiota shedding in laying hens fed corn-soybean-meal-wheat-based diets supplemented with xylanase.

Lei, X. J., Lee, K. Y., & Kim, I. H. (2018). Poultry science, 97(6), 2071-2077.

The aim of this study was to evaluate the effects of dietary levels of xylanase on production performance, egg quality, nutrient digestibility, and excreta microbiota shedding of laying hens in a 12-week trial. Two-hundred-forty Hy-Line brown laying hens (44 wk old) were distributed according to a randomized block experimental design into one of 4 dietary treatments with 10 replicates of 6 birds each. The 4 dietary treatments were corn-soybean-meal-wheat-based diets supplemented with 0, 225, 450, or 900 U/kg xylanase. Daily feed intake, egg production, egg weight, egg mass, feed conversion ratio, and damaged egg rate showed no significant response to increasing xylanase supplementation during any phase (P > 0.05). No significant responses were observed for apparent total tract digestibility of dry matter, nitrogen, or gross energy (P > 0.05). A significant linear increase to increasing xylanase supplementation was seen for lactic acid bacteria numbers, although coliforms and Salmonella counts were not affected. Increasing the dietary xylanase resulted in a significant linear increase in eggshell thickness in wk 3, 6, 9, and 12 (P < 0.05). In addition, a significant linear increase occurred for Haugh unit and albumen height in wk 12 (P < 0.05). In summary, the inclusion of xylanase in corn-soybean-meal-wheat-based diets increased eggshell thickness, Haugh unit, albumen height, and excreta lactic acid bacteria count but had no effect on production performance or nutrient digestibility.

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A biorefinery approach for fractionation of Miscanthus lignocellulose using subcritical water extraction and a modified organosolv process.

Kubota, A. M., Kalnins, R. & Overton, T. W. (2018). Biomass and Bioenergy, 111, 52-59.

Using a biorefinery approach, biomass polymers such as lignin and carbohydrates can be selectively purified from lignocellulosic feedstocks with the aim of generating not only lignocellulosic bioethanol but also high value bio-based compounds. Furthermore, the efficient use of the entire biomass can increase overall feedstock value and significantly contribute to process cost-effectiveness. Therefore, the aim of this work was to fractionate the main compounds of the energy crop Miscanthus x giganteus (MxG) using ‘green’ solvents in order to obtain cellulose-enriched fibres as well as non-toxic streams rich in hemicellulose and lignin. Two processing routes were compared: a direct 1-step modified organosolv method for simultaneous lignin and hemicellulose removal; and a 3-step sequential process using subcritical water extraction for recovery of first extractives then hemicellulose, followed by modified organosolv lignin extraction. Both methods successfully generated cellulose-enriched fibres; from a complex mixture of compounds present in MxG, it was possible to obtain fibres comprising 78% cellulose without the use of commonly-applied toxic solvents that can potentially limit end uses for processed biomass and/or need additional neutralization steps. Fibres generated by the direct and sequential processes were very similar in composition; however, physicochemical analysis of the fibres using scanning electron microscopy, Fourier-transform infrared spectroscopy and principal component analysis confirmed structural differences resulting from the two processing routes, which were demonstrated to have an impact on downstream processing.

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