scholarly journals Effect of Soluble Phenolic Compounds From Hydrothermally Pretreated Wheat Straw on Cellulose Degrading Enzymes

2021 ◽  
Author(s):  
Anna S. Borisova ◽  
Ville Pihlajaniemi ◽  
Riin Kont ◽  
Klaus Niemelä ◽  
Taru Koitto ◽  
...  
Keyword(s):  
Phenolic Compounds ◽  
Enzymatic Hydrolysis ◽  
Degradation Products ◽  
Cellulose Degradation ◽  
Hydrolytic Activity ◽  
Cellulolytic Enzymes ◽  
Crystalline Cellulose ◽  
Lytic Polysaccharide Monooxygenase ◽  
Enzyme Cocktail ◽  
Pretreatment Conditions

Abstract Background: Hydrothermal methods are commonly applied in pretreatment of lignocellulose for enhanced enzymatic hydrolysis and further conversion to biofuels and chemicals. The pretreatment partially disassemble and solubilize cell wall polymers. Besides mono- and oligosaccharides, the soluble degradation products include various phenolic compounds, which may affect the efficiency of enzymatic hydrolysis. Results: The phenolic compounds were isolated from pretreatment liquor and their effects on cellulolytic enzymes were investigated. The major enzymes in crystalline cellulose degradation, cellobiohydrolases, were inhibited by the oligophenolics and phenolic-carbohydrate conjugates the latter of which could be mitigated by other enzymes, i.e. xylanases and endoglucanases. Hydrolytic activity of a commercial enzyme cocktail containing lytic polysaccharide monooxygenase (LPMO) was enhanced in presence of low concentrations of phenolics.Conclusions: The effects of the pretreatment liquor phenolics is dependent on enzyme concentration and type of the phenolic compounds. For optimized performance, the pretreatment conditions and enzyme cocktail composition should be designed to promote oxidative activities for enhanced hydrolysis, degradation of the oligosaccharides linked to phenolics and resistance to oligophenolic compounds.

scholarly journals Supercharged Cellulases Show Reduced Non-Productive Binding, But Enhanced Activity, on Pretreated Lignocellulosic Biomass

2021 ◽  
Author(s):  
Bhargava Nemmaru ◽  
Jenna Douglass ◽  
John M Yarbrough ◽  
Antonio De Chellis ◽  
Srivatsan Shankar ◽  
...  
Keyword(s):  
Cell Wall ◽  
Corn Stover ◽  
Lignocellulosic Biomass ◽  
Hydrolytic Activity ◽  
Fine Tuning ◽  
Cellulolytic Enzymes ◽  
Crystalline Cellulose ◽  
Cell Wall Components ◽  
Carbohydrate Binding Modules ◽  
Wall Components

Non-productive adsorption of cellulolytic enzymes to various plant cell wall components, such as lignin and cellulose, necessitates high enzyme loadings to achieve efficient conversion of pretreated lignocellulosic biomass to fermentable sugars. Carbohydrate-binding modules (CBMs), appended to various catalytic domains (CDs), promote lignocellulose deconstruction by increasing targeted substrate-bound CD concentration but often at the cost of increased non-productive enzyme binding. Here, we demonstrate how a computational protein design strategy can be applied to a model endocellulase enzyme (Cel5A) from Thermobifida fusca to allow fine-tuning its CBM surface charge, which led to increased hydrolytic activity towards pretreated lignocellulosic biomass (e.g., corn stover) by up to ~330% versus the wild-type Cel5A control. We established that the mechanistic basis for this improvement arises from reduced non-productive binding of supercharged Cel5A mutants to cell wall components such as crystalline cellulose (up to 1.7-fold) and lignin (up to 1.8-fold). Interestingly, supercharged Cel5A mutants that showed improved activity on various forms of pretreated corn stover showed increased reversible binding to lignin (up to 2.2-fold) while showing no change in overall thermal stability remarkably. In general, negative supercharging led to increase hydrolytic activity towards both pretreated lignocellulosic biomass and crystalline cellulose whereas positive supercharging led to a reduction of hydrolytic activity. Overall, selective supercharging of protein surfaces was shown to be an effective strategy for improving hydrolytic performance of cellulolytic enzymes for saccharification of real-world pretreated lignocellulosic biomass substrates. Future work should address the implications of supercharging cellulases from various families on inter-enzyme interactions and synergism.

scholarly journals Proteomic Dissection of the Cellulolytic Machineries Used by Soil-DwellingBacteroidetes

mSystems ◽  
2018 ◽  
Vol 3 (6) ◽  
Author(s):  
Marcel Taillefer ◽  
Magnus Ø. Arntzen ◽  
Bernard Henrissat ◽  
Phillip B. Pope ◽  
Johan Larsbrink
Keyword(s):  
Cellular Localization ◽  
Cellulose Degradation ◽  
Biomass Conversion ◽  
Cellulolytic Enzymes ◽  
Crystalline Cellulose ◽  
Glycoside Hydrolase Family ◽  
Label Free ◽  
Cellulose Conversion ◽  
Content Type ◽  
Highly Efficient

ABSTRACTBacteria of the phylumBacteroidetesare regarded as highly efficient carbohydrate metabolizers, but most species are limited to (semi)soluble glycans. The soilBacteroidetesspeciesCytophaga hutchinsoniiandSporocytophaga myxococcoideshave long been known as efficient cellulose metabolizers, but neither species conforms to known cellulolytic mechanisms. Both species require contact with their substrate but do not encode cellulosomal systems of cell surface-attached enzyme complexes or the polysaccharide utilization loci found in many otherBacteroidetesspecies. Here, we have fractionated the cellular compartments of each species from cultures growing on crystalline cellulose and pectin, respectively, and analyzed them using label-free quantitative proteomics as well as enzymatic activity assays. The combined results enabled us to highlight enzymes likely to be important for cellulose conversion and to infer their cellular localization. The combined proteomes represent a wide array of putative cellulolytic enzymes and indicate specific and yet highly redundant mechanisms for cellulose degradation. Of the putative endoglucanases, especially enzymes of hitherto-unstudied glycoside hydrolase family, 8 were abundant, indicating an overlooked important role during cellulose metabolism. Furthermore, both species generated a large number of abundant hypothetical proteins during cellulose conversion, providing a treasure trove of targets for future enzymology studies.IMPORTANCECellulose is the most abundant renewable polymer on earth, but its recalcitrance limits highly efficient conversion methods for energy-related and material applications. Though microbial cellulose conversion has been studied for decades, recent advances showcased that large knowledge gaps still exist. Bacteria of the phylumBacteroidetesare regarded as highly efficient carbohydrate metabolizers, but most species are limited to (semi)soluble glycans. A few species, including the soil bacteriaC. hutchinsoniiandS. myxococcoides, are regarded as cellulose specialists, but their cellulolytic mechanisms are not understood, as they do not conform to the current models for enzymatic cellulose turnover. By unraveling the proteome setups of these two bacteria during growth on both crystalline cellulose and pectin, we have taken a significant step forward in understanding their idiosyncratic mode of cellulose conversion. This report provides a plethora of new enzyme targets for improved biomass conversion.

scholarly journals Components Analysis of Recycled Alkali Black Liquor Combined with Corn Straw under Ozone Pretreatment

2021 ◽  
Author(s):  
Fei Li ◽  
Xiaohong Lu ◽  
Yiming Li ◽  
Shuo Fang ◽  
Xia Zhou ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Degradation Products ◽  
Lignin Content ◽  
Black Liquor ◽  
Hydrolysis Rate ◽  
Corn Straw ◽  
Pretreatment Conditions ◽  
Total Dissolved Solid ◽  
Hydrolysis Of ◽  
Cellulase Hydrolysis

Abstract Previous studies showed that the cellulase hydrolysis of corn straw pretreated with circulating alkali black liquor combined with ozone was suppressed. In this paper, the alkali black liquor was sequentially withdrawn for 0–6 times under the optimal pretreatment conditions, and components characterization was analyzed to identify the main factors inhibiting cellulase hydrolysis in recycled alkali black liquor. Through the component analysis, the organic matter and acid precipitation contents increased throughout the cycles. At the fourth cycle, the cellulase hydrolysis rate was decreased significantly, the growth of lignin content in alkali black liquor was slowed down and the total dissolved solid increment was decreased to 8.33mg/mL, 69.52% lower than previous cycle increase. GC-MS results showed that phenols, benzene ring heterocyclic and furans were main degradation products. It indicated that small molecular organics and lignin were inhibitors of cellulase hydrolysis, which accumulated during recycling, reducing alkali utilization and delignification efficiency, resulting in lower enzymatic hydrolysis rate. This study has revealed the components inhibiting the enzymatic hydrolysis of corn straw in recycled alkali black liquor, which is beneficial to the recovery and efficient utilization of recycled alkali black liquor.

scholarly journals Synergistic Saccharification, and Direct Fermentation to Ethanol, of Amorphous Cellulose by Use of an Engineered Yeast Strain Codisplaying Three Types of Cellulolytic Enzyme

2004 ◽  
Vol 70 (2) ◽  
pp. 1207-1212 ◽  
Author(s):  
Yasuya Fujita ◽  
Junji Ito ◽  
Mitsuyoshi Ueda ◽  
Hideki Fukuda ◽  
Akihiko Kondo
Keyword(s):  
Cell Surface ◽  
Yeast Strain ◽  
Cellulose Degradation ◽  
Surface Display ◽  
Hydrolytic Activity ◽  
Cellulolytic Enzymes ◽  
Cellulolytic Enzyme ◽  
Amorphous Cellulose ◽  
Endoglucanase Ii ◽  
Cellobiohydrolase Ii

ABSTRACT A whole-cell biocatalyst with the ability to induce synergistic and sequential cellulose-degradation reaction was constructed through codisplay of three types of cellulolytic enzyme on the cell surface of the yeast Saccharomyces cerevisiae. When a cell surface display system based on α-agglutinin was used, Trichoderma reesei endoglucanase II and cellobiohydrolase II and Aspergillus aculeatus β-glucosidase 1 were simultaneously codisplayed as individual fusion proteins with the C-terminal-half region of α-agglutinin. Codisplay of the three enzymes on the cell surface was confirmed by observation of immunofluorescence-labeled cells with a fluorescence microscope. A yeast strain codisplaying endoglucanase II and cellobiohydrolase II showed significantly higher hydrolytic activity with amorphous cellulose (phosphoric acid-swollen cellulose) than one displaying only endoglucanase II, and its main product was cellobiose; codisplay of β-glucosidase 1, endoglucanase II, and cellobiohydrolase II enabled the yeast strain to directly produce ethanol from the amorphous cellulose (which a yeast strain codisplaying β-glucosidase 1 and endoglucanase II could not), with a yield of approximately 3 g per liter from 10 g per liter within 40 h. The yield (in grams of ethanol produced per gram of carbohydrate consumed) was 0.45 g/g, which corresponds to 88.5% of the theoretical yield. This indicates that simultaneous and synergistic saccharification and fermentation of amorphous cellulose to ethanol can be efficiently accomplished using a yeast strain codisplaying the three cellulolytic enzymes.

scholarly journals Steam Explosion for Wheat Straw Pretreatment for Sugars Production

Bioethanol ◽  
2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Pablo Alvira ◽  
María José Negro ◽  
Ignacio Ballesteros ◽  
Alberto González ◽  
Mercedes Ballesteros
Keyword(s):  
Enzymatic Hydrolysis ◽  
Wheat Straw ◽  
Steam Explosion ◽  
Large Scale ◽  
Degradation Products ◽  
Transport Sector ◽  
High Solids Loading ◽  
Hydrolysis Process ◽  
Pretreatment Conditions ◽  
Pretreated Wheat Straw

AbstractDevelopment of biofuels such as lignocellulosic ethanol represents a sustainable alternative in the transport sector. Wheat straw is a promising feedstock for bioethanol production in Europe due to its large production and high carbohydrates content. In a process to produce cellulosic ethanol, previous to the enzymatic hydrolysis to obtain fermentable sugars and the subsequent fermentation, a pretreatment step to break down the recalcitrance of lignocellulose fiber is essential. In this work, a range of steam explosion pretreatment conditions were evaluated according to different parameters: sugars recovery, degradation products generation, and enzymatic hydrolysis yields. Moreover, the enzymatic hydrolysis process was also studied at high substrate loadings, since operating at high solids loading is crucial for large scale development of ethanol production. Pretreatment at 200°C - 10 min resulted in higher enzymatic hydrolysis yield (91.7%) and overall glucose yields (35.4 g glucose/100 g wheat straw) but also higher production of toxic compound. In turn, the characteristics of the pretreated wheat straw at lower severity (Log R0=3.65) correspond to 190°C and 10 min, with minimal sugars degradation and toxics formation indicated a great potential for maximizing total sugars production by using optimal enzyme combinations including accessory enzymes in the enzymatic hydrolysis step.

scholarly journals Olive Pomace Phenolic Compounds Stability and Safety Evaluation: From Raw Material to Future Ophthalmic Applications

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 6002
Author(s):  
Nikolaos Katsinas ◽  
Amalia Enríquez-de-Salamanca ◽  
Andreia Bento da Bento da Silva ◽  
Maria Rosário Bronze ◽  
Soraya Rodríguez-Rojo
Keyword(s):  
Phenolic Compounds ◽  
Ocular Surface ◽  
Degradation Products ◽  
Safety Evaluation ◽  
Raw Material ◽  
Total Phenolic ◽  
Olive Pomace ◽  
Pretreatment Conditions ◽  
The Stability ◽  
Compounds Stability

Nowadays, increasing interest in olive pomace (OP) valorization aims to improve olive’s industry sustainability. Interestingly, several studies propose a high-value application for OP extracts containing its main phenolic compounds, hydroxytyrosol and oleuropein, as therapy for ocular surface diseases. In this work, the stability and accessibility of OP total phenolic and flavonoid content, main representative compounds, and antioxidant activity were assessed under different pretreatment conditions. Among them, lyophilization and supercritical CO2 extraction were found to increase significantly most responses measured in the produced extracts. Two selected extracts (CONV and OPT3) were obtained by different techniques (conventional and pressurized liquid extraction); Their aqueous solutions were characterized by HPLC-DAD-MS/MS. Additionally, their safety and stability were evaluated according to EMA requirements towards their approval as ophthalmic products: their genotoxic effect on ocular surface cells and their 6-months storage stability at 4 different temperature/moisture conditions (CPMP/ICH/2736/99), together with pure hydroxytyrosol and oleuropein solutions. The concentration of hydroxytyrosol and oleuropein in pure or extract solutions was tracked, and possible degradation products were putatively identified by HPLC-DAD-MS/MS. Hydroxytyrosol and oleuropein had different stability as standard or extract solutions, with oleuropein also showing different degradation profile. All compounds/extracts were safe for ophthalmic use at the concentrations tested.

scholarly journals Generation of highly amenable cellulose-Iβ via selective delignification of rice straw using a reusable cyclic ether-assisted deep eutectic solvent system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chiranjeevi Thulluri ◽  
Ravi Balasubramaniam ◽  
Harshad Ravindra Velankar
Keyword(s):  
Enzymatic Hydrolysis ◽  
Rice Straw ◽  
Deep Eutectic Solvent ◽  
Solvent System ◽  
Cyclic Ether ◽  
Cellulolytic Enzymes ◽  
Ammonium Bromide ◽  
Selective Delignification ◽  
Cellulose Iβ ◽  
Hydrolysis Of

AbstractCellulolytic enzymes can readily access the cellulosic component of lignocellulosic biomass after the removal of lignin during biomass pretreatment. The enzymatic hydrolysis of cellulose is necessary for generating monomeric sugars, which are then fermented into ethanol. In our study, a combination of a deep eutectic (DE) mixture (of 2-aminoethanol and tetra-n-butyl ammonium bromide) and a cyclic ether (tetrahydrofuran) was used for selective delignification of rice straw (RS) under mild conditions (100 °C). Pretreatment with DE-THF solvent system caused ~ 46% delignification whereas cellulose (~ 91%) and hemicellulose (~ 67%) recoveries remained higher. The new solvent system could be reused upto 10 subsequent cycles with the same effectivity. Interestingly, the DE-THF pretreated cellulose showed remarkable enzymatic hydrolysability, despite an increase in its crystallinity to 72.3%. Contrary to conventional pretreatments, we report for the first time that the enzymatic hydrolysis of pretreated cellulose is enhanced by the removal of lignin during DE-THF pretreatment, notwithstanding an increase in its crystallinity. The current study paves way for the development of newer strategies for biomass depolymerization with DES based solvents.

P. vortex-mediated strategies for polysaccharides decomposition

TECHNOLOGY ◽  
2015 ◽  
Vol 03 (02n03) ◽  
pp. 80-83
Author(s):  
Mark Polikovsky ◽  
Eshel Ben-Jacob ◽  
Alin Finkelshtein
Keyword(s):  
Degradation Products ◽  
Cellulose Degradation ◽  
Cellulose Hydrolysis ◽  
Industrial Applications ◽  
Biofuel Production ◽  
E Coli ◽  
Novel Approach ◽  
Textile Manufacture ◽  
Hydrolysis Of Cellulose ◽  
The Relationship

Cellulose hydrolysis has many industrial applications such as biofuel production, food, paper and textile manufacture. Here, we present a novel approach to cellulose hydrolysis using a consortium of motile bacteria, Paenibacillus vortex, that can swarm on solid medium carrying a non-motile recombinant E. coli cargo strain expressing the β-glucosidase and cellulase genes that facilitate the hydrolysis of cellulose. These two species cooperate; the relationship is mutually beneficial: the E. coli is dispersed over long distances, while the P. vortex bacteria gain from the supply of cellulose degradation products. This enables the use of such consortia in this area of biotechnology.

Sorption of radionuclides to a cementitious backfill material under near-field conditions

2012 ◽  
Vol 76 (8) ◽  
pp. 3401-3410 ◽  
Author(s):  
M. Felipe-Sotelo ◽  
J. Hinchliff ◽  
N. Evans ◽  
P. Warwick ◽  
D. Read
Keyword(s):  
Organic Compounds ◽  
Degradation Products ◽  
Cellulose Degradation ◽  
Near Field ◽  
Organic Ligand ◽  
Sorption Isotherms ◽  
Field Conditions ◽  
Sorption Behaviour ◽  
Backfill Material ◽  
Order Of Magnitude

AbstractThe sorption behaviour of I−, Cs+, Ni2+, Eu3+, Th4+ and UO2+2on NRVB (Nirex reference vault backfill) a possible vault backfill, at pH 12.8 was studied. Sorption isotherms generated were compared to results obtained in the presence of cellulose degradation products (CDP). Whereas Cs was not affected by the presence of the organic compounds, a notable reduction in the sorption of Th and Eu to cement was observed. The results also indicated limited removal of Ni from solution (with or without an organic ligand) by sorption, the concentration in solution seemingly being determined solely by solubility processes. In the case of uranium, the presence of CDP increased the sorption to cement by almost one order of magnitude. Further studies into the uptake of CDP by cement are being undertaken to identify the mechanism(s) responsible.

scholarly journals Novel Kinetic Models of Xylan Dissolution and Degradation during Ethanol Based Auto-Catalyzed Organosolv Pretreatment of Bamboo

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1149 ◽  
Author(s):  
Jing Liu ◽  
Zhenggang Gong ◽  
Guangxu Yang ◽  
Lihui Chen ◽  
Liulian Huang ◽  
...  
Keyword(s):  
Kinetic Models ◽  
Degradation Products ◽  
Practical Significance ◽  
Order Kinetic ◽  
Organosolv Pretreatment ◽  
Dependent Parameter ◽  
Pretreatment Temperature ◽  
Pretreatment Conditions ◽  
Main Components ◽  
The Relationship

Due to the invalidity of traditional models, pretreatment conditions dependent parameter of susceptible dissolution degree of xylan (dX) was introduced into the kinetic models. After the introduction of dX, the dissolution of xylan, and the formation of xylo-oligosaccharides and xylose during ethanol based auto-catalyzed organosolv (EACO) pretreatments of bamboo were well predicted by the pseudo first-order kinetic models (R2 > 97%). The parameter of dX was verified to be a variable dependent of EACO pretreatment conditions (such as solvent content in pretreatment liquor and pretreatment temperature). Based on the established kinetic models of xylan dissolution, the dissolution of glucan and the formation of degradation products (furfural and acetic acid) could also be empirically modeled (R2 > 97%). In addition, the relationship between xylan and lignin removal can provide guidance for alleviating the depositions of lignin or pseudo-lignin. The parameter of dX derived novel kinetic models can not only be used to reveal the multi-step reaction mechanisms of xylan, but also control the final removal of main components in bamboo during EACO pretreatments, indicating scientific and practical significance for governing the biorefinery of woody biomass.

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