Search

Enzyme immobilization has emerged as one of the pivotal technologies in enzyme engineering, offering substantial cost reductions associated with enzyme isolation and utilization. However, efficient catalysis of solid substrates with solid immobilized enzymes remains a challenge, typically exemplified by the hydrolysis of cellulose using immobilized cellulase. In this study, a novel system of reversible release and recycling of cellulase on the surface of low-density polyethylene (LDPE) "hull" was developed, inspired by the operational dynamics of carrier-based aircraft. The reversible formation and disruption of multiple hydrogen bonds between the grafted gelatin molecular chain on the LDPE surface and the modification arm of cellulase (poly (methacrylic acid-propenoic acid; PAA-PMAA) can be achieved through temperature control, thus enabling the reversible release and recycling of modified cellulase molecules on the LDPE surface. Results demonstrated that the release of modified cellulase (PLANE) from the LDPE surface overcame the mass transfer barrier inherent in traditional immobilized enzyme systems for catalyzing insoluble substrates. This was attributed to the dissolution of PLANE in the developed system, rendering its hydrolysis of the insoluble cellulose substrate comparable to that of the free enzyme. Upon completion of the reaction, the PLANE could be reversibly recycled on the surface of the macroscopic LDPE membrane, facilitated by the regeneration of multiple hydrogen bonds. Furthermore, the facile removal of the membrane aided in the convenient recycling of cellulase. Notably, the cellulase molecules in the system retained more than 50% of their biological activity even after 8 batches of reuse, making the process cost-effective. This method addressed the limitations of traditional immobilized enzymes, allowing the catalysis of solid substrates with elevated mass transfer and simultaneous easy recovery, thus standing out as a universal immobilization method. [ABSTRACT FROM AUTHOR]

This study proposes a chemical recycling pathway for valorizing the cellulosic component of municipal waste streams such as textile, cleaning wipes, corrugated cardboard, contaminated cardboard (i.e. a pizza box), paper-plastic laminate (PPL) coffee cups and cigarette butts (CBs). The goal of this study is to establish an experimental procedure that allows to test a broad range of cellulose-containing waste materials, laying the groundwork for commercial deployment of their chemical recycling. The cellulose contained in these materials is transformed into 5-chloromethylfurfural (CMF), a precursor for bio-based plastics, without affecting the plastic counterpart (if present). We employ a biphasic system concept using aqueous HCl solutions for CMF formation and in situ extraction from the reaction medium using immiscible organic solvents, enabling straightforward product separation. This method allows to hydrolyze cellulosic materials from waste without affecting PET or polyolefin plastic also present, facilitating the subsequent recycling of this plastic as well. This study serves as a foundation to assess the feasibility of using cellulose-containing waste streams for chemical recycling and to offer recommendations on selecting optimal reaction procedures.

The conversion of biomass into sugar platform compounds is very important for the biorefinery industry. Pretreatment is essential to the biomass of the sugar platform, however, the lignin obtained by pretreatment, as a key part of lignocellulose, generally has a passive effect on the enzymatic hydrolysis of cellulose into sugars. In this study, p-TsOH (p-toluenesulfonic acid), DES (Deep eutectic solvent) and CAOSA (cooking with active oxygen and solid alkali) pretreatment ways were used to fraction lignin from bamboo biomass. After CAOSA treatment, the hydrolysis efficiency of the pulp was 95.57%. Moreover, the effect of different treatment methods on lignin properties was studied and the promotion effect of lignin was investigated by adding it to the cellulose enzymatic hydrolysis system. In this work, the results showed that CAOSA-extracted lignin with lower Đ (1.31–1.25) had a better adsorption effect on the enzyme protein. p-TsOH-extracted lignin with a larger S/G ratio enhanced the inhibition of enzymatic hydrolysis. In addition, the presence of -COOHs in lignin could reduce its inhibitory effect on cellulose saccharification.

Increasing the efficiency of cellulose hydrolysis is a crucial milestone to enable its use as a platform for the production of renewable chemicals. Consequently, exploring alternative techniques for cellulose dissolution and subsequent depolymerization and hydrolysis remains a pivotal area of research. This study delves into the performance of diverse solid acid catalysts (ion-exchange resins, metal oxides, and zeolites) for cellulose depolymerization when combined with a concentrated solution of zinc chloride (ZnCl2) as the reaction medium and extractant. The influence of this molten salt hydrate on cellulose dissolution and the stability of the tested catalysts was thoroughly investigated. Optimal mild operating conditions (90 °C and 2 h) that facilitate enhanced conversion and selective glucose production were identified. The highest glucose yields (exceeding 40%) were obtained with Amberlyst-15 and HZSM-5 (SiO2/Al2O3 = 23), effectively mitigating product degradation and equaling or surpassing the traditional homogeneous system using H2SO4. Furthermore, insights into the deactivation mechanisms affecting the best catalysts are provided. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals are an important class of bio‐based crystalline nanostructures, finding application in several technological fields, including paper and textile coating, biocomposite engineering, biocatalysts immobilization, etc. This study explores enzymatic hydrolysis of Avicel, using endoglucanase from Aspergillus niger, to find an environmentally friendly method to extract cellulose nanocrystals from cellulose sources. Enzymatic hydrolysis has the advantage of reduced energy consumption and higher environmental friendliness compared to acid hydrolysis. In this work, we report for the first time very high nanocrystals yield by combining mechanical pretreatment of the cellulose starting material with a ball miller and endoglucanase hydrolysis, as a result of an extensive optimization of reaction conditions. In particular, a ball milling pretreatment carried out for 50 minutes at 3 Hz, allowed to isolate enzymatic CNCs with 76 % yield and with crystallinity as high as 75 %. The materials were characterized by X‐Ray diffractometry, attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, dynamic light scattering, zeta potential and field emission scanning electron microscopy (FE‐SEM). Their characteristics were compared with the properties of sulfated CNCs, prepared from Avicel by sulfuric acid hydrolysis. Our results are technologically relevant, as they contribute to the accessibility and sustainability of CNCs for a wide range of applications in various industries. [ABSTRACT FROM AUTHOR]

Understanding the reaction mechanisms involved in the enzymatic hydrolysis of cellulose is important because it is kinetically the most limiting step of the bioethanol production process. The present work focuses on the enzymatic deactivation at the air–liquid interface, which is one of the aspects contributing to this global deactivation. This phenomenon has already been experimentally proven, but this is the first time that a model has been proposed to describe it. Experiments were performed by incubating Celluclast cocktail solutions on an orbital stirring system at different enzyme concentrations and different surface‐to‐volume ratios. A 5‐day follow‐up was carried out by measuring the global FPase activity of cellulases for each condition tested. The activity loss was proven to depend on both the air–liquid surface area and the enzyme concentration. Both observations suggest that the loss of activity takes place at the air–liquid surface, the total amount of enzymes varying with volume or enzyme concentration. Furthermore, tests performed using five individual enzymes purified from a Trichoderma reesei cocktail showed that the only cellulase that is deactivated at the air–liquid interface is cellobiohydrolase II. From the experimental data collected by varying the initial enzyme concentration and the ratio surface to volume, it was possible to develop, for the first time, a model that describes the loss of activity at the air‐liquid interface for this configuration. [ABSTRACT FROM AUTHOR]

This study aimed to extract xylan by hydrogen peroxide in an alkaline medium, recover lignin, and evaluate the use of the pretreated material in the production of glucose via enzymatic hydrolysis. The formation of briquettes using different anatomical fractions of sugarcane (bagasse, epidermis-free stem, external fraction containing epidermis, and bagasse with the addition of lignin) was also evaluated. After xylan extraction with a yield of 62.71%, 33.6 2% of lignin was recovered by acid precipitation. The enzymatic hydrolysis of the pretreated material resulted in 71.10% of glucose. The briquettes made from the epidermis-free stem and external fraction showed better results in terms of ash, volatiles, and fixed carbon contents. Sugarcane bagasse generated briquettes with an energy density of 23,544.9 MJ/m3, and an external fraction of 25,711.8 MJ/m3. For the volumetric expansion, the briquettes made from bagasse and bagasse with the addition of lignin (recovered from xylan solubilization) presented less volumetric variation. The briquettes made from the external fraction with and without heating showed durability of over 97%. [ABSTRACT FROM AUTHOR]

Glycoside hydrolase family 7 (GH7) cellulases are key enzymes responsible for carbon cycling on earth through their role in cellulose degradation and constitute highly important industrial enzymes as well. Although these enzymes are found in a wide variety of evolutionarily distant organisms across eukaryotes, they exhibit remarkably conserved features within two groups: exo‐acting cellobiohydrolases and endoglucanases. However, recently reports have emerged of a separate clade of GH7 endoglucanases from protist symbionts of termites that are 60–80 amino acids shorter. In this work, we describe the first crystal structure of a short GH7 endoglucanase, RsSymEG1, from a symbiont of the lower termite Reticulitermes speratus. A more open flat surface and shorter loops around the non‐reducing end of the cellulose‐binding cleft indicate enhanced access to cellulose chains on the surface of cellulose microfibrils. Additionally, when comparing activities on polysaccharides to a typical fungal GH7 endoglucanase (Trichoderma longibrachiatum Cel7B), RsSymEG1 showed significantly faster initial hydrolytic activity. We also examine the prevalence and diversity of GH7 enzymes that the symbionts provide to the termite host, compare overall structures and substrate binding between cellobiohydrolase and long and short endoglucanase, and highlight the presence of similar short GH7s in other organisms. [ABSTRACT FROM AUTHOR]

In order to enhance the valorization of corncob, corncob-based solid acid catalysts were prepared via the method of partial carbonization followed by sulfonation. The prepared acid catalysts were either derived from raw corncob (hemicellulose, cellulose, and lignin), or its residues after different pretreatments, i.e., furfural residue (cellulose and lignin) and hydrolysis residue (humins and lignin), to investigate the components' effect on the performance of solid acid. These catalysts were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), nitrogen adsorption/desorption analysis, scanning electron microscope (SEM), elemental analysis, and acid–base titration. The analysis results suggested that the solid acid (Catalyst-3) derived from the hydrolysis residue had the best performance, with a BET surface area of 338.23 m2 g−1 and total acid densities of 6.43 mmol g−1. This results indicated –SO3H groups were loaded onto the catalyst successfully. The catalytic activity was tested by cellulose hydrolysis in lithium bromide trihydrate solution (LBTH) system. The yield of glucose was as high as 80.1% at the temperature of 110 °C for 10 h. Moreover, the prepared solid acid had the advantages of easy separation, mild reaction, and producing less by-products compared with traditional liquid acids. This work provides a promising strategy for corncob waste utilization and cellulose efficient hydrolysis, which is of great significance for biomass valorization and conversion. [ABSTRACT FROM AUTHOR]

Synchrotron infrared hyperspectral microscopy is a label-free and non-invasive technique well suited for imagingof chemical events in situ. It can track the spatial and temporal distributions of molecules of interests in a specimenin its native state by the molecule’s characteristic vibrational modes. Despite tremendous progress made in recentyears, IR hyperspectral imaging of chemical events in biomaterials in liquids remains challenging because of thedemanding requirements on environmental control and strong infrared absorption of water. Here we report amulti-phase capillary-driven membrane device for label-free and real-time investigation of enzymaticdeconstruction of algal cellulose purified from Cladophora aegagropila.

Kinetic modeling is essential in understanding and controlling the process of cellulose hydrolysis for producing value-added cellulose derivatives. This study aims to adopt a set of dominate kinetic ordinary differential equations of cornstalk cellulose hydrolysis in supercritical water for mechanism-based prediction of the production of cellulose, glucose, fructose, glyceraldehyde, erythrose, 5-hydroxymethyl furfural, glycolaldehyde, threose, aldose, and other cellulose derivatives from cornstalks under processing conditions with a pressure of 89 MPa and a temperature of 378 °C, as considered in a recent experimental study in the literature. The yield rates of several cellulose derivatives, e.g., glucose, fructose, 5-HMF, and erythrose as predicted by the present model, are close to those of experimental measurements. The model is further used to predict the yield rates of a few new cellulose derivatives, e.g., glycolaldehyde, threose, and aldose, that are potentially generated in cornstalk cellulose hydrolysis in supercritical water. The present model and computational simulations can be utilized as a rational tool to predict, control, and optimize the derivative yields in cellulose hydrolysis in supercritical water via tuning the process parameters, and, therefore, are useful for the optimal production of targeted bio-based fuels and chemicals from cornstalks and other agricultural and municipal wastes. [ABSTRACT FROM AUTHOR]

A comparative evaluation between two scenarios to utilize Empty Fruit Bunch (EFB) biomass residue for producing bioethanol was performed. The simulations included EFB-to Ethanol integrated into the Refined, Bleached & Deodorized (RBD) palm oil scenario as the first archetype and EFB-to-ethanol integrated with the pulping plant scenario as the second archetype. Literature reviews for each archetype were conducted to accomplish data for definitions, assumptions, and simulation analysis of each production stage. Ethanol production capacity was set at 255.55 kg as the basic calculation for mass and energy balances. The energy preference focused on energy efficiency and the environmental preference focused on consumed water and wastewater load. The simulation showed that excess energy from the Refined, Bleached & Deodorized Palm Oil (RBDPO) plant, which processes 5 tons of Fresh Fruit Bunch (FFB) equals to 82% of the required energy for producing 255.55 kg of ethanol. This required energy could also be supplied by excess energy from the combustion of 14.9 tons of dried black liquor in EFB pulping plant with 10.5 tons production capacity. The additional wastewater from the EFB-to-ethanol unit in the second archetype was only 2% of the wastewater from the EFB pulping plant with only a 5% increase in water consumption but it required a large production capacity. The first archetype could use 58.4% of the EFB waste. However, the required water increased from 5.3m3 to 20.88m3 for this archetype and required additional water treatment plant due to the different pollutant components from the additional installation units. The first archetype could gain additional income, which equals 18.5% of RBDPO sales. However, investment for integration of the first archetype was larger than the second archetype due to different types of additional installation units. Integration as in the second archetype required small modification and installation, with 2% additional income in 10.5 tons of pulp daily sales.

A highly efficient reactor with a stirring device was specially designed with the intent of performing the hydrolysis of pure crystalline cellulose using a carbon-based solid acid catalyst. This catalyst comprised an amorphous carbon-based material bearing –SO3H, –COOH and –OH groups. The stirring apparatus had seven blades coated with polytetrafluoroethylene and arranged axially at regular intervals with a 60° offset. This design proved highly effective, providing double the glucose yield compared with conventional stirring systems. The basic properties of this novel reactor were investigated and analyzed and are discussed herein.

The powder properties of a carbon-based solid acid catalyst, an amorphous carbon material bearing SO3H, COOH and OH groups, were investigated for the hydrolysis of cellulose. The Carr flowability and floodability indices, the angle of internal friction (adherence), and the particle size distribution and shape for the powder catalyst were determined. The need to develop a special reactor with a stirring apparatus for the hydrolysis of cellulose was determined based on the Carr flowability index. Insight into the interaction or adherence between the catalyst and crystalline cellulose during the hydrolysis process was gained by measuring the internal friction angle. The optimum moisture content in the catalyst to achieve the maximum adherence was investigated.

An innovative catalyst was developed for the purpose of simplifying the manufacturing process of biofuels without the need for costly materials. The incorporation of pyridine sulfonic acid (PSA) into silica rice husk (RH) was achieved by two distinct strategies, resulting in the production of a heterogeneous catalyst. The first catalyst, RHAPSA@Dir, was prepared using the Sol-Gel technique through a one-pot synthesis approach. The second catalyst, RHAPSA@Ref, was created through post-synthesis means. BET analysis of RHAPSA@Dir showed a significant improvement in surface area to 416 m2/g, while RHAPSA@Ref only exhibited 48.2 m2/g. Upon conducting elemental research on both catalysts, it was observed that the presence of carbon, nitrogen, and sulfur was apparent. The thermal study conducted indicated that approximately 47–48% of organic matter was lost from the silica at the anticipated temperature. The SEM analysis of RHAPSA@Dir revealed that a minor level of pore arrangement was observed. Furthermore, the TEM analysis of RHAPSA@Dir demonstrated that a few particles exhibited spherical nano shapes that were clearly visible. Conversely, the SEM analysis of RHAPSA@Ref showed a rough and porous surface with large particles. Lastly, the TEM micrograph of RHAPSA@Ref revealed spherical particles with an approximate diameter of 6 nm. The use of electron microscopy revealed the presence of spherical nanostructures. Both cellulose and glucose underwent hydrolyzation over the catalysts within 2–6 h at 140 °C. The essential properties of both catalysts were their stability and reusability.

The plantain agro-industry generates different residues in the harvest and post-harvest stages. Therefore, new processes for its valorization are required. The aim of this research was to propose a general methodological framework for the design and analysis of multi-input biorefineries for the valorization of residues with a high content of lignocellulosic and starchy materials. This approach was based on the independent processing of the starchy and lignocellulosic materials in the first steps of the biorefinery and relies on process simulation and hierarchic process design procedures. A case study for the design of a multi-input biorefinery for the valorization of residues from the plantain agro-industry was performed by applying the framework proposed. The biorefinery was simulated using SuperPro Designer software. The results obtained suggest that the best alternative for the valorization of plantain residues under Colombian conditions corresponded to the following distribution of key residues: 100% leaf sheaths processed into the natural fiber production section, and 25% peels and 25% rachis processed into the starch extraction and liquefaction section; with this distribution, an NPV of $21,348,000 can be achieved. This work shows that waste from the plantain agro-industry exhibits high potential as a feedstock for the production of value-added products. [Display omitted] • Novel framework to design multi-input biorefineries was developed and applied. • The framework considers the separation of lignocellulosic and starchy components. • Distribution of residual feedstocks directly impacts biorefinery profitability. • Several processes using plantain waste were integrated into a biorefinery. • Plantain residues have high potential as feedstocks in a multi-input biorefinery. [ABSTRACT FROM AUTHOR]

The cellulose-water interface is a dynamic environment mostly dominated by interactions between water molecules and hydroxyl groups protruding from the top layer of the polysaccharide chains. This interface has attracted increasing interest within the context of hydrolysis with glycosyl hydrolases, and studies on the role of tightly bound and free water has emerged. At the molecular level, cellulose-bound water has been considered important to allow enzymatic hydrolysis at industrial relevant conditions, i.e. at high dry matter (HDM) contents. In the presence of lytic polysaccharide monooxygenase enzymes, the hydrolysis can with effective yields be run at well beyond the dry matter limit previously set by the 1st generation of enzyme preparations lacking LPMOs. The oxidative cleavage of the cellulose chain performed by LPMOs allow a higher level of synergism with GH in terms of accessibility of the cellulose surface. In this work, we studied how cellulose oxidation by LPMO increases the cellulose-water interaction and the impact of this on cellulose saccharification. Low-field NMR, water constraint and enzyme kinetics at high dry matter contents were used to characterize the cellulose-water interaction and its implications in enzymatic cellulose hydrolysis. [ABSTRACT FROM AUTHOR]

Lignin is one of the important components of lignocellulosic cell walls, which endows plant cell walls with rigidity and strength and protects them from microbial invasion. The presence of lignin is thought to hinder the conversion of biomass to bioenergy, so understanding enzyme-lignin interactions is very important in order to reduce the inhibition of lignin and improve the hydrolysis yields. Conversion of lignocellulosic raw materials into bioethanol is divided into pretreatment, enzymatic hydrolysis, and fermentation. In this paper, both pretreatment and enzymatic hydrolysis of lignocellulose are described in detail. Finally, the reasons why lignin hinders enzymatic hydrolysis efficiency, mainly from forming spatial barriers and interacting with cellulase, are discussed, and the influencing factors and mechanisms of action of cellulase hydrolysis are explored with a view to targeted regulation of lignin structure to improve lignocellulosic saccharification.

Pulp and paper mill sludge (PPMS) is currently disposed of into landfills which are reaching their maximum capacity. Valorisation of PPMS by enzymatic hydrolysis using cellulases is an alternative strategy. Existing commercial cellulases are expensive and contain low titres of β-glucosidases. In this study, β-glucosidase production was optimised by Aspergillus japonicus VIT-SB1 to obtain higher β-glucosidase titres using the One Variable at a Time (OVAT), Plackett Burman (PBD), and Box Behnken design (BBD)of experiments and the efficiency of the optimised cellulase cocktail to hydrolyse cellulose was tested. β-Glucosidase production was enhanced from 0.4 to 10.13 U/mL, representing a 25.3-fold increase in production levels after optimisation. The optimal BBD production conditions were 6 days of fermentation at 20 °C, 125 rpm, 1.75% soy peptone, and 1.25% wheat bran in (pH 6.0) buffer. The optimal pH for β-glucosidase activity in the crude cellulase cocktail was (pH 5.0) at 50 °C. Optimal cellulose hydrolysis using the crude cellulase cocktail occurred at longer incubation times, and higher substrate loads and enzyme doses. Cellulose hydrolysis with the A. japonicus VIT-SB1 cellulase cocktail and commercial cellulase cocktails resulted in glucose yields of 15.12 and 12.33 µmol/mL glucose, respectively. Supplementation of the commercial cellulase cocktail with 0.25 U/mg of β-glucosidase resulted in a 19.8% increase in glucose yield. [ABSTRACT FROM AUTHOR]

A comparative evaluation between two scenarios to utilize Empty Fruit Bunch (EFB) biomass residue for producing bioethanol was performed. The simulations included EFB-to Ethanol integrated into the Refined, Bleached & Deodorized (RBD) palm oil scenario as the first archetype and EFB-to-ethanol integrated with the pulping plant scenario as the second archetype. Literature reviews for each archetype were conducted to accomplish data for definitions, assumptions, and simulation analysis of each production stage. Ethanol production capacity was set at 255.55 kg as the basic calculation for mass and energy balances. The energy preference focused on energy efficiency and the environmental preference focused on consumed water and wastewater load. The simulation showed that excess energy from the Refined, Bleached & Deodorized Palm Oil (RBDPO) plant, which processes 5 tons of Fresh Fruit Bunch (FFB) equals to 82% of the required energy for producing 255.55 kg of ethanol. This required energy could also be supplied by excess energy from the combustion of 14.9 tons of dried black liquor in EFB pulping plant with 10.5 tons production capacity. The additional wastewater from the EFB-to-ethanol unit in the second archetype was only 2% of the wastewater from the EFB pulping plant with only a 5% increase in water consumption but it required a large production capacity. The first archetype could use 58.4% of the EFB waste. However, the required water increased from 5.3 m3 to 20.88 m3 for this archetype and required additional water treatment plant due to the different pollutant components from the additional installation units. The first archetype could gain additional income, which equals 18.5% of RBDPO sales. However, investment for integration of the first archetype was larger than the second archetype due to different types of additional installation units. Integration as in the second archetype required small modification and installation, with 2% additional income in 10.5 tons of pulp daily sales. [ABSTRACT FROM AUTHOR]

Cyanobacteria are rich sources of secondary metabolites and have the potential to be excellent industrial enzyme producers. β-glucosidases are extensively employed in processing biomass degradation as they mediate the most crucial step of bioconversion of cellobiose (CBI), hence controlling the efficiency and global rate of biomass hydrolysis. However, the production and availability of these enzymes derived from cyanobacteria remains limited. In this study, we evaluated the β-glucosidase from Microcystis aeruginosa CACIAM 03 (MaBgl3) and its potential for bioconversion of cellulosic biomass by analyzing primary/secondary structures, predicting physicochemical properties, homology modeling, molecular docking, and simulations of molecular dynamics (MD). The results showed that MaBgl3 derives from an N-terminal domain folded as a distorted β-barrel, which contains the conserved His–Asp catalytic dyad often found in glycosylases of the GH3 family. The molecular docking results showed relevant interactions with Asp81, Ala271 and Arg444 residues that contribute to the binding process during MD simulation. Moreover, the MD simulation of the MaBgl3 was stable, shown by analyzing the root mean square deviation (RMSD) values and observing favorable binding free energy in both complexes. In addition, experimental data suggest that MaBgl3 could be a potential enzyme for cellobiose-hydrolyzing degradation. [ABSTRACT FROM AUTHOR]

Cellulosic ethanol produced using the enzymatic method is promising; however, developing an efficient and green cellulase hydrolysis system to cut the cost of cellulosic ethanol and promote cleaner biofuel production remains challenging. Herein, based on the fact that multiple hydrogen bond can be generated between poly (methyl acrylic acid- co -acrylic acid) and gelatin, cellulase was first covalently bonded to the copolymer and then mixed with gelatin, to endow the cellulase with ideal upper critical solution temperature (UCST). As a result, the affinity between cellulase and the substrate did not decrease significantly after the modification (the K m value of modified cellulase (4.62 g/L) was not significantly different from that of free cellulase (4.55 g/L)). The enzymes can be switched on-demand between free state (above 36 °C), enabling high hydrolysis reactivity for insoluble substrates such as paper or corn stalks, and fixed state (at 4 °C), facilitating enzymes separation and reuse (the modified cellulase still has 58.2% of its initial activity for 20 batches). Thus, the cost of cellulosic ethanol production could be significantly reduced in the precondition of high catalytic efficiency. Furthermore, the system presents nontoxic and biodegradable properties. The system can be completely degraded in soil after 7 days and the inhibition rate of the degraded products on luminescent bacteria was only 2%, which can promote cleaner cellulosic biofuel production. [Display omitted] [ABSTRACT FROM AUTHOR]

This work evaluated the effectiveness of a novel deep eutectic solvents (DES) prepared from guaiacol (GG), and p-hydroxybenzoic acid (PB) as a double hydrogen bond donor and choline chloride (ChCl) as a hydrogen bond receptor. The effect of ChCl-GG-PB on the structural properties and enzymatic hydrolysis of peanut shell was analyzed. Furthermore, the performance of ChCl-GG-PB as a hydrogen bond donor was compared with two other DES of PB and GG as hydrogen bond donors, and the effects of molar ratio, temperature and time were studied. The results showed that after ChCl-GG-PB pretreatment, hemicellulose and lignin were effectively removed, the removal rate was about 63.36% and 69.54%, respectively, and the enzymatic glycosaccharification efficiency was significantly improved, of which the xylose content was 5.5 times higher than the untreated. In addition, ChCl-GG-PB pretreated showed significant changes in the structure and morphology, with the highest crystallinity and lowest solid recovery. These results affirms that the proposed novel ternary DES is a promising pretreatment solvent that can effectively deconstruct lignocellulose and improve cellulose digestibility, thereby achieving an economically viable biomass conversion method. [Display omitted] [ABSTRACT FROM AUTHOR]

Lignin is one of the important components of lignocellulosic cell walls, which endows plant cell walls with rigidity and strength and protects them from microbial invasion. The presence of lignin is thought to hinder the conversion of biomass to bioenergy, so understanding enzyme-lignin interactions is very important in order to reduce the inhibition of lignin and improve the hydrolysis yields. Conversion of lignocellulosic raw materials into bioethanol is divided into pretreatment, enzymatic hydrolysis, and fermentation. In this paper, both pretreatment and enzymatic hydrolysis of lignocellulose are described in detail. Finally, the reasons why lignin hinders enzymatic hydrolysis efficiency, mainly from forming spatial barriers and interacting with cellulase, are discussed, and the influencing factors and mechanisms of action of cellulase hydrolysis are explored with a view to targeted regulation of lignin structure to improve lignocellulosic saccharification. [ABSTRACT FROM AUTHOR]

A sucralose-derived magnetically separable carbon-based solid acid catalyst with cellulose-binding and catalytic sites has been successfully prepared by incompletely carbonizing the sulfonated sucralose with Fe3+ at high temperature to load ɤ-Fe2O3 nanoparticles onto the surface of the catalyst. The resultant magnetic catalyst was fully characterized and found to be suitable in the hydrolysis of cellulose. Microcrystalline cellulose pretreated by ball milling achieved the highest glucose yield of 32% using this neoteric catalyst at 363 K. Catalysts retained 90% of their activity after five runs recycle. The introduction of magnetic properties into the catalyst system will combine the high catalytic capacity for hydrolyzing cellulose and magnetic materials' separation convenience. [ABSTRACT FROM AUTHOR]

[Display omitted] Growing populations and climate change pose great challenges to food security. Humankind is confronting a serious question: how will we feed the world in the near future? This study presents an out-of-the-box solution involving the highly efficient biosynthesis of artificial starch and microbial proteins from available and abundant agricultural residue as new feed and food sources. A one-pot biotransformation using an in vitro coenzyme-free synthetic enzymatic pathway and baker's yeast can simultaneously convert dilute sulfuric acid-pretreated corn stover to artificial starch and microbial protein under aerobic conditions. The β-glucosidase-free commercial cellulase mixture plus an ex vivo two-enzyme complex containing cellobiose phosphorylase and potato α-glucan phosphorylase displayed on the surface of Saccharomyces cerevisiae , showed better cellulose hydrolysis rates than a commercial β-glucosidase-rich cellulase mixture. This is because the channeling of the hydrolytic product from the solid cellulosic feedstock to the yeast mitigated the inhibition of the cellulase cocktail. Animal tests have shown that the digestion of artificial amylose results in slow and relatively small changes in blood sugar levels, suggesting that it could be a new health food component that prevents obesity and diabetes. A combination of the utilization of available agricultural residue and the biosynthesis of starch and microbial protein from non-food biomass could address the looming food crisis in the food–energy–water nexus. [ABSTRACT FROM AUTHOR]

• The Ru-30WOx-C catalyst exhibits the best acid-metal balance (7.4). • The 3%Ru supported on 30%WO X -C exhibited the highest ethylene glycol yield (61.3%). • 30%WOx-C facilitates Ru dispersion and provides rich acid sites. • Reasonable adjustment of acid-metal facilitates ethylene glycol production notably. Ru-WO X composites are usually bi-functional catalysts for cellulose hydrogenolysis, but the proportion/synergism of Ru (metal) and WO X (acidity) are mismatched/unclear, this leads to low ethylene glycol (EG) yield. In this work, we doped Ru‑WO X on low-costed biochar for cellulose hydrogenolysis. The acid-metal balance was adjusted by change the WO X load, and our results show that the activity and EG yield have the order of Ru-30WO X -C > Ru-40WO X -C > Ru-20WO X -C > Ru-10WO X -C, and it is interesting found that a linear relationship between acid/metal ratio and EG yield. Under the optimum conditions (240 °C, 3 MPa and 3 h), Ru-30WO X -C catalyst can achieve 100% cellulose conversion and 61.3% EG yield. 30%WO X facilitates Ru dispersion/reduction, and provides rich acid sites, accompanied by a large number of acid centers (oxygen vacancies), this more easily adsorbed cellulose monomer and activated glucose to glycolaldehyde, and benefit to EG productive. This work provides a guidance to design new bio-functional catalysts for biomass conversion. [Display omitted] [ABSTRACT FROM AUTHOR]

Efficient conversion of cellulose to glucose is a crucial challenge for the energy and materialization of non-food biomass. Solid acids' adsorption strength is essential to affecting mass transfer efficiency. In this study, solid acids with different particle sizes (from 0.25 to 10.10 μm) modified with -OH and -PO 3 H 2 were obtained by hydrothermal method. Hydrolysis of cellulose at 180 °C for 4 h revealed that the particle size of the solid acids was directly proportional to the cellulose conversion (R2 = 0.925). Still, there was no significant correlation with the glucose yield (R2 = 0.632). Eventually, the cellulose conversion reached 98.9 %, with a 30 % glucose yield. The solid acids demonstrated good stability and recoverability. This study fills the gap in the influence of solid acid particle size and reveals the mechanism of strong adsorptive mass transfer and hydrolysis efficiency. It provides the theoretical basis for the design of high-performance solid acids. The particle size of solid acids plays a pivotal role in enhancing mass transfer efficiency during catalytic cellulose hydrolysis. Generally, solid acids with a diameter of approximately 10 μm exhibit an external erosion mechanism, gradually degrading cellulose layers at the surface. This approach yields relatively low conversion (37.2 %) and glucose yield (20.7 %). In contrast, a smaller acid particle size of 0.25 μm facilitates penetration into cellulose's core, enabling simultaneous disintegration and catalysis from within and outside. This strategy achieves significantly higher conversion (98.2 %) and glucose yield (48.5 %). Consequently, particle size significantly affects mass transfer and hydrolysis efficiency. [Display omitted] • Particle size significantly affects mass transfer and hydrolysis efficiency. • Solid acid particle size significantly correlates with cellulose conversion (R2 = 0.925). • Nanoscale solid acid can disrupt the inner of cellulose, accelerating mass transfer. • Different particle sizes of solid acids were prepared by hydrothermal method. [ABSTRACT FROM AUTHOR]

Cellulose is a major renewable resource for a wide variety of sustainable industrial products. However, for its utilization, finding new efficient enzymes for plant cell wall depolymerization is crucial. In addition to microbial sources, cellulases also exist in plants, however, are less studied. Fleshy fruit ripening includes enzymatic cell wall hydrolysis, leading to tissue softening. Therefore, bilberry (Vaccinium myrtillus L.), which produces small fruits that undergo extensive and rapid softening, was selected to explore cellulases of plant origin. We identified 20 glycoside hydrolase family 9 (GH9) cellulases from a recently sequenced bilberry genome, including four of which showed fruit ripening-specific expression and could be associated with fruit softening based on phylogenetic, transcriptomic and gene expression analyses. These four cellulases were secreted enzymes: two B-types and two C-types with a carbohydrate binding module 49. For functional characterization, these four cellulases were expressed in Pichia pastoris. All recombinant enzymes demonstrated glucanase activity toward cellulose and hemicellulose substrates. Particularly, VmGH9C1 demonstrated high activity and ability to degrade cellulose, xyloglucan, and glucomannan. In addition, all the enzymes retained activity under wide pH (6–10) and temperature ranges (optimum 70 °C), revealing the potential applications of plant GH9 cellulases in the industrial bioprocessing of lignocellulose. [Display omitted] [ABSTRACT FROM AUTHOR]

The hydrolysis of the lignocelluloses to fermentable sugars seems to be the main reason for the high producing cost of ethanol from lignocelluloses. The objective of this work is to test two strains of Trichoderma in liquid state and solid state cultures for cellulase production, and to compare the productivity and efficiency of the two systems of fermentation. Submerged liquid cultures (SLC) and solid state cultures (SSC) were carried out to compare the productivity of the two strains of Trichoderma. Comparing the productions of cellulases in the systems applied in this study, data indicate the system of solid state culture with flushing as the most efficient (660% more efficient in T. viride ATCC 13.631 SSC+f than in SLC and 455% more efficient in T. viride CMGB1 SSC+f than in SLC). Still, T. viride CMGB1 show a higher production (2160 FPU in SSC+f) than T. viride ATCC 13.631 (1880 FPU in SSC+fm) in laboratory conditions. These results recommend solid state cultures as systems for producing cellulases at lower price than liquid state cultures. These low cost cellulases can lower the price of ethanol produces from lignocellulosic biomass.

The plantain agro-industry generates different residues in the harvest and post-harvest stages. Therefore, the design of processes for valorization is required. The aim of this work was to design and techno-economically evaluate the processes for the production of single-cell protein, natural fibers, and biomethane from plantain residues by process simulation in the framework of the design of a future biorefinery for valorization of these residues. The processes were simulated using SuperPro Designer. The scale size was calculated at 1,267,071 tons for the processing of plantain lignocellulosic waste (pseudostems) and 3179 tons for the processing of starchy waste (rejected unripe plantain fruits). The results obtained suggest that the best alternative for the valorization of plantain residues corresponded to the production of natural fibers, with a net present value of $29,299,000. This work shows that waste from the plantain agro-industry exhibits high potential as a feedstock for the production of value-added products. In addition, the process flowsheets simulated in this work can be integrated into the basic design of a biorefinery processing plantain waste. [ABSTRACT FROM AUTHOR]

Commercial cellulase Cellic CTec2 was immobilized by the entrapment technique in sol–gel matrices, and sol–gel entrapment with deposition onto magnetic nanoparticles, using binary or ternary systems of silane precursors with alkyl- or aryl-trimethoxysilanes, at different molar ratios. Appropriate tailoring of the sol–gel matrix allowed for the enhancement of the catalytic efficiency of the cellulase biocatalyst, which was then evaluated in the hydrolysis reaction of Avicel microcrystalline cellulose. A correlation between the catalytic activity with the properties of the sol–gel matrix of the nanobiocatalysts was observed using several characterization methods: scanning electron microscopy (SEM), fluorescence microscopy (FM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA/DTA). The homogeneous distribution of the enzymes in the sol–gel matrix and the mass loss profile as a function of temperature were highlighted. The influence of temperature and pH of the reaction medium on the catalytic performance of the nanobiocatalysts as well as the operational stability under optimized reaction conditions were also investigated; the immobilized biocatalysts proved their superiority in comparison to the native cellulase. The magnetic cellulase biocatalyst with the highest efficiency was reused in seven successive batch hydrolysis cycles of microcrystalline cellulose with remanent activity values that were over 40%, thus we obtained promising results for scaling-up the process. [ABSTRACT FROM AUTHOR]

A systematic and structure-agnostic method for identifying heterogeneous activity of solid acids for catalyzing cellulose hydrolysis is presented. The basis of the method is preparation of a supernatant liquid by exposing the solid acid to reaction conditions and subsequent use of the supernatant liquid as a cellulose hydrolysis catalyst to determine the effects of in situ generated homogeneous acid species. The method was applied to representative solid acid catalysts, including polymer-based, carbonaceous, inorganic, and bifunctional materials. In all cases, supernatant liquids produced from these catalysts exhibited catalytic activity for cellulose hydrolysis. Direct comparison of the activity of the solid acid catalysts and their supernatants could not provide unambiguous detection of heterogeneous catalysis. A reaction pathway kinetic model was used to evaluate potential false-negative interpretation of the supernatant liquid test and to differentiate heterogeneous from homogeneous effects on cellulose hydrolysis. Lastly, differences in the supernatant liquids obtained in the presence and absence of cellulose were evaluated to understand possibility of false-positive interpretation, using structural evidence from the used catalysts to gain a fresh understanding of reactant–catalyst interactions. While many solid acid catalysts have been proposed for cellulose hydrolysis, to our knowledge, this is the first effort to attempt to differentiate the effects of heterogeneous and homogeneous activities. The resulting supernatant liquid method should be used in all future attempts to design and develop solid acids for cellulose hydrolysis.

The dissolving of cellulose under harsh and environmentally unfavorable circumstances is the basis of traditional chemical methods for nanocellulose (NC) or derivatization. Due to the limitations of present methods for dissolving and processing NC, more efficient and ecologically acceptable solvents are required. Because of their excellent thermal and chemical stability, non-flammability, and miscibility with many other solvent systems, ionic liquids (ILs) have emerged as useful and environmentally friendly solvents. Meanwhile, another procedure for producing NC with homogeneous and extremely crystalline characteristics is ultra-sonification. Ultrasound energy is delivered to cellulose chains during ultrasonication by a process known as cavitation, which refers to the development, growth, and collapse of cavities in a liquid medium. Cavitation provides 10–100 kJ/mol of energy in this so-called sonochemistry, which is within the hydrogen bond energy scale. As a result, both catalytic IL treatments and ultrasonication influence the progressive disintegration of NC synthesis. [ABSTRACT FROM AUTHOR]

A novel boronic acid and carboxyl‐modified glucose molecularly imprinted polymer were prepared through suspension polymerization, which is based on 1.0 mmol glucose as a template, 1.2 mmol methacrylamidophenylboronic acid, and 6.8 mmol methacrylic acids as monomers, 19 mmol ethyleneglycol dimethacrylate, and 1 mmol methylene‐bis‐acrylamide as crosslinkers. The prepared glucose‐molecularly imprinted polymer had a particle size of 25–70 μm, and was thermally stable below 215°C, with a specific surface area of 174.82 m2/g and average pore size of 9.48 nm. The best selectivity between glucose and fructose was 2.71 and the maximum adsorption capacity of glucose‐ molecularly imprinted polymer was up to 236.32 mg/g which was consistent with the Langmuir adsorption model. The similar adsorption abilities in six successive runs and the good desorption rate (99.4%) verified glucose‐molecularly imprinted polymer could be reused. It was successfully used for extracting glucose from cellulose hydrolysis. The adsorption amount of glucose was 2.61 mg/mL and selectivity between glucose and xylose reached 4.12. A newly established chromatography (glucose‐molecularly imprinted polymer) mediated hollow fiber membrane method in time separated pure glucose from cellulose hydrolysates on a large scale, and purified glucose solution with a concentration of 3.84 mg/mL was obtained, which offered a feasible way for the industrial production of glucose from cellulose hydrolysates. [ABSTRACT FROM AUTHOR]

The necessity to look into waste biomass resource regeneration has increased due to growing environmental and energy-related problems. This study successfully developed an innovative fishbone-derived carbon-based solid acid catalyst using the carbonation-sulfonation method, which was subsequently applied to catalyze the hydrolysis of cellulose to produce nanocellulose. The data analysis reveals that the sulfonation treatment affects the microstructure of the catalyst, resulting in a decline in its specific surface area (134.48 m2/g decreased to 9.66 m2/g). However, this treatment doesn't hinder the introduction of acidic functional groups. In particular, the solid acid catalyst derived from fishbone exhibited a total acid content of 3.76 mmol/g, with a concentration of -SO 3 H groups at 0.48 mmol/g. Furthermore, the solid acids originating from fishbones manifested remarkable thermal stability, exhibiting a mass loss of <15 % at temperatures up to 600 °C. Moreover, the catalyst displayed exceptional catalytic performance during the cellulose hydrolysis reaction, achieving an optimum nanocellulose yield of 45.7 % at an optimized reaction condition. An additional noteworthy feature is the solid acid catalyst's impressive recyclability, maintaining a nanocellulose yield of 44.87 % even after undergoing five consecutive usage cycles. This research outcome underscores an innovative approach to for the sustainable utilization of waste biomass resources. [Display omitted] • A new type of fishbone solid acid was prepared by carbonization-sulfonation method. • CA-T showed high activity and stability in the preparation of nano-cellulose. • A yield of 45.7 % for nanocellulose was achieved by using CA-T. • Nanocelluloses had 150–250 nm in length and 50 nm in diameter. [ABSTRACT FROM AUTHOR]

Cyanobacteria are rich sources of secondary metabolites and have the potential to be excellent industrial enzyme producers. β-glucosidases are extensively employed in processing biomass degradation as they mediate the most crucial step of bioconversion of cellobiose (CBI), hence controlling the efficiency and global rate of biomass hydrolysis. However, the production and availability of these enzymes derived from cyanobacteria remains limited. In this study, we evaluated the β-glucosidase from Microcystis aeruginosa CACIAM 03 (MaBgl3) and its potential for bioconversion of cellulosic biomass by analyzing primary/secondary structures, predicting physicochemical properties, homology modeling, molecular docking, and simulations of molecular dynamics (MD). The results showed that MaBgl3 derives from an N-terminal domain folded as a distorted β-barrel, which contains the conserved His–Asp catalytic dyad often found in glycosylases of the GH3 family. The molecular docking results showed relevant interactions with Asp81, Ala271 and Arg444 residues that contribute to the binding process during MD simulation. Moreover, the MD simulation of the MaBgl3 was stable, shown by analyzing the root mean square deviation (RMSD) values and observing favorable binding free energy in both complexes. In addition, experimental data suggest that MaBgl3 could be a potential enzyme for cellobiose-hydrolyzing degradation.

The indiscriminate accumulation of plastic waste has prompted research that leads to obtaining biobased materials. The research aim was to evaluate the effect of incorporating fique bagasse microparticles (FBM) in a cassava starch-based foamed material. First, the FBM extraction conditions were established by acid hydrolysis, for which the effect of acid concentration (5, 10 and 15% H 2 SO 4), temperature (70, 80 and 90 °C) and extraction time (3, 5 and 7 h) on particle size, functional groups, color, and thermal properties was evaluated. The addition of FBM to the foamed material was then carried out. To do this, a completely randomized design with five treatments (0, 0.5, 0.75, 1.0 and 1.25% FBM) was evaluated. The response variables were the apparent density, expansion and spring index, compressibility, water absorption, thermal properties and FTIR. The results showed that the acid concentration, temperature and time had an effect on the morphological, chemical and thermal properties of FBM, with 10%, 70 °C and 7 h being the conditions that allowed obtaining the smallest particle size (61.69 ± 12.88 μm2). Moreover, the FBM concentration had a significant effect on the physical and mechanical properties of the foam, unleashing the treatment properties of 0.75%. This indicates that FBM have potential for use in obtaining biobased materials. • Fique bagasse can be valorized through the extraction of microparticles. • MBF are an important component for the development of bio-based materials. • MBF extraction conditions affect their properties. • MBF concentration influences the properties of starch-based foams. • The incorporation of 0.75% MBF positively affected the foam properties. [ABSTRACT FROM AUTHOR]

The present work was designed to isolate and characterise the actinobacteria in the Polar Front region of the Southern Ocean waters and species of Nocardiopsis and Streptomyces were identified. Among those, the psychrophilic actinobacterium, Nocardiopsis dassonvillei PSY13 was found to have good cellulolytic activity and it was further studied for the production and characterisation of cold-active cellulase enzyme. The latter was found to have a specific activity of 6.36 U/mg and a molar mass of 48 kDa with a 22.9-fold purification and 5% recovery at an optimum pH of 7.5 and a temperature of 10 °C. Given the importance of psychrophilic actinobacteria, N. dassonvillei PSY13 can be further exploited for its benefits, meaning that the Southern Ocean harbours biotechnologically important microorganisms that can be further explored for versatile biotechnological and industrial applications. [ABSTRACT FROM AUTHOR]

Lignocellulose, the most abundant biomass resource, was a promising alternative to oil resources. The acid catalyst can hydrolyze lignocellulose to reduce sugars, the raw material for lipid production via fermentation. However, the by-product yield during hydrolysis would inhibit yeast activity when directly applying lignocellulose hydrolysate from dilute acid-catalyzed to microbial lipid production. In this paper, a solid acid catalyst highly selective for lignocellulose (rice straw) hydrolysis was prepared to minimize the effects of by-products. Also, a combination of solid acid catalysts to generate glucose with subsequent microbial fermentation was studied to obtain the higher efficiency of lipid production. A carbon-based solid acid catalyst with an enhanced hydrolysis capacity of cellulose and lignocellulose was efficiently prepared. It resulted in 71% yield of glucose with 97% of selectivity with optimal catalyst in hydrolyzing milled cellulose. The optimal preparation conditions of the catalyst were: carbonization temperature 642 K, sulfonation temperature 412 K, initial sulfonation time 12.5 h, and liquid-to-solid ratio 11.5. To expand the catalyst' application, the rice straw hydrolysate catalyzed by the prepared catalyst was then applied to the microbial lipid production for the first time. Both dilute sulfuric acid and Amberlyst-15 resin as hydrolysis catalysts caused a decrease in yeast biomass, lipid content, and lipid yield. However, when the hydrolysate was obtained from co-heating rice straw with sucralose-derived solid acid catalyst, the yeast biomass, lipid content, and lipid yield in the presence of 5-HMF (0.39 g/L) were 12.6 g/L, 48.1%, and 7.6 g/L, respectively, and were almost similar to the control group. Our results showed that a combination of solid acid catalysts with subsequent microbial fermentation to generate lipid was confirmed to be environmentally friendly and low cost. [ABSTRACT FROM AUTHOR]

The optimization of cellulose hydrolysis in a microwave reactor (MWR) in the presence of bamboo-derived sulfonated catalyst was studied through a response surface methodology (RSM). Three-factor and three-level Box-Behnken design was employed to study the effects of hydrolysis temperature, hydrolysis time, and catalyst to substrate ratio on total converted cellulose and glucose yield. Quadratic models were proposed for both responses. The respective analysis of variance (ANOVA) showed that the proposed quadratic models could be used to navigate the design space. The optimum hydrolysis conditions were found to be hydrolysis temperature of 175 °C, hydrolysis time of 74 min, and catalyst to substrate ratio of 1.25 g/g. Under these conditions, the total amount of converted cellulose and glucose yield was 79.4% and 61.1%, respectively. Validation of the models indicated that the predicted values were in a good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Reducing chain ends in various hydrolyzed cellulose samples were quantitatively analyzed by solid-state 13C NMR. Cellulose di- and tetramers served as model systems to demonstrate that distinct signals at 97 ppm and 92.7 ppm can be detected quantitatively and assigned unambiguously to reducing chain ends in β and α anomers, respectively. In standard Avicel microcrystalline cellulose, the same signals were detected at the expected low intensity; their strength increased significantly upon further hydrolysis. The assignment of the 97 and 92.7 ppm signals to reducing chain ends was confirmed by their absence after ethanolysis, which instead produced an α-ethyl-ether end group signal at 99 ppm. Due to moderate-amplitude chain-end mobility, chain-end signals were relatively enhanced in direct-polarization 13C NMR with heteronuclear Overhauser enhancement. In 13C-enriched hydrolyzed cellulose, the assignment of the C–OH chain-end signals was further corroborated by hydroxyl-proton selection and two-dimensional 13C-13C NMR. From the fractional chain-end signal intensity, the number-average degree of polymerization (DPn) was determined. For Avicel, this yielded DPn = 43 (+ 50, -6), consistent with gel-permeation chromatography but significantly lower than deduced from a more indirect optical method likely hampered by limited chain-end accessibility. After 60 min of hydrolysis of ball-milled Avicel or cellulose from maize, highly reliable values of DPn = 18 ± 3 and 15 ± 3, respectively, were obtained. Solid-state NMR completely avoids the potential loss of low-molar-mass chains in solution-based approaches. The accurate, solvent-free solid-state NMR method introduced here can serve as a primary standard to calibrate other methods for molar-mass determination in hydrolyzed cellulose. [ABSTRACT FROM AUTHOR]

Microbial degradation of organic matter is a key driver of subsurface biogeochemistry. Here, we present a bioenergetics-informed kinetic model for the anaerobic degradation of macromolecular organic matter that accounts for extracellular hydrolysis, fermentation, and respiration. The catabolic energy generated by fermentation and respiration is allocated to biomass growth, production of extracellular hydrolytic enzymes, and cellular maintenance. Microbial cells are assumed to exist in active or dormant states with marked differences in maintenance energy requirements. Dormant cells are further assumed to fulfill their maintenance energy requirements by utilizing their own biomass instead of relying on external substrates. When the catabolic Gibbs energy production for a given functional group of microorganisms exceeds the total maintenance energy requirement of the active cells, biomass growth, re-activation of dormant cells, and production of extracellular hydrolytic enzymes are possible. The latter, in turn, allows the microbial community to access more of the available external organic substrates. In the opposite case, active cells decay or become dormant. We apply the model to simulate the anaerobic degradation of cellulose by a hypothetical microbial community consisting of cellulolytic fermenting bacteria and sulfate-reducing bacteria, under conditions representative of those encountered in water-saturated subsurface environments. [ABSTRACT FROM AUTHOR]

In the era of high-throughput sequencing, genetic information that is inherently whispering hints of the microbes’ functional niches is becoming easily accessible; however, properly identifying and characterizing these genetic hints to infer the microbes’ functional niches remains a challenge. Regarding genome-centric interpretation on the specific functional niche of cellulose hydrolysis for anaerobes, often encountered in practice is a lack of confidence in predicting the anaerobes’ real cellulolytic competency based solely on abundances of the varying carbohydrate-active enzyme modules annotated or on their taxonomy affiliation. Recognition of the synergy machineries that include but not limited to the cellulosome gene clusters is equally important as the annotation of individual carbohydrate-active modules or genes. In the interpretation of complete genomes of 2,768 microbe strains whose phenotypes have been well documented, with the incorporation of an automatic recognition of synergy among the carbohydrate active elements annotated, an explicit genotype–phenotype correlation was evidenced to be feasible for cellulolytic anaerobes, and a bioinformatic pipeline was developed accordingly. This genome-centric pipeline would categorize putative cellulolytic anaerobes into six genotype groups based on differential cellulose-hydrolyzing capacity and varying synergy mechanisms. Suggested in this genotype–phenotype correlation analysis was a finer categorization of the cellulosome gene clusters: although cellulosome complexes, by their nature, could enable the assembly of a number of carbohydrate-active units, they do not certainly guarantee the formation of the cellulose–enzyme–microbe complex or the cellulose-hydrolyzing activity of the corresponding anaerobe strains, for example, the well-known Clostridium acetobutylicum strains. Also, recognized in this genotype-phenotype correlation analysis was the genetic foundation of a previously unrecognized machinery that may mediate the microbe–cellulose adhesion, to be specific, enzymes encoded by genes harboring both the surface layer homology and cellulose-binding CBM modules. Applicability of this pipeline on scalable annotation of large genome datasets was further tested with the annotation of 7,902 reference genomes downloaded from NCBI, from which 14 genomes of putative paradigm cellulose-hydrolyzing anaerobes were identified. We believe the pipeline developed in this study would be a good add as a bioinformatic tool for genome-centric interpretation of uncultivated anaerobes, specifically on their functional niche of cellulose hydrolysis.