Hydrolysis Of Cellulosic Biomass Research Articles

Cellulase entrapment in calcium alginate hydrogel beads for improved reusability and hydrolysis of cellulosic biomass

Cellulase entrapment in calcium alginate hydrogel beads for improved reusability and hydrolysis of cellulosic biomass

Light-Driven Depolymerization of Cellulosic Biomass into Hydrocarbons.

Cellulose and hemicellulose are the main constituents of lignocellulosic biomass. Chemical derivatization of lignocellulosic biomass leads to a range of C5 and C6 organic compounds. These C5 and C6 compounds are valuable precursors (or fine chemicals) for developing sustainable chemical processes. Therefore, depolymerization of cellulose and hemicellulose is essential, leading to the development of various materials that have applications in biomaterial industries. However, most depolymerized processes for cellulose have limited success because of its structural quality: crystallinity, high hydrogen-bond networking, and mild solubility in organic and water. As a result, various chemical treatments, acidic (mineral or solid acids) and photocatalysis, have developed. One of the significant shortcomings of acidic treatment is that the requirement for high temperatures increases the commercial end cost (energy) and hampers product selectivity. For example, a catalyst with prolonged exposure to high temperatures damages the catalyst surface over time; therefore, it cannot be used for iterative cycles. Photocatalysts provide ample application to overcome such flaws as they do not require high temperatures to perform efficient catalysis. Various photocatalysts have shown efficient cellulosic biomass conversion into its C6 and C5 hydrocarbons and the production of hydrogen (as a green energy component). For example, TiO2-based photocatalysts are the most studied for biomass valorization. Herein, we discussed the feasibility of a photocatalyst with application to cellulosic biomass hydrolysis.

Production of fermentable glucose from bioconversion of cellulose using efficient microbial cellulases produced from water hyacinth waste

The economic production of cellulase enzymes for various industrial applications is one of the major research areas. A number of broad industrial applications, for example, in cellulosic biomass hydrolysis for simple sugars such as glucose and subsequent biofuel production, make these enzyme systems the third most demanding enzymes. Nevertheless, due to their production on commercial substrates, cellulases fall into the category of costly enzymes. Therefore, the goal of the present work is to evaluate the enhancement of cellulase production and its utilization in the enzymatic hydrolysis of biomass using low-cost cellulosic substrate, which is abundant and widely available. In this context, waste biomasses of water hyacinth (WH), including leaves and stems, have been used as feedstock to produce cellulases via solid-state fermentation (SSF) in the current study, which improves its production as well as activity. Furthermore, the impact of process parameters like temperature and pH has been investigated for improved cellulase production. At optimum concentration using 10 g of feedstock, 22 IU/gds of FP, 92 IU/gds of BGL, and 111 IU/gds of EG have been noticed in day 5 of SSF. Herein, 40 °C has been identified as the optimum temperature for cellulase production, whereas 50-55 °C has been recorded as the optimum reaction temperature for cellulase enzyme activity. Additionally, pH 5.5 has been identified as the optimum pH for cellulase enzyme production, whereas this enzyme was thermally stable (55 °C) at pH 5.0 up to 3.5 h. Further, the cellulosic biomass hydrolysis of WH leaves via an optimized crude enzyme has been performed, and this could release 24.34 g/L of glucose in 24 h of the reaction. The current findings may have potential for developing cellulases for mass-scale production using WH-based waste bioresources for numerous biorefinery applications.

Molecular insight into cellulose degradation by the phototrophic green alga Scenedesmus.

Lignocellulose is the most abundant natural biopolymer on earth and a potential raw material for the production of fuels and chemicals. However, only some organisms such as bacteria and fungi produce enzymes that metabolize this polymer. In this work we have demonstrated the presence of cellulolytic activity in the supernatant of Scenedesmus quadricauda cultures and we identified the presence of extracellular cellulases in the genome of five Scenedesmus species. Scenedesmus is a green alga which grows in both freshwater and saltwater regions as well as in soils, showing highly flexible metabolic properties. Sequence comparison of the different identified cellulases with hydrolytic enzymes from other organisms using multisequence alignments and phylogenetic trees showed that these proteins belong to the families of glycosyl hydrolases 1, 5, 9, and 10. In addition, most of the Scenedesmus cellulases showed greater sequence similarity with those from invertebrates, fungi, bacteria, and other microalgae than with the plant homologs. Furthermore, the data obtained from the three dimensional structure showed that both, their global structure and the main amino acid residues involved in catalysis and substrate binding are well conserved. Based on our results, we propose that different species of Scenedesmus could act as biocatalysts for the hydrolysis of cellulosic biomass produced from sunlight.

Cellulase production on easy-to-handle solid media containing agricultural waste and its application for enzymatic hydrolysis of cellulosic biomass

Cellulase production on easy-to-handle solid media containing agricultural waste and its application for enzymatic hydrolysis of cellulosic biomass

Statistical optimization of cellulase production and its efficacy in hesperidin extraction from orange peel and bioethanol production from rice straw by simultaneous saccharification and fermentation

Cellulolytic enzymes are of great interest for the hydrolysis of cellulosic biomass and their demand is increasing intensely due to their potential applications in second generation bioethanol production. In this study, cellulase production from Bacillus cereus KG10 was explored and the production media and cultural conditions were optimized through Box-Behnken design. Under optimized conditions, the cellulase activity was improved to 0.51 U/mL. The purity and the molecular mass of the enzyme (55.1 kDa) were confirmed by HPLC and MOLDI-TOF MS respectively. Additionally, cellulase mediated extraction of hesperidin was performed to prove extraction efficiency by ESI-MS. Likewise, the cellulase efficiency in bioconversion of lignocellulosic biomass was also confirmed towards improving the ethanol yield. The results showed that higher amounts of reducing sugar 73.2 and 89.3 % were explored from cellulase mediated hydrolysis of rice straw than that from acidalkali mediated hydrolysis. A high ethanol yield was also achieved in media added with cellulase treated rice straw (38.1 g/L) than that of acid-alkali treated rice straw (27.4 g/L) through simultaneous saccharification and fermentation (SSF) process using cellulase from B. subtilis KG10 and Saccharomyces cerevisiae. Thus, the cellulase from B. cereus KG10 could be a potential candidate in various industrial sectors.

Purification, biochemical characterization, and molecular cloning of cellulase from Bacillus licheniformis strain Z9 isolated from soil

BackgroundCellulose is the most prevalent biomass and renewable energy source in nature. The hydrolysis of cellulosic biomass to glucose units is essential for the economic exploitation of this natural resource. Cellulase enzyme, which is largely generated by bacteria and fungus, is commonly used to degrade cellulose. Cellulases are used in a variety of industries, including bioethanol manufacturing, textiles, detergents, drugs, food, and paper. As part of our quest to find an efficient biocatalyst for the hydrolysis of cellulosic biomass, we describe the amplification, cloning, and sequencing of cellulase (cel9z) from Bacillus licheniformis strain Z9, as well as the characterization of the resulting enzyme. ResultsCellulase was partially purified from B. licheniformis strain Z9 using (NH4)2SO4 precipitation and Sephadex G-100 gel column chromatography with 356.5 U/mg specific activity, 2.1-purification fold, and 3.07 % yield. The nucleotide sequence of the cellulase gene was deposited to the GenBank, B. licheniformis strain Z9 cellulase (cel9z) gene, under accession number MK814929. This corresponds to 1453 nucleotides gene and encodes for a protein composed of 484 amino acids. Comparison of deduced amino acids sequence to other related cellulases showed that the enzyme cel9z can be classified as a glycoside hydrolase family 9. SDS-PAGE analysis of the purified enzyme revealed that the molecular mass was 54.5 kDa. The optimal enzyme activity was observed at pH 7.4 and 30 °C. The enzyme was found to be strongly inhibited by Mg2+ and Na+, whereas strongly activated by Fe3+, Cu2+, and Ca2+. ConclusionsB. licheniformis strain Z9 and its cellulase gene can be further utilized for recombinant production of cellulases for industrial application.

Fast Self‐Assembly of Scalable Photonic Cellulose Nanocrystals and Hybrid Films via Electrophoresis

Nano-enabled, bio-based, functional materials are key for the transition to a sustainable society as they can be used, owing to both their performance and nontoxicity, to gradually replace existing nonrenewable engineering materials. Cellulose nanocrystals (CNCs), produced by acid hydrolysis of cellulosic biomass, have been shown to possess distinct self-assembly, optical, and electromechanical properties, and are anticipated to play an important role in the fabrication of photonic, optoelectronic, and functional hybrid materials. To facilitate CNCs' technological viability, a method suitable for industrial exploitation is developed to produce photonic films possessing long-range chirality on conductive, rigid, or flexible, substrates within a few minutes. The approach is based on electrophoretic deposition (EPD)-induced self-assembly of CNCs, where photonic films of any size can be produced by controlling CNC surface properties and EPD parameters. CNC film coloration can be determined by the CNC aqueous suspension characteristics, while their reflected intensity can be tuned by changing the duration and number of electrodeposition cycles. EPD-induced self-assembly of CNCs is compatible with in situ reduction of gold precursors without the need to use additional reducing agents (some of which are considered toxic), thereby allowing the preparation of hybrid photonic films with tunable plasmonic response in a one-pot process.

Study of Progress on Nanocrystalline Cellulose and Natural Fiber Reinforcement Biocomposites

Cellulosic biomass hydrolysis yields a nanoscale substance known as nanocrystalline cellulose (NCC). Gel, liquid, or powder is adaptable to a variety of uses. Nanocrystalline cellulose has unique renewability, biodegradability, and mechanical and physicochemical qualities, and abundance boosts the material’s mechanical strength by many orders of magnitude when introduced into the material matrix (polymer, ceramic, or metal). Nanocrystalline cellulose is not related with any serious environmental issues because it is a natural substance. The progress of this biomaterial as a green and renewable biomaterial for the fabrication of lightweight and biodegradable composite materials gives further impetus. The current aim of nanocrystalline cellulose research is to optimise nanocrystalline cellulose characteristics for dispersion in hydrophilic and hydrophilic media. To assess the nanocrystalline cellulose reinforcing, antibacterial, stability, hydrophilicity, and biodegradability, imaging methods and protocols in complicated matrices will need to be developed. This review includes a discussion on nanocrystalline cellulose biocomposites.

Graphene oxide mediated enhanced cellulase production using pomegranate waste following co-cultured condition with improved pH and thermal stability

High production cost of cellulase enzyme is one of the major hurdles in economic biomass to biofuel production process at industrial scale. In this context, development of advanced approaches to produce low-cost commercial cellulase is highly demanding. Therefore, in the present study, simultaneous effect of pomegranate waste (PW) and graphene oxide (GO) has been studied to improve the cellulase production along with improved stability towards the incubation temperature and different pH environment. Crude cellulase production has been achieved at high substrate concentration of PW using co-culturing of strains Cladosporium cladosporioides NS2 and Rhizopus oryzae NS5 under the solid-state fermentation (SSF) while using GO as the nanocatalyst. At a substrate concentration of 7.0 g of PW, highest enzymatic activity of 42 IU/gds FP, 271 IU/gds EG and 422 IU/gds BGL have been achieved by mean of 1.5% GO after 72 h. In addition, crude enzyme exhibits 45–55 °C and 3.5–6.5 as the most favorable incubation temperature and pH range, respectively in presence of 1.5% GO. This study reports a potential strategy to improve the production of crude enzyme along with enhanced thermal and pH stability with the implementation of GO as a nanocatalyst. Thus, the present approach offers a sustainable way to produce crude enzyme that can have numerous industrial applications along with economic biomass to biofuels production technology by providing easy, as well as high yield of sugar production via enzymatic hydrolysis of cellulosic biomass. Nevertheless, recycling of GO when employed as catalyst during the entire process remains to be challenging, and therefore efforts should made to overcome this issue.

New thermostable endoglucanase from Spirochaeta thermophila and its mutants with altered substrate preferences.

Endoglucanases are key elements in several industrial applications, such as cellulosic biomass hydrolysis, cellulose fiber modification for the production paper and composite materials, and in nanocellulose production. In all of these applications, the desired function of the endoglucanase is to create nicks in the amorphous regions of the cellulose. However, endoglucanase can be diverted from its activity on the fibers by other substrates-soluble oligosaccharides. This issue was addressed in the current study using enzyme engineering and an enzyme evolution approach. To this end, a hypothetical endoglucanase from a thermostable bacterium Spirochaeta thermophila was for the first time cloned and characterized. The wild-type enzyme was used as a starting point for mutagenesis and molecular evolution toward a preference for the higher molecular weight substrates. The best of the evolved enzymes was more active than the wild-type enzyme toward high molecular weight substrate at temperatures below 45 °C (3-fold more active at 30 °C) and showed little or no activity with low molecular weight substrates. These findings can be instrumental in bioeconomy sectors, such as second-generation biofuels and biomaterials from lignocellulosic biomass. KEY POINTS: • A new thermostable endoglucanase was characterized. • The substrate specificity of this endoglucanase was changed by means of genetic engineering. • A mutant with a preference for long molecular weight substrate was obtained and proposed to be beneficial for cellulose fiber modification.

Synergistic Action of a Lytic Polysaccharide Monooxygenase and a Cellobiohydrolase from Penicillium funiculosum in Cellulose Saccharification under High-Level Substrate Loading.

Lytic polysaccharide monooxygenases (LPMOs) are crucial industrial enzymes required in the biorefinery industry as well as in the natural carbon cycle. These enzymes, known to catalyze the oxidative cleavage of glycosidic bonds, are produced by numerous bacterial and fungal species to assist in the degradation of cellulosic biomass. In this study, we annotated and performed structural analysis of an uncharacterized LPMO from Penicillium funiculosum (PfLPMO9) based on computational methods in an attempt to understand the behavior of this enzyme in biomass degradation. PfLPMO9 exhibited 75% and 36% sequence identities with LPMOs from Thermoascus aurantiacus (TaLPMO9A) and Lentinus similis (LsLPMO9A), respectively. Furthermore, multiple fungal genetic manipulation tools were employed to simultaneously overexpress LPMO and cellobiohydrolase I (CBH1) in a catabolite-derepressed strain of Penicillium funiculosum, PfMig188 (an engineered variant of P. funiculosum), to improve its saccharification performance toward acid-pretreated wheat straw (PWS) at 20% substrate loading. The resulting transformants showed improved LPMO and CBH1 expression at both the transcriptional and translational levels, with ∼200% and ∼66% increases in ascorbate-induced LPMO and Avicelase activities, respectively. While the secretome of PfMig88 overexpressing LPMO or CBH1 increased the saccharification of PWS by 6% or 13%, respectively, over the secretome of PfMig188 at the same protein concentration, the simultaneous overexpression of these two genes led to a 20% increase in saccharification efficiency over that observed with PfMig188, which accounted for 82% saccharification of PWS under 20% substrate loading.IMPORTANCE The enzymatic hydrolysis of cellulosic biomass by cellulases continues to be a significant bottleneck in the development of second-generation biobased industries. While increasing efforts are being made to obtain indigenous cellulases for biomass hydrolysis, the high production cost of this enzyme remains a crucial challenge affecting its wide availability for the efficient utilization of cellulosic materials. This is because it is challenging to obtain an enzymatic cocktail with balanced activity from a single host. This report describes the annotation and structural analysis of an uncharacterized lytic polysaccharide monooxygenase (LPMO) gene in Penicillium funiculosum and its impact on biomass deconstruction upon overexpression in a catabolite-derepressed strain of P. funiculosum Cellobiohydrolase I (CBH1), which is the most important enzyme produced by many cellulolytic fungi for the saccharification of crystalline cellulose, was further overexpressed simultaneously with LPMO. The resulting secretome was analyzed for enhanced LPMO and exocellulase activities and the corresponding improvement in saccharification performance (by ∼20%) under high-level substrate loading using a minimal amount of protein.

An Overview of Recent Developments in Hetero-Catalytic Conversion of Cellulosic Biomass


 
 
 In recent years, research activities involved in the production of nanocellulosic materials have grown substantially, rapidly stimulating the development of innovative production techniques. These materials are chemically extracted by acid-catalyzed Hydrolysis of the renewable and widely available cellulosic biomass. In this regard, sulfuric acid-catalyzed Hydrolysis of cellulosic biomass is a commonly known method for the production of nanostructured cellulose. However, this method may result in many disadvantages, including short catalyst-lifetime, corrosive to the reactor materials and managing the spent sulfuric acid resulted from the production process. This dictates the implementation of an eco-industrial alternative for the catalytic production of nanocrystalline cellulose (NCC). A viable and practical alternative is the application of heterogeneous (solid acids) catalysts, which can be more conducive in providing favorable platforms for efficient cellulose hydrolysis. This review highlights the current production methods of nanocrystalline cellulose. Further, recent literature on the heterogeneous-catalytic conversion of cellulosic biomass is briefly discussed. The limitations and disadvantages of these techniques are also described.
 
 

Thermostable Cellulases from the Yeast Trichosporon sp.

Objectives Identification of cellulolytic microorganisms is of great interest to the hydrolysis of cellulosic biomass. This study focuses on the identification of cellulolytic yeasts and the optimization of cellulase activities produced by the best performing isolate. Results 30 cellulolytic yeast isolates were selected. Enzymes produced by an isolate from the Trichosporon genus showed the property to hydrolyze different substrates: carboxymethyl cellulose (CMC), cellulose fiber, and filter paper (FP). The optimum measured temperature was 55°C for CMCase and 60°C for FPase. The optimal pH was 5 for CMCase and 4 to 6 for FPase. The effect of the substrates concentration showed that the best activities were obtained at 100 mg/mL CMC or FP. The highest activities were 0.52 for the CMCase and 0.56 for the cellulase fiber at 10 min incubation, 0.44 IU/mL at 15 min incubation, and 24 h FPase preincubation. Conclusion Cellulases produced by the studied yeast are capable of hydrolyzing soluble and insoluble substrates at elevated temperatures and at a wide pH range. They are considerable interest in the production of fermentable sugars from lignocellulosic substrates.

Efficient hydrolysis of cellulosic biomass into free sugars for a future development processing a biorefinery context

Abstract Due to the commitments for environment preservation, there has been a growing interest in the use of alternative energy sources for the production of bioproducts of added value. In this context, sisal has been considered a promising alternative to meet the global demand in a more sustainable way. Thus, the aim of this study was to optimize the acid hydrolysis of sisal bagasse to obtain hydrolyzed liquor rich in xylose and arabinose for a future development process in a biorefining context. Thermal analysis was held for bagasse characterization, and sugars and fermentation inhibitors (acetic acid, furfural and hydroxymethylfurfural) in the prehydrolyzed liquor. The 23 + 3 factorial experimental design was applied with a total of 11 experiments to investigate the influence of variables temperature, bagasse/acid diluted and acid concentration to evaluate the release of pentoses (xylose and arabinose) and hexose (glucose) in the prehydrolyzed liquor, fixing the reaction time in 1 h. The liquor from the acid hydrolysis should operate under conditions at levels −1 (110 oC, 1,5% and 1:12), obtaining pentose yields (xylose and arabinose), which are the best conditions indicated in planning with 34.39% conversion. It was observed that acid treatment liquor is very effective in providing high-susceptibility substrates for arabitol and xylitol production.

Cellulolytic Bacillus May or May Not Produce β -Glucosidase Due to Their Environmental Origin – A Case Study

Microbial cellulases have been drawing attention worldwide because of their massive capacity to process the most abundant cellulosic biomass into sustainable biofuels and other valuable products. Profitable biomass conversion processes are highly dependent on the use of efficient enzymes for lignocellulose degradation. Among the cellulose degrading enzymes, β-glucosidases are essential for efficient hydrolysis of cellulosic biomass as they relieve the inhibition of the cellobiohydrolases and endoglucanases by reducing cellobiose accumulation. In this study cellulolytic bacteria with potential β-glucosidases activity were isolated and screened from biogas plant effluent and dairy effluent near Jahangirnagar University campus. From initial screening a total of 16 isolates were found to have cellulolytic activity, among them three isolates (B1, B5, D4) were selected based on their superior results. All the three bacterial isolates were identified as B. subtilis (B1), Bacillus amyloliquefaciens (B5) and B. subtilis (D4) respectively based on their morphological, biochemical and molecular characteristics. The β-glucosidases activity of these three potential cellulolytic bacteria was performed by measuring the release of PNP using pNPG as a substrate and interestingly D4 strain was resulted with β-glucosidases negative where B1 strain was found to have efficient for β-glucosidases activity.

P7 希硫酸を用いたセルロース系バイオマスの加水分解における超音波照射と物理的前処理の効果(ポスターセッション)

P7 希硫酸を用いたセルロース系バイオマスの加水分解における超音波照射と物理的前処理の効果(ポスターセッション)

Stimulation and inhibition of enzymatic hydrolysis by organosolv lignins as determined by zeta potential and hydrophobicity

BackgroundLignin typically inhibits enzymatic hydrolysis of cellulosic biomass, but certain organosolv lignins or lignosulfonates enhance enzymatic hydrolysis. The hydrophobic and electrostatic interactions between lignin and cellulases play critical roles in the enzymatic hydrolysis process. However, how to incorporate these two interactions into the consideration of lignin effects has not been investigated.ResultsWe examined the physicochemical properties and the structures of ethanol organosolv lignins (EOL) from hardwood and softwood and ascertained the association between lignin properties and their inhibitory and stimulatory effects on enzymatic hydrolysis. The zeta potential and hydrophobicity of EOL lignin samples, isolated from organosolv pretreatment of cottonwood (CW), black willow (BW), aspen (AS), eucalyptus (EH), and loblolly pine (LP), were determined and correlated with their effects on enzymatic hydrolysis of Avicel. EOLs from CW, BW, and AS improved the 72 h hydrolysis yield by 8–12%, while EOLs from EH and LP decreased the 72 h hydrolysis yield by 6 and 16%, respectively. The results showed a strong correlation between the 72 h hydrolysis yield with hydrophobicity and zeta potential. The correlation indicated that the hydrophobicity of EOL had a negative effect and the negative zeta potential of EOL had a positive effect. HSQC NMR spectra showed that β-O-4 linkages in lignin react with ethanol to form an α-ethoxylated β-O-4ʹ substructure (Aʹ) during organosolv pretreatment. Considerable amounts of C2,6–H2,6 correlation in p-hydroxybenzoate (PB) units were observed for EOL–CW, EOL–BW, and EOL–AS, but not for EOL–EH and EOL–LP.ConclusionsThis study revealed that the effect of lignin on enzymatic hydrolysis is a function of both hydrophobic interactions and electrostatic repulsions. The lignin inhibition is controlled by lignin hydrophobicity and the lignin stimulation is governed by the negative zeta potential. The net effect of lignin depends on the combined influence of hydrophobicity and zeta potential. This study has potential implications in biomass pretreatment for the reduction of lignin inhibition by increasing lignin negative zeta potential and decreasing hydrophobicity.

Growth and expression of relevant metabolic genes of Clostridium thermocellum cultured on lignocellulosic residues.

The plant cell wall is a source of fermentable sugars in second-generation bioethanol production. However, cellulosic biomass hydrolysis remains an obstacle to bioethanol production in an efficient and low-cost process. Clostridium thermocellum has been studied as a model organism able to produce enzymatic blends that efficiently degrade lignocellulosic biomass, and also as a fermentative microorganism in a consolidated process for the conversion of lignocellulose to bioethanol. In this study, a C. thermocellum strain (designated B8) isolated from goat rumen was characterized for its ability to grow on sugarcane straw and cotton waste, and to produce cellulosomes. We also evaluated C. thermocellum gene expression control in the presence of complex lignocellulosic biomasses. This isolate is capable of growing in the presence of microcrystalline cellulose, sugarcane straw and cotton waste as carbon sources, producing free enzymes and residual substrate-bound proteins (RSBP). The highest growth rate and cellulase/xylanase production were detected at pH 7.0 and 60°C, after 48h. Moreover, this strain showed different expression levels of transcripts encoding cellulosomal proteins and proteins with a role in fermentation and catabolic repression.

3-10-4 ウシ唾液によるセルロース分解促進効果の作用機序に関する検討(Session 3-10 エタノール2)

3-10-4 ウシ唾液によるセルロース分解促進効果の作用機序に関する検討(Session 3-10 エタノール2)