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1.
Curr Microbiol ; 78(8): 3201-3211, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34213616

RESUMO

Cellulase plays an important role in addressing the issue of the energy crisis. However, the yield and degradation efficiency of cellulase remain a major challenge. In the present study, we aimed to verify whether ammonium ion (NH4+) could induce cellulase synthesis from T. koningii AS3.2774 and to explore new functional genes related to the cellulase production. Our results indicated that NH4+ induces cellulase production in a way different from nitrogen sources. NH4+-mediated mycelia displayed a significant increase in transport vesicles. Under NH4+ mediation, CBHI, CBHII, glycoside hydrolase family 5 proteins, Hap2/3/5 complexes, "ribosome biogenesis", and "heme binding" were significantly up-regulated, and differentially expressed genes (DEGs) were mainly involved in "Metabolism". Collectively, our findings illustrated that NH4+ induced the cellulase production at morphological and gene expression levels, which might be related to the Hap2/3/5 complex, ribosomes, and genes involved in various amino acid metabolism, pyruvate metabolism, and glycolysis/gluconeogenesis. Taken together, our results provided valuable insights into the regulatory network of cellulase gene expression in filamentous fungi.


Assuntos
Compostos de Amônio , Celulase , Trichoderma , Celulase/genética , Celulase/metabolismo , Regulação Fúngica da Expressão Gênica , Hypocreales , Íons , Trichoderma/genética , Trichoderma/metabolismo
2.
Bioresour Technol ; 337: 125365, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34102515

RESUMO

The feasibility of co-fermentation of food waste and spent mushroom substance for lactic acid with Aspergillus niger cellulase replacing commercial cellulase was explored. In this study, Enterococcus mundtii was used in this study because it could utilize hexose and pentose. When the ratio of food waste and spent mushroom substance was 1:2, lactic acid concentration was 39.22 g/L, 39.28% higher than the weighted average of experimental lactic acid concentrations, indicating that the co-fermentation had positive synergistic effects. Results showed 92.62% of sugars of pretreated spent mushroom substance was released by Aspergillus niger cellulase. Moreover, when Aspergillus niger cellulase was added into the lactic acid fermentation system at 24 h, lactic acid concentration reached 48.72 g/L, which was 22.97% higher than that of the control group with commercial cellulase, because of the disappearance of Veillonella and Saccharomycetales with the Aspergillus niger cellulase addition, thus making more substrates converted into lactic acid.


Assuntos
Agaricales , Celulase , Ácido Láctico/biossíntese , Agaricales/metabolismo , Aspergillus niger/enzimologia , Celulase/metabolismo , Enterococcus , Fermentação , Alimentos , Eliminação de Resíduos
3.
Bioresour Technol ; 337: 125366, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34144430

RESUMO

Penicillium oxalicum has received increasing attention as a potential cellulase-producer. In this study, a copper-controlled flippase recombination enzyme/recognition target (FLP/FRT)-mediated recombination system was constructed in P. oxalicum, to overcome limited availability of antibiotic resistance markers. Using this system, two crucial transcription repressor genes atf1 and cxrC for the production of cellulase and xylanase under solid-state fermentation (SSF) were simultaneously deleted, thereby leading to 2.4- to 29.1-fold higher cellulase and 78.9% to 130.8% higher xylanase production than the parental strain under SSF, respectively. Glucose and xylose released from hydrolysis of pretreated sugarcane bagasse achieved 10.6%-13.5% improvement by using the crude enzymes from the engineered strain Δatf1ΔcxrC::flp under SSF in comparison with that of the parental strain. Consequently, these results provide a feasible strategy for improved cellulase and xylanase production by filamentous fungi.


Assuntos
Celulase , Penicillium , Celulase/metabolismo , Fermentação , Engenharia Genética , Penicillium/genética , Penicillium/metabolismo , Recombinação Genética
4.
Int J Biol Macromol ; 183: 2100-2108, 2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-34102235

RESUMO

Effect of edible coatings of gum Arabic, carrageenan and xanthan gum containing lemon grass essential oil 1% w/v on postharvest quality of strawberry was studied under refrigeration for a period of 12 days. Results showed all the three coatings maintained fruit quality parameters during storage compared to control. Among all the coatings, carrageenan coated fruits showed delayed weight loss (10.1 to 8%), decay percentage (78.42 to 14.29%), retained ascorbic acid (0.15 to 0.27 g kg-1), antioxidant activity (18.17 to 25.85%), firmness (9.07 to 12.43 N), L* (32.38 to 40.42), a* (16.08 to 17.22) and b* (27.36 to 33.54). Carrageenan gum also showed lowest cellulase activity (0.03 units h-1 mg protein-1), pectin methylesterase activity (1.13 A620 min-1 mg protein-1) and ß-galactosidase activity (0.51 µmol min-1 mg protein-1), while showed maximum reduction in polygalacturonase activity (0.07 units h-1 mg protein-1) at the end of storage. Carrageenan gum was found effective in retention of anthocyanins and phenolic compounds during storage. Coatings loaded with antimicrobial agent inhibited psychrophilic bacteria, yeast and mold growth. It is concluded that carrageenan gum could better retain strawberry quality up to 12 days under refrigeration.


Assuntos
Anti-Infecciosos/química , Carragenina/química , Filmes Comestíveis , Embalagem de Alimentos , Conservação de Alimentos , Fragaria/enzimologia , Frutas/enzimologia , Goma Arábica/química , Óleos Vegetais/química , Polissacarídeos Bacterianos/química , Antocianinas/metabolismo , Anti-Infecciosos/farmacologia , Antioxidantes/metabolismo , Ácido Ascórbico/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Celulase/metabolismo , Cymbopogon , Microbiologia de Alimentos , Armazenamento de Alimentos , Fragaria/microbiologia , Frutas/microbiologia , Fenóis/química , Óleos Vegetais/isolamento & purificação , Óleos Vegetais/farmacologia , Poligalacturonase/metabolismo , Refrigeração , Fatores de Tempo , beta-Galactosidase/metabolismo
5.
Environ Pollut ; 287: 117370, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34020262

RESUMO

Fruit wastes can be imperative to elevate economical biomass to biofuels production process at pilot scale. Because of the renewable features, huge availability, having low lignin content organic nature and low cost; these wastes can be of much interest for cellulase enzyme production. This review provides recent advances on the fungal cellulase production using fruit wastes as a potential substrate. Also, the availability of fruit wastes, generation and processing data and their potential applications for cellulase enzyme production have been discussed. Several aspects, including cellulase and its function, solid-state fermentation, process parameters, microbial source, and the application of enzyme in biofuels industries have also been discussed. Further, emphasis has been made on various bottlenecks and feasible approaches such as use of nanomaterials, co-culture, molecular techniques, genetic engineering, and cost economy analysis to develop a low-cost based comprehensive technology for viable production of cellulase and its application in biofuels production technology.


Assuntos
Celulase , Biocombustíveis , Biomassa , Celulase/metabolismo , Fermentação , Frutas/metabolismo , Lignina/metabolismo , Tecnologia
6.
Int J Biol Macromol ; 182: 1611-1617, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34044029

RESUMO

The production of curdlan oligosaccharides, a multifunctional and valuable carbohydrate, by hydrolyzing polysaccharides is of great interest. The endo-ß-1,3-glucanase derived from Trichoderma harzianum was expressed in Pichia pastoris with three commonly used promoters (AOX1, GAP and FLD1). The purified recombinant endo-ß-1,3-glucanase expressed by Pichia pastoris with GAP promoter displayed high specific activity at pH 5.5 and 50 °C. Thereafter, a co-culture system of Pichia pastoris GS115 (GAP promoter) and Agrobacterium sp. was constructed in which Agrobacterium sp.-metabolized curdlan can be directly hydrolyzed by Pichia pastoris-secreted endo-ß-1,3-glucanase to produce functional curdlan oligosaccharides. The co-culture conditions were optimized and the process was carried out in a 7-L bioreactor. The maximum yield of curdlan oligosaccharides reached 18.77 g/L with 3-10 degrees of polymerization. This study presents a novel and easy curdlan oligosaccharide production strategy that can replace traditional sophisticated production procedures and could potentially be implemented for production of other oligosaccharides.


Assuntos
Celulase/metabolismo , Oligossacarídeos/biossíntese , beta-Glucanas/metabolismo , Agrobacterium/genética , Agrobacterium/metabolismo , Celulase/genética , Técnicas de Cocultura , Pichia/genética , Pichia/metabolismo , Saccharomycetales/genética , Saccharomycetales/metabolismo
7.
Int J Biol Macromol ; 182: 1793-1802, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34058212

RESUMO

Cellulose is a very abundant polymer that is found in nature. Cellulose has been used as a raw material for production of biofuels for many years. However, there are multiple processing steps that are required so that cellulose can be used as a raw material for biofuel production. One of the most important steps is the breakdown of cellulose into intermediate sugars which can then be a viable substrate for biofuel production. Cellulases are enzymes which play a role in the catalysis of the breakdown of cellulose into glucose. Nanomaterials and micromaterials have been gaining a lot of attention over the past few years for its potential in immobilizing enzymes for industrial procedures. Immobilization of enzymes on these nanomaterials has been observed to be of great value due to the improvement in thermal stability, pH stability, regenerative capacity, increase in activity and the reusability of enzymes. Similarly, there have been multiple reports of cellulase enzymes being immobilized on various nanoparticles. The immobilization of these cellulase enzymes have resulted in very efficient processing and provide a great and economic solution for the processing of cellulose for biofuel production. Hence in this paper, we review and discuss the various advantages and disadvantages of enzymes on various available nanomaterials.


Assuntos
Biocombustíveis , Celulase/metabolismo , Celulose/metabolismo , Enzimas Imobilizadas/metabolismo , Nanoestruturas/química , Estruturas Metalorgânicas/química
8.
Biomolecules ; 11(4)2021 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-33805256

RESUMO

The objective of this study was to investigate structural changes and lignin redistribution in Eucalyptus globulus pre-treated by steam explosion under different degrees of severity (S0), in order to evaluate their effect on cellulose accessibility by enzymatic hydrolysis. Approximately 87.7% to 98.5% of original glucans were retained in the pre-treated material. Glucose yields after the enzymatic hydrolysis of pre-treated material improved from 19.4% to 85.1% when S0 was increased from 8.53 to 10.42. One of the main reasons for the increase in glucose yield was the redistribution of lignin as micro-particles were deposited on the surface and interior of the fibre cell wall. This information was confirmed by laser scanning confocal fluorescence and FT-IR imaging; these microscopic techniques show changes in the physical and chemical characteristics of pre-treated fibres. In addition, the results allowed the construction of an explanatory model for microscale understanding of the enzymatic accessibility mechanism in the pre-treated lignocellulose.


Assuntos
Eucalyptus/metabolismo , Lignina/metabolismo , Celulase/metabolismo , Hidrólise , Lignina/química , Microscopia Confocal , Análise de Componente Principal , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura
9.
Int J Biol Macromol ; 182: 701-711, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33862072

RESUMO

A study was carried out to investigate the characterization of a novel Aspergillus sulphureus JCM01963 xylanase (AS-xyn10A) with a carbohydrate binding module (CBM) and its application in degrading alkali pretreated corncob, rapeseed meal and corn stover alone and in combination with a commercial cellulase. In this study, the 3D structure of AS-xyn10A, which contained a CBM at C-terminal. AS-xyn10A and its CBM-truncated variant (AS-xyn10A-dC) was codon-optimized and over-expressed in Komagaella phaffii X-33 (syn. Pichia pastoris) and characterized with optimal condition at 70 °C and pH 5.0, respectively. AS-xyn10A displayed high activity to xylan extracted from corn stover, corncob, and rapeseed meal. The concentration of hydrolyzed xylo-oligosaccharides (XOSs) reached 1592.26 µg/mL, 1149.92 µg/mL, and 621.86 µg/mL, respectively. Xylobiose was the main product (~70%) in the hydrolysis mixture. AS-xyn10A significantly synergized with cellulase to improve the hydrolysis efficiency of corn stover, corncob, and rapeseed meal to glucose. The degree of synergy (DS) was 1.32, 1.31, and 1.30, respectively. Simultaneously, XOSs hydrolyzed with AS-xyn10A and cellulase was improved by 46.48%, 66.13% and 141.45%, respectively. In addition, CBM variant decreased the yields of xylo-oligosaccharide and glucose in rapeseed meal degradation. This study provided a novel GH10 endo-xylanase, which has potential applications in hydrolysis of biomass.


Assuntos
Aspergillus/enzimologia , Celulase/metabolismo , Dissacarídeos/metabolismo , Endo-1,4-beta-Xilanases/metabolismo , Proteínas Fúngicas/metabolismo , Biomassa , Brassica napus/química , Celulase/química , Endo-1,4-beta-Xilanases/química , Estabilidade Enzimática , Proteínas Fúngicas/química , Hidrólise , Ligação Proteica , Especificidade por Substrato , Zea mays/química
10.
Int J Biol Macromol ; 182: 1161-1169, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33892036

RESUMO

Endoglucanases from glycoside hydrolase family 5 (GH5) are the key enzymes in degradation of diverse plant polysaccharides. Present study reports purification, characterization and partial sequencing of novel thermostable GH5 family endoglucanase from a newly isolated brown rot fungi Fomitopsis meliae CFA 2. Endoglucanase was purified 34.18 fold with a specific activity of 302.90 U/mg. The molecular weight of the endoglucanase was 37.87 kDa as determined by SDS PAGE. LC MS/MS analysis identified the protein to be a member of GH5_5 family. The temperature and pH optima for endoglucanase activity were 70 °C and 4.8, respectively. The enzyme catalyzed the hydrolysis of carboxymethyl-cellulose with a Km of 12.0 mg/ml, Vmax of 556.58 µmol/min/mg and Kcat of 129.41/sec. The enzyme was stimulated by Zn+2 and K+ metal ions and DTT. Half-life (t1/2) for endoglucanase was found to be 11.36 h with decimal reduction time (D) of 37.75 h at 70 °C. The activation energy for endoglucanase was found to be 30.76 kJ/mol (50 °C-70 °C). Looking at the results, the endoglucanase from Fomitopsis meliae CFA 2 seems to be a promising thermostable enzyme which may be applicable in applications like biomass hydrolysis.


Assuntos
Celulase/metabolismo , Coriolaceae/enzimologia , Biomassa , Celulase/química , Eletroforese em Gel de Poliacrilamida , Peso Molecular , Espectrometria de Massas em Tandem
11.
Int J Biol Macromol ; 183: 101-109, 2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-33905799

RESUMO

Nanocellulose isolation from lignocellulose is a tedious and expensive process with high energy and harsh chemical requirements, primarily due to the recalcitrance of the substrate, which otherwise would have been cost-effective due to its abundance. Replacing the chemical steps with biocatalytic processes offers opportunities to solve this bottleneck to a certain extent due to the enzymes substrate specificity and mild reaction chemistry. In this work, we demonstrate the isolation of sulphate-free nanocellulose from organosolv pretreated birch biomass using different glycosyl-hydrolases, along with accessory oxidative enzymes including a lytic polysaccharide monooxygenase (LPMO). The suggested process produced colloidal nanocellulose suspensions (ζ-potential -19.4 mV) with particles of 7-20 nm diameter, high carboxylate content and improved thermostability (To = 301 °C, Tmax = 337 °C). Nanocelluloses were subjected to post-modification using LPMOs of different regioselectivity. The sample from chemical route was the least favorable for LPMO to enhance the carboxylate content, while that from the C1-specific LPMO treatment showed the highest increase in carboxylate content.


Assuntos
Betula/metabolismo , Celulase/metabolismo , Celulose/metabolismo , Lignina/metabolismo , Oxigenases de Função Mista/metabolismo , Nanofibras , Biomassa , Celulase/genética , Celulose/isolamento & purificação , Hidrólise , Lacase/genética , Lacase/metabolismo , Lignina/isolamento & purificação , Oxigenases de Função Mista/genética , Phanerochaete/enzimologia , Phanerochaete/genética , Saccharomycetales/enzimologia , Saccharomycetales/genética , Sordariales/enzimologia , Sordariales/genética , Especificidade por Substrato , Xilosidases/genética , Xilosidases/metabolismo
12.
Biochemistry (Mosc) ; 86(Suppl 1): S166-S195, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33827407

RESUMO

The review discusses various aspects of renewable plant biomass conversion and production of the second-generation biofuels, including the types of plant biomass, its composition and reaction ability in the enzymatic hydrolysis, and various pretreatment methods for increasing the biomass reactivity. Conversion of plant biomass into sugars requires the use of a complex of enzymes, the composition of which should be adapted to the biomass type and the pretreatment method. The efficiency of enzymatic hydrolysis can be increased by optimizing the composition of the enzymatic complex and by increasing the catalytic activity and operational stability of its constituent enzymes. The availability of active enzyme producers also plays an important role. Examples of practical implementation and scaling of processes for the production of second-generation biofuels are presented together with the cost analysis of bioethanol production.


Assuntos
Biocombustíveis , Biomassa , Custos e Análise de Custo , Celulase/metabolismo
13.
Molecules ; 26(5)2021 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-33800895

RESUMO

The biological activity of apple pectin extracted conventionally or enzymatically using endo-xylanase and endo-cellulase, was tested in vitro. The analyses were performerd in tetraplicates and the statistical significance of the differences were assessed using ANOVA, Tukey post hoc and LSD (the least significant difference) tests. Multivariate regression analysis was applied to determine the structural components that have a crucial importance for antioxidant and antitumor properties of pectins. The pectins extracted by enzymes contained up to four times more ferulic acid and showed twice as great ability to neutralize free radicals and Fe(III) reduction. The antiradical potential positively correlated with phenols, fucose and rhamnose content. In the assays performed on HT-29 human adenocarcinoma and B16F10 melanoma cell cultures, the "green" pectins, contrary to acid isolated ones, exhibited remarkable anti-neoplastic potential while being nontoxic to nontransformed L929 cell line. The pectins in the dose of 1 mg/mL were capable of inhibiting adhesion (max 23.1%), proliferation (max 40.4%), invasion (max 76.9%) and anchorage-independent growth (max 90%) of HT-29 cells (significance level p < 0.001). These pectin preparations were slightly less active towards B16F10 cells. The enzyme-isolated apple pectins may be useful as a functional food additive and an ingredient of the ointment formulas for post-surgical melanoma treatment.


Assuntos
Antineoplásicos/farmacologia , Antioxidantes/farmacologia , Celulase/metabolismo , Neoplasias do Colo/tratamento farmacológico , Endo-1,4-beta-Xilanases/metabolismo , Malus/química , Melanoma/tratamento farmacológico , Pectinas/farmacologia , Apoptose , Proliferação de Células , Neoplasias do Colo/patologia , Humanos , Melanoma/patologia , Células Tumorais Cultivadas
14.
Nat Commun ; 12(1): 2178, 2021 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-33846336

RESUMO

Many phytopathogens secrete cell wall degradation enzymes (CWDEs) to damage host cells and facilitate colonization. As the major components of the plant cell wall, cellulose and hemicellulose are the targets of CWDEs. Damaged plant cells often release damage-associated molecular patterns (DAMPs) to trigger plant immune responses. Here, we establish that the fungal pathogen Magnaporthe oryzae secretes the endoglucanases MoCel12A and MoCel12B during infection of rice (Oryza sativa). These endoglucanases target hemicellulose of the rice cell wall and release two specific oligosaccharides, namely the trisaccharide 31-ß-D-Cellobiosyl-glucose and the tetrasaccharide 31-ß-D-Cellotriosyl-glucose. 31-ß-D-Cellobiosyl-glucose and 31-ß-D-Cellotriosyl-glucose bind the immune receptor OsCERK1 but not the chitin binding protein OsCEBiP. However, they induce the dimerization of OsCERK1 and OsCEBiP. In addition, these Poaceae cell wall-specific oligosaccharides trigger a burst of reactive oxygen species (ROS) that is largely compromised in oscerk1 and oscebip mutants. We conclude that 31-ß-D-Cellobiosyl-glucose and 31-ß-D-Cellotriosyl-glucose are specific DAMPs released from the hemicellulose of rice cell wall, which are perceived by an OsCERK1 and OsCEBiP immune complex during M. oryzae infection in rice.


Assuntos
Ascomicetos/fisiologia , Parede Celular/metabolismo , Oligossacarídeos/metabolismo , Oryza/imunologia , Oryza/microbiologia , Imunidade Vegetal , Proteínas de Plantas/metabolismo , Celulase/metabolismo , Resistência à Doença , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Modelos Biológicos , Fenótipo , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Espécies Reativas de Oxigênio/metabolismo , Especificidade da Espécie , Transcrição Genética
15.
J Chem Inf Model ; 61(4): 1902-1912, 2021 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-33760586

RESUMO

Glycoside hydrolases (GH) cleave carbohydrate glycosidic bonds and play pivotal roles in living organisms and in many industrial processes. Unlike acid-catalyzed hydrolysis of carbohydrates in solution, which can occur either via cyclic or acyclic oxocarbenium-like transition states, it is widely accepted that GH-catalyzed hydrolysis proceeds via a general acid mechanism involving a cyclic oxocarbenium-like transition state with protonation of the glycosidic oxygen. The GH45 subfamily C inverting endoglucanase from Phanerochaete chrysosporium (PcCel45A) defies the classical inverting mechanism as its crystal structure conspicuously lacks a general Asp or Glu base residue. Instead, PcCel45A has an Asn residue, a notoriously weak base in solution, as one of its catalytic residues at position 92. Moreover, unlike other inverting GHs, the relative position of the catalytic residues in PcCel45A impairs the proton abstraction from the nucleophilic water that attacks the anomeric carbon, a key step in the classical mechanism. Here, we investigate the viability of an endocyclic mechanism for PcCel45A using hybrid quantum mechanics/molecular mechanics (QM/MM) simulations, with the QM region treated with the self-consistent-charge density-functional tight-binding level of theory. In this mechanism, an acyclic oxocarbenium-like transition state is stabilized leading to the opening of the glucopyranose ring and formation of an unstable acyclic hemiacetal that can be readily decomposed into hydrolysis product. In silico characterization of the Michaelis complex shows that PcCel45A significantly restrains the sugar ring to the 4C1 chair conformation at the -1 subsite of the substrate binding cleft, in contrast to the classical exocyclic mechanism in which ring puckering is critical. We also show that PcCel45A provides an environment where the catalytic Asn92 residue in its standard amide form participates in a cooperative hydrogen bond network resulting in its increased nucleophilicity due to an increased negative charge on the oxygen atom. Our results for PcCel45A suggest that carbohydrate hydrolysis catalyzed by GHs may take an alternative route from the classical mechanism.


Assuntos
Celulase , Celulase/metabolismo , Celulose , Hidrólise , Simulação de Dinâmica Molecular , Teoria Quântica
16.
Carbohydr Polym ; 260: 117795, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712143

RESUMO

High-value utilization of cellulosic biomasses via the most promising enzymatic method is the key to solve a series of global strategic issues but its industrialization was seriously hindered by the high cost. Immobilization of enzyme to realize its recycling is one solution; however, how to capture and hydrolyze the insoluble cellulose effectively via the immobilization system remains challenging. Herein, inspired by the predation process of the sea anemone, a cost-effective biomimetic cellulase-loaded enzymatic film was constructed. The cellulase loaded on the film can adjust its spatial orientation freely, thus their catalytic centres can easily reach the surface of the cellulose to perform the "predation" process effectively. As a result, this immobilization system can largely increase the efficiency of the insoluble cellulose hydrolysis and can be recycled for at least 8 cycles without activities loss. Therefore, it can largely reduce the cost of the cellulose conversion in the industrial areas.


Assuntos
Anemone/química , Celulase/metabolismo , Celulose/metabolismo , Materiais Biomiméticos/química , Catálise , Celulase/química , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Hidrólise , Polietileno/química
17.
Sheng Wu Gong Cheng Xue Bao ; 37(3): 1058-1069, 2021 Mar 25.
Artigo em Chinês | MEDLINE | ID: mdl-33783168

RESUMO

The efficient production of lignocellulolytic enzyme systems is an important support for large-scale biorefinery of plant biomass. On-site production of lignocellulolytic enzymes could increase the economic benefits of the process by lowering the cost of enzyme usage. Penicillium species are commonly found lignocellulose-degrading fungi in nature, and have been used for industrial production of cellulase preparations due to their abilities to secrete complete and well-balanced lignocellulolytic enzyme systems. Here, we introduce the reported Penicillium species for cellulase production, summarize the characteristics of their enzymes, and describe the strategies of strain engineering for improving the production and performance of lignocellulolytic enzymes. We also review the progress in fermentation process optimization regarding the on-site production of lignocellulolytic enzymes using Penicillium species, and suggest prospect of future work from the perspective of building a "sugar platform" for the biorefinery of lignocellulosic biomass.


Assuntos
Celulase , Penicillium , Biomassa , Celulase/metabolismo , Fermentação , Fungos/metabolismo , Lignina/metabolismo
18.
Acta Crystallogr D Struct Biol ; 77(Pt 2): 205-216, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33559609

RESUMO

The ability of retaining glycoside hydrolases (GHs) to transglycosylate is inherent to the double-displacement mechanism. Studying reaction intermediates, such as the glycosyl-enzyme intermediate (GEI) and the Michaelis complex, could provide valuable information to better understand the molecular factors governing the catalytic mechanism. Here, the GEI structure of RBcel1, an endo-1,4-ß-glucanase of the GH5 family endowed with transglycosylase activity, is reported. It is the first structure of a GH5 enzyme covalently bound to a natural oligosaccharide with the two catalytic glutamate residues present. The structure of the variant RBcel1_E135A in complex with cellotriose is also reported, allowing a description of the entire binding cleft of RBcel1. Taken together, the structures deliver different snapshots of the double-displacement mechanism. The structural analysis revealed a significant movement of the nucleophilic glutamate residue during the reaction. Enzymatic assays indicated that, as expected, the acid/base glutamate residue is crucial for the glycosylation step and partly contributes to deglycosylation. Moreover, a conserved tyrosine residue in the -1 subsite, Tyr201, plays a determinant role in both the glycosylation and deglycosylation steps, since the GEI was trapped in the RBcel1_Y201F variant. The approach used to obtain the GEI presented here could easily be transposed to other retaining GHs in clan GH-A.


Assuntos
Celulase/química , Oligossacarídeos , Celulase/metabolismo , Cristalografia por Raios X , Substâncias Macromoleculares , Oligossacarídeos/química , Oligossacarídeos/metabolismo , Ligação Proteica
19.
Int J Biol Macromol ; 177: 211-220, 2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33549667

RESUMO

Due to the importance of using lignocellulosic biomass, it is always important to find an effective novel enzyme or enzyme cocktail or fusion enzymes. Identification of bifunctional enzymes through a metagenomic approach is an efficient method for converting agricultural residues and a beneficial way to reduce the cost of enzyme cocktail and fusion enzyme production. In this study, a novel stable bifunctional cellulase/xylanase, PersiCelXyn1 was identified from the rumen microbiota by the multi-stage in-silico screening pipeline and computationally assisted methodology. The enzyme exhibited the optimal activity at pH 5 and 50°C. Analyzing the enzyme activity at extreme temperature, pH, long-term storage, and presence of inhibitors and metal ions, confirmed the stability of the bifunctional enzyme under harsh conditions. Hydrolysis of the rice straw by PersiCelXyn1 showed its capability to degrade both cellulose and hemicellulose polymers. Also, the enzyme improved the degradation of various biomass substrates after 168 h of hydrolysis. Our results demonstrated the power of the multi-stage in-silico screening to identify bifunctional enzymes from metagenomic big data for effective bioconversion of lignocellulosic biomass.


Assuntos
Lignina/metabolismo , Microbiota/fisiologia , Animais , Big Data , Biomassa , Celulase/metabolismo , Celulose/metabolismo , Endo-1,4-beta-Xilanases/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Metagenoma/fisiologia , Metagenômica/métodos , Oryza/metabolismo , Polissacarídeos/metabolismo , Rúmen/metabolismo , Temperatura , Termodinâmica
20.
Curr Opin Biotechnol ; 67: 141-148, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33550093

RESUMO

Enzyme performance is critical to the future bioeconomy based on renewable plant materials. Plant biomass can be efficiently hydrolyzed by multifunctional cellulases (MFCs) into sugars suitable for conversion into fuels and chemicals, and MFCs fall into three functional categories. Recent work revealed MFCs with broad substrate specificity, dual exo-activity/endo-activity on cellulose, and intramolecular synergy, among other novel characteristics. Binding modules and accessory catalytic domains amplify MFC and xylanase activity in a wide variety of ways, and processive endoglucanases achieve autosynergy on cellulose. Multidomain MFCs from Caldicellulosiruptor are heat-tolerant, adaptable to variable cellulose crystallinity, and may provide interchangeable scaffolds for recombinant design. Further studies of MFC properties and their reactivity with plant biomass are recommended for increasing biorefinery yields.


Assuntos
Celulase , Celulases , Biomassa , Celulase/metabolismo , Celulose , Especificidade por Substrato
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