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1.
Int J Mol Sci ; 22(17)2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34502540

RESUMO

The functionalization of microcrystalline cellulose (MCC) is an important strategy for broadening its application fields. In the present work, MCC was functionalized by phosphorylation reaction with phytic acid (PA) for enhanced flame retardancy. The conditions of phosphorylation reaction including PA concentration, MCC/PA weight ratio and temperature were discussed, and the thermal degradation, heat release and char-forming properties of the resulting PA modified MCC were studied by thermogravimetric analysis and pyrolysis combustion flow calorimetry. The PA modified MCC, which was prepared at 90 °C, 50%PA and 1:3 weight ratio of MCC to PA, exhibited early thermal dehydration with rapid char formation as well as low heat release capability. This work suggests a novel strategy for the phosphorylation of cellulose using PA and reveals that the PA phosphorylated MCC can act as a promising flame retardant material.


Assuntos
Celulose/química , Ácido Fítico/química , Celulose/metabolismo , Retardadores de Chama , Temperatura Alta , Estrutura Molecular , Fosforilação , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Temperatura , Têxteis/análise , Termogravimetria/métodos
2.
Phys Chem Chem Phys ; 23(37): 20919-20935, 2021 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-34541592

RESUMO

Computational studies on the pyrolysis of lignin using electronic structure methods have been largely limited to dimeric or trimeric models. In the current work we have modeled a lignin oligomer consisting of 10 syringyl units linked through 9 ß-O-4' bonds. A lignin model of this size is potentially more representative of the polymer in angiosperms; therefore, we used this representative model to examine the behavior of hardwood lignin during the initial steps of pyrolysis. Using this oligomer, the present work aims to determine if and how the reaction enthalpies of bond cleavage vary with positions within the chain. To accomplish this, we utilized a composite method using molecular mechanics based conformational sampling and quantum mechanically based density functional theory (DFT) calculations. Our key results show marked differences in bond dissociation enthalpies (BDE) with the position. In addition, we calculated standard thermodynamic properties, including enthalpy of formation, heat capacity, entropy, and Gibbs free energy for a wide range of temperatures from 25 K to 1000 K. The prediction of these thermodynamic properties and the reaction enthalpies will benefit further computational studies and cross-validation with pyrolysis experiments. Overall, the results demonstrate the utility of a better understanding of lignin pyrolysis for its effective valorization.


Assuntos
Lignina/química , Celulose/química , Celulose/metabolismo , Teoria da Densidade Funcional , Lignina/metabolismo , Conformação Molecular , Pressão , Pirólise , Temperatura , Termodinâmica
3.
PLoS One ; 16(9): e0258065, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34591932

RESUMO

The changes in lignocellulosic biomass composition and in vitro rumen digestibility of oil palm empty fruit bunch (OPEFB) after pre-treatment with the fungus Ganoderma lucidum were evaluated. The results demonstrated that the pre-treatment for 2-12 weeks has gradually degraded the OPEFB in a time-dependent manner; whereby lignin, cellulose, and hemicellulose were respectively degraded by 41.0, 20.5, and 26.7% at the end of the incubation period. The findings were corroborated using the physical examination of the OPEFB by scanning electron microscopy. Moreover, the OPEFB pre-treated for 12 weeks has shown the highest in vitro digestibility of dry (77.20%) and organic (69.78%) matter, where they were enhanced by 104.07 and 96.29%, respectively, as compared to the untreated control. The enhancement in the in vitro ruminal digestibility was negatively correlated with the lignin content in the OPEFB. Therefore, biologically delignified OPEFB with G. lucidum fungal culture pre-treatment have the potential to be utilized as one of the ingredients for the development of a novel ruminant forage.


Assuntos
Celulose/metabolismo , Frutas/metabolismo , Lignina/metabolismo , Óleo de Palmeira/metabolismo , Reishi , Biomassa
4.
Molecules ; 26(18)2021 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-34577096

RESUMO

To adapt to various ecological niches, the members of genus Bacillus display a wide spectrum of glycoside hydrolases (GH) responsible for the hydrolysis of cellulose and lignocellulose. Being abundant and renewable, cellulose-containing plant biomass may be applied as a substrate in second-generation biotechnologies for the production of platform chemicals. The present study aims to enhance the natural cellulase activity of two promising 2,3-butanediol (2,3-BD) producers, Bacillus licheniformis 24 and B. velezensis 5RB, by cloning and heterologous expression of cel8A and cel48S genes of Acetivibrio thermocellus. In B. licheniformis, the endocellulase Cel8A (GH8) was cloned to supplement the action of CelA (GH9), while in B. velezensis, the cellobiohydrolase Cel48S (GH48) successfully complemented the activity of endo-cellulase EglS (GH5). The expression of the natural and heterologous cellulase genes in both hosts was demonstrated by reverse-transcription PCR. The secretion of clostridial cellulases was additionally enhanced by enzyme fusion to the subtilisin-like signal peptide, reaching a significant increase in the cellulase activity of the cell-free supernatants. The results presented are the first to reveal the possibility of genetic complementation for enhancement of cellulase activity in bacilli, thus opening the prospect for genetic improvement of strains with an important biotechnological application.


Assuntos
Bacillus licheniformis/enzimologia , Bacillus licheniformis/genética , Bacillus/enzimologia , Bacillus/genética , Celulases/genética , Celulases/metabolismo , Clostridium/genética , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Celulose/metabolismo , Clonagem Molecular , Hidrólise , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
5.
Nat Commun ; 12(1): 5042, 2021 08 19.
Artigo em Inglês | MEDLINE | ID: mdl-34413297

RESUMO

Food production must increase significantly to sustain a growing global population. Reducing plant water loss may help achieve this goal and is especially relevant in a time of climate change. The plant cuticle defends leaves against drought, and so understanding water movement through the cuticle could help future proof our crops and better understand native ecology. Here, via mathematical modelling, we identify mechanistic properties of water movement in cuticles. We model water sorption in astomatous isolated cuticles, utilising three separate pathways of cellulose, aqueous pores and lipophilic. The model compares well to data both over time and humidity gradients. Sensitivity analysis shows that the grouping of parameters influencing plant species variations has the largest effect on sorption, those influencing cellulose are very influential, and aqueous pores less so but still relevant. Cellulose plays a significant role in diffusion and adsorption in the cuticle and the cuticle surfaces.


Assuntos
Celulose/metabolismo , Plantas/metabolismo , Água/metabolismo , Adsorção , Transporte Biológico , Difusão , Secas , Umidade , Modelos Biológicos , Permeabilidade , Epiderme Vegetal/metabolismo , Folhas de Planta/metabolismo
6.
Biomed Res Int ; 2021: 6620574, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34337038

RESUMO

In this study, 16S rRNA high-throughput sequencing technology was used to analyze the composition and diversity of bacterial and fungal communities in mushroom residue samples at different composting stages. During the composting process, the maximum temperature in the center of the pile can reach 52.4°C, and the temperature above 50°C has been maintained for about 8 days. The results showed that Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, and Chloroflexi were the main microorganisms in the composting process, accounting for 98.9%-99.7% of the total bacteria. Furthermore, in order to obtain the protein expressed in each stage of composting, the nonstandard quantitative method (label free) was used to analyze it quantitatively by mass spectrometry, anda total of 22815 proteins were identified. It indicated that the number of identified proteins related to cellulose decomposition and the number of differentially expressed proteins were significantly enriched, and the functional proteins related to cellulose decomposition had significant stage correspondence.


Assuntos
Agaricales/metabolismo , Microbiota , Aerobiose , Bactérias/metabolismo , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental , Celulose/metabolismo , Compostagem , Ontologia Genética , Sequenciamento de Nucleotídeos em Larga Escala , Peptídeos/metabolismo , Proteômica , Temperatura
7.
Bioresour Technol ; 340: 125675, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34333349

RESUMO

This study investigated the impact of the potential cellulose degrading bacteria that could be bioaugmented in the solid-state anaerobic digestion (SSAD) of bagasse to enhance the methane yield. The prospective anaerobic cellulose degrading bacteria was isolated from the soil. SSAD experiments were organized with & without bioaugmentation with a substrate total solid (TS) of 25%, 30%, 40% and 50% at an optimized feed to microorganism (F/M) ratio of 1:1. The maximum yield of 0.44 L CH4/ (g VS added) was obtained from bioaugmented bagasse at a TS of 40% whereas it was 0.34 L CH4/(g VS added) for non-bioaugmented bagasse. The isolated bacterial strain was identified that belongs species Pseudomonas of Gamma Proteobacteria which exhibited good cellulolytic activity. Metagenomic studies found 90% of archaeal microorganisms affiliated to Methanosaeta, a strict acetoclastic methanogen.


Assuntos
Metano , Saccharum , Anaerobiose , Bactérias/metabolismo , Reatores Biológicos , Celulose/metabolismo , Estudos Prospectivos , Saccharum/metabolismo
8.
Water Sci Technol ; 84(3): 656-666, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34388125

RESUMO

This study compares the H2 production from glucose, xylose, and acidic hydrolysates of Agave tequilana bagasse as substrates. The fermentation was performed in a granular sludge reactor operated in two phases: (1) model substrates (glucose and xylose) and (2) acidic hydrolysates at 35 °C, pH 4.5 and a hydraulic retention time of 5.5 h with glucose (10 g L-1) and xylose (12 g L-1). A sequencing batch reactor was used to acclimate the biomass between the glucose and xylose continuous fermentation (with a mixture of xylose-glucose) and acidic hydrolysates. During the discontinuous acclimating step, the xylose/glucose ratio increment negatively affected the H2 productivity. Although the continuous H2 production with xylose was negligible, the co-fermentation with glucose (88-12%) allowed H2 productivity of 2,889 ± 502 mL H2 L-1d-1. An acidic hydrolysate concentration of 3.3 gcarbohydrate L-1 showed a three-fold higher H2 productivity than with a concentration of 10 g L-1. The results indicated that xylose, as the only substrate, was challenging to metabolize by the inoculum, and its mixture with glucose improved the H2 productivity. Therefore, the low H2 productivity with hydrolysates could be related to the presence of xylose.


Assuntos
Agave , Xilose , Agave/metabolismo , Celulose/metabolismo , Fermentação , Glucose
9.
New Phytol ; 232(4): 1718-1737, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34245570

RESUMO

Cotton fibre is the most important source for natural textiles. The secondary cell walls (SCWs) of mature cotton fibres contain the highest proportion of cellulose content (> 90%) in any plant. The onset and progression of SCW cellulose synthesis need to be tightly controlled to balance fibre elongation and cell wall deposition. However, regulatory mechanisms that control cellulose synthesis during cotton fibre growth remain elusive. Here, we conducted genetic and functional analyses demonstrating that the R2R3-MYB GhMYB7 controls cotton fibre cellulose synthesis. Overexpression of GhMYB7 in cotton sped up SCW cellulose biosynthesis in fibre cells, and led to shorter fibres with thicker walls. By contrast, RNA interference (RNAi) silencing of GhMYB7 delayed fibre SCW cellulose synthesis and resulted in elongated fibres with thinner walls. Furthermore, we demonstrated that GhMYB7 regulated cotton fibre SCW cellulose synthases by directly binding to three distinct cis-elements in the respective GhCesA4, GhCesA7 and GhCesA8 promoters. We found that this regulatory mechanism of cellulose synthesis was 'hi-jacked' also by other GhMYBs. Together, our findings uncover a hitherto-unknown mechanism that cotton fibre employs to regulate SCW cellulose synthesis. Our results also provide a strategy for genetic improvement of SCW thickness of cotton fibre.


Assuntos
Celulose , Fibra de Algodão , Parede Celular/metabolismo , Celulose/metabolismo , Expressão Gênica , Regulação da Expressão Gênica de Plantas , Gossypium/genética , Gossypium/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas/metabolismo
10.
J Biol Chem ; 297(2): 100931, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34216620

RESUMO

Family 7 glycoside hydrolases (GH7) are among the principal enzymes for cellulose degradation in nature and industrially. These enzymes are often bimodular, including a catalytic domain and carbohydrate-binding module (CBM) attached via a flexible linker, and exhibit an active site that binds cello-oligomers of up to ten glucosyl moieties. GH7 cellulases consist of two major subtypes: cellobiohydrolases (CBH) and endoglucanases (EG). Despite the critical importance of GH7 enzymes, there remain gaps in our understanding of how GH7 sequence and structure relate to function. Here, we employed machine learning to gain data-driven insights into relationships between sequence, structure, and function across the GH7 family. Machine-learning models, trained only on the number of residues in the active-site loops as features, were able to discriminate GH7 CBHs and EGs with up to 99% accuracy, demonstrating that the lengths of loops A4, B2, B3, and B4 strongly correlate with functional subtype across the GH7 family. Classification rules were derived such that specific residues at 42 different sequence positions each predicted the functional subtype with accuracies surpassing 87%. A random forest model trained on residues at 19 positions in the catalytic domain predicted the presence of a CBM with 89.5% accuracy. Our machine learning results recapitulate, as top-performing features, a substantial number of the sequence positions determined by previous experimental studies to play vital roles in GH7 activity. We surmise that the yet-to-be-explored sequence positions among the top-performing features also contribute to GH7 functional variation and may be exploited to understand and manipulate function.


Assuntos
Glicosídeo Hidrolases , Aprendizado de Máquina , Domínio Catalítico , Celulose/metabolismo , Cinética , Simulação de Dinâmica Molecular
11.
Enzyme Microb Technol ; 149: 109833, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34311878

RESUMO

Endoglucanase and xylanase are critical enzymes for liquefaction and enzyme hydrolysis of high solids lignocellulosic biomass to facilitate its transport and production of desired derived products. Here is reported how combinations of different spore concentrations and pH influence microbial morphology, and how this may be used to direct expression and secretion of enzymes by Aspergillus niger. While xylanase production is not affected by A. niger morphology changes, endoglucanase production is enhanced under conditions of lower stress and by morphology that results in pellets. ß-glucosidase production is enhanced under dispersed morphology, which results in up to fourfold increase of this enzyme production under the tested experimental conditions. A morphologic scale (Y) is proposed based on a form factor that considers the size and frequency of each morphology class, and that points to conditions that result in high selectivity for either endoglucanase or ß-glucosidase production. An equation proposed to relate enzyme activity to morphology provides a useful tool for tuning enzyme production of A. niger, where morphology is a first indication of relative enzyme activities in a fermentation broth.


Assuntos
Celulase , Celulose , Aspergillus niger/genética , Aspergillus niger/metabolismo , Celulase/genética , Celulose/metabolismo , Fermentação , Hidrólise
12.
Int J Mol Sci ; 22(14)2021 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-34299085

RESUMO

The ongoing search for effective treatment of Acne vulgaris is concentrated, i.a., on natural peptides with antimicrobial properties. The aim of this work was the development of new amino acid derivatives with potential activity on dermal infections against selected microorganisms, including the facultative anaerobe C. acne. The peptides P1-P6 were synthesized via Fmoc solid phase peptide synthesis using Rink amide AM resin, analyzed by RP-HPLC-MS, FTIR, DPPH radical scavenging activity, and evaluated against C. acne and S. aureus, both deposited and non-deposited in BC. Peptides P1-P6 presented a lack of cytotoxicity, antimicrobial activity, or antioxidative properties correlated with selected structural properties. P2 and P4-P6 sorption in BC resulted in variable data, i.a., confirming the prospective topical application of these peptides in a BC carrier.


Assuntos
Acne Vulgar/tratamento farmacológico , Antibacterianos/farmacologia , Antioxidantes/farmacologia , Celulose/metabolismo , Fragmentos de Peptídeos/farmacologia , Propionibacterium acnes/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Acne Vulgar/metabolismo , Humanos , Staphylococcus aureus/metabolismo
13.
PLoS One ; 16(7): e0253754, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34288928

RESUMO

Subacute rumen acidosis (SARA) occurs when highly fermentable carbohydrates are introduced into the diet, decreasing pH and disturbing the microbial ecology of the rumen. Rumen amylolytic bacteria rapidly catabolize starch, fermentation acids accumulate in the rumen and reduce environmental pH. Historically, antibiotics (e.g., monensin, MON) have been used in the prevention and treatment of SARA. Biochanin A (BCA), an isoflavone produced by red clover (Trifolium pratense), mitigates changes associated with starch fermentation ex vivo. The objective of the study was to determine the effect of BCA on amylolytic bacteria and rumen pH during a SARA challenge. Twelve rumen fistulated steers were assigned to 1 of 4 treatments: HF CON (high fiber control), SARA CON, MON (200 mg d-1), or BCA (6 g d-1). The basal diet consisted of corn silage and dried distiller's grains ad libitum. The study consisted of a 2-wk adaptation, a 1-wk HF period, and an 8-d SARA challenge (d 1-4: 40% corn; d 5-8: 70% cracked corn). Samples for pH and enumeration were taken on the last day of each period (4 h). Amylolytic, cellulolytic, and amino acid/peptide-fermenting bacteria (APB) were enumerated. Enumeration data were normalized by log transformation and data were analyzed by repeated measures ANOVA using the MIXED procedure of SAS. The SARA challenge increased total amylolytics and APB, but decreased pH, cellulolytics, and in situ DMD of hay (P < 0.05). BCA treatment counteracted the pH, microbiological, and fermentative changes associated with SARA challenge (P < 0.05). Similar results were also observed with MON (P < 0.05). These results indicate that BCA may be an effective alternative to antibiotics for mitigating SARA in cattle production systems.


Assuntos
Acidose/tratamento farmacológico , Ração Animal , Doenças dos Bovinos/tratamento farmacológico , Bovinos/microbiologia , Fibras na Dieta , Conteúdo Gastrointestinal/microbiologia , Microbioma Gastrointestinal/efeitos dos fármacos , Genisteína/uso terapêutico , Rúmen/microbiologia , Acidose/microbiologia , Animais , Bactérias/efeitos dos fármacos , Bactérias/isolamento & purificação , Carga Bacteriana , Doenças dos Bovinos/microbiologia , Celulose/metabolismo , Desoxiglucose/farmacologia , Carboidratos da Dieta/metabolismo , Fibras na Dieta/metabolismo , Proteínas na Dieta/metabolismo , Fermentação , Genisteína/farmacologia , Concentração de Íons de Hidrogênio , Ionóforos/farmacologia , Masculino , Distribuição Aleatória , Silagem , Amido/metabolismo
14.
J Microbiol Biotechnol ; 31(7): 1035-1043, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34226403

RESUMO

Although engineered Saccharomyces cerevisiae fermenting cellobiose is useful for the production of biofuels from cellulosic biomass, cellodextrin accumulation is one of the main problems reducing ethanol yield and productivity in cellobiose fermentation with S. cerevisiae expressing cellodextrin transporter (CDT) and intracellular ß-glucosidase (GH1-1). In this study, we investigated the reason for the cellodextrin accumulation and how to alleviate its formation during cellobiose fermentation using engineered S. cerevisiae fermenting cellobiose. From the series of cellobiose fermentation using S. cerevisiae expressing only GH1-1 under several culture conditions, it was discovered that small amounts of GH1-1 were secreted and cellodextrin was generated through trans-glycosylation activity of the secreted GH1-1. As GH1-1 does not have a secretion signal peptide, non-conventional protein secretion might facilitate the secretion of GH1-1. In cellobiose fermentations with S. cerevisiae expressing only GH1-1, knockout of TLG2 gene involved in non-conventional protein secretion pathway significantly delayed cellodextrin formation by reducing the secretion of GH1-1 by more than 50%. However, in cellobiose fermentations with S. cerevisiae expressing both GH1-1 and CDT-1, TLG2 knockout did not show a significant effect on cellodextrin formation, although secretion of GH1-1 was reduced by more than 40%. These results suggest that the development of new intracellular ß-glucosidase, not influenced by non-conventional protein secretion, is required for better cellobiose fermentation performances of engineered S. cerevisiae fermenting cellobiose.


Assuntos
Celobiose/metabolismo , Celulose/análogos & derivados , Dextrinas/metabolismo , Saccharomyces cerevisiae/metabolismo , beta-Glucosidase/metabolismo , Biocombustíveis , Celulose/metabolismo , Etanol/metabolismo , Fermentação , Glicosilação , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Engenharia Metabólica , Proteínas Qa-SNARE/genética , Proteínas Qa-SNARE/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Via Secretória/genética , beta-Glucosidase/genética
15.
Carbohydr Polym ; 269: 118346, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34294353

RESUMO

In the present study, the novel Ag/cellulose nanocrystal (CNC)-doped CeO2 quantum dots (QDs) with highly efficient catalytic performance were synthesized using one pot co-precipitation technique, which were then applied in the degradation of methylene blue and ciprofloxacin (MBCF) in wastewater. Catalytic activity against MBCF dye was significantly reduced (99.3%) for (4%) Ag dopant concentration in acidic medium. For Ag/CNC-doped CeO2 vast inhibition domain of G-ve was significantly confirmed as (5.25-11.70 mm) and (7.15-13.60 mm), while medium- to high-concentration of CNC levels were calculated for G + ve (0.95 nm, 1.65 mm), respectively. Overall, (4%) Ag/CNC-doped CeO2 revealed significant antimicrobial activity against G-ve relative to G + ve at both concentrations, respectively. Furthermore, in silico molecular docking studies were performed against selected enzyme targets dihydrofolate reductase (DHFR), dihydropteroate synthase (DHPS), and DNA gyrase belonging to folate and nucleic acid biosynthetic pathway, respectively to rationalize possible mechanism behind bactericidal potential of CNC-CeO2 and Ag/CNC-CeO2.


Assuntos
Antibacterianos/farmacologia , Celulose/química , Cério/química , Corantes/química , Pontos Quânticos/química , Prata/farmacologia , Antibacterianos/química , Antibacterianos/metabolismo , Antibacterianos/efeitos da radiação , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Catálise/efeitos da radiação , Celulose/síntese química , Celulose/metabolismo , Celulose/efeitos da radiação , Cério/metabolismo , Cério/efeitos da radiação , Ciprofloxacina/química , DNA Girase/química , DNA Girase/metabolismo , Di-Hidropteroato Sintase/química , Di-Hidropteroato Sintase/metabolismo , Escherichia coli/efeitos dos fármacos , Escherichia coli/enzimologia , Luz , Azul de Metileno/química , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Ligação Proteica , Pontos Quânticos/metabolismo , Pontos Quânticos/efeitos da radiação , Prata/química , Prata/metabolismo , Prata/efeitos da radiação , Staphylococcus aureus/efeitos dos fármacos , Tetra-Hidrofolato Desidrogenase/química , Tetra-Hidrofolato Desidrogenase/metabolismo , Poluentes Químicos da Água/química , Purificação da Água/métodos
16.
World J Microbiol Biotechnol ; 37(7): 120, 2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34132920

RESUMO

The diversity of actinobacteria associated with marine ascidian Phallusia nigra from Andaman Islands was investigated. A total of 10 actinobacteria were isolated and based on the biochemical and molecular characterization, the isolates were assigned to 7 different actinobacterial genera. Eight putatively novel species belonging to genera Rhodococcus, Kineococcus, Kocuria, Janibacter, Salinispora and Arthrobacter were identified based on 16S rDNA sequence similarity with the NCBI database. The organic extracts of ten isolates displayed considerable bioactivity against test pathogens, which were Gram-positive and Gram-negative in nature. PCR-based screening for type I and type II polyketide synthases (PKS-I, PKS-II) and nonribosomal peptide synthetases (NRPS) revealed that, 10 actinobacterial isolates encoded at least one type of polyketide synthases biosynthesis gene. Majority of the isolates found to produce industrially important enzymes; amylase, protease, gelatinase, lipase, DNase, cellulase, urease, phosphatase and L-asparaginase. The present study emphasized that, ascidians are a prolific resource for novel bioactive actinobacteria with potential for novel drug discovery. This result expands the scope to functionally characterize the novel ascidian associated marine actinobacteria and their metabolites could be a source for the novel molecules of commercial interest.


Assuntos
Actinobacteria/classificação , Actinobacteria/enzimologia , Actinobacteria/genética , Organismos Aquáticos/microbiologia , Simbiose , Urocordados/microbiologia , Actinobacteria/metabolismo , Amilases/metabolismo , Animais , Antibacterianos/metabolismo , Asparaginase/metabolismo , Proteínas de Bactérias/metabolismo , Técnicas de Tipagem Bacteriana , Biodiversidade , Celulase/metabolismo , Celulose/metabolismo , DNA Bacteriano , Microbiologia Industrial , Ilhas , Lipase/metabolismo , Peptídeo Hidrolases/metabolismo , Peptídeo Sintases/genética , Policetídeo Sintases/genética , RNA Ribossômico 16S , Análise de Sequência de DNA
17.
Food Microbiol ; 99: 103828, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34119113

RESUMO

In this study, a composite film was prepared with bacterial cellulose (BC) of Gluconacetobacter xylinus and cell-free supernatant (CFS) of Enterococcus faecium TJUQ1, which was named BC-E. The optimum conditions for the preparation of the composite film with a minimal antibacterial activity were the soak of BC in 80 AU/mL CFS for 6 h. By scanning electron microscope observation, the surface network structure of BC-E was denser than that of BC. The tensile strength of BC and BC-E was 4.65 ± 0.88 MPa and 16.30 ± 0.92 MPa, the elongation at break of BC and BC-E was 3.33 ± 0.89% and 31.60 ± 1.15%, respectively, indicating the mechanical properties of BC-E were significantly higher than that of BC (P < 0.05). The swelling ratio of BC-E (456.67 ± 7.20%) was lower than that of BC (1377.78 ± 9.07%), demonstrating BC-E films presented better water resistance. BC-E films were soaked with 320 AU/mL CFS, and then used to pack the ground meat with 6.55 log10 CFU/g of Listeria monocytogenes. After 8 days of storage, the number of bacteria decreased by 3.16 log10 CFU/g. Similarly, total mesophilic bacterial levels in the ground meat decreased by 2.41 log10 CFU/g compared to control groups.


Assuntos
Antibacterianos/química , Celulose/química , Enterococcus faecium/metabolismo , Embalagem de Alimentos/instrumentação , Gluconacetobacter xylinus/metabolismo , Polímeros/química , Animais , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Hidrocarbonetos Aromáticos com Pontes/química , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Celulose/metabolismo , Enterococcus faecium/química , Gluconacetobacter xylinus/química , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/crescimento & desenvolvimento , Carne/análise , Carne/microbiologia , Polímeros/farmacologia , Suínos , Resistência à Tração
18.
Nat Commun ; 12(1): 3847, 2021 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-34158485

RESUMO

Enzyme reactions, both in Nature and technical applications, commonly occur at the interface of immiscible phases. Nevertheless, stringent descriptions of interfacial enzyme catalysis remain sparse, and this is partly due to a shortage of coherent experimental data to guide and assess such work. In this work, we produced and kinetically characterized 83 cellulases, which revealed a conspicuous linear free energy relationship (LFER) between the substrate binding strength and the activation barrier. The scaling occurred despite the investigated enzymes being structurally and mechanistically diverse. We suggest that the scaling reflects basic physical restrictions of the hydrolytic process and that evolutionary selection has condensed cellulase phenotypes near the line. One consequence of the LFER is that the activity of a cellulase can be estimated from its substrate binding strength, irrespectively of structural and mechanistic details, and this appears promising for in silico selection and design within this industrially important group of enzymes.


Assuntos
Algoritmos , Celulases/metabolismo , Celulose/metabolismo , Simulação de Dinâmica Molecular , Biocatálise , Celulases/química , Hidrólise , Cinética , Ligação Proteica , Domínios Proteicos , Especificidade por Substrato
19.
Nat Plants ; 7(6): 826-841, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34112988

RESUMO

The leaf epidermis is a dynamic biomechanical shell that integrates growth across spatial scales to influence organ morphology. Pavement cells, the fundamental unit of this tissue, morph irreversibly into highly lobed cells that drive planar leaf expansion. Here, we define how tissue-scale cell wall tensile forces and the microtubule-cellulose synthase systems dictate the patterns of interdigitated growth in real time. A morphologically potent subset of cortical microtubules span the periclinal and anticlinal cell faces to pattern cellulose fibres that generate a patch of anisotropic wall. The subsequent local polarized growth is mechanically coupled to the adjacent cell via a pectin-rich middle lamella, and this drives lobe formation. Finite element pavement cell models revealed cell wall tensile stress as an upstream patterning element that links cell- and tissue-scale biomechanical parameters to interdigitated growth. Cell lobing in leaves is evolutionarily conserved, occurs in multiple cell types and is associated with important agronomic traits. Our general mechanistic models of lobe formation provide a foundation to analyse the cellular basis of leaf morphology and function.


Assuntos
Arabidopsis/citologia , Células Vegetais , Folhas de Planta/citologia , Folhas de Planta/crescimento & desenvolvimento , Arabidopsis/crescimento & desenvolvimento , Fenômenos Biomecânicos , Forma Celular , Parede Celular/fisiologia , Celulose/metabolismo , Análise de Elementos Finitos , Microscopia Eletrônica de Transmissão , Microtúbulos/metabolismo , Modelos Biológicos , Mutação , Células Vegetais/metabolismo , Plantas Geneticamente Modificadas , Plasmodesmos
20.
Commun Biol ; 4(1): 727, 2021 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-34117349

RESUMO

Lytic Polysaccharide Monooxygenases (LPMOs) are powerful redox enzymes able to oxidatively cleave recalcitrant polysaccharides. Widely conserved across biological kingdoms, LPMOs of the AA9 family are deployed by phytopathogens to deconstruct cellulose polymers. In response, plants have evolved sophisticated mechanisms to sense cell wall damage and thus self-triggering Damage Triggered Immunity responses. Here, we show that Arabidopsis plants exposed to LPMO products triggered the innate immunity ultimately leading to increased resistance to the necrotrophic fungus Botrytis cinerea. We demonstrated that plants undergo a deep transcriptional reprogramming upon elicitation with AA9 derived cellulose- or cello-oligosaccharides (AA9_COS). To decipher the specific effects of native and oxidized LPMO-generated AA9_COS, a pairwise comparison with cellobiose, the smallest non-oxidized unit constituting cellulose, is presented. Moreover, we identified two leucine-rich repeat receptor-like kinases, namely STRESS INDUCED FACTOR 2 and 4, playing a crucial role in signaling the AA9_COS-dependent responses such as camalexin production. Furthermore, increased levels of ethylene, jasmonic and salicylic acid hormones, along with deposition of callose in the cell wall was observed. Collectively, our data reveal that LPMOs might play a crucial role in plant-pathogen interactions.


Assuntos
Arabidopsis/imunologia , Botrytis/imunologia , Celulose/metabolismo , Oxigenases de Função Mista/metabolismo , Oligossacarídeos/metabolismo , Doenças das Plantas/imunologia , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Resistência à Doença , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Oxigenases de Função Mista/fisiologia , Oligossacarídeos/fisiologia , Doenças das Plantas/microbiologia , Sordariales/metabolismo
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