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1.
Food Chem ; 332: 127383, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32615383

RESUMO

This study represents a rapid and non-destructive approach based on mid-infrared (MIR) spectroscopy, time domain nuclear magnetic resonance (TD-NMR), and machine learning classification models (ML) for monitoring soluble pectin content (SPC) changes in orange juice. Current reference methods of SPC in orange juice are laborious, requiring several extractions with successive adjustments hindering rapid process intervention. 109 fresh orange juices samples, representing different harvests, were analysed using MIR, TD-NMR and reference method. Unsupervised algorithms were applied for natural clustering of MIR and TD-NMR data in two groups. Analyses of variance of the two MIR and TD-NMR datasets show that only the MIR groups were different at 95% confidence for SPC average values. This approach allows build classification models based on MIR data achieving 85% and 89% of accuracy. Results demonstrate that MIR/ML can be a suitable strategy for the quick assessment of SPC trends in orange juices.


Assuntos
Citrus sinensis/química , Sucos de Frutas e Vegetais/análise , Aprendizado de Máquina , Pectinas/química , Citrus sinensis/metabolismo , Análise por Conglomerados , Humanos , Espectroscopia de Ressonância Magnética , Pectinas/metabolismo , Análise de Componente Principal , Espectrofotometria Infravermelho
2.
Sheng Wu Gong Cheng Xue Bao ; 36(6): 1021-1030, 2020 Jun 25.
Artigo em Chinês | MEDLINE | ID: mdl-32597053

RESUMO

Pectin methylesterase (PME) is an important pectinase that hydrolyzes methyl esters in pectin to release methanol and reduce the degree of methylation of pectin. At present, it has broad application prospects in food processing, tea beverage, paper making and other production processes. With the in-depth study of PME, the crystal structures with different sources have been reported. Analysis of these resolved crystal structures reveals that PME belongs to the right-hand parallel ß-helix structure, and its catalytic residues are two aspartic acids and a glutamine, which play the role of general acid-base, nucleophile and stable intermediate, in the catalytic process. At the same time, the substrate specificity is analyzed to understand the recognition mechanism of the substrate and active sites. This paper systematically reviews these related aspects.


Assuntos
Hidrolases de Éster Carboxílico , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/metabolismo , Domínio Catalítico , Cristalografia , Pectinas/metabolismo , Estrutura Terciária de Proteína , Especificidade por Substrato
3.
Artigo em Inglês | MEDLINE | ID: mdl-32480237

RESUMO

Root growth is reduced in soils with low pH [H+] and abundant soluble aluminum [Al3+], which can be a consequence of the interaction between Al3+ and cell wall composition. The competition between Al3+ and Ca2+ toward binding to pectin molecules was evaluated in roots of Urochloa decumbens, an African grass highly adapted to acidic Al-rich soils. Variations in the composition and distribution of pectins can change the extensibility, rigidity, porosity, and adhesive properties of plant cell walls, which were tested in seedlings of U. decumbens exposed to pH 3.5, 4.5 and 5.8 and to 0, 80, 160 and 320 µM of Al3+ for 80h. Root growth corroborated that U. decumbens is very tolerant to soil acidity, with effective reduction of root growth only at pH 3.5. Immunocytochemical approaches demonstrated variations in pectin composition induced both by Al3+ and by H+ in root tissues and zones. Based on the usual linkage between Ca2+ and pectins, Density Functional Theory (DFT) analyses indicated that Al3+ bound easier to pectins than Ca2+ did, leading to the formation of more Al3+-pectate complexes than Ca2+-pectate complexes, which resulted in higher rigidity of cell walls, and hampered cell extension.


Assuntos
Alumínio/metabolismo , Cálcio/metabolismo , Pectinas/metabolismo , Raízes de Plantas/metabolismo , Poaceae/metabolismo , Parede Celular , Teoria da Densidade Funcional , Imuno-Histoquímica
4.
Food Chem ; 331: 127203, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32574943

RESUMO

Effects of high hydrostatic pressure (HHP) (50, 100, 150, 200 and 250 MPa) pretreatment on water mobility and distribution, drying duration, microstructure, color, cell wall fraction and tissue structure of strawberry slices were investigated. HHP significantly increased water mobility of the strawberry slices, resulting in the reduction of drying duration by 9-24%. As the pretreatment pressure was increased, redness value and anthocyanin content continuously increased, soluble pectin (SBP) content increased and then decreased, while the contents of protopectin (PTP) and cellulose decreased. After the HHP pretreatment, chromoplasts and moisture was distributed more uniformly in the strawberry slices. Microscopy images showed the formation of microscopic holes or channels in the matrix and the breakdown of tissue structure by HHP. Results suggested HHP pretreatment disrupted the integrity of the fresh strawberry which enhanced the drying efficiency and migration of the chromoplasts during the vacuum-freeze drying process.


Assuntos
Fragaria/química , Liofilização , Antocianinas/química , Antocianinas/metabolismo , Celulose/química , Cor , Fragaria/metabolismo , Pressão Hidrostática , Espectroscopia de Ressonância Magnética , Pectinas/química , Pectinas/metabolismo , Água/química
5.
PLoS One ; 15(5): e0227591, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32433654

RESUMO

Plants emit high rates of methanol (meOH), generally assumed to derive from pectin demethylation, and this increases during abiotic stress. In contrast, less is known about the emission and source of acetic acid (AA). In this study, Populus trichocarpa (California poplar) leaves in different developmental stages were desiccated and quantified for total meOH and AA emissions together with bulk cell wall acetylation and methylation content. While young leaves showed high emissions of meOH (140 µmol m-2) and AA (42 µmol m-2), emissions were reduced in mature (meOH: 69%, AA: 60%) and old (meOH: 83%, AA: 76%) leaves. In contrast, the ratio of AA/meOH emissions increased with leaf development (young: 35%, mature: 43%, old: 82%), mimicking the pattern of O-acetyl/methyl ester ratios of leaf bulk cell walls (young: 35%, mature: 38%, old: 51%), which is driven by an increase in O-acetyl and decrease in methyl ester content with age. The results are consistent with meOH and AA emission sources from cell wall de-esterification, with young expanding tissues producing highly methylated pectin that is progressively demethyl-esterified. We highlight the quantification of AA/meOH emission ratios as a potential tool for rapid phenotype screening of structural carbohydrate esterification patterns.


Assuntos
Ácido Acético/metabolismo , Parede Celular/metabolismo , Metanol/metabolismo , Folhas de Planta/metabolismo , Acetilação , Atmosfera , Hidrolases de Éster Carboxílico/metabolismo , Esterificação , Metilação , Pectinas/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/genética , Populus/efeitos dos fármacos , Populus/crescimento & desenvolvimento , Populus/metabolismo , Estresse Fisiológico/genética
6.
Nature ; 579(7800): 561-566, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32214247

RESUMO

Species that propagate by sexual reproduction actively guard against the fertilization of an egg by multiple sperm (polyspermy). Flowering plants rely on pollen tubes to transport their immotile sperm to fertilize the female gametophytes inside ovules. In Arabidopsis, pollen tubes are guided by cysteine-rich chemoattractants to target the female gametophyte1,2. The FERONIA receptor kinase has a dual role in ensuring sperm delivery and blocking polyspermy3. It has previously been reported that FERONIA generates a female gametophyte environment that is required for sperm release4. Here we show that FERONIA controls several functionally linked conditions to prevent the penetration of female gametophytes by multiple pollen tubes in Arabidopsis. We demonstrate that FERONIA is crucial for maintaining de-esterified pectin at the filiform apparatus, a region of the cell wall at the entrance to the female gametophyte. Pollen tube arrival at the ovule triggers the accumulation of nitric oxide at the filiform apparatus in a process that is dependent on FERONIA and mediated by de-esterified pectin. Nitric oxide nitrosates both precursor and mature forms of the chemoattractant LURE11, respectively blocking its secretion and interaction with its receptor, to suppress pollen tube attraction. Our results elucidate a mechanism controlled by FERONIA in which the arrival of the first pollen tube alters ovular conditions to disengage pollen tube attraction and prevent the approach and penetration of the female gametophyte by late-arriving pollen tubes, thus averting polyspermy.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Fertilização , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Óxido Nítrico/metabolismo , Óvulo Vegetal/metabolismo , Pectinas/metabolismo , Fosfotransferases/metabolismo , Tubo Polínico/metabolismo , Parede Celular/química , Parede Celular/metabolismo , Óvulo Vegetal/citologia , Pectinas/química , Tubo Polínico/citologia
7.
Proc Natl Acad Sci U S A ; 117(11): 6003-6013, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32111691

RESUMO

Filamentous fungi, such as Neurospora crassa, are very efficient in deconstructing plant biomass by the secretion of an arsenal of plant cell wall-degrading enzymes, by remodeling metabolism to accommodate production of secreted enzymes, and by enabling transport and intracellular utilization of plant biomass components. Although a number of enzymes and transcriptional regulators involved in plant biomass utilization have been identified, how filamentous fungi sense and integrate nutritional information encoded in the plant cell wall into a regulatory hierarchy for optimal utilization of complex carbon sources is not understood. Here, we performed transcriptional profiling of N. crassa on 40 different carbon sources, including plant biomass, to provide data on how fungi sense simple to complex carbohydrates. From these data, we identified regulatory factors in N. crassa and characterized one (PDR-2) associated with pectin utilization and one with pectin/hemicellulose utilization (ARA-1). Using in vitro DNA affinity purification sequencing (DAP-seq), we identified direct targets of transcription factors involved in regulating genes encoding plant cell wall-degrading enzymes. In particular, our data clarified the role of the transcription factor VIB-1 in the regulation of genes encoding plant cell wall-degrading enzymes and nutrient scavenging and revealed a major role of the carbon catabolite repressor CRE-1 in regulating the expression of major facilitator transporter genes. These data contribute to a more complete understanding of cross talk between transcription factors and their target genes, which are involved in regulating nutrient sensing and plant biomass utilization on a global level.


Assuntos
Parede Celular/metabolismo , Proteínas Fúngicas/metabolismo , Neurospora crassa/genética , Pectinas/metabolismo , Polissacarídeos/metabolismo , Fatores de Transcrição/metabolismo , Biocombustíveis , Biomassa , Repressão Catabólica , Parede Celular/química , Regulação Fúngica da Expressão Gênica , Engenharia Metabólica/métodos , Redes e Vias Metabólicas/genética , Neurospora crassa/metabolismo , RNA-Seq
8.
Science ; 367(6481): 1003-1007, 2020 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-32108107

RESUMO

The process by which plant cells expand and gain shape has presented a challenge for researchers. Current models propose that these processes are driven by turgor pressure acting on the cell wall. Using nanoimaging, we show that the cell wall contains pectin nanofilaments that possess an intrinsic expansion capacity. Additionally, we use growth models containing such structures to show that a complex plant cell shape can derive from chemically induced local and polarized expansion of the pectin nanofilaments without turgor-driven growth. Thus, the plant cell wall, outside of the cell itself, is an active participant in shaping plant cells. Extracellular matrix function may similarly guide cell shape in other kingdoms, including Animalia.


Assuntos
Arabidopsis/embriologia , Pectinas/metabolismo , Pectinas/ultraestrutura , Células Vegetais , Desenvolvimento Vegetal , Epiderme Vegetal/citologia , Arabidopsis/citologia , Forma Celular , Parede Celular/metabolismo , Cotilédone/citologia , Cotilédone/embriologia , Metilação , Imagem Molecular
9.
Arch Microbiol ; 202(5): 1077-1084, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32030461

RESUMO

Plant material falling into the ultra-basic (pH 11.5-11.9) springs within The Cedars, an actively serpentinizing site in Sonoma County, California, is subject to conditions that mimic the industrial pretreatment of lignocellulosic biomass for biofuel production. We sought to obtain hemicellulolytic/cellulolytic bacteria from The Cedars springs that are capable of withstanding the extreme alkaline conditions wherein calcium hydroxide-rich water removes lignin, making cell wall polysaccharides more accessible to microorganisms and their enzymes. We enriched for such bacteria by adding plant debris from the springs into a synthetic alkaline medium with ground tissue of the biofuel crop switchgrass (Panicum virgatum L.) as the sole source of carbon. From the enrichment culture we isolated the facultative anaerobic bacterium Cellulomonas sp. strain FA1 (NBRC 114238), which tolerates high pH and catabolizes the major plant cell wall-associated polysaccharides cellulose, pectin, and hemicellulose. Strain FA1 in monoculture colonized the plant material and degraded switchgrass at a faster rate than the community from which it was derived. Cells of strain FA1 could be acclimated through subculturing to grow at a maximal concentration of 13.4% ethanol. A strain FA1-encoded ß-1, 4-endoxylanase expressed in E. coli was active at a broad pH range, displaying near maximal activity at pH 6-9. Discovery of this bacterium illustrates the value of extreme alkaline springs in the search for microorganisms with potential for consolidated bioprocessing of plant biomass to biofuels and other valuable bio-inspired products.


Assuntos
Biocombustíveis/microbiologia , Cellulomonas/isolamento & purificação , Cellulomonas/metabolismo , Endo-1,4-beta-Xilanases/metabolismo , Lignina/metabolismo , Composição de Bases/genética , Biomassa , Celulose/metabolismo , Endo-1,4-beta-Xilanases/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Etanol/metabolismo , Panicum/química , Panicum/genética , Panicum/metabolismo , Pectinas/metabolismo , Filogenia , Plantas/metabolismo , Polissacarídeos/metabolismo , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
10.
J Photochem Photobiol B ; 203: 111745, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31931381

RESUMO

Light affects many aspects of cell development. Tomato seedlings growing at different light qualities (white, blue, green, red, far-red) and in the dark displayed alterations in cell wall structure and composition. A strong and negative correlation was found between cell wall thickness and hypocotyl growth. Cell walls was thicker under blue and white lights and thinner under far-red light and in the dark, while intermediate values was observed for red or green lights. Additionally, the inside layer surface of cell wall presented random deposited microfibrillae angles under far-red light and in the dark. However, longitudinal transmission electron microscopy indicates a high frequency of microfibrils close to parallels related to the elongation axis in the outer layer. This was confirmed by ultra-high resolution small angle X-ray scattering. These data suggest that cellulose microfibrils would be passively reoriented in the longitudinal direction. As the cell expands, the most recently deposited layers (inside) behave differentially oriented compared to older (outer) layers in the dark or under FR lights, agreeing with the multinet growth hypothesis. High Ca and pectin levels were found in the cell wall of seedlings growing under blue and white light, also contributing to the low extensibility of the cell wall. Low Ca and pectin contents were found in the dark and under far-red light. Auxins marginally stimulated growth in thin cell wall circumstances. Hypocotyl growth was stimulated by gibberellins under blue light.


Assuntos
Parede Celular/fisiologia , Luz , Lycopersicon esculentum/fisiologia , Antocianinas/análise , Cálcio/metabolismo , Parede Celular/química , Cromatografia Líquida de Alta Pressão , Lycopersicon esculentum/crescimento & desenvolvimento , Lycopersicon esculentum/efeitos da radiação , Microfibrilas/química , Microscopia Eletrônica de Transmissão , Pectinas/metabolismo , Reguladores de Crescimento de Planta/análise , Reguladores de Crescimento de Planta/metabolismo , Análise de Componente Principal , Espalhamento a Baixo Ângulo , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Plântula/efeitos da radiação , Difração de Raios X
11.
Proc Natl Acad Sci U S A ; 117(6): 3281-3290, 2020 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-31974310

RESUMO

There is considerable interest in engineering plant cell wall components, particularly lignin, to improve forage quality and biomass properties for processing to fuels and bioproducts. However, modifying lignin content and/or composition in transgenic plants through down-regulation of lignin biosynthetic enzymes can induce expression of defense response genes in the absence of biotic or abiotic stress. Arabidopsis thaliana lines with altered lignin through down-regulation of hydroxycinnamoyl CoA:shikimate/quinate hydroxycinnamoyl transferase (HCT) or loss of function of cinnamoyl CoA reductase 1 (CCR1) express a suite of pathogenesis-related (PR) protein genes. The plants also exhibit extensive cell wall remodeling associated with induction of multiple cell wall-degrading enzymes, a process which renders the corresponding biomass a substrate for growth of the cellulolytic thermophile Caldicellulosiruptor bescii lacking a functional pectinase gene cluster. The cell wall remodeling also results in the release of size- and charge-heterogeneous pectic oligosaccharide elicitors of PR gene expression. Genetic analysis shows that both in planta PR gene expression and release of elicitors are the result of ectopic expression in xylem of the gene ARABIDOPSIS DEHISCENCE ZONE POLYGALACTURONASE 1 (ADPG1), which is normally expressed during anther and silique dehiscence. These data highlight the importance of pectin in cell wall integrity and the value of lignin modification as a tool to interrogate the informational content of plant cell walls.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Lignina/metabolismo , Caules de Planta/metabolismo , Poligalacturonase/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Parede Celular/genética , Parede Celular/metabolismo , Pectinas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Poligalacturonase/genética
12.
BMC Plant Biol ; 20(1): 13, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31914938

RESUMO

BACKGROUND: Pectin methylesterase (PME) is a hydrolytic enzyme that catalyzes the demethylesterification of homogalacturonans and controls pectin reconstruction, being essential in regulation of cell wall modification. During fruit ripening stage, PME-mediated cell wall remodeling is an important process to determine fruit firmness and softening. Strawberry fruit is a soft fruit with a short postharvest life, due to a rapid loss of firm texture. Hence, preharvest improvement of strawberry fruit rigidity is a prerequisite for extension of fruit refreshing time. Although PME has been well characterized in model plants, knowledge regarding the functionality and evolutionary property of PME gene family in strawberry remain limited. RESULTS: A total of 54 PME genes (FvPMEs) were identified in woodland strawberry (Fragaria vesca 'Hawaii 4'). Phylogeny and gene structure analysis divided these FvPME genes into four groups (Group 1-4). Duplicate events analysis suggested that tandem and dispersed duplications effectively contributed to the expansion of the PME family in strawberry. Through transcriptome analysis, we identified FvPME38 and FvPME39 as the most abundant-expressed PMEs at fruit ripening stages, and they were positively regulated by abscisic acid. Genetic manipulation of FvPME38 and FvPME39 by overexpression and RNAi-silencing significantly influences the fruit firmness, pectin content and cell wall structure, indicating a requirement of PME for strawberry fruit softening. CONCLUSION: Our study globally analyzed strawberry pectin methylesterases by the approaches of phylogenetics, evolutionary prediction and genetic analysis. We verified the essential role of FvPME38 and FvPME39 in regulation of strawberry fruit softening process, which provided a guide for improving strawberry fruit firmness by modifying PME level.


Assuntos
Hidrolases de Éster Carboxílico/genética , Fragaria , Frutas/metabolismo , Pectinas/metabolismo , Ácido Abscísico/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Parede Celular/metabolismo , Fragaria/genética , Fragaria/metabolismo , Frutas/genética , Perfilação da Expressão Gênica , Genes de Plantas , Filogenia , Interferência de RNA
13.
Arch Microbiol ; 202(5): 1005-1013, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31932863

RESUMO

Pectinase is widely used in numerous industrial fields, including the food, wine, and paper industries. In this work, seven bacteria were isolated from orange peel and their pectinase production activity was assayed. One bacterium (OR-B2) identified as a Bacillus sp. showed the highest enzyme activity towards others. A gene encoding a pectate lyase designed as PelB-B2 in this work was amplified and heterogeneous expressed in E.coli. PelB-B2 was defined as a member of the PelB pectate lyase family after phylogenic tree analysis. 3D model of PelB-B2 was constructed by SWISS-MODEL and PelB-B2 showed conserved para-ß structure. After inducing culture and purified by Ni-affinity chromatography, the properties of the purified PelB-B2 were assayed. Optimal pH and temperature for PelB-B2 was pH 8.0 and 50 °C, respectively. PelB-B2 showed excellent pH stability and thermostability. It was stable within pH range 3.0-11.0 and retained more than 51% activity after incubation at 40 °C, 50 °C, or 60 °C for 1 h. Furthermore, we determined that PelB-B2 was a Ca2+-dependent pectinase and the pectin extracted from citrus was the benefit substrate for PelB-B2. The Km and Vmax of PelB-B2 were 1.64 g/L and 232.56 mol/(L min), respectively. The OR-B2 can be a new resource for pectinase production and the PelB-B2 has potential for industrial application. 7 bacteria were isolated from orange peel, namely OR-B1 to OR-B7 and their pectinase activities were assayed. One pectate lyase belongs to PelB family was cloned from OR-B2 and heterogeneous expressed in E. coli. Purified PelB-B2 was further studied with its properties. Effects of pH, temperature, chemicals, substrate on the enzyme activity were assayed and the enzyme kinetic was also measured.


Assuntos
Bacillus/enzimologia , Pectinas/metabolismo , Poligalacturonase/metabolismo , Bacillus/genética , Bacillus/metabolismo , Citrus/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Poligalacturonase/biossíntese , Polissacarídeo-Liase/metabolismo , Temperatura
14.
Biochem J ; 477(2): 341-356, 2020 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-31967651

RESUMO

Plant polysaccharides (cellulose, hemicellulose, pectin, starch) are either direct (i.e. leaf starch) or indirect products of photosynthesis, and they belong to the most abundant organic compounds in nature. Although each of these polymers is made by a specific enzymatic machinery, frequently in different cell locations, details of their synthesis share certain common features. Thus, the production of these polysaccharides is preceded by the formation of nucleotide sugars catalyzed by fully reversible reactions of various enzymes, mostly pyrophosphorylases. These 'buffering' enzymes are, generally, quite active and operate close to equilibrium. The nucleotide sugars are then used as substrates for irreversible reactions of various polysaccharide-synthesizing glycosyltransferases ('engine' enzymes), e.g. plastidial starch synthases, or plasma membrane-bound cellulose synthase and callose synthase, or ER/Golgi-located variety of glycosyltransferases forming hemicellulose and pectin backbones. Alternatively, the irreversible step might also be provided by a carrier transporting a given immediate precursor across a membrane. Here, we argue that local equilibria, established within metabolic pathways and cycles resulting in polysaccharide production, bring stability to the system via the arrangement of a flexible supply of nucleotide sugars. This metabolic system is itself under control of adenylate kinase and nucleoside-diphosphate kinase, which determine the availability of nucleotides (adenylates, uridylates, guanylates and cytidylates) and Mg2+, the latter serving as a feedback signal from the nucleotide metabolome. Under these conditions, the supply of nucleotide sugars to engine enzymes is stable and constant, and the metabolic process becomes optimized in its load and consumption, making the system steady and self-regulated.


Assuntos
Redes e Vias Metabólicas/genética , Fosfotransferases/genética , Fotossíntese/genética , Polissacarídeos/genética , Adenilato Quinase/genética , Parede Celular/genética , Parede Celular/metabolismo , Celulose/biossíntese , Celulose/genética , Celulose/metabolismo , Metabolismo Energético/genética , Glucose-1-Fosfato Adenililtransferase/genética , Núcleosídeo-Difosfato Quinase/genética , Pectinas/biossíntese , Pectinas/genética , Pectinas/metabolismo , Fosfotransferases/metabolismo , Plantas , Polissacarídeos/biossíntese , Polissacarídeos/metabolismo , Amido/biossíntese , Amido/genética , Amido/metabolismo
15.
Appl Biochem Biotechnol ; 190(1): 129-137, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31304561

RESUMO

Apple pomace, an abundant accessible source of carbohydrate platform chemicals, is refractory to cellulase degradation because of the main barrier problem of pectin constitute. A rapid and portable method for the coproduction of pectin and fermentable sugars was developed using the pretreatment of acetic acid, followed by enzymatic hydrolysis. Compared with pectinase, acetic acid pretreatment provided the highest pectin yield of 19.1% and the highest enzymatic hydrolysis yield from apple pomace. The acidic pretreated apple pomace cellulose was easily and completely hydrolyzed into fermentable sugars. More than 98.2% conversion of cellulose was achieved in a batch hydrolysis using a cellulase loading of 25 FPU/g cellulose and 10% total solids without any special strategies. A mass balance analysis showed that 95.5 g pectin and 110.2 g fermentable sugars were produced from 500-g oven-dried apple pomace. The integrated process is suggestive of environment-friendly and recyclable methods for the industrial utilization of apple pomace.


Assuntos
Fermentação , Malus/metabolismo , Pectinas/biossíntese , Açúcares/metabolismo , Ácido Acético/química , Indústria Alimentícia , Ácidos Hexurônicos/metabolismo , Hidrólise , Resíduos Industriais , Pectinas/metabolismo , Poligalacturonase/metabolismo
16.
J Biosci Bioeng ; 129(1): 16-22, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31400994

RESUMO

The economical production of pectin oligosaccharides with a specific degree of polymerization and structure from agro-food waste is an industrially important process. This study identified a novel pectate lyase gene (plhy1) from the thermophilic cellulolytic fungus H. insolens Y1 and tested its ability to produce pectin oligosaccharides. The recombinant PLHY1 produced in Pichia pastoris was superior to other similar enzymes due to its high thermal and pH stability. PLHY1 demonstrated optimal enzymatic activity at 55°C and pH 10.0 in the presence of 0.4 mM Ca2+, and preferred methyl esterified substrates for digestion. High performance anion exchange chromatography-pulsed amperometric detector and ultra high performance liquid chromatography in combination with electrospray ionization tandem mass spectrometry analysis showed that galacturonic acid-oligosaccharides with a small degree of polymerization (4-6) were the major hydrolysates produced by the degradation of apple peel pectin by PLHY1. The properties of PLHY1 make it valuable for application in the agro-food industry for the production of pectin oligosaccharides.


Assuntos
Proteínas Fúngicas/química , Oligossacarídeos/metabolismo , Pectinas/química , Polissacarídeo-Liase/química , Sordariales/enzimologia , Biocatálise , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Ácidos Hexurônicos/química , Ácidos Hexurônicos/metabolismo , Pectinas/metabolismo , Polissacarídeo-Liase/genética , Polissacarídeo-Liase/metabolismo , Sordariales/química , Sordariales/genética
17.
Food Chem ; 310: 125965, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31835222

RESUMO

We studied the effects of ethylene on softening and sucrose metabolism in postharvest blueberry fruit by examining the responses of fruit firmness, cell wall polysaccharides, cell wall enzymes, four key genes of cell wall degradation and metabolism, enzyme activities, and five key genes of sucrose metabolism to exogenous ethylene treatments. Ethylene was found to accelerate blueberry softening, as it promoted the degradation of pectin and expression of pectinesterase (PE) and polygalacturonase (PG). Sucrose catabolism was accelerated with fruit softening, while sucrose content, sucrose phosphate synthase (SPS) activity were positively correlated with the loss of fruit firmness. Exogenous ethylene treatments promoted sucrose metabolism by inhibiting the expression of VcSPS1 and VcNIN2 and stimulating the expression of VcSS1 and VcCWINV1. These results indicate that ethylene plays an important role in fruit softening and sucrose metabolism of blueberry at 20 °C, and there may be a link between sucrose metabolism and fruit softening.


Assuntos
Mirtilos Azuis (Planta)/metabolismo , Etilenos/metabolismo , Sacarose/metabolismo , Mirtilos Azuis (Planta)/efeitos dos fármacos , Mirtilos Azuis (Planta)/genética , Hidrolases de Éster Carboxílico/metabolismo , Parede Celular/química , Parede Celular/metabolismo , Etilenos/farmacologia , Frutas/efeitos dos fármacos , Frutas/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Glucosiltransferases/metabolismo , Pectinas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Poligalacturonase/metabolismo , Polissacarídeos/farmacologia
18.
Chemosphere ; 241: 125095, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31683432

RESUMO

Cultivating cadmium (Cd)-safe rice lines, which show low Cd accumulation in brown rice, is generally beneficial to ensure food safety. The Cd retention in root of Cd-safe rice line D62B plays an important role in its low Cd translocation from root to shoot. To understand the mechanism of Cd retention in root, a hydroponic experiment was conducted to investigate the subcellular distribution of Cd and the contribution of polysaccharides to Cd binding to the root cell wall of a Cd-safe rice line D62B with a common rice line Luhui17 as a control material. D62B retained more Cd in the root by sequestrated a higher proportion of Cd in the cell wall, further it transferred less Cd to shoot. Close to half of the Cd in the root cell wall of D62B was accumulated in the hemicellulose 1 (HC1), and the proportions of HC1 in it were 1.2-1.7 times higher than these of Luhui17. The proportion of Cd in the pectin showed a dose-dependent increase in two rice lines. D62B contained significantly higher uronic acid concentrations of the pectin and greater pectin methyl esterase (PME) activities than Luhui17 in the root cell wall. These results indicated that a superior Cd binding capacity of the cell wall polysaccharides in D62B played an important role in its Cd retention in root.


Assuntos
Cádmio/farmacocinética , Parede Celular/metabolismo , Oryza/efeitos dos fármacos , Raízes de Plantas/metabolismo , Cádmio/metabolismo , Parede Celular/química , Parede Celular/efeitos dos fármacos , Hidroponia , Oryza/citologia , Oryza/metabolismo , Pectinas/química , Pectinas/metabolismo , Células Vegetais/efeitos dos fármacos , Células Vegetais/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/efeitos dos fármacos , Polissacarídeos/química , Polissacarídeos/metabolismo , Poluentes do Solo/metabolismo , Poluentes do Solo/farmacocinética
19.
Food Chem ; 305: 125433, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31499293

RESUMO

Native high methoxy citrus pectin (NP) was de-esterified by pectin methyl esterase to produce modified pectins [MP (42, 37, and 33)] having different degrees of esterification. Complex coacervation between a pea protein isolate (PPI) and each pectin was investigated as a function of pH (8.0-1.5) and mixing ratio (1:1-30:1, PPI-pectin). Complex formation was found to be optimal for biopolymer-mixing ratios of 8:1, 8:1, 25:1 and 25:1 for PPI complexed with NP, MP42, MP37 and MP33, respectively, at pHs 3.6, 3.5, 3.9 and 3.9. And, the critical pHs associated with complex formation (accessed by turbidity) was found to shift significantly to higher pHs as the degree of esterification of the pectin decreased, whereas the shift in the pH corresponding to their initial interactions was minimal with degree of esterification. Complexation of PPI with NP and MP42 greatly improved the protein solubility.


Assuntos
Proteínas de Ervilha/química , Pectinas/química , Hidrolases de Éster Carboxílico/metabolismo , Citrus/enzimologia , Concentração de Íons de Hidrogênio , Pectinas/metabolismo , Solubilidade
20.
Food Chem ; 302: 125343, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31430630

RESUMO

Pectin was extracted from blueberry powder as water soluble fraction (WSF), rich in branched regions, and chelator soluble fraction (CSF), linear, with strong negative charge. Binding of pectins with three anthocyanin standards (malvidin-3-glucoside; M3G, cyanidin-3-glucoside; C3G, and delphinidin-3-glucoside; D3G) and blueberry extract (BBE) were used. Without blueberry pectin, M3G was the most stable followed by C3G, whereas D3G completely disappeared after gastrointestinal digestion. CSF prevented M3G and C3G degradation more than WSF, the in vitro stability was highest with CSF and C3G. Increased stability of anthocyanins after simulated gastrointestinal digestion suggests that anthocyanins can be transported to colon where gut microbiota actively produce anthocyanin metabolites. The amount of bound anthocyanins that interacted with blueberry pectin increased as the number of hydroxyl groups increased on anthocyanins. Hydrogen bonding in addition to electrostatic interaction contribute to stability of pectin-anthocyanins interaction at pH 4.0 and contribute to stability under gastrointestinal simulation.


Assuntos
Antocianinas/química , Antocianinas/farmacocinética , Mirtilos Azuis (Planta)/química , Pectinas/química , Antocianinas/metabolismo , Digestão , Glucosídeos/química , Glucosídeos/metabolismo , Glucosídeos/farmacocinética , Ligação de Hidrogênio , Concentração de Íons de Hidrogênio , Pectinas/metabolismo , Pectinas/farmacocinética , Extratos Vegetais/química , Eletricidade Estática
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