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1.
Food Chem ; 356: 129657, 2021 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-33836359

RESUMO

Subgroups of starch granules from five maize phenotypes including waxy-, normal-, popcorn-, sweet corn- and high-amylose maize were sorted by flow cytometry (FC) utilizing the side scatter channel (SSC) and forward scatter channel (FSC). SSC and FSC mainly reflecting internal object complexity, and object size, respectively. Subgroups with higher FSC signal always showed higher SSC signal, indicating larger granules exhibited higher internal structural complexity. Wide-angle and small-angle X-ray scattering analysis showed that the subgroups showing high SSC signal intensity also had high lamellar scattering intensity, and low crystallinity. Vibrational transitions of bonds analyzed by Fourier Transform Infrared Spectroscopy (FT-IR) showed that the subgroups of maize starches, except sweet corn starch, with high SSC signal had high intensities at 1045 and 1022 cm-1. Hence, our data demonstrate that the structural complexity detected by the SSC signal is mainly associated with lamellar and crystalline features of starch granules.

2.
Food Chem ; 354: 129513, 2021 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-33765464

RESUMO

A raw starch digesting α-amylase from Nile tilapia (Oreochromis niloticus) intestine was identified. The α-amylase, AMY-T, had an estimated molecular weight of 60 kDa and purified to near homogeneity. AMY-T showed an apparent KM 4.78 mg/mL and Vmax 0.44 mg/mL/min) towards soluble starch. It was highly stable for 24 h in the pH range 3.0-10.0, and to solvents like methanol, isopropanol, butanol, dimethylformamide, DMSO and ethyl-ether. AMY-T was able to digest different carbohydrates, mainly showing endo-activity. Importantly, AMY-T was catalytically efficient and adsorbing towards raw potato starch at temperature documented for other raw starch digesting α-amylases. Thin layer and anion exchange chromatography characterization showed that the end products of raw starch hydrolysis were glucose, maltose and maltodextrins, with degree of polymerisation ranging 1-8. Scanning electron microscopy analysis of the AMY-T treated starch granules documented both granular exo- and endo-attack by AMY-T. These catalytic capabilities suggest high potential for AMY-T for industrial use.

3.
J Agric Food Chem ; 69(9): 2805-2815, 2021 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-33645979

RESUMO

The molecular structure and the expression levels of starch biosynthesis-related genes of three types of high-amylose maize (HAM) genotypes and one normal maize (NM) genotype at 5-35 days after pollination (DAP) were studied. Size exclusion chromatography (SEC) analysis showed that the molecular size of amylopectin molecules in NM increased from 5 to 35 DAP and the amylose content in HAM genotypes increased from 15 to 35 DAP. Correlation analysis for both NM and HAMs combined showed that SBEIIb and ISAII were negatively correlated with the contents of amylose and long amylopectin chains (DP > 30) and positively correlated with the content of short amylopectin chains (DP ≤ 31) and the molecular size of amylopectin molecules. Correlation analysis for only the HAMs showed that amylose content was negatively correlated with SBEI and SSIIa. In both correlation analyses, SSIIa showed a negative correlation with the average chain lengths of amylose chains.

4.
Carbohydr Polym ; 258: 117616, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33593533

RESUMO

The relationship between molecular structure and crystalline and lamellar structures of fifteen types of rice starches was studied. GPC and HPAEC were used for the molecular chain analysis and WAXS, SAXS, and CP/MAS 13C NMR were employed for aggregation structural analysis. The amylopectin content and the average lengths of fb1-chains (the degree of polymerization (DP) 13-24) were positively correlated with the amount of double helices (r2 = 0.92 and 0.57, respectively). In contrast, amylose content was positively correlated with the amounts of amorphous materials in starch (r2 = 0.77). The amount of double helices, which constitute a major part of the crystalline matrix, was positively correlated with the lamellar ordering (r2 = 0.81), and negatively correlated with the thickness of crystalline lamellae (r2 = 0.90) and lamellar repeat distance (r2 = 0.84). Conversely, the amount of the amorphous matrix was correlated with these parameters in the opposite way (r2 = 0.50, 0.75, and 0.75, respectively).

5.
Carbohydr Polym ; 251: 117056, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33142608

RESUMO

We describe a method for permitting efficient modification by transglucosidase (TGA), from glycoside hydrolase family 31 (GH31), sequentially after the pre-treatment by maltogenic α-amylases (MA) from GH13. TGA treatment without MA pre-treatment had negligible effects on native starch, while TGA treatment with MA pre-treatment resulted in porous granules and increased permeability to enzymes. MA→TGA treatments lead to decreased molecular size of amylopectin molecules, increased α-1,6 branching, and increased amounts of amylopectin chains with the degree of polymerization (DP)<10 and decreased amounts of DP 10-28 after debranching. Wide-angle X-ray scattering (WAXS) data showed a general decrease in crystallinity except for a long term (20 h) TGA post-treatment which increased the relative crystallinity back to normal. MA→TGA treatment significantly lowered the starch retrogradation of starch and retarded the increase of storage- and loss moduli during storage. This work demonstrates the potential of sequential addition of starch active enzymes to obtain granular starch with improved functionality.

6.
Carbohydr Polym ; 253: 117277, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33278948

RESUMO

Thermoplastic, polysaccharide-based plastics are environmentally friendly. However, typical shortcomings include lack of water resistance and poor mechanical properties. Nanocomposite manufacturing using pure, highly linear, polysaccharides can overcome such limitations. Cast nanocomposites were fabricated with plant engineered pure amylose (AM), produced in bulk quantity in transgenic barley grain, and cellulose nanofibers (CNF), extracted from agrowaste sugar beet pulp. Morphology, crystallinity, chemical heterogeneity, mechanics, dynamic mechanical, gas and water permeability, and contact angle of the films were investigated. Blending CNF into the AM matrix significantly enhanced the crystallinity, mechanical properties and permeability, whereas glycerol increased elongation at break, mainly by plasticizing the AM. There was significant phase separation between AM and CNF. Dynamic plasticizing and anti-plasticizing effects of both CNF and glycerol were demonstrated by NMR demonstrating high molecular order, but also non-crystalline, and evenly distributed 20 nm-sized glycerol domains. This study demonstrates a new lead in functional polysaccharide-based bioplastic systems.

7.
Carbohydr Polym ; 247: 116681, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32829809

RESUMO

Two high amylose (HAM) inbred lines with apparent amylose contents of 55 % and 62 %, respectively, were selected to explore the relationship between molecular structure and gene expression of starch-synthase involved enzymes. GPC analysis of debranched starches showed that the HAM starches (HAMSs) had shorter amylose chains and longer amylopectin chains than normal maize starch (NMS). FACE analysis showed that these HAMSs had a higher content of amylopectin chains of DP > 21. Quantitative Real-Time PCR analysis showed that the HAM lines had specifically low expression of the starch branching enzyme IIb (SBEIIb), and the starch synthase IIIa (SSIIIa) homologue, and high expression of the isoamylase 2 (ISA2), potentially suppressing the generation of amylopectin molecules through deficient branching and excessive debranching process, thereby increasing the relative amylose content. A high expression of GBSS1 was potentially associated with increased short amylose chain lengths in HAMSs.

8.
Carbohydr Polym ; 247: 116741, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32829860

RESUMO

Effects of different pre-treatments of granular rice starch using ethanol (ET) and maltogenic α-amylase (MA), separately or combined sequentially ET→MA, were performed to enable efficient subsequent modification with branching enzyme (BE). The pre-treated samples were characterized with respect to morphology, molecular structure, physicochemical properties and the rate of digestion to amylolytic enzymes. MA produced pores and also eroded the granular surface whereas ET caused coapted granules, noticeable swelling but no pores. Crystallinity and enthalpy of gelatinization dramatically decreased with ET and ET→MA. Subsequent BE catalysis increased the specific surface area, crystallinity, α-1,6-glucosidic linkage ratio and enthalpy. BE catalyzed branching resulted in more intact granules, less swelling capacity, solubility and granular separation as compared to their control. These effects were related to reduced amylolytic susceptibility. Pre-treatment prior to BE catalysis offers an efficient alternative way to modify granular starch with different structure and properties depending on the pre-treatment protocol.

9.
Plant Biotechnol J ; 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-32096588

RESUMO

Solanum tuberosum potato lines with high amylose content were generated by crossing with the wild potato species Solanum sandemanii followed by repeated backcrossing to Solanum tuberosum lines. The trait, termed increased amylose (IAm), was recessive and present after three generations of backcrossing into S. tuberosum lines (6.25% S. sandemanii genes). The tubers of these lines were small, elongated and irregular with small and misshaped starch granules and high sugar content. Additional backcrossing resulted in less irregular tuber morphology, increased starch content (4.3%-9.5%) and increased amylose content (29%-37.9%) but indifferent sugar content. The amylose in the IAm starch granules was mainly located in peripheral spots, and large cavities were found in the granules. Starch pasting was suppressed, and the digestion-resistant starch (RS) content was increased. Comprehensive microarray polymer profiling (CoMPP) analysis revealed specific alterations of major pectic and glycoprotein cell wall components. This complex phenotype led us to search for candidate IAm genes exploiting its recessive trait. Hence, we sequenced genomic DNA of a pool of IAm lines, identified SNPs genome wide against the draft genome sequence of potato and searched for regions of decreased heterozygosity. Three regions, located on chromosomes 3, 7 and 10, respectively, displayed markedly less heterozygosity than average. The only credible starch metabolism-related gene found in these regions encoded the isoamylase-type debranching enzyme Stisa1. Decreased expression of mRNA (>500 fold) and reduced enzyme activity (virtually absent from IAm lines) supported Stisa1 as a candidate gene for IAm.

10.
Carbohydr Polym ; 230: 115611, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31887905

RESUMO

Porous starch is attractive by providing high surface area for many applications. In this study amyloglucosidase (AMG) and maltogenic α-amylase (MA) were investigated in direct comparison to elucidate potential effects in producing porous starch using high amylose rice starch as a substrate. Both enzymes generated pores at the surface as illustrated by Scanning Electron Microscopy (SEM). The enzyme-treated granules had higher relative crystallinity as deduced from Wide Angle X-ray Scattering (WAXS). MA treatment increased the number of short amylopectin chains and decreased the molecular weight with extended incubation time. The MA-treated starch had higher solubility whereas swelling capacity, amylose content, peak viscosity, final viscosity, breakdown and setback of both treatments were decreased compared to the control. Enzymatic treatments produced starch with delayed gelatinization temperature and increased the enthalpy. The results demonstrate that porous rice starch can provide different functionalities depending on the enzyme mechanisms, extending the range of applications.


Assuntos
Amilose/química , Glucana 1,4-alfa-Glucosidase/metabolismo , Oryza/química , alfa-Amilases/metabolismo , Biocatálise , Interações Hidrofóbicas e Hidrofílicas , Maltose/química , Porosidade , Viscosidade
11.
Int J Biol Macromol ; 145: 100-107, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31862366

RESUMO

The effects of multicycle ultrasound-assisted ice recrystallization (US+IR) combined with amyloglucosidase (AMG) or maltogenic α-amylase (MA) catalyzed hydrolysis on structure were investigated. Scanning electron microscopy (SEM) showed that the US+IR produced shallow indentations and grooves on the exterior of granules while the combination US+IR and enzyme hydrolysis created additional pores on starch granules. MA displayed a higher number of pores than AMG. The highest values of specific surface area (SBET) and the total pore volume were obtained for US+IR→MA (1.96 m2 g-1 and 7.26 × 10-3 cm3 g-1, respectively). The US+IR treatment significantly decreased the relative crystallinity, amylose content and swelling capacity. Those parameters were further efficiently decreased following enzymatic hydrolysis. The combined treatments generated products with higher initial gelatinization temperature (Ti) compared to the corresponding controls. The US+IR increased the digestion rate constant (k-value) compared to native starch. However, the combined treatment, US+IR→AMG, significantly decreased the k-value from 2.97 × 10-3 to 2.50 × 10-3 min-1 compared to its control. Our study demonstrates that US+IR treatment in combination with enzyme hydrolysis is a useful method to produce specifically functionalized porous rice starch that can be used as e.g. absorbents and for further chemical modifications.


Assuntos
Enzimas/química , Enzimas/metabolismo , Oryza/química , Oryza/metabolismo , Amido/química , Amido/metabolismo , Amilose/química , Amilose/metabolismo , Cristalização/métodos , Glucana 1,4-alfa-Glucosidase/química , Glucana 1,4-alfa-Glucosidase/metabolismo , Hidrólise , Porosidade , Temperatura , alfa-Amilases/química , alfa-Amilases/metabolismo
12.
Carbohydr Polym ; 229: 115481, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31826407

RESUMO

Structural dynamics of starch granules selected for different amylose content and crystalline type were analysed in excess water upon heating observed in-situ using SAXS and WAXS. The results showed that NMS and MBS exhibited higher degree of lamellar order than HAM. The peak width at half-maximum (FWHM) of HAM and NMS increased with temperature, demonstrating a gradual radial swelling of the lamellae during gelatinization. For NMS and HAM FWHM increased, suggesting that the dynamics of lamellar thicknesses of these starches were increased during hydrothermal compression exerted by the amorphous lamella. The decrease in FWHM found for MBS indicates that these lamellae were very vulnerable for dissolution. The changes in SAXS peak areas found for NMS and MBS were different from the areas of HAM indicating that A-type starch, as compared to B-type starch, possesses higher degree of lamellae ordering. Our data are potentially useful in starch-based materials processing.


Assuntos
Amilose/análise , Gelatina/química , Amido/química
13.
J Exp Bot ; 71(1): 234-246, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31494665

RESUMO

The biosynthesis of starch granules in plant plastids is coordinated by the orchestrated action of transferases, hydrolases, and dikinases. These enzymes either contain starch-binding domain(s) themselves, or are dependent on direct interactions with co-factors containing starch-binding domains. As a means to competitively interfere with existing starch-protein interactions, we expressed the protein module Carbohydrate-Binding Motif 20 (CBM20), which has a very high affinity for starch, ectopically in barley plastids. This interference resulted in an increase in the number of starch granules in chloroplasts and in formation of compound starch granules in grain amyloplasts, which is unusual for barley. More importantly, we observed a photosystem-independent inhibition of CO2 fixation, with a subsequent reduced growth rate and lower accumulation of carbohydrates with effects throughout the metabolome, including lower accumulation of transient leaf starch. Our results demonstrate the importance of endogenous starch-protein interactions for controlling starch granule morphology and number, and plant growth, as substantiated by a metabolic link between starch-protein interactions and control of CO2 fixation in chloroplasts.

14.
Sci Rep ; 9(1): 17715, 2019 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-31776399

RESUMO

CRISPR/Cas9 editing efficacies in tetraploid potato were highly improved through the use of endogenous potato U6 promoters. Highly increased editing efficiencies in the Granular Bound Starch Synthase gene at the protoplast level were obtained by replacement of the Arabidopsis U6 promotor, driving expression of the CRISPR component, with endogenous potato U6 promotors. This translated at the ex-plant level into 35% full allelic gene editing. Indel Detection Amplicon Analysis was established as an efficient tool for fast assessment of gene editing in complex genomes, such as potato. Together, this warrants significant reduction of laborious cell culturing, ex-plant regeneration and screening procedures of plants with high complexity genomes.


Assuntos
Sistemas CRISPR-Cas , Edição de Genes/métodos , Melhoramento Vegetal/métodos , Solanum tuberosum/genética , Tetraploidia
15.
Food Res Int ; 125: 108644, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31554129

RESUMO

Potato fiber is a side product in starch manufacturing rich in dietary fibers such as pectin, cellulose, hemicellulose and resistant starch. So far, the beneficial properties of potato fiber have been poorly characterized. This study investigated the effect of FiberBind 400, a commercial potato fiber product, on survival of probiotic Lactobacillus strains at simulated gastric conditions and on the composition and metabolic activity of the gut microbiota, using the TIM-2 colon model. Resistant starch and native starch from potato were used as reference substrates. FiberBind 400 had an ability to improve survival of the four tested strains, Lactobacillus fermentum PCC®, L. rhamnosus LGG®, L. reuteri RC-14® and L. paracasei F-19® in a strain-dependent way. The highest effect was observed for L. fermentum PCC® and L. rhamnosus LGG®. The effect of starches on bacterial survival was insignificant. Composition of the fecal microbiota in TIM-2 fermentations was assessed by high-throughput sequencing of 16S rRNA gene amplicon. Fermentation of FiberBind 400 resulted in more diverse microbial communities compared to starches. Changes in microbial abundances specifically mediated by FiberBind 400, included increases in the genera Lachnospira, Butyrivibrio, Mogibacterium, Parabacteroides, Prevotella and Desulfovibrio, and the species B. ovatus, as well as decreases in Ruminococcus torques and unassigned Ruminococcus spp. Shifts in other bacterial populations, such as increased abundances of Oscillospira, Enterococcus, Bacteroidales, Citrobacter, along with reduction of Roseburia, Ruminococcus, and Faecalibacterium prausnitzii were not significantly different between the substrates. Cumulative production of individual short-chain fatty acids was similar between potato fiber and starches. The study demonstrated that FiberBind 400 had a potential to protect probiotic Lactobacillus strains during the passage through the gastrointestinal tract and selectively modulate the gut bacterial populations. This knowledge can support application of potato fiber as a functional food ingredient with added biological benefits.


Assuntos
Fibras na Dieta/administração & dosagem , Microbioma Gastrointestinal/fisiologia , Lactobacillus/fisiologia , Probióticos , Solanum tuberosum/química , Digestão , Ácidos Graxos/biossíntese , Ácidos Graxos Voláteis , Fezes/microbiologia , Fermentação , Alimento Funcional , Microbioma Gastrointestinal/efeitos dos fármacos , Trato Gastrointestinal/metabolismo , Lactobacillus/efeitos dos fármacos , Lactobacillus/crescimento & desenvolvimento , Especificidade da Espécie , Amido/administração & dosagem
16.
Mol Plant ; 12(11): 1474-1484, 2019 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-31260813

RESUMO

In the phloem cap region of Arabidopsis plants, sulfur-rich cells (S-cells) accumulate >100 mM glucosinolates (GLS), but are biosynthetically inactive. The source and route of S-cell-bound GLS remain elusive. In this study, using single-cell sampling and scanning electron microscopy with energy-dispersive X-ray analysis we show that two GLS importers, NPF2.10/GTR1 and NPF2.11/GTR2, are critical for GLS accumulation in S-cells, although they are not localized in the S-cells. Comparison of GLS levels in S-cells in multiple combinations of homo- and heterografts of gtr1 gtr2, biosynthetic null mutant and wild-type plants indicate that S-cells accumulate GLS via symplasmic connections either directly from neighboring biosynthetic cells or indirectly to non-neighboring cells expressing GTR1/2. Distinct sources and transport routes exist for different types of GLS, and vary depending on the position of S-cells in the inflorescence stem. Based on these findings, we propose a model illustrating the GLS transport routes either directly from biosynthetic cells or via GTR-mediated import from apoplastic space radially into a symplasmic domain, wherein the S-cells are the ultimate sink. Similarly, we observed accumulation of the cyanogenic glucoside defensive compounds in high-turgor cells in the phloem cap of Lotus japonicus, suggesting that storage of defensive compounds in high-turgor cells may be a general mechanism for chemical protection of the phloem cap.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Glucosinolatos/metabolismo , Inflorescência/citologia , Floema/citologia , Enxofre/metabolismo , Arabidopsis/imunologia , Inflorescência/metabolismo , Modelos Biológicos , Floema/metabolismo , Transporte Proteico
17.
Int J Biol Macromol ; 137: 870-877, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31279879

RESUMO

Microwave processing is a suitable technology for starch-based food processing. This work investigated the changes of structures and properties of high-amylose maize starch (HAMS) during short-time microwave irradiation (1-4 min). After 1 min of treatment, short amylopectin chains (DP 6-36) and intermediate amylose chains (DP 150-2000) of HAMS were partially broken down. Compared with native HAMS, treated HAMS (1 min) had the higher relative crystallinity, the intensity of the 9 nm lamellar peak, and fluorescence intensity under CLSM. Moreover, 1-min microwaving caused the lower viscosity and higher resistant starch content of HAMS. In the 2-4 min of treatment, the crystallinity, intensity of the lamellar peak and fluorescence intensity of HAMS granules decreased significantly, but no breakdown of starch molecule chains was observed, suggesting the realignment of the crystalline region during the process. Correspondingly, the viscosity increased and resistant starch content decreased. Our study provides a deeper understanding of the mechanistic effects of short-time microwave irradiation on high-amylose starch, which is of value for the processing of HAMS to produce novel functionality and nutritional values.


Assuntos
Amilose/análise , Digestão , Micro-Ondas , Amido/química , Zea mays/química , Indústria Alimentícia , Hidrólise , Fenômenos Mecânicos , Valor Nutritivo , Amido/metabolismo , Fatores de Tempo , Viscosidade
18.
Int J Food Microbiol ; 304: 106-118, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31176963

RESUMO

Nicaraguan cocoa bean fermentations of several single local cocoa varieties originating from the same region (North Highlands of Nicaragua, San Jose de Bocay/El Cuá) were compared to fermentations of blended cocoa varietals from other producing regions of the country (Waslala and Nueva Guinea) making use of High Throughput Sequencing techniques, metabolite target analysis and sensory evaluation of cocoa liquor samples. A succession of the important cocoa-related yeasts Hanseniaspora uvarum/opuntiae, Saccharomyces cerevisiae and/or Pichia kudriavzevii was seen for single varietals and Nueva Guinea fermentations, while Kazachstania humilis dominated the mid and end phase of the Waslala cocoa fermentations. Tatumella species (mainly Tatumella terrea and Tatumella punctata) predominated the bacterial community at the onset of all fermentations followed by unusually late (generally 2 days into the fermentations) appearance of Lactobacillus fermentum relative to fermentations in other parts of the World. Acetobacter spp. were the main acetic acid bacteria during all fermentations, but also Gluconobacter spp. were involved in some single-variety fermentations. All fermentations proved complete as determined by metabolite analysis with bean sucrose being fully depleted and pulp sugars exhausted after 48-72 h of fermentation. From an organoleptic point of view, all Nicaraguan cocoas of this study reflected fine fruity (citrus or berry-like) flavours with distinct herbal or caramel notes. Floral notes were associated with the cases where P. kudriavzevii was involved in the later stages of fermentation. Intense citrus/fruity character was related to high pulp and bean citrate concentrations. Off-notes were found in some over-fermented batches where Bacillus spp. was detected. No relation between cut-test results and organoleptic appreciation was seen.


Assuntos
Bactérias/metabolismo , Cacau/microbiologia , Chocolate/microbiologia , Fermentação/fisiologia , Fungos/metabolismo , Ácido Acético/metabolismo , Acetobacter/metabolismo , Bactérias/isolamento & purificação , Reatores Biológicos/microbiologia , Enterobacteriaceae/metabolismo , Fungos/isolamento & purificação , Gluconobacter/metabolismo , Hanseniaspora/metabolismo , Lactobacillus fermentum/metabolismo , Pichia/metabolismo , Saccharomyces cerevisiae/metabolismo
19.
Front Microbiol ; 10: 223, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30828323

RESUMO

Pectins are plant cell-wall polysaccharides which can be utilized by commensal bacteria in the gut, exhibiting beneficial properties for the host. Knowledge of the impact of pectins on intestinal bacterial communities is insufficient and limited to a few types of pectins. This study characterized the relationship between the structural properties of pectins and their potential to modulate composition and activity of the gut microbiota in a beneficial way. For this purpose we performed in vitro fermentations of nine structurally diverse pectins from citrus fruits and sugar beet, and a pectic derivative, rhamnogalacturonan I (RGI), using a TIM-2 colon model. The composition of microbiota during TIM-2 fermentations was assessed by 16S rRNA gene amplicon sequencing. Both general and pectin-specific changes were observed in relative abundances of numerous bacterial taxa in a time-dependent way. Bacterial populations associated with human health, such as Faecalibacterium prausnitzii, Coprococcus, Ruminococcus, Dorea, Blautia, Oscillospira, Sutterella, Bifidobacterium, Christensenellaceae, Prevotella copri, and Bacteroides spp. were either increased or decreased depending on the substrate, suggesting that these bacteria can be controlled using structurally different pectins. The main structural features linked to the pectin-mediated shifts in microbiota included degree of esterification, composition of neutral sugars, distribution of homogalacturonan and rhamnogalacturonan fractions, degree of branching, and the presence of amide groups. Cumulative production of the total short chain fatty acids and propionate was largest in fermentations of the high methoxyl pectins. Thus, this study indicates that microbial communities in the gut can be specifically modulated by pectins and identifies the features in pectin molecules linked to microbial alterations. This knowledge can be used to define preferred dietary pectins, targeting beneficial bacteria, and favoring more balanced microbiota communities in the gut.

20.
Gut ; 68(1): 83-93, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29097438

RESUMO

OBJECTIVE: To investigate whether a whole grain diet alters the gut microbiome and insulin sensitivity, as well as biomarkers of metabolic health and gut functionality. DESIGN: 60 Danish adults at risk of developing metabolic syndrome were included in a randomised cross-over trial with two 8-week dietary intervention periods comprising whole grain diet and refined grain diet, separated by a washout period of ≥6 weeks. The response to the interventions on the gut microbiome composition and insulin sensitivity as well on measures of glucose and lipid metabolism, gut functionality, inflammatory markers, anthropometry and urine metabolomics were assessed. RESULTS: 50 participants completed both periods with a whole grain intake of 179±50 g/day and 13±10 g/day in the whole grain and refined grain period, respectively. Compliance was confirmed by a difference in plasma alkylresorcinols (p<0.0001). Compared with refined grain, whole grain did not significantly alter glucose homeostasis and did not induce major changes in the faecal microbiome. Also, breath hydrogen levels, plasma short-chain fatty acids, intestinal integrity and intestinal transit time were not affected. The whole grain diet did, however, compared with the refined grain diet, decrease body weight (p<0.0001), serum inflammatory markers, interleukin (IL)-6 (p=0.009) and C-reactive protein (p=0.003). The reduction in body weight was consistent with a reduction in energy intake, and IL-6 reduction was associated with the amount of whole grain consumed, in particular with intake of rye. CONCLUSION: Compared with refined grain diet, whole grain diet did not alter insulin sensitivity and gut microbiome but reduced body weight and systemic low-grade inflammation. TRIAL REGISTRATION NUMBER: NCT01731366; Results.


Assuntos
Microbioma Gastrointestinal , Inflamação/sangue , Perda de Peso , Grãos Integrais , Adulto , Idoso , Glicemia/metabolismo , Estudos Cross-Over , Dinamarca , Dieta , Ingestão de Energia , Fezes/microbiologia , Feminino , Humanos , Inflamação/dietoterapia , Resistência à Insulina , Interleucina-6/sangue , Lipídeos/sangue , Masculino , Metabolômica , Pessoa de Meia-Idade
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