Plant-derived Polysaccharide Research Articles

Structural characterization of a α-d-glucan from Ginkgo biloba seeds and its protective effects on non-alcoholic fatty liver disease in mice

Nonalcoholic fatty liver disease (NAFLD) poses a great global challenge to public health, yet it holds promise for amelioration through plant-derived polysaccharide. Ginkgo biloba seeds have long been used as medicine and food, which has potential benefits for various chronic diseases. However, the protective role of Ginkgo biloba seed polysaccharide against NAFLD remains unclear. In this study, we isolated and purified polysaccharide (GBSP-2) from Ginkgo biloba seeds. GBSP-2 is composed of α-d-glucopyranose residues, which are interconnected with α-d-glucopyranose units linked by (1→4) bonds, (1→4,6) bonds and (1→3,4) bonds, the ratio distribution is 15:1:1. By studying a mouse model, we investigated the effect of GBSP-2 (100 or 200 mg/kg) on high-fat-diet-induced NAFLD. We demonstrated that GBSP-2 significantly alleviated NAFLD, as evidenced by reduced hepatic steatosis, decreased inflammation, improved oxidative stress and ameliorative glucolipid metabolic disorders. Furthermore, GBSP-2 mitigated gut microbiota disturbance of NAFLD mice and markedly increased the abundance of Akkermansia, Romboutsia, Lactobacillus and Bacteroides. Mechanistically, GBSP-2 could activate AMPK/ACC signaling pathway to inhibit lipid synthesis by generating 3,4-dihydroxyphenylpropionic acid (DHPPA). Overall, these findings suggest that GBSP-2 plays a multi-channel and multi-target role in improving NAFLD through the gut-liver axis.

The Role of Pectin Hydrogel Systems Plus Iodine and Phyto Extract in Second-Degree Burn in Rats.

Skin injuries, such as burns, can result in an open wound that can lead to the deterioration of the skin, which acts as a protective barrier against external agents, and can cause serious health problems. Pectin, a plant-derived polysaccharide, is a suitable candidate for wound care due to its gel-forming ability and biocompatibility. Pectin absorbs wound exudates to form a soft gel and is known for its strong anti-inflammatory efects. Pectin-based hydrogel systems promote wound healing by promoting fibroblast proliferation and keratinocyte migration. In the study, 60 male Wistar albino rats were used, and 6 diferent treatment groups were formed: Healthy control, burn control, silver sulfadiazine, pectin-based hydrogel system, pectin-based hydrogel system+iodine, pectin-based hydrogel system+plant extract. Rats with burn wounds were treated for 21 days, and the wound healing process was evaluated by macroscopic, biochemical, and histopathological analysis. The results showed that the pectin-based hydrogel system, iodine, and plant extracts promoted healing in burn wounds. Especially in the groups treated with silver sulfadiazine and plant extracts, the development of granulation tissue and regeneration of collagen fibers showed significant improvement. Furthermore, the pectin-based hydrogel system is thought to contribute to wound healing by maintaining skin moisturization. Vascular endothelial growth factor (VEGF) and transforming growth factor-β (TGF-β) levels decreased in the treatment groups compared to the burn group, and it was determined that these factors play an important role in wound healing. This study shows that pectin-based hydrogel systems can be an efective alternative in burn treatment, and their healing efects can be enhanced by the addition of iodine and plant extracts.

Fabrication of Anatomically Equivalent Pectin-Based Multifilament Nerve Conduits.

Reuniting denuded nerve ends after a long segmental peripheral nerve defect is challenging due to delayed axonal regeneration and incomplete, nonspecific reinnervation, as conventional hollow nerve guides fail to ensure proper fascicular complementation and obstruct axonal guidance across the defects. This study focuses on fabricating multifilament conduits using a plant-derived anionic polysaccharide, pectin, where the abundant availability of carboxylate (COO-) functional groups in pectin facilitates instantaneous sol-gel transition upon interaction with divalent cations. Despite their advantages, pectin hydrogels encounter structural instability under physiological conditions. Hence, pectin is conjugated with light-sensitive methacrylate residues (49.8% methacrylation) to overcome these issues, enabling the fabrication of dual cross-linked multifilament nerve conduits through an ionic interaction-driven, template-free 3D wet writing process, followed by photo-cross-linking at 525 nm. The anatomical equivalence including peri-, epi-, and endoneurium structures of the customized multifilament conduits was confirmed through scanning electron micrographs and micro-CT analysis of rat and goat sciatic nerve tissues. Furthermore, the fabricated multifilament nerve conduits demonstrated cytocompatibility and promoted the expression of neuron-specific intermediate filament protein (NF-200) in PC12 cells and neurite outgrowth of 16.90 ± 1.82 μm on day 14. Micro-CT imaging of an anastomosed native goat sciatic nerve with an 8-filament conduit demonstrated precise fascicular complementation in an ex vivo interpositional goat model. This approach not only eliminates the need for a suture-intensive ligation process but also highlights the customizability of multifilament conduits to meet patient- and injury-specific needs.

A novel dual-function antiscalant carboxymethyl cellulose-graft-protocatechuic acid for efficient scaling and biofouling prevention

Despite antiscalants playing a critical role in desalination and cooling water systems, their potential to support microbial growth pose a significant threat to water treatment processes by promoting biofouling. In this work, a novel dual-function antiscalant carboxymethyl cellulose-graft-protocatechuic acid (CMC-g-PA) was prepared using plant-derived antibacterial protocatechuic acid (PA) and natural polysaccharide cellulose, and its scale inhibition effect on CaSO4 scale and antibacterial performance on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were evaluated. Results indicated that the inhibition efficiency against CaSO4 scale and the induction time of CaSO4 crystallization process in the presence of CMC-g-PA were remarkably enhanced compared to unmodified CMC. Microscope and XRD characterizations demonstrated significant alterations in the crystal morphology and size of the formed scale using CMC-g-PA as antiscalant. Molecular dynamics (MD) analysis also showed that CMC-g-PA could intensively interact with the crystal plane of CaSO4 with the binding energy reaching 746.73 kcal/mol, thereby affecting crystal growth and causing crystal distortion. Additionally, an obvious inhibitory effect of CMC-g-PA on the growth of E. coli and S. aureus was observed, attributed primarily to the antibacterial activity of the introduced phenolic hydroxyl groups. In short, bio-derived CMC-g-PA, characterized in its environmental-friendliness, antiscaling efficiency and antibacterial activity, holds immense potential for mitigating scaling and biofouling in desalination/cooling water systems.

Salvia miltiorrhiza polysaccharide mitigates AFB1-induced liver injury in rabbits

Aflatoxin B1 (AFB1) is one of the common dietary contaminants worldwide, which can harm the liver of humans and animals. Salvia miltiorrhiza polysaccharide (SMP) is a natural plant-derived polysaccharide with numerous pharmacological activities, including hepatoprotective properties. The purpose of this study is to explore the intervention effect of SMP on AFB1-induced liver injury and its underlying mechanisms in rabbits. The rabbits were administered AFB1 (25 μg/kg/feed) and or treatment with SMP (300, 600, 900 mg/kg/feed) for 42 days. The results showed that SMP effectively alleviated the negative impact of AFB1 on rabbits' productivity by increasing average daily weight gain (ADG) and feed conversion rate (FCR). SMP reduced aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) levels in serum, ameliorating AFB1-induced hepatic pathological changes. Additionally, SMP enhanced superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) activity, and inhibited reactive oxygen species (ROS), malondialdehyde (MDA), 4-Hydroxynonenal (4-HNE), interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) expression, thus mitigating AFB1-induced oxidative stress and inflammatory responses. Moreover, SMP upregulated the expression of nuclear factor E2 related factor 2 (Nrf2), heme oxygenase 1 (HO-1), NADPH quinone oxidoreductase 1 (NQO1) and B-cell lymphoma 2 (Bcl2) while downregulating kelch like ECH associated protein 1 (Keap1), cytochrome c (cyt.c), caspase9, caspase3, and Bcl-2-associated X protein (Bax) expression, thereby inhibiting AFB1-induced hepatocyte apoptosis. Consequently, our findings conclude that SMP can mitigate AFB1-induced liver damage by activating the Nrf2/HO-1 pathway and inhibiting mitochondria-dependent apoptotic pathway in rabbits.

Boundary Lubrication Performance of Polyelectrolyte-Surfactant Complexes on Biomimetic Surfaces.

Aqueous mixtures of oppositely charged polyelectrolytes and surfactants are useful in many industrial applications, such as shampoos and hair conditioners. In this work, we investigate the friction between biomimetic hair surfaces in the presence of adsorbed complexes formed from cationic polyelectrolytes and anionic surfactants in an aqueous solution. We apply nonequilibrium molecular dynamics (NEMD) simulations using the coarse-grained MARTINI model. We first developed new MARTINI parameters for cationic guar gum (CGG), a functionalized, plant-derived polysaccharide. The complexation of CGG and the anionic surfactant sodium dodecyl sulfate (SDS) on virgin and chemically damaged biomimetic hair surfaces was studied using a sequential adsorption approach. We then carried out squeeze-out and sliding NEMD simulations to assess the boundary lubrication performance of the CGG-SDS complex compressed between two hair surfaces. At low pressure, we observe a synergistic friction behavior for the CGG-SDS complex, which gives lower shear stress than either pure CGG or SDS. Here, friction is dominated by viscous dissipation in an interfacial layer comprising SDS and water. At higher pressures, which are probably beyond those usually experienced during hair manipulation, SDS and water are squeezed out, and friction increases due to interdigitation. The outcomes of this work are expected to be beneficial to fine-tune and screen sustainable hair care formulations to provide low friction and therefore a smooth feel and reduced entanglement.

Injectable plant-derived polysaccharide hydrogels with intrinsic antioxidant bioactivity accelerate wound healing by promoting epithelialization and angiogenesis

Skin wound healing is a complex and dynamic process involving hemostasis, inflammatory response, cell proliferation and migration, and angiogenesis. Currently used wound dressings remain unsatisfactory in the clinic due to the lack of adjustable mechanical property for injection operation and bioactivity for accelerating wound healing. In this work, an “all-sugar” hydrogel dressing is developed based on dynamic borate bonding network between the hydroxyl groups of okra polysaccharide (OP) and xyloglucan (XG). Benefiting from the reversible crosslinking network, the resulting composite XG/OP hydrogels exhibited good shear-thinning and fast self-healing properties, which is suitable to be injected at wound beds and filled into irregular injured site. Besides, the proposed XG/OP hydrogels showed efficient antioxidant capacity by scavenging DPPH activity of 73.9 %. In vivo experiments demonstrated that XG/OP hydrogels performed hemostasis and accelerated wound healing with reduced inflammation, enhanced collagen deposition and angiogenesis. This plant-derived dynamic hydrogel offers a facile and effective approach for wound management and has great potential for clinical translation in feature.

A Prospective Analysis of the Effects of a Powder-Type Hemostatic Agent on the Short-Term Outcomes after Liver Resection.

Background and Objectives: Postoperative bleeding is a significant cause of morbidity and mortality following liver resection. Therefore, it is crucial to minimize bleeding during liver resection and effectively manage it when it occurs. Arista® AH (Becton, Dickinson and Company, Franklin Lakes, NJ, USA) is a microporous polysaccharide hemosphere (MPH), a new plant-derived polysaccharide powder hemostat that can be applied to the entire surgical field. This study prospectively assessed the effectiveness of Arista for bleeding control when applied intraoperatively to the liver resection surface. Materials and Methods: Data were collected at Seoul National University Bundang Hospital for patients who underwent liver resection owing to malignant hepatocellular carcinoma or benign liver diseases. We compared the outcomes between 45 patients managed with Arista® AH (data were prospectively collected between September 2022 and May 2023) and 156 patients managed without the use of Arista® AH (data were retrospectively collected between January 2021 and December 2021). Results: There were no significant differences in patient characteristics between the two groups. The estimated blood loss (EBL) was significantly lower in the Arista® AH group compared with the control group (495.56 ± 672.7 mL vs. 691.9 ± 777.5 mL, p = 0.049). The mean postoperative hospital stay was significantly shorter in the Arista® AH group (5.93 ± 1.88 days vs. 6.94 ± 4.17 days, p = 0.024). The time to Jackson-Pratt drain removal was also significantly shorter in the Arista® AH group (4.64 ± 1.31 days vs. 5.30 ± 2.87 days, p = 0.030). The patient subgroup was divided into four categories based on the type of resection and the presence or absence of cirrhosis. Within the subgroup of major resections in non-cirrhotic patients, the Arista® AH group demonstrated significantly better outcomes compared to the control group, showed lower EBL, reduced need for blood transfusions, decreased volume of drain fluid collected within 48 h, earlier removal of drains, and shorter hospital stays. In contrast, for the other subgroups such as minor resection (both non-cirrhotic and cirrhotic) and major resection with cirrhosis, the differences between the Arista® AH and control groups in various parameters like EBL, blood transfusion rates, drain fluid volume, time to drain removal, and duration of hospital stay were not statistically significant. Conclusions: Arista® AH significantly improved intraoperative blood management and postoperative recovery in patients undergoing liver resection, particularly in non-cirrhotic patients who underwent major resection.

Unveiling Plant-Based Pectins: Exploring the Interplay of Direct Effects, Fermentation, and Technological Applications in Clinical Research with a Focus on the Chemical Structure.

Pectin, a plant-derived polysaccharide, possesses immense technological and biological application value. Several variables influence pectin's physicochemical aspects, resulting in different fermentations, interactions with receptors, and other functional properties. Some of those variables are molecular weight, degree of methylation and blockiness, and monosaccharide composition. Cancer cell cytotoxicity, important fermentation-related byproducts, immunomodulation, and technological application were found in cell culture, animal models, and preclinical and clinical assessments. One of the greater extents of recent pectin technological usage involves nanoencapsulation methods for many different compounds, ranging from chemotherapy and immunotherapy to natural extracts from fruits and other sources. Structural modification (modified pectin) is also utilized to enhance the use of dietary fiber. Although pectin is already recognized as a component of significant importance, there is still a need for a comprehensive review that delves into its intricate relationships with biological effects, which depend on the source and structure of pectin. This review covers all levels of clinical research, including cell culture, animal studies, and clinical trials, to understand how the plant source and pectin structures influence the biological effects in humans and some technological applications of pectin regarding human health.

The gastrointestinal microbiome in dairy cattle is constrained by the deterministic driver of the region and the modified effect of diet

BackgroundDairy cattle (Bos taurus), especially Holstein cows, which are the highest-producing dairy animals and are widely bred to provide milk products to humans, rely critically on their associated gastrointestinal tract (GIT) microbiota to digest plant feed. However, the region-specific taxonomic composition and function of the GIT microbiome in dairy cattle and the mechanistic basis for the diet-induced effects remain to be elucidated. ResultsWe collected 120 digesta samples from 10 GIT regions of 12 Holstein cows fed forage- and grain-based diets and characterized their GIT microbiome via functional shotgun metagenomics and the resolution of metagenome-assembled genomes. Our results demonstrated that the GIT microbiome was mainly partitioned into three distinct clusters, four-chambered stomach, small intestine, and large intestine. Moreover, we found that the four-chambered stomach microbiome with the highest diversity had a strong ability to degrade recalcitrant polysaccharide substrates, underpinned by the prevalence of potential cellulosome-­producing and plant-derived polysaccharide utilization loci-encoding consortia. In contrast, the post-gastric intestinal microbiome orchestrated alternative fermentation pathways to adapt to nutrient availability and energy acquisition. Diet shifts selectively modified the metabolic cascades of the microbiome in specific GIT regions, evidenced by the loss of fiber-degrading taxa and increased hydrogen sinks in propionate after grain introduction.ConclusionsOur findings provide new insights into GIT microbial organization and function in dairy cattle by GIT regions and diet regimes, which offers clues for improving animal production and health in the future.4ZJAH2fLvvvrZAThHy4aExVideo

Tablet formulation with dual control concept for efficient colonic drug delivery

Aim of this study was to develop a tablet formulation for targeted colonic drug release by implementing two control mechanisms: A pH-sensitive coating layer based on Eudragit® FS 30 D to prevent drug release in the upper gastrointestinal tract, combined with a matrix based on plant-derived polysaccharide xyloglucan to inhibit drug release after coating removal in the small intestine and to allow microbiome triggered drug release in the colon. In vitro dissolution tests simulated the passage through the entire gastrointestinal tract with a four-stage protocol, including microbial xyloglucanase addition in physiologically relevant concentrations as microbiome surrogate to the colonic dissolution medium. Matrix erosion was monitored in parallel to drug release by measurement of reducing sugar equivalents resulting from xyloglucan hydrolysis. Limited drug release in gastric and small intestinal test stages and predominant release in the colonic stage was achieved. The xyloglucan matrix controlled drug release after dissolution of the enteric coating through the formation of a gummy polysaccharide layer at the tablet surface. Matrix degradation was dependent on enzyme concentration in the colonic medium and significantly accelerated drug release resulting in erosion-controlled release process. Drug release at physiologically relevant enzyme concentration was completed within the bounds of colonic transit time. The dual control concept was applicable to two drug substances with different solubility, providing similar release rates in colonic environment containing xyloglucanase. Drug solubility mechanistically affected release, with diffusion of caffeine, but not of 5-ASA, contributing to the overall release rate out of the matrix tablet.

Tuning heterologous glucan biosynthesis in yeast to understand and exploit plant starch diversity

BackgroundStarch, a vital plant-derived polysaccharide comprised of branched glucans, is essential in nutrition and many industrial applications. Starch is often modified post-extraction to alter its structure and enhance its functionality. Targeted metabolic engineering of crops to produce valuable and versatile starches requires knowledge of the relationships between starch biosynthesis, structure, and properties, but systematic studies to obtain this knowledge are difficult to conduct in plants. Here we used Saccharomyces cerevisiae as a testbed to dissect the functions of plant starch biosynthetic enzymes and create diverse starch-like polymers.ResultsWe explored yeast promoters and terminators to tune the expression levels of the starch-biosynthesis machinery from Arabidopsis thaliana. We systematically modulated the expression of each starch synthase (SS) together with a branching enzyme (BE) in yeast. Protein quantification by parallel reaction monitoring (targeted proteomics) revealed unexpected effects of glucan biosynthesis on protein abundances but showed that the anticipated broad range of SS/BE enzyme ratios was maintained during the biosynthetic process. The different SS/BE ratios clearly influenced glucan structure and solubility: The higher the SS/BE ratio, the longer the glucan chains and the more glucans were partitioned into the insoluble fraction. This effect was irrespective of the SS isoform, demonstrating that the elongation/branching ratio controls glucan properties separate from enzyme specificity.ConclusionsOur results provide a quantitative framework for the in silico design of improved starch biosynthetic processes in plants. Our study also exemplifies a workflow for the rational tuning of a complex pathway in yeast, starting from the selection and evaluation of expression modules to multi-gene assembly and targeted protein monitoring during the biosynthetic process.

Plant Polysaccharides in Engineered Pharmaceutical Gels.

Hydrogels are a great ally in the pharmaceutical and biomedical areas. They have a three-dimensional polymeric structure that allows the swelling of aqueous fluids, acting as an absorbent, or encapsulating bioactive agents for controlled drug release. Interestingly, plants are a source of biogels, specifically polysaccharides, composed of sugar monomers. The crosslinking of these polymeric chains forms an architecture similar to the extracellular matrix, enhancing the biocompatibility of such materials. Moreover, the rich hydroxyl monomers promote a hydrophilic behavior for these plant-derived polysaccharide gels, enabling their biodegradability and antimicrobial effects. From an economic point of view, such biogels help the circular economy, as a green material can be obtained with a low cost of production. As regards the bio aspect, it is astonishingly attractive since the raw materials (polysaccharides from plants-cellulose, hemicelluloses, lignin, inulin, pectin, starch, guar, and cashew gums, etc.) might be produced sustainably. Such properties make viable the applications of these biogels in contact with the human body, especially incorporating drugs for controlled release. In this context, this review describes some sources of plant-derived polysaccharide gels, their biological function, main methods for extraction, remarkable applications, and properties in the health field.

Administration of probiotic lactic acid bacteria to modulate fecal microbiome in feedlot cattle

Modulation of animal gut microbiota is a prominent function of probiotics to improve the health and performance of livestock. In this study, a large-scale survey to evaluate the effect of lactic acid bacteria probiotics on shaping the fecal bacterial community structure of feedlot cattle during three experimental periods of the fattening cycle (163 days) was performed. A commercial feedlot located in northwestern Argentina was enrolled with cattle fed mixed rations (forage and increasing grain diet) and a convenience-experimental design was conducted. A pen (n = 21 animals) was assigned to each experimental group that received probiotics during three different periods. Groups of n = 7 animals were sampled at 40, 104 and 163 days and these samples were then pooled to one, thus giving a total of 34 samples that were subjected to high-throughput sequencing. The microbial diversity of fecal samples was significantly affected (p < 0.05) by the administration period compared with probiotic group supplementation. Even though, the three experimental periods of probiotic administration induced changes in the relative abundance of the most representative bacterial communities, the fecal microbiome of samples was dominated by the Firmicutes (72–98%) and Actinobacteria (0.8–27%) phyla, while a lower abundance of Bacteroidetes (0.08–4.2%) was present. Probiotics were able to modulate the fecal microbiota with a convergence of Clostridiaceae, Lachnospiraceae, Ruminococcaceae and Bifidobacteriaceae associated with health and growth benefits as core microbiome members. Metabolic functional prediction comparing three experimental administration periods (40, 104 and 163 days) showed an enrichment of metabolic pathways related to complex plant-derived polysaccharide digestion as well as amino acids and derivatives during the first 40 days of probiotic supplementation. Genomic-based knowledge on the benefits of autochthonous probiotics on cattle gastrointestinal tract (GIT) microbiota composition and functions will contribute to their selection as antibiotic alternatives for commercial feedlot.

Structural Characterization of Degraded Lycium barbarum L. Leaves' Polysaccharide Using Ascorbic Acid and Hydrogen Peroxide.

Plant-derived polysaccharide’s conformation and chain structure play a key role in their various biological activities. Lycium barbarum L. leaves’ polysaccharide is well renowned for its health functions. However, its functional bioactivities are greatly hindered by its compact globular structure and high molecular weight. To overcome such issue and to improve the functional bioactivities of the polysaccharides, degradation is usually used to modify the polysaccharides conformation. In this study, the ethanol extract containing crude Lycium barbarum L. leaves’ polysaccharide was first extracted, further characterized, and subsequently chemically modified with vitamin C (Ascorbic acid) and hydrogen peroxide (H2O2) to produce degraded Lycium barbarum L. leaves’ polysaccharide. To explore the degradation effect, both polysaccharides were further characterized using inductively coupled plasma mass spectrometry (ICP-MS), gas chromatography–mass spectrometry (GC–MS), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), high performance gel permeation chromatography (HPGPC), and scanning electron microscope (SEM). Results shown that both polysaccharides were rich in sugar and degradation had no significant major functional group transformation effect on the degraded product composition. However, the molecular weight (Mw) had decreased significantly from 223.5 kDa to 64.3 kDa after degradation, indicating significant changes in the polysaccharides molecular structure caused by degradation.

Searching for Versatile Polysaccharide-Degrading Alkali-tolerant or Alkaliphilic Bacillus Strains

The plant-derived polysaccharides (Cellulose, xylose and amylose, etc.) are the most abundant renewable raw materials in nature. Cellulose and xylose are the predominant carbohydrate polymer components of the plant cell walls and the most abundant biopolymers in the world. Another plant-derived polysaccharide, starch is found in plant tubers, roots and seed endosperms as a major carbohydrate reserve. In this study, it was aimed to find multi-enzyme producer bacteria strains in terms of industrially important enzymes such as cellulase, xylanase and amylase. For this purpose, isolated Bacillus strains from different samples were qualitatively evaluated for cellulase, xylanase and amylase enzyme production potentials. The isolates that have the highest enzyme activity were selected for biochemical tests, molecular and phenotypic characterization. As a result of these characterization process, SB57, SB104, SB155, SB178, SB197 and SB199 strains were identified as Bacillus pumilus and SB118, SB138 strains were identified as Bacillus safensis. In addition to these strains, SB120 and SB147 strains were identified as Bacillus aerius and Bacillus licheniformis respectively. 16S rDNA sequence analysis results of these Bacillus strains were deposited in NCBI GenBank® under accession number KT371465 - KT371474 respectively.

Comparative Metagenomics of the Active Layer and Permafrost from Low-Carbon Soil in the Canadian High Arctic.

Approximately 87% of the Arctic consists of low-organic carbon mineral soil, but knowledge of microbial activity in low-carbon permafrost (PF) and active layer soils remains limited. This study investigated the taxonomic composition and genetic potential of microbial communities at contrasting depths of the active layer (5, 35, and 65 cm below surface, bls) and PF (80 cm bls). We showed microbial communities in PF to be taxonomically and functionally different from those in the active layer. 16S rRNA gene sequence analysis revealed higher biodiversity in the active layer than in PF, and biodiversity decreased significantly with depth. The reconstructed 91 metagenome-assembled genomes showed that PF was dominated by heterotrophic, fermenting Bacteroidota using nitrite as their main electron acceptor. Prevalent microbes identified in the active layer belonged to bacterial taxa, gaining energy via aerobic respiration. Gene abundance in metagenomes revealed enrichment of genes encoding the plant-derived polysaccharide degradation and metabolism of nitrate and sulfate in PF, whereas genes encoding methane/ammonia oxidation, cold-shock protein, and two-component systems were generally more abundant in the active layer, particularly at 5 cm bls. The results of this study deepen our understanding of the low-carbon Arctic soil microbiome and improve prediction of the impacts of thawing PF.

Metagenomic insights into the diversity of carbohydrate-degrading enzymes in the yak fecal microbial community

BackgroundYaks are able to utilize the gastrointestinal microbiota to digest plant materials. Although the cellulolytic bacteria in the yak rumen have been reported, there is still limited information on the diversity of the major microorganisms and putative carbohydrate-metabolizing enzymes for the degradation of complex lignocellulosic biomass in its gut ecosystem.ResultsHere, this study aimed to decode biomass-degrading genes and genomes in the yak fecal microbiota using deep metagenome sequencing. A comprehensive catalog comprising 4.5 million microbial genes from the yak feces were established based on metagenomic assemblies from 92 Gb sequencing data. We identified a full spectrum of genes encoding carbohydrate-active enzymes, three-quarters of which were assigned to highly diversified enzyme families involved in the breakdown of complex dietary carbohydrates, including 120 families of glycoside hydrolases, 25 families of polysaccharide lyases, and 15 families of carbohydrate esterases. Inference of taxonomic assignments to the carbohydrate-degrading genes revealed the major microbial contributors were Bacteroidaceae, Ruminococcaceae, Rikenellaceae, Clostridiaceae, and Prevotellaceae. Furthermore, 68 prokaryotic genomes were reconstructed and the genes encoding glycoside hydrolases involved in plant-derived polysaccharide degradation were identified in these uncultured genomes, many of which were novel species with lignocellulolytic capability.ConclusionsOur findings shed light on a great diversity of carbohydrate-degrading enzymes in the yak gut microbial community and uncultured species, which provides a useful genetic resource for future studies on the discovery of novel enzymes for industrial applications.

Marine polysaccharides from Gelidium pacificum Okamura and Cereus sinensis reveal prebiotic functions

Many marine polysaccharides as prebiotics can promote host health by modulating gut microbiota. This study investigated the beneficial effects of purified marine plant-derived Gelidium pacificum Okamura polysaccharide (GPOP-1) and marine animal-derived Cereus sinensis polysaccharide (CSP-1) on normal mice by modulating gut microbiota. The composition and diversity of gut microbiota were evaluated using 16S rRNA high-throughput sequencing. The results showed that GPOP-1 and CSP-1 altered the composition of the gut microbiota and promoted the growth of beneficial bacteria. At the genus level, GPOP-1 increased the relative abundance of Bacteroides, Phascolarctobacterium, and decreased the relative abundance of Ruminococcus, Helicobacter, Allobaculum, Dorea and AF12. While CSP-1 increased the relative abundance of Coprococcus, Adlercreutzia, Roseburia, Phascolarctobacterium, and decreased the relative abundance of Bacteroides, Ruminococcus and Oscillospira. The changes in the gut microbiota may affect the body weight, immune organ index and the production of short-chain fatty acids in normal mice. Compared to the normal control group, GPOP-1 decreased average weight gain while CSP-1 increased average weight gain. Furthermore, both GPOP-1 and CSP-1 significantly increased thymus and spleen indexes and total short chain fatty acids production in mice. In summary, GPOP-1 and CSP-1 exerted prebiotic effects on normal mice.

The antioxidant capacity evaluation of polysaccharide hydrolyzates from pumpkin using Caenorhabditis elegans model.

Our previous study has optimized the acid hydrolysis process of pumpkin polysaccharides (PPe) with scavenging ability based on central composite design. The aim of this study was to explore the in vivo-antioxidant ability of PPe and pumpkin polysaccharides acid-hydrolysis (PPe-S) using Caenorhabditis elegans. In composition analysis, the constituents of total sugar, protein, uronic acid, and sulfur groups in PPe-S were 87.03±1.21%, 1.25±0.78%, 37.61±0.97%, and 0.14±0.04%, respectively. Besides, results of antioxidant ability showed that PPe and PPe-S could reduce the oxidative stress (OS) induced by methyl viologen, extend lifespan of worms, and reduce reactive oxygen species (ROS) level under oxidative conditions significantly (p<.05). Furthermore, PPe and PPe-S could enhance the stress-resistance related antioxidant enzymes including catalase (CAT) and superoxide dismutase (SOD) significantly (p<.05). Moreover, the antioxidant effect of PPe-S was superior to PPe at the concentration of 4.0mg/ml. In summary, this study demonstrated that the derived hydrolyzates from PPe had protective effects on the damage induced by the generation of intracellular free radical agents. PRACTICAL APPLICATIONS: OS plays an important role in the pathogenesis of metabolic diseases, including type 2 diabetes. It is widely acknowledged that diabetes and its complications pose a threat to human's health, and the number of people with diabetes will expand to 640 million in the 2040year. Current studies have shown that all diabetes drugs have a kind of side effects. Fortunately, researchers have found and confirmed that plant-derived polysaccharide had a notable hypoglycemic effect via reducing the OS level in cell and tissue, and could decrease the diabetes symptoms as well. In this study, we proved that the polysaccharide derived from pumpkin could effectively ameliorate the OS level in C. elegans, including decreasing the damage of biofilm and ROS level. Therefore, our study shows that there is a high potential for pumpkin-derived polysaccharide and its hydrolyzates to be a bioactive component to prevent diabetes. In other words, this research can be applied to diabetes prevention and other diseases induced by OS.