Purification, characterization and partial biological activities of exopolysaccharide produced by Saccharomyces cerevisiae Y3

Paotianxiong polysaccharides potential prebiotics: Structural analysis and prebiotic properties

Paotianxiong (PTX) is a processing product of Aconitum carmichaelii Debx., often used as a tonic food daily. However, the structure and activity of the polysaccharide component that plays a major role still need to be determined. In our work, two new polysaccharides were purified from PTX and named PTXP-1 and PTXP-2. Structural analysis showed that PTXP-1 is a glucan with a molecular weight of 915 Da and a structure of 4)-α-D-Glcp-(1 → as the main chain. PTXP-2 is a glucose arabinoglycan with 4)-α-D-Glcp-(1 → as the main chain, containing 8 glycosidic bonds attached, and a molecular weight of 57.9KDa. In vitro probiotic experiments demonstrated that PTXP-1 could significantly promote probiotic growth and acid production. In vivo experiments demonstrated that both PTXP-1 and PTXP-2 exhibited significant effectiveness in promoting the growth of intestinal probiotics. These findings help expand the application of polysaccharide components extracted from tonic herbs as functional food ingredients.

Structure and Properties of Exopolysaccharide Produced by Gluconobacter frateurii and Its Potential Applications

An exopolysaccharide (EPS)-producing bacterium was isolated from apricot fermentation broth and identified as Gluconobacter frateurii HDC-08 (accession number: OK036475.1). HDC-08 EPS is a linear homopolysaccharide mainly composed of glucose linked by α-(1,6) glucoside bonds. It contains C, H, N and S elements, with a molecular weight of 4.774 × 106 Da. Microscopically, it has a smooth, glossy and compact sheet structure. It is an amorphous noncrystalline substance with irregular coils. Moreover, the EPS showed surface hydrophobicity and high thermal stability with a degradation temperature of 250.76 °C. In addition, it had strong antioxidant properties against DPPH radicals, ABPS radicals, hydroxyl radicals and H2O2. The EPS exhibited high metal-chelating activity and strong emulsifying ability for soybean oil, petroleum ether and diesel oil. The milk solidification test indicated that the EPS had good potential in fermented dairy products. In general, all the results demonstrate that HDC-08 EPS has promise for commercial applications as a food additive and antioxidant.

Structures, physical properties and antibacterial activity of silver nanoparticles of Lactiplantibacillus plantarum exopolysaccharide

Lactic acid bacteria (LAB) exopolysaccharide (EPS) has good water absorption, high viscosity, good stability, so it was widely used in probiotics fields. In this study, EPS-producing LAB strain Lactiplantibacillus plantarum HDL-03 was isolated and identified. Moreover, the HDL-03 EPS was used as a stabilizer and mixed with AgNO3 to synthesize a novel nanoparticle AgNPs whose structure and properties were explored. The monosaccharide composition and molecular weight indicated that HDL-03 EPS was a heteropolysaccharide composed of mannose and glucose. Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy analysis and methylation results jointly proved it was a heteropolysaccharide containing 1,3-Manp and 1,6-Glcp. The X-Ray diffraction (XRD) results showed that this EPS has an amorphous structure, while the synthesized AgNPs have crystalline properties. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results indicated EPS had a smooth and dense sheet structure, while the surface of AgNPs became rougher and large holes appeared after synthesis. Zeta particle size analysis suggested that the particle size of AgNPs increased by 36.63 nm compared to HDL-03 EPS. FT-IR analysis exhibited that the position of the characteristic peaks of AgNPs changed. The OH moving from a wavelength of 3388.49 cm-1 to a wavelength of 3316.79 cm-1 and telescopic vibration peak changed from 1356.07 cm-1 to 1344.22 cm-1. A plate inhibition test revealed the effect of different concentrations of EPS and AgNO3 synthesized AgNPs on the diameter of inhibition circle produced by the indicator bacteria Escherichia coli and Staphylococcus aureus. Furthermore, AgNPs were applied to the indicator bacteria, which the minimum inhibitory concentration (MIC), time-inhibitory curve, and changes in extracellular conductivity, nucleic acids, proteins, ATP, and lactate dehydrogenase (LDH) levels were determined. The AgNPs inhibited the growth of E. coli and S. aureus and exhibited outstanding antimicrobial properties. With the increase of treatment time, the degree of cell membrane damage increased, the permeability enhanced, and the intracellular substances leaked. These results indicate that HDL-03 EPS has good potential for applications in the production of food packaging, antimicrobials, catheters, textiles and coatings.

Adsorption of aflatoxin B1 by different antimycotoxin additives: bentonite, clinoptilolite, and beta-glucans extracted from yeast cell wall

The present study aims to evaluate and compare antimycotoxin additives (AMAs) composed of bentonite (AMA 1), clinoptilolite (AMA 2), and beta-glucans extracted from yeast cell wall (AMA 3), with respect to their ability to bind Aflatoxin B1 (AFB1) using the isothermal models of Freundlich, Langmuir, and BET. The additives were submitted to an in vitro adsorption experiment with AFB1 (0.05-4 mg L-1), using solutions of pH 3 and pH 6, with an inclusion rate of 0.5%, and analyzed by HPLC-MS/MS. At pH 3, for the seven concentrations evaluated, AMA 1 obtained adsorption rates (99.69 to 99.98%) higher (p < 0. 05) than the other AMAs, which were from 82.97 to 88.72% (AMA 2) and from 79.43 to 89.32% (AMA 3). At pH 6, in concentrations of 1, 2, and 4 mg L-1 of AFB1, AMA 1 obtained higher (p < 0.05) adsorption results (97.86 to 99.86%) than AMA 2 (91.98 to 96.12%) and AMA 3 (87.56 to 93.50%). The Freundlich model best fitted the AMA 1 adsorption data. For the other additives, the Langmuir model obtained the best fit, demonstrating qm of 8.6 mg g-1 at pH 3 and 2.3 mg g-1 at pH 6 for AMA 2; and for AMA 3, with qm of 3.4 mg g-1 at pH 3 and 2.3 mg g-1 at pH 6. The isotherm models work as an effective tool to describe the adsorption process whereas the AMA adsorption capacity varies as a function of product composition, pH, and mycotoxin content.

Fungi-derived natural antioxidants

In humans, exogenous antioxidants aid the endogenous antioxidant system to detoxify excess ROS generated during oxidative stress, thereby protecting the body against various diseases and stressful conditions. The majority of natural antioxidants available on the consumer market are plant-based; however, fungi are being recognized as alternative sources of various natural antioxidants such as polysaccharides, pigments, peptides, sterols, phenolics, alkaloids, and flavonoids. In addition, some exogenous antioxidants are exclusively found in fungi. Fungi-derived antioxidants exhibit scavenging activities against DPPH, ABTS, hydroxyl, superoxide, hydrogen peroxide, and nitric oxide radicals in vitro. Furthermore, in vivo models, application of fungal-derived antioxidants increase the level of various antioxidant enzymes, such as catalases, superoxide dismutases, and glutathione peroxidases, and reduce the level of malondialdehyde. Therefore, fungi-derived antioxidants have potential to be used in the food, cosmetic, and pharmaceutical industries. This review summarizes the antioxidant potential of different fungi (mushrooms, yeasts, and molds)-derived natural compounds such as polysaccharides, pigments, peptides, ergothioneine, ergosterol, phenolics, alkaloids, etc.

Glucans with Different Degrees of Polymerization from Leuconostoc mesenteroides CICC6055: Analysis of Physicochemical Properties and Intestinal Prebiotic Function

This study explored the physicochemical properties and prebiotic activities of glucans and oligoglucans. Oligoglucans were obtained through the fermentation of Leuconostoc mesenteroides CICC6055 and the glucansucrase of strain CICC6055, while glucans were obtained only through fermentation. Thin-layer chromatography and high-performance liquid chromatography identified enzymatically synthesized oligoglucans with a higher yield. Differential scanning calorimetry and derivative thermogravimetry analyses revealed the heat resistance of the glucans and oligoglucans at 280-300 °C. Fourier transform-infrared spectroscopy and nuclear magnetic resonance analyses demonstrated that their main chains were linked with α-1,6-glycosidic bonds accompanied by glucose residue branching. In vitro fermentation experiments demonstrated that they not only improved the contents of short-chain fatty acids but also raised the abundance of predominant flora, such as Bacteroides, Firmicutes, Verrucomicrobia, and Proteobacteria. These results implicate glucansucrase as an efficacious tool for the enzyme synthesis of oligoglucans. Furthermore, both polysaccharides with different degrees of polymerization may be beneficial in maintaining a healthy human gut.

Structural Characterization and Immunomodulatory Activity of a Mannose-Rich Polysaccharide Isolated from Bifidobacterium breve H4-2

In this study, a novel homogeneous mannose-rich polysaccharide named EPS-1 from the fermentation broth of Bifidobacterium breve H4-2 was isolated and purified by anion exchange column chromatography and gel column chromatography. The primary structure of EPS-1 was analyzed by high-performance liquid chromatography, Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry, and nuclear magnetic resonance. The results indicated that EPS-1 had typical functional groups of polysaccharides. EPS-1 with an average molecular weight of 3.99 × 104 Da was mainly composed of mannose (89.65%) and glucose (5.84%). The backbone of EPS-1 was →2,6)-α-d-Manp-(1→2)-α-d-Manp-(1→2,6)-α-d-Manp-(1→2)-α-d-Manp-(1→2,6)-α-d-Manp-(1→6)-α-d-Glcp-(1→ simultaneously containing two kinds of branched chains (α-d-Manp-(1→3)-α-d-Manp-(1→ and α-d-Manp-(1→). Besides, EPS-1 had a triple-helical conformation and exhibited excellent thermal stability. Moreover, the immunomodulatory activity of EPS-1 was evaluated by RAW 264.7 cells. Results indicated that EPS-1 significantly enhanced the viability of RAW 264.7 cells. EPS-1 could also be recognized by toll-like receptor 4, thereby activating the nuclear factors-κB (NF-κB) signaling pathway, promoting phosphorylation of related nuclear transcription factors, improving cell phagocytic activity, and promoting the secretion of NO, IL-6, IL-1β, and TNF-α. Thus, EPS-1 could activate the TLR4-NF-κB signaling pathway to emerge immunomodulatory activity on macrophages. The above results indicate that EPS-1 can serve as a potential immune-stimulating polysaccharide.

Preparation and characterization of soluble dietary fiber from tiger nut residues, showing enhanced antioxidant activity and metal-ion-binding properties

To improve the utilization of soluble dietary fiber (SDF) from tiger nut residues, the response surface methodology was used to optimize the conditions of superfine grinding to produce SDF with antioxidant and metal-ion-binding properties. The yield was increased (30.56%) and the average particle diameter of SDF was decreased (D50: 32.80 μm) under the optimal conditions (a proportion of grinding medium of 100%, a feeding mass of 0.90 kg, a grinding time of 20 min, and a moisture content of 8.00%). In addition, superfine grinding substantially modified the surface morphology and increased the SDF content and the proportion of monosaccharides by decreasing the molecular weight. Moreover, superfine grinding remarkably enhanced the in vitro antioxidant activities (ABTS+, DPPḤ, and ·OH) of the SDF, which also exhibited favorable metal-ion-binding properties (Ca2+, Zn2+, and Co2+). These results suggest that superfine grinding can be used as a technique to modify dietary fiber to manufacture functional SDF.

Evaluation of antioxidation, regulation of glycolipid metabolism and potential as food additives of exopolysaccharide from Sporidiobolus pararoseus PFY-Z1

At present, there are relatively few studies on the production of exopolysaccharide (EPS) by yeasts. Therefore, exploring the properties of EPS produced by yeast can not only enrich the source of EPS, but also play an important role in its future application in the food field. The aim of this study was to explore the biological activities of EPS (named SPZ) from Sporidiobolus pararoseus PFY-Z1, as well as the dynamic changes in physical and chemical properties that occur during simulated gastrointestinal digestion, and the effects of SPZ on microbial metabolites during fecal fermentation in vitro. The results revealed that SPZ had good water solubility index, water-holding capacity, emulsifying ability, coagulated skim milk, antioxidant properties, hypoglycemic activities, and bile acid-binding abilities. Furthermore, the content of reducing sugars increased from 1.20 ± 0.03 to 3.34 ± 0.11 mg/mL after gastrointestinal digestion, and had little effect on antioxidant activities. Moreover, SPZ could promote the production of short-chain fatty acids during fermentation for 48 h, in particular, propionic acid and n-butyric acid increased to 1.89 ± 0.08 and 0.82 ± 0.04 mmol/L, respectively. Besides this, SPZ could inhibit LPS production. In general, this study can help us to better understand the potential bioactivities, and the changes in bio-activities of compounds after digestion of SPZ.

Recent advances in polysaccharide biomodification by microbial fermentation: production, properties, bioactivities, and mechanisms

Polysaccharides are natural chemical compounds that are extensively employed in the food and pharmaceutical industries. They exhibit a wide range of physical and biological properties. These properties are commonly improved by using chemical and physical methods. However, with the advancement of biotechnology and increased demand for green, clean, and safe products, polysaccharide modification via microbial fermentation has gained importance in improving their physicochemical and biological activities. The physicochemical and structural characteristics, biological activity, and modification mechanisms of microbially fermented polysaccharides were reviewed and summarized in this study. Polysaccharide modifications were categorized and discussed in terms of strains and fermentation techniques. The effects of microbial fermentation on the physicochemical characteristics of polysaccharides were highlighted. The impact of modification of polysaccharides on their antioxidant, immune, hypoglycemic, and other activities, as well as probiotic digestive enhancement, were also discussed. Finally, we investigated a potential enzyme-based process for polysaccharide modification via microbial fermentation. Modification of polysaccharides via microbial fermentation has significant value and application potential.

Anti-Diabetic Activity of a Novel Exopolysaccharide Produced by the Mangrove Endophytic Fungus Penicillium janthinellum N29

Marine microorganisms often produce exopolysaccharides with novel structures and diverse biological activities due to their specific marine environment. The novel active exopolysaccharides from marine microorganisms have become an important research area in new drug discovery, and show enormous development prospects. In the present study, a homogeneous exopolysaccharide from the fermented broth of the mangrove endophytic fungus Penicillium janthinellum N29, designated as PJ1-1, was obtained. The results of chemical and spectroscopic analyses showed that PJ1-1 was a novel galactomannan with a molecular weight of about 10.24 kDa. The backbone of PJ1-1 was composed of →2)-α-d-Manp-(1→, →4)-α-d-Manp-(1→, →3)-β-d-Galf-(1→ and →2)-β-d-Galf-(1→ units with partial glycosylation at C-3 of →2)-β-d-Galf-(1→ unit. PJ1-1 had a strong hypoglycemic activity in vitro, evaluated using the assay of α-glucosidase inhibition. The anti-diabetic effect of PJ1-1 in vivo was further investigated using mice with type 2 diabetes mellitus induced by a high-fat diet and streptozotocin. The results indicated that PJ1-1 markedly reduced blood glucose level and improved glucose tolerance. Notably, PJ1-1 increased insulin sensitivity and ameliorated insulin resistance. Moreover, PJ1-1 significantly decreased the levels of serum total cholesterol, triglyceride and low-density lipoprotein cholesterol, enhanced the level of serum high-density lipoprotein cholesterol and alleviated dyslipidemia. These results revealed that PJ1-1 could be a potential source of anti-diabetic agent.

Purification of exopolysaccharides from Lactobacillus rhamnosus and changes in their characteristics by regulating quorum sensing genes via polyphenols

To explore the effect of Lonicera caerulea fruit polyphenols (LCP) on caries-causing bacteria, strain RYX-01 with high production of biofilm and exopolysaccharides (EPS) was isolated from the oral cavity of caries patients and was identified as Lactobacillus rhamnosus by 16S rDNA analysis and morphology. The characteristics of EPS produced by RYX-01 (EPS-CK) and those produced by adding L. caerulea fruit polyphenols (EPS-LCP) were compared to reveal whether LCP reduced the cariogenicity of RYX-01 by influencing the structure and composition of EPS. The results showed that LCP could increase the content of galactose in EPS and destroy the original aggregation state of EPS-CK but had no significant effect on the molecular weight and functional group composition of EPS (p > 0.05). At the same time, LCP could inhibit the growth of RYX-01, reduce EPS and biofilm formation and inhibit the expression of quorum sensing (QS, luxS)- and biofilm formation (wzb)-related genes. Therefore, LCP could change the surface morphology, content and composition of RYX-01 EPS and reduce the cariogenic effect of EPS and biofilm. In conclusion, LCP can be used as a potential plaque biofilm inhibitor and QS inhibitor in drugs and functional foods.

Production, characterization and antioxidant activity of exopolysaccharide from Sporidiobolus pararoseus PFY-Z1

At present, the study on exopolysaccharid is mainly focused on lactic acid bacteria, and the research on exopolysaccharide produced by yeast, especially Sporidiobolus pararoseus, is relatively few. Therefore, the aim of this study was to explore the characterization and antioxidant activities of a novel neutral exopolysaccharide SPZ, which was isolated and purified from S. pararoseus PFY-Z1. The results showed that SPZ was mainly composed of mannose, followed by glucose, with a molecular weight was 24.98 kDa, had O-glycosidic bonds, no crystalline, and no triple helix structure. Based on fourier transform-infrared, high-performance liquid chromatography and nuclear magnetic resonance analyses, SPZ was identified to be a exopolysaccharide with some side chains, presence of α-, β-pyranose ring and nine sugar residues. Furthermore, the morphology features of SPZ have performed a relatively rough and uneven surface, covered with small pores and fissures. Moreover, SPZ had higher antioxidant activities and the maximum scavenging abilities of ⋅OH, NO₂^- and reducing power were 28.05 ± 0.73%, 92.76 ± 1.86% and 0.345 ± 0.024, respectively. Hence, SPZ could be used as a potential antioxidant application in the food and pharmaceutical industries.

Characterization of exopolysaccharide produced by Levilactobacillus brevis HDE-9 and evaluation of its potential use in dairy products

The bacterial strain HDE-9 was isolated from sauerkraut and identified as Levilactobacillus brevis. An exopolysaccharide (EPS) was isolated and purified from L. brevis HDE-9, and a preliminary investigation of its structural characteristics and biological activity was conducted. The molecular weight of the EPS was >1.0 × 10⁶ Da. Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy revealed that the EPS was composed of α-(1 → 6) linked d-glucopyranose units. X-ray diffraction (XRD) data on the EPS revealed its non-crystalline amorphous structure. Scanning electron microscopy (SEM) of the EPS revealed a smooth surface with sheet structures. The EPS exhibited the high value in thermal stability, water solubility, water holding capacity (WHC), and emulsification activity (EA). The water contact angle of the EPS revealed relatively high hydrophobicity in the presence of sucrose. The EPS also showed a strong milk solidification capacity in a dose-dependent manner. The EPS could significantly improve the texture of yoghurt, indicating its potential application as a functional starter in the production of fermented dairy products.