Yeast Glucan Research Articles

Exploring yeast glucans for vaccine enhancement: Sustainable strategies for overcoming adjuvant challenges in a SARS-CoV-2 model

Vaccine adjuvants are important for enhancing vaccine efficacy, and although aluminium salts (Alum) are the most used, their limited ability to induce specific immune responses has spurred the search for new adjuvants. However, many adjuvants fail during product development due to manufacturability, supply, stability, or safety concerns. This work hypothesizes that protein-free yeast glucans can be used as vaccine adjuvants due to their known immunostimulatory activity and high abundancy. Thus, high molecular weight glucans with over 99% purity, comprising 64–70% β-glucans and 29–35% α-glucans, were extracted from a wild-type yeast and an engineered yeast to produce a steviol glycoside. These glucans underwent carboxymethylation to enhance solubility. Both water-dispersible and particulate glucans were evaluated as adjuvants, either alone or in combination with Alum or squalene stable emulsion (SE), for a SARS-CoV-2 vaccine. The study demonstrated that glucans triggered a robust immune response and enhanced the effects of Alum and SE when used in combination, both in vitro and in vivo. Water-dispersible glucans combined with Alum, and particulate glucans combined with SE, increased the production of specific antibodies against SARS-CoV-2 spike protein and enhanced serum neutralization titers against SARS-CoV-2 pseudovirus. Furthermore, the results indicated that larger molecular weight glucans from engineered yeast exhibited stronger immunogenic activity in comparison to wild-type yeast glucans. In conclusion, appropriately formulated glucans have the potential to be scalable, low-cost vaccine adjuvants, potentially overcoming the limitations of current adjuvants.

Spent brewer yeast glucan improves metabolic parameters and inflammatory markers reducing health risky changes imposed by the consumption of hypercaloric diet

β-glucans from yeasts are prebiotic health-promoting food ingredients able to boost immune response. An environmentally friendly source of yeast glucans is the spent brewer's yeast. This study investigated the effects of the administration of carboxymethyl glucan (CMG) (20 mg/kg, 12 weeks, orally), a derivative of the β-glucan from spent brewer's yeast, on food intake, weight gain, dyslipidemia, glucose intolerance, pro-inflammatory state, and hepatic steatosis of rats receiving a hypercaloric diet. The animals were divided into three groups: Normocaloric control (NCT); Hypercaloric diet and saline (HCT); and Hypercaloric diet and CMG (H-CMG). CMG administration could reduce rats' caloric value and food intake, reducing the index of adiposity (HCT:7.2±0.4% vs H-CMG:5.3±0.4% p < 0.05) and weight gain (HCT:111.1±3.8g vs H-CMG: 68.3±4.9g p < 0.05). Furthermore, it improved lipemic and glycemic profiles and lowered hepatic lipid accumulation. CMG decreased Monocyte Chemoattractant Protein (MCP)-1 (H-CT: 89.5±1.8 pg/mL vs H-CMG: 50.7±12.2 pg/mL p < 0.05), Interleukin (IL)-12 (H-CT: 206.0±14.0 pg/mL vs H-CMG:132.4±19.9 pg/mL, p < 0.05), and C-reactive protein (CRP) levels and increased IL-10 levels, decreasing the cardiovascular risk and pro-inflammatory state. Therefore, CMG has beneficial effects in preventing weight gain and, consequently, improves the metabolic profile in rats while consuming a hypercaloric diet. Findings indicate the spent brewer's yeast CMG can be a strategy to attenuate the risky metabolic changes related to the consumption of a hypercaloric diet.

Selective adsorption of oxidized yeast glucan for Pb2+: Influencing factors, adsorption site and mechanism

This work investigated the influencing factors and mechanism of Pb2+ adsorbed by oxidized yeast glucan (OYG). Firstly, OYG showed greater Pb2+ adsorption performance than yeast glucan, and the adsorption capacity was greater with the oxidation degree increased. The optimal pH range for Pb2+ adsorption was 6–7. The adsorption capacity of Pb2+ reached its maximum of 86.68 and 96.88 mg/g for 20 mg of OYG1 and OYG2, respectively. In addition, OYG exhibited selective adsorption, with adsorption capacity in the order: Pb2+ > Cd2+ > Cu2+ > Ca2+. Then adsorption isotherm was established by fitting Langmuir and Freundlich isotherm adsorption models. Freundlich model could better fit the adsorption process of lead by OYG, indicating that the adsorption process was heterogeneous. According to the Langmuir model, the maximum lead adsorption capacities of OYG1 and OYG2 at 298 K were 100.70 and 131.06 mg/g, respectively. Thermodynamic data indicated a spontaneous endothermic process (ΔG < 0, ΔH > 0), accompanied by increased system disorder (ΔS > 0), involving physical and chemical adsorptions. Finally, FT-IR and XPS results revealed -COOH and -OH were the primary adsorption sites in OYG, and the interaction between these groups and Pb2+ was mainly achieved by electrostatic interaction (or ion-dipole interaction).

Probiotics‐Loaded Selenium Nanoparticles Effectively Alleviated DSS‐Induced Colitis by Scavenging ROS and Remodeling Intestinal Innate Immune and Microbiota

AbstractAlterations in the intestinal microenvironment, including increased levels of reactive oxygen species (ROS), abnormalities in intestinal mucosal immune regulation, and dysbiosis of the intestinal microbiota, are crucial to the development of inflammatory bowel disease (IBD). Herein, an oral colon‐targeting Se‐Probiotic@Alginate bead (BLSe) with ROS‐scavenging ability and gut immune‐microbiota microenvironment remodeling ability is developed using alginate as the primary outer shell encapsulated with probiotics Bacillus licheniformis (BL) and selenium nanoparticles stabilized by yeast glucan (SeNPs). In vitro studies have shown that SeNPs possess antioxidant activity and BLSe exhibits excellent stability in gastric fluids and are released in intestinal fluids. In vivo studies have also shown that BLSe significantly alleviated dextran sulphate sodium (DSS)‐induced colitis in mice by inhibiting colon shortening, enhancing antioxidant activity, reducing pro‐inflammatory cytokine secretion, and protecting the intestinal mucosal barrier. 16S ribosomal RNA sequencing shows that BLSe can remodel the composition of the gut microbiota by improving bacterial diversity and restoring the relative abundance of beneficial bacteria in the colon. Overall, this study advances a promising probiotic‐based nanomedicine for managing IBD.

Magnetic Yeast Glucan Particles for Antibody-Free Separation of Viable Macrophages from Drosophila melanogaster.

Currently available methods for cell separation are generally based on fluorescent labeling using either endogenously expressed fluorescent markers or the binding of antibodies or antibody mimetics to surface antigenic epitopes. However, such modification of the target cells represents potential contamination by non-native proteins, which may affect further cell response and be outright undesirable in applications, such as cell expansion for diagnostic or therapeutic applications, including immunotherapy. We present a label- and antibody-free method for separating macrophages from living Drosophila based on their ability to preferentially phagocytose whole yeast glucan particles (GPs). Using a novel deswelling entrapment approach based on spray drying, we have successfully fabricated yeast glucan particles with the previously unachievable content of magnetic iron oxide nanoparticles while retaining their surface features responsible for phagocytosis. We demonstrate that magnetic yeast glucan particles enable macrophage separation at comparable yields to fluorescence-activated cell sorting without compromising their viability or affecting their normal function and gene expression. The use of magnetic yeast glucan particles is broadly applicable to situations where viable macrophages separated from living organisms are subsequently used for analyses, such as gene expression, metabolomics, proteomics, single-cell transcriptomics, or enzymatic activity analysis.

Synthesis, characterization and anti-inflammatory activity of selenium nanoparticles stabilized by aminated yeast glucan

Improving the dispersed stability of selenium nanoparticles (SeNPs) is the key to its application. In this study, yeast glucan with different degrees of amination (BNs) were used as stabilizers and capping agent to prepare dispersed SeNPs. The size, storage stability, and morphology of BNs/SeNPs were characterized. Results show that BNs/SeNPs presented positive potential and spherical morphologies with average particle size about 100–300 nm and kept stable at room temperature for a long time. The CCK-8 assay showed that BNs/SeNPs had significantly lower toxicity to RAW264.7 cells than SeNPs. Moreover, BNs/SeNPs could inhibit the generation of NO, IL-1β and IL-6 effectively in RAW 264.7 macrophages induced by LPS, and down-regulate the mRNA transcription of iNOS, IL-1β, IL-6 and chemokines (CCL2 and CCL5), indicating that BNs/SeNPs had good anti-inflammatory activity. Therefore, aminated yeast glucan could improve the stability and bioactivity of SeNPs simultaneously, which is a promising stabilizer for SeNPs.

Immune-enhancing effect of water-soluble beta-glucan derived from enzymatic hydrolysis of yeast glucan

Immunostimulants play an important role in the treatment of immunodeficiency. Macrophages are the first line in our immune defense system and play a critical role in the immune response. Therefore, finding new and better substances to induce an immune response by activating macrophages is an attractive research topic, especially in the fields of immunopharmacology and cancer prevention. Keratinocytes actively crosstalk with immune cells during wound repair, so enhancing the function of keratinocytes is also an important part of improving immunity. Beta-glucans are naturally occurring polysaccharides, consisting of d-glucose monomers linked by beta-glycosidic bonds. Several studies have investigated the immunomodulatory effects of beta-glucan, such as its anti-inflammatory and antibacterial properties. However, the use of yeast cell wall glucan has been limited because it is not soluble in water. In this study, we produced low-molecular-weight water-soluble yeast glucan (WSY glucan) and confirmed various aspects of its immune-enhancing effect. The structure of the beta-(1→3) and (1→6) bonds of WSY glucan were confirmed by nuclear magnetic resonance spectroscopy (1H-NMR) analysis. Our results showed that treatment with WSY glucan significantly and dose-dependently induced the production of inflammatory mediators (prostaglandin E2 (PGE2) and nitric oxide (NO)) and pro-inflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-6) in macrophages. In addition, WSY glucan treatment showed changes in the morphological structure of the macrophages and promoted phagocytic activity of the macrophages and wound healing in keratinocytes. Based on these results, WSY glucan is considered as a potential candidate for the treatment of diseases related to the weakening of the immune system without the limitation of insolubility.

β-Glucan bioactivities from Cystobasidium benthicum in Totoaba macdonaldi thymus cells

The overuse of antibiotics in aquaculture has led to serious concerns on microbial resistance and chemical residues. Novel sources of immunostimulants could help to solve this problem by stimulating the immune system to fight against pathogens. Therefore, this study aims to explore the immunostimulant potential of Cystobacidium benthicum-β-glucans (Cb-βG) using thymus cells from Totoaba (Totoaba macdonaldi), a recently farmed fish species in Mexico. The Cb-βG was characterized and tested for its own antioxidant capacity. Then, a Cb-βG safety experiment was carried out in thymus cells by evaluating the effects on immune parameters and immune-related genes. Cb-βG had a molecular weight of 2.32 kDa, comprised of β-1,3–1,6-glucan (53.4%), and showed strong antioxidant capacity compared to that of the positive antioxidant control. Cb-βG had no toxic effects of thymus cells and enhanced phagocytic, respiratory burst, myeloperoxidase and superoxide activities. Additionally, immune-related genes implicated in recognition and effector functions of yeast glucans were up-regulated (Toll like receptor 2, C-type lectin family 17 member A, colony-stimulating factor 1 receptor 2, macrophage mannose receptor 1, and Interleukin-1β). In conclusion, the glucan -characterized physically-chemically from the yeast C. benthicum (Cb-βG)- was safe, had strong antioxidant capacity to scavenge free radicals, and stimulated immune parameters and immune-related gene expressions on thymus cells from Totoaba macdonaldi.

Functional Characterization of the Novel Laminaripentaose-Producing β-1,3-Glucanase MoGluB and Its Biocontrol of Magnaporthe oryzae

Fungal cell wall synthesizing enzymes or remodeling enzymes represent key factors for the interaction of plant pathogen and antifungal agents, which are regarded as potential biocontrol agents. In this study, a novel endo-β-1,3-glucanase from Magnaporthe oryzae was expressed and characterized. The expression of MoGluB was significantly upregulated after 2 days of liquid culture and 48 h after infection, indicating that it may be involved in cell wall reconstitution. Purified MoGluB exhibited high activity on insoluble β-glucans, with a specific activity of 8.18 U/mg toward yeast glucan at pH 9.0 and 50 °C. MoGluB hydrolyzed pachymaran and yeast glucan into oligosaccharides dominated by laminaripentaose, suggesting that it is an endo-β-1,3-glucanase. Incubation of 8 μg of MoGluB with 106 spores/mL resulted in the inhibition of conidial germination and appressorium formation of M. oryzae, illustrating effective biocontrol activity. Hydrolysates of pachymaran induced the expression of defense genes restricting M. oryzae infection in rice plants, indicating an immunostimulatory effect of MoGluB hydrolysates.

A novel β-1,3-glucanase Gns6 from rice possesses antifungal activity against Magnaporthe oryzae

As members of the pathogenesis-related protein (PR)-2 family, β-1,3-glucanases play pivotal roles in plant defense. Previous study showed that the rice genome contains 16 genes encoding putative β-1,3-glucanases, and the β-1,3-glucanases in subfamily A were deduced to be involved in plant defense. However, there was limited direct evidence.In this study, the expression of rice β-1,3-glucanases Gns2–Gns6 belonging to subfamily A in rice plant infection with Magnaporthe oryzae was investigated, and the enhanced expression of Gns6 during infection confirmed its crucial role in the defense of rice seedlings. Enzymological characterization revealed that Gns6 preferentially hydrolyzed laminarin, pachymaran, and yeast glucan. The β-1,3; 1,6-glucanase Gns6 exhibited a specific activity of 1.2 U/mg with laminarin as the substrate. In addition, Gns6 could hydrolyze laminarin via an endo-type mechanism, yielding a series of oligosaccharides with various degrees of polymerization that are known immune elicitors in plants. Moreover, Gns6 exhibited a significant inhibitory effect against the formation of the germ tubes and appressoria, with potential applications in plant protection. Taken together, this study shows that Gns6 is an essential effector in the defensive response of rice against pathogenic fungi.

Capacity of myofibrillar protein to adsorb characteristic fishy-odor compounds: Effects of concentration, temperature, ionic strength, pH and yeast glucan addition

The capacity of myofibrillar protein (MP) to adsorb fishy-odors (hexanal, nonanal, 1-octen-3-ol) was investigated under the influences of concentration, temperature, pH, ionic strength and yeast glucan (YG) addition. The adsorption of MP for fishy-odors was in the order of nonanal > hexanal > 1-octen-3-ol. With increasing MP concentration, the binding of protein-aldehydes was facilitated, in contrast to a decrease trend in binding to 1-octen-3-ol. Meanwhile, MP adsorption capacity for off-odors peaked at 40 °C. Additionally, low ionic strength (0.2 mol/L) could promote MP adsorption for off-odors, while high ionic strength (0.6–1.0 mol/L) could reduce its adsorption for hexanal and 1-octen-3-ol. Moreover, MP had higher adsorption capacity under extreme pH values (pH 3 and 11). Furthermore, YG was shown as an ideal additive to adsorb off-odors due to its large specific surface area and good stability. This work provides useful information on how to deodorize fishy-odors in fish products.

Spent Brewer's Yeast as a Source of Insoluble β-Glucans.

In the brewing process, the consumption of resources and the amount of waste generated are high and due to a lot of organic compounds in waste-water, the capacity of natural regeneration of the environment is exceeded. Residual yeast, the second by-product of brewing is considered to have an important chemical composition. An approach with nutritional potential refers to the extraction of bioactive compounds from the yeast cell wall, such as β-glucans. Concerning the potential food applications with better textural characteristics, spent brewer’s yeast glucan has high emulsion stability and water-holding capacity fitting best as a fat replacer in different food matrices. Few studies demonstrate the importance and nutritional role of β-glucans from brewer’s yeast, and even less for spent brewer’s yeast, due to additional steps in the extraction process. This review focuses on describing the process of obtaining insoluble β-glucans (particulate) from spent brewer’s yeast and provides an insight into how a by-product from brewing can be converted to potential food applications.

Fluorescence versus radioactivity for assaying antifungal compound inhibited yeast 1,3-β-glucan synthase activity

Yeast membrane (1,3)-β-glucan synthase (GS; EC 2.4.1.34) activity was assayed by a fluorescent dye-binding method and a conventional radioactivity method to compare its in vitro inhibition by the echinocandin-class antifungal compound. In the fluorescence method, GS-containing microsomal plasma membrane was first reacted with UDP-glucose substrate to form the 1,3-β-glucan product. The product was then solubilized and bound specifically with aniline blue to form a 1,3-β-glucan-fluorochrome dye complex for reporting the GS activity. The effect of each component in the GS assay buffer on fluorescence was examined. A calibration curve was constructed using yeast glucan as standard. In addition, the GS activities using the same amount of 1 μg/μL microsomal concentration in the two assays were compared. The radioactivity assay showed 38.3 μM UDP-glucose incorporation and corresponded to the formation of equivalent 262 μM yeast glucan in the fluorescent assay. It indicated a possible underestimation of 1,3-β-glucan products in the radioactivity assay or an overestimation of the products in the fluorescence assay. However, pneumocandin A0 exhibited an IC50 value of 1.25 μM in the fluorescent assay closely comparable with that of 1 μM in the radioactivity assay. In summary, both the fluorescence and radioactivity tests generated similar data and pneumocandin inhibited GS. Possible limitations in the radioactivity assay were also discussed.

Influence of autolyzed whole yeast and yeast components on broiler chickens challenged with salmonella lipopolysaccharide

ABSTRACTThe objective of this study was to assess the effect of dietary yeast products on broiler chickens challenged with salmonella lipopolysaccharide (LPS). The chicks were divided into 8 treatments with 6 replicates and 9 birds per replicate. The treatments consisted of a positive control (PC) [without supplementation and not challenged]; negative control (NC) [without supplementation but challenged]; whole yeast and challenged; yeast cell wall and challenged; yeast glucan and challenged; yeast mannan and challenged; zinc bacitracin and challenged; and Salinomycin and challenged. Whole yeast or Yeast cell wall was included at 2.0 g/kg diet. Yeast glucan or mannan was added at 0.20 g/kg diet. Zinc bacitracin (ZNB) and Salinomycin (SAL) was included at 50 and 60 ppm, respectively. Dietary treatments had no effect (P > 0.05) on feed intake (FI) at day 10. Supplementation with yeast and its derivatives improved (P < 0.05) body weight gain (BWG) and feed conversion ratio (FCR) on day 10. On days 24 and 35, LPS challenge declined FI, BWG, FCR, and flock uniformity (day 28) in the NC group compared to the PC group. Yeast products and antibiotics improved (P < 0.05) FI, BWG, FCR, and flock uniformity in LPS-challenged birds. On day 24, spleen weight increased while bursa weight decreased in the NC group relative to the PC group; this effect was reversed (P < 0.05) by feeding all yeasts and antibiotics. On day 24, application of all the dietary treatments ameliorated the changes observed in white blood cell, lymphocyte and monocyte counts as well as albumin and immunoglobulin G of NC birds. On day 35, all yeasts additives, ZNB and SAL improved (P < 0.05) the meat yield of broilers challenged with LPS. In conclusion, supplementation of diets with yeast and its derivatives can ameliorate the negative effects of salmonella LPS challenge on broiler chicks, thus improving the performance, flock uniformity, and meat yield.

Response of Broiler Chickens to Dietary Supplementation of Enzymatically Hydrolyzed Glucan or Mannan Yeast Products

SUMMARY The effect of varying levels of enzymatically hydrolyzed soluble yeast glucan (YG) and yeast mannan (YM) products on broiler chickens was studied. A total of 486 day-old male Ross 308 broiler chicks were allocated to 9 dietary treatments consisting of YG and YM supplemented at 0.05, 0.10, 0.15, or 0.20 g/kg diet, respectively, and a control without yeast supplementation. Each treatment was replicated 6 times with 9 birds per replicate. The supplements did not affect body weight gain (BWG) and feed conversion ratio (FCR) in the starter phase nor feed intake at any stage. However, birds especially in the 0.20 g YM/kg diet group had improved (P

Administration of Yeast Glucan on Immunity of Offspring in Turbot Scophthalmus maximus: A Trans-Generational Immune-Enhancing Effect

β-glucan has been shown to increase immunity and survival in various juvenile and adult fish both in freshwater and marine aquaculture species as well as in marine fish larvae. However, information about the trans-generational immune-enhancing effects of β-glucan remains rather limited. Here we clearly show that dietary intake of β-glucan enhanced the levels of C3, Bf and lysozyme in the serum of turbot as well as in their eggs released. We also show that yeast glucan induced a significant increase in lysozyme activity in both the serum and eggs. Moreover, the embryos derived from yeast glucan-treated turbot were more resistant to bacterial challenge than control embryos. By contrast, the administration of yeast glucan on female turbots had little influence on the egg development and embryonic development. Collectively, these data indicate that yeast glucan can be safely used to promote the non-specific trans-generational immunity in offspring of turbot.

Immobilizing yeast β-glucan on zinc-layered hydroxide nanoparticle improves innate immune response in fish leukocytes

Nanoparticle-based delivery technologies have played a central role in a wide variety of applications, including cell therapy, gene transformation, and cellular delivery of molecular dyes. This work synthesized via ionic exchange a nanoparticle consisting of zinc-layered hydroxychloride coupled with yeast β-glucan (ZG), whose cellular immune response was evaluated using fish spleen leukocytes. Leukocytes from the marine Pacific red snapper (Lutjanus peru) were stimulated with zinc-layered hydroxychloride (ZHC) coupled with yeast β-glucan (GLU) and challenged with live Vibrio parahaemolyticus after 24 h. Structural characterization of this yeast glucan by proton nuclear magnetic resonance (NMR) indicated structures containing (1–6)-branched (1–3)-β-D-glucan. The ZHC and ZG were characterized with X-ray diffraction, infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The results of the immunological study showed that ZHC, GLU or ZG were safe for leukocytes because cell viability was higher than 80% compared with DMSO or V. parahaemolyticus exposure. The ZG or GLU treatments enhanced nitric oxide production, superoxide dismutase, catalase and peroxidase activities. Induction of anti- and pro-inflammatory cytokine (IL-1β, IL-6, IL-8, IL-10, IL-12 and IL-17) genes was more pronounced in ZG or GLU treatments compared to the other groups. Based on the results, ZHC nanoparticles can be used as a delivery carrier of yeast β-glucan for enhancing immunity in fish and have great potential application in the aquaculture industry.

Immunostimulant effects and potential application of β-glucans derived from marine yeast Debaryomyces hansenii in goat peripheral blood leucocytes

Debaryomyces hansenii has been described to be effective probiotic and immunostimulatory marine yeast in fish. Nonetheless, to the best of our knowledge, it has been not assayed in ruminants. This study attempts to describe the immunostimulatory effects of its β-glucan content through in vitro assays using goat peripheral blood leukocytes at 24 h of stimulation. The structural characterization of yeast glucans by proton nuclear magnetic resonance indicated structures containing (1-6)-branched (1-3)-β-D-glucan. In vitro assays using peripheral blood leukocytes stimulated with β-glucans derived from three D. hansenii strains and zymosan revealed that β-glucans significantly increased cell immune parameters, such as phagocytic ability, reactive oxygen species production (respiratory burst), peroxidase activity and nitric oxide production. Antioxidant enzymes revealed an increase in superoxide dismutase and catalase activities in leukocytes stimulated with yeast β-glucans. This study revealed that yeast β-glucans were able to activate dectin-1 mRNA gene expression in leukocytes. The TLR4 gene expression was up-regulated in leukocytes after stimulation with yeast β-glucans. In conclusion, β-glucans were able to modulate the immune system by promoting cell viability, phagocytic activity, antioxidant immune response and immune-related gene expression in leukocytes. Therefore, β-glucans derived from Debaryomyces hansenii should be considered a potential immunostimulant for goat production systems.

Sterigmatomyces halophilus β-glucan improves the immune response and bacterial resistance in Pacific red snapper (Lutjanus peru) peripheral blood leucocytes: In vitro study

β-Glucans are naturally occurring polysaccharides that are produced by bacteria, fungi and yeast. They are considered immunostimulants in fish acting on non-specific defense mechanism. Yeast-derived glucans from cell wall (Sterigmatomyces halophilus, β-Gluc/Sh) have been used for this purpose in this study. Therefore, an in vitro assay using peripheral blood leucocytes (PBLs) from Pacific red snapper was performed to evaluate the stimulant effects of β-Gluc/Sh and zymosan A (positive control) for 12 and 24 h and after bacterial challenge with Aeromonas hydrophila at 24 h. In addition, structural characterization of this marine yeast glucan was performed by proton nuclear magnetic resonance (NMR) revealing structures containing (1-6)-branched (1-3)-β-D-glucan. PBLs responded positively to β-Gluc/Sh where cell viability was higher than 80%. After challenge, β-Gluc/Sh was able to inhibit cytotoxicity caused by A. hydrophila, highlighting that the PBLs incubated with β-Gluc/Sh significantly increased the non-specific immune response, such as phagocytic activity, respiratory burst, nitric oxide and peroxidase activities followed by an increase in superoxide dismutase and catalase activities after 12 and 24 h post-stimulation and after challenge with the pathogen. Regarding induction of antioxidant gene expression, it was more pronounced in stimulated β-Gluc/Sh leucocytes compared to other groups at all experimental times of the trial and after bacterial challenge. Indeed, our results clearly showed the ability of leucocytes to strongly react to β-Gluc/Sh with an increase in cytokine gene expression, particularly the IL-1β, IL-10 and IL-17 genes. These results confirm that S. halophilus yeast-derived β-glucan, isolated from an extreme marine environment, is beneficial for increasing innate immune response and enhancing resistance against A. hydrophila in vitro.

Orally Administered Baker's Yeast β-Glucan Promotes Glucose and Lipid Homeostasis in the Livers of Obesity and Diabetes Model Mice.

Baker's yeast glucan (BYG) has been reported to be an anti-diabetic agent. In the work described herein, further study on the effect of orally administered BYG on glucose and lipid homeostasis in the livers of ob/ob mice was performed. It was found that BYG decreased the blood glucose and the hepatic glucose and lipid disorders. Western blotting analysis revealed that BYG up-regulated p-AKT and p-AMPK, and down-regulated p-Acc in the liver. Furthermore, RNA-Seq analysis indicated that BYG down-regulated genes responsible for gluconeogenesis (G6pase and Got1), fatty acid biosynthesis (Acly, Acc, Fas, etc.), glycerolipid synthesis (Gpam and Lipin1/2), and cholesterol synthesis (Hmgcr, Fdps, etc.). Additionally, BYG decreased glucose transporters SGLT1 and GLUT2, fat emulsification, and adipogenic genes/proteins in the intestine to decrease glucose and lipid absorption. All these findings demonstrated that BYG is beneficial for regulating glucose and lipid homeostasis in diabetic mice, and thus has potential applications in anti-diabetic foods or drugs.