Yeast-Derived β-1,3-Glucan Substrate Significantly Increased the Diversity of Methanogens During In vitro Fermentation of Porcine Colonic Digesta

The β-1,3-glucan from yeast has been extensively examined for its immuno-enhancing effects in animals.However,investigation on the relationship among β-glucan,gut microbiota and immune-modulating effects remains limited particularly in pigs.Considering the critical roles of gut methanogens in the microbial fermentation,energy metabolism and disease resistance,we investigated the phylogenetic diversity of methanogens from fermented cultures of porcine colonic digesta with（G） or without（N） yeast β-glucan based on sequences of the archaeal 16S rRNA gene.A total of 145 sequences in the G library were assigned into 8 operational taxonomic units（OTUs） with the majority of sequences（114/145） related to strains Methanobrevibacter millerae or Methanobrevibacter gottschalkii with high identities ranging from 97.9 to 98.6%,followed by 23 sequences to Methanobrevibacter ruminantium,2 sequences to Methanobrevibacter smithii and one sequence to Methanobrevibacter wolinii.The 142 sequences in the N library were assigned to 2 OTUs with most sequences（127/142） related to strains M.millerae or M.gottschalkii with sequence identities ranging from 97.9 to 98.5%,and 15 sequences related to M.gottschalkii with 97.9% identity.Shannon diversity index showed that the G library exhibited significantly higher archaeal diversity（P0.05） and Libshuff analysis indicated the differences in the community structure between the two libraries were significant（P0.0001）.In conclusion,the current study provides evidence that addition of yeast β-glucan significantly increased the diversity of methanogens in in vitro fermented porcine colonic digesta.

Effects of β-Glucan Supplementation on Repairing of Phenol-Induced Vaginal Mucosal Epithelium Damage in Rats

Objective: To investigate the effects of different concentrations of β-glucan on the repair of damaged vaginal mucosa, the expression of vascular endothelial growth factor (VEGF), and the inflammatory factor-6 (IL-6) in vaginal tissues. Methods: Thirty-six adult female specific pathogen free (SPF)-grade Wistar rats were randomly divided into 3 phase groups with 12 rats each. Vaginal inflammation rat models were established by injecting phenol gel into the vagina of each rat at a dose of 0.1 ml/100g body weight. After modeling, rats were divided into 4 groups based on different concentrations of the test agent. The control group was injected with 0.5 ml of saline, experimental group A was injected with 0.375 ml saline 0.125 ml β-glucan, experimental group B was injected with 0.25 ml saline 0.25 ml β-glucan, and experimental group C was injected with 0.50 ml β-glucan. The injection sites were selected at the 3 o’clock and 9 o’clock positions of the vagina. Rats were sacrificed at 7-, 14-, and 28-days post-injection, and tissue samples were collected from the injection sites and prepared for histological analysis. New blood vessels and fibroblast numbers in the tissues were observed after Hematoxylin-eosin (HE) staining. The expression levels of VEGF and IL-6 in the tissues were measured using quantificational reverse transcription polymerase chain reaction (qRT-PCR). Results: Histological examination of vaginal tissue specimens at 7-, 14-, and 28-days post-injection showed that on day 7, there were no significant changes in the experimental groups compared to the control group. However, on days 14 and 28, the experimental groups showed more new blood vessels, macrophages, and fibroblasts with increased activity compared to the control group. The expression levels of VEGF in vaginal tissues were elevated on days 14 and 28 in the experimental groups. The comparison of IL-6 levels in vaginal tissues on day 28 showed that serum IL-6 levels returned to normal, and there was no statistically significant difference between the experimental and control groups. Conclusion: In the 3 experimental phases, the increase in VEGF levels in vaginal tissues on day 14 post-injection was more pronounced with higher concentrations of β-glucan, and IL-6 levels returned to normal on day 28. β-Glucan can enhance VEGF levels in damaged vaginal tissues, promote the repair of damaged vaginal tissues, and higher concentrations of β-glucan have a better effect.

Effects of dietary yeast β-glucan on nutrient digestibility and serum profiles in pre-ruminant Holstein calves

This study aimed to investigate the effects of dietary supplementation of yeast 13-glucan on the nutrient digestibility and serum profiles in pre-ruminant Holstein calves. Forty-two neonatal Holstein calves （（39.6＋4.2） kg） were randomly allotted to six groups, and each was offered one of the following diets： a basal diet （control） or the basal diet supplemented with 25, 50, 75, 100 or 200 mg of yeast 13-glucan kg-~ feed （dry matter basis）. The basal diet consisted of a milk replacer and a starter feed. The trial lasted for 56 d. Two digestibility trials were conducted from d 14 to 20 and from d 42 to 48. Blood samples were collected on d 0, 14, 28 and 42 for serum profile analyses. On d 56, three calves from each group were slaughtered, and intestinal samples were collected to assess the villous height, crypt depth and mucosal thickness. Although feed intake was not affected by dietary treatment （P〉0.05）, the average daily gain （ADG） and gain-to-feed ratios were higher （P〈0.05） for the calves fed 75 mg of yeast β-glucan kg^-1 feed than those in the other groups. The supplementation of yeast β-glucan at 75 mg kg^-1 feed increased the apparent digestibility of dry matter （DM）, crude protein （CP）, ether extract （EE）, and phosphorus （P） （P〈0.05） and the ratio of intestinal villous height to crypt depth （V/C） （P〈0.05） when compared with the control group. No effects of yeast β-glucan on the serum concentrations of total protein （TP）, albumin （ALB）, serum urea nitrogen （SUN） and glucose （GLU） were observed （P〉0.05）. Compared with the control group, supplementation of yeast β-glucan decreased （P〈0.05） the serum concentrations of triglycerides （TG） and total cholesterol （TC）. The serum concentration of immunoglobulin G （IgG） and immunoglobulin M （IgM） increased quadratically （P〈0.05）, whereas the serum concentration of immunoglobulin A （IgA） was unaffected by dietary treatments （P〉0.05）. The supplementation of yeast β-glucan stimu- lated the enzymatic activity of alkaline phosphatase （ALP） （P〈0.05） compared with the control group. The lysozyme （LYZ） concentration increased quadratically （P〈0.05） with increasing yeast β-glucan levels. The results suggested that dietary supplementation of yeast 13-glucan at 75 mg kg^-1 feed improved nutrient digestibility, enhanced immunity by increasing the immunoglobulin concentration and stimulating ALP, and exerted no adverse effects on metabolism in pre-ruminant calves.

Effects of Dietary β-Glucan and Glycyrrhizin on Non-Specific Immunity and Disease Resistance of the Sea Cucumber (Apostichopus japonicus Selenka) Challenged with Vibrio splendidus

Sea cucumbers, Apostichopus japonicus Selenka, were fed diets containing non-immunostimulant (basal diet), 0.2% β-glucan and 0.02% glycyrrhizin in a recirculatory water system for 45 days, and subsequently challenged with Vibrio splendidus by injection at 1.0×108 cfu/sea cucumber for 15 days.Phagocytic capacity (PC), intracellular superoxide anion production (ISAP), ly-sozyme (LSZ) activity and superoxide dismutase (SOD) activity in the coelomic fluid were analyzed on the 0th, 5th, 10th and 15th days after injection.Results showed that after the 45-day feeding period, PC, ISAP, LSZ activity and SOD activity in sea cucumbers fed with dietary β-glucan or glycyrrhizin were significantly higher than in those fed with the basal diet.On the 5th day after infection, all the immune parameters examined in the sea cucumbers injected with V.splendidus decreased in value significantly.On the 15th day, PC, ISAP and LSZ activity returned to levels similar to those on the 0th day.For the sea cucumbers injected with saline, there were no significant differences in all the immune parameters examined and in the cumulative morbidity during the 15-day challenging trial.After injecting with V.splendidus, the cumulative morbidity of sea cucumbers fed with the basal diet was significantly higher than those fed with dietary β-glucan or glycyrrhizin when challenged with V.splendidus challenged sea cucumber fed with the basal diet was significantly higher than those fed with dietary β-glucan or glycyrrhizin.There was no significant difference in cumulative morbidity between the dietary β-glucan and glycyrrhizin treatments over time.

Genome-Wide Identification of Candidate Genes Associated with β-glucan Traits in a Hulled and Hulless Barley (Hordeum vulgare L.) Population

Barley grain is a valuable source ofβ-glucan,which is an important component of dietary fiber with significant human health benefits.Although the genetic basis ofβ-glucan biosynthesis has been widely studied,a genome-wide association study(GWAS)is still required for a scan of the candidate genes related to the complex quantitative trait based on the high-quality barley reference genome.In this study,a GWAS was conducted using a population composed of 87 barley landraces(39 hulled and 48 hulless,β-glucan from 2.07%to 6.56%)with 191,098 nucleotide polymorphisms(SNPs)markers to cover the chromosomes with the highest density.The population was divided into four sub-populations(POP1~POP4),and theβ-glucan content in POP2 was significantly higher than that in other groups,in which most of the hulless barley landraces are from Qinghai-Tibet Plateau in China.Among seven SNP markers identified by GWAS,two(SNP2 and SNP3)of them showed positive correlation toβ-glucan trait and the remaining five(SNP1,SNP4,SNP5,SNP6 and SNP7)showed the negative relationship.Two candidate genes linked to SNP7,HORVU7Hr1G000320 and HORVU7Hr1G000040,belong to the nucleotide triphosphate hydrolase super-family which is probable to affect the activities ofβ-glucan synthase.Another candidate gene associated with SNP1,HORVU1Hr1G000010,is possibly involved in sugar response.In conclusion,our results provide new insights into the genetic basis ofβ-glucan accumulation in barley grains,and the discovery of new SNP markers distributed in each chromosome and the associated candidate genes will be valuable for the breeding of functional barley varieties with high β-glucan.

Noble strain of Sparassis latifolia produces high content of β-glucan

Objective: To classify four new Sparassis strains(CLM1, CKM1, CKM2, and KJM1) using the internal transcribed spacer sequence and to elucidate their β-glucan content and mycelial growth.Methods: Two different microbiological media were used to determine growth rate. The β-glucan contents were analyzed using the Megazyme Mushroom and Yeast Beta-Glucan kit. To determine the genetic relationships, phylogenetic trees were constructed using ClustalX. Multiple sequence alignments were printed and shaded with the BOXSHADE 3.21 program. Results: In this study, four new Sparassis strains were isolated from the southern region of the Korea Peninsula. They were all classified into the Sparassis latifolia clade as a monophyletic group based on the internal transcribed spacer sequence. Mycelial growth rate of the CLM1 strain was highest in potato dextrose agar and potato dextrose agar larch. The β-glucan content of the CLM1 strain was highest at 29.5%(w/w). A high degree of sequence divergence was detected in the RNA polymerase second largest subunit II gene(RPB2) within Sparassis spp. tested. The putative amino acid sequences of the RPB2 had a distinct sequence. The nucleotide sequences of the RPB2's intron were also divergent among Sparassis spp., even though their nucleotide length was well conserved within Sparassis latifolia. Conclusions: These results indicate that the nucleotide sequences and the amino acid sequences of RPB2 can be used to identify individual Sparassis sp. The Sparassis strain CLM1 may be best for developing a remedy to prevent or treat cancer and other chronic diseases.

Mushroomβ-glucan and polyphenol formulations as natural immunity boosters and balancers:nature of the application

Mushrooms are experiencing a kind of renaissance as a part of the contemporary human diet.These valuable organisms are more than food,they fit in perfectly as a novel market group known as nutra-mycoceuticals.Immune-balancing mushroom dietary fibers and secondary metabolites such as polyphenols are the main focus of the healthcare industry.Wellness and cosmetic companies are increasingly using mushroom extracts rich in these ingredients.This review considers the basic molecular immunomodulatory mechanisms of action of the most commonly used mushroom dietary fibers,β-glucans.The literature data on their bioavailability,metabolic transformations,preclinical and human clinical research,and safety are discussed.Immunomodulatory mechanisms of polyphenol ingredients are also considered.These molecules present great potential in the design of the new immunity balancer formulations according to their widespread structural diversity.Finally,we draw attention to the perspectives of modern trends in mushroom nutraceutical and cosmeceutical formulations to strengthen and balance immunity.

The Variation of β-glucan and Protein Content in Barley as Affected by Agronomic Practices

The influences of N application rate, timing, sowing date and seeding rate on β-glucan and protein content in barley grains were studied through the field experiments in Hangzhou, China during 1997 -2001. Protein content increased with N application rate and with N proportion applied at late stage. β-glucan content also responded significantly to N application rate and timing, but with different pattern with protein content. Of three N rate treatments, the medium N rate (135 kg ha-1) had the highest β-glucan content, being significantly higher than low N rate (90 kg ha-1) and no difference with high N rate (180 kg ha-1). A-mong three N timing treatments, two times of N top-dressing at both tillering and booting stage had significantly higher β-glucan content than once N top-dressing at tillering or booting stage. Sowing date has the dramatic effect on both β-glucan and protein content. Protein content decreased with the delayed sowing, and kernel weight showed opposite tendency. Either earlier or later sowing caused increased β-glucan content relative to sowing in early November, which is the normal date for barley sowing locally. Seeding rate had no significant influence on both β-glucan and protein content.

Cultivar and Environmental Effects on p-glucanase Activity in Both Barley Grain and Malt and Its Function in β-glucan Degradation

Eight two-rowed barley cultivars were grown at seven locations in the southern winter-barley zone of China. Mean grainβ-glucanase activity ranged from 39.89 U kg-1 for Suyin2 to 49.75 U kg-1 for Xi-umai3 in 8 cultivars grown at 7 locations, and from 38. 74 U kg-1 in Zhengzhou to 57. 96 U kg-1 in Putian among 7 locations on an average of all cultivars. Correspondingly, mean malt β-glucanase activity of 8 cultivars ranged from 313.33 U kg-1 for ZAU3 to 489. 89 U kg-1 for Daner Barley, and of 7 locations from 330.40 U kg-1 in Yancheng to 418. 24 U kg-1 in Putian. There were significant differences among cultivars and locations in maltβ-glucanase activities. The locations showed much larger variation in maltβ-glucanase activities than cultivars. The reduction of total β-glucan content after malting varied in both cultivars and locations, with a mean of 78.31%. The analysis of correlations showed that maltβ-glucan content was significantly positively and negatively correlated with grain β-glucan content and malt β-glucanase activity, respectively, and malt β-glucanase activity was significantly positively correlated with grain β-glucanase activity.

Effect of Discontinuous Administration of β -glucan and Glycyrrhizin on the Growth and Immunity of Pacific White Shrimp Litopenaeus Vannamei

A six-week growth trial was conducted to compare the effects of different feeding strate- gies of dietary immunostimulants on the growth and immunity of white shrimp Litopenaeus vannamei （4.70 ±0.20g）. Shrimps were fed with diet containing glycyrrhizin continuously, containing β -glucan continuously, discontinuously （seven days with diet containing β -gluseven days with diet without -glucan; two days with diet containing β-glucan following five days with diet without -glucan）,

β-Glucans: Characterization, Extraction Methods, and Valorization

β-glucans are bioactive compounds with a wide range of biological properties, including anticancer, anti-inflammatory, antioxidant, and immune-modulating properties. Due to their specific physical properties, such as (in)solubility, viscosity, and gelation, β-glucans are increasingly being used in the food, pharmaceutical, and cosmetic industries. The purpose of this review is to provide an overview of the different types of β-glucans, their sources, especially Saccharomyces cerevisiae yeasts, and the methods of extraction, isolation, and purification of β-glucans, with the aim of optimizing these methods for the efficient production process. Moreover, the physico-chemical properties, modifications, current applications and future prospects of the use of β-glucans in food, medicines, cosmetics and other potential value-added products are summarized. The data presented indicate that β-glucans will play an increasingly important role in the sector of special-purpose food products as well as in other current and future areas.

Application of naturalβ-glucans as biocompatible functional nanomaterials

Naturally-occurringβ-glucans are mostly investigated for their antitumor activity and immunomodulatory property.They have been widely regarded as a natural source for functional foods and pharmaceuticals.However,the physico-chemically stable and biocompatible properties ofβ-glucans are rarely explored as a coating material for nanomaterials to overcome the problems of aggregation and cytotoxicity.This article reviews on the exploration ofβ-glucans,in particular those derived from mushrooms,as a natural coating material to modify the surface properties of bioactive substances as a relatively simple and cost-effective strategy to produce stable and biocompatible nanohybrids used for biopharmaceutical use.It is envisaged that suchβ-glucan-based coating method will provide new opportunities to design biocompatible functional nanomaterials for wider clinical applications.

Quality and Sensory Properties of Reduced Fat Yoghurt Made with Addition of <i>β</i>-Glucans

β-Glucans, isolated from Pleurotus citrinopileatus mushroom, were used in the manufacture of yoghurt from reduced fat cow milk with added proteins. β-Glucans were added to the milk in the form of a paste containing 1.21% (on a dry weight basis) of β-glucans, such that the final concentrations in the yoghurt were 0.3%, 0.4% and 0.5%. Control yoghurt was also manufactured from the same milk without the addition of β-glucans. The resultant yoghurts were examined for their physicochemical and microbial characteristics, gel formation and sensory properties and compared to the control at 1, 7, 14 and 21 days of storage. Results showed that the microbial population, pH, titratable acidity, ash and syneresis were not affected by the addition of different levels of glucans. The lowest fat, total solids and protein contents were recorded in the yoghurt containing 0.5% glucan. The yoghurt containing 0.3% β-glucan had the same viscosity as the control and the yoghurt containing 0.5% β-glucan had the lowest viscosity. Yoghurt with β-glucans received slightly higher scores for flavour, appearance and texture than the control. It was concluded that the incorporation of 0.3% or 0.4% β-glucans isolated from edible mushrooms, into the yoghurt does not affect the final product, which is similar or sensorially even better than the control.

Antioxidant and Pasting Properties of Oat <i>β</i>-Glucan Hydrocolloids

Four oat β-glucan enriched hydrocolloids (Nutrim10, C-Trim20, C-Trim30, C-Trim50), oat bran concentrate (OBC), and β-Glucan95 were investigated for antioxidant and pasting properties. C-Trim30 had the highest soluble phenolic content, followed by C-Trim20. The trend of antioxidant activity was similar with that of phenolic contents. The phenolic content of the extracts increased with increasing temperatures. The highest content of soluble phenolic compounds was found at temperatures up to 100℃ for most samples regardless of solvent. Water extracts had significantly higher phenolic contents than extracts from 50% ethanol at 100℃ for all samples with the exception of C-Trim30. However, the effect of temperature and solvent concentrations was not as apparent for antioxidant activity as that observed for phenolic content. In general, the differences in three different solvents were not as apparent. Significantly higher water holding capacities were found for C-Trim30 and C-Trim50 than the other samples while β-Glucan 95 had substantially the highest paste viscosity followed by C-Trim50 and C-Trim30.

β-Glucan Fiber from Spent Brewer’s Yeast Reduces Early Atherosclerosis Greater Than Psyllium in Hypercholesterolemic Syrian Golden Hamsters

β-Glucans, mostly from oats, have been shown to reduce blood concentrations of total and LDL-cholesterol in animals and humans. After processing, spent brewer’s yeast, a by-product of the fermentation process, contains 85% - 90% β-glucans. The purpose of this study was to evaluate the effect of yeast-derived β-glucan fiber on plasma lipids and early atherosclerosis development in hamsters consuming a semi-purified hypercholesterolemic diet (HCD). Animals were fed either the HCD or the HCD containing psyllium or β-glucan fiber from yeast for 12 weeks. Both the psyllium and β-glucan fiber from yeast showed significant decreases in plasma total cholesterol, non-HDL-C, triacylglycerol, and aortic fatty streak area when compared to the HCD. Also, the β-glucan fiber from yeast had significantly less aortic fatty streak area compared to the psyllium diet. Findings from this study show that while both β-glucan fiber from yeast and psyllium produced similar reductions in plasma lipid and lipoprotein concentrations, the β-glucan fiber from yeast prevented the development early atherosclerosis better than psyllium in the hamsters.

A Review on the Impact of the Plant Bioactive Compound β-Glucans as Phytochemicals for Boosting Human and Animals’ Immune Response—β-Glucans as Immunostimulants

The influence of food and nutrition on health and immunity for both human and animals are being demonstrated. Phytochemicals are natural compounds present in cereals, beans, fruits, vegetable, and other plants, believed to enhance immune response for both human and animals. One of these phytochemicals is β-Glucans that are heterogeneous polysaccharides consisted of branched long chains of D-Glucose units present in cereals such as barley, wheat, and oats, and also present in microbial cell walls for yeasts, fungi, bacteria, and algae. β-Glucans extracted from cereals and mushroom were investigated for their positive impact on immunomodulation for both human and animal health. These β-Glucans proved to enhance immune system for innate response as the first defense against microbial infection, toxins, and self-tumor cells, and also, enhance adaptive immune that also referred to specific immunity as the second defense in response to antigen-specific lymphocytes against microbial infection, toxins, and self-tumor cells.

Periodontitis and Inflammation: Plasma High Titer Naturally Occurring Anti-Glucan Antibodies Form Immune Complex with Streptococcus mutans Antigen

Atheromatous plaques usually contain antigens of the periodontitis-causing bacteria Streptococcus mutans though molecular mechanism of this incorporation remains unknown. Since vascular adhesion and inflammatory potential of Immune Complexes (IC) are known we investigated the naturally occurring plasma antibodies that recognize major antigens from S. mutans. S. mutans-binding plasma proteins (SMBP) prepared by affinity chromatography on a column of heat-killed S. mutans could recognize α- and β-linked glucose in dextran and yeast respectively but not galactose in glycoproteins. SMBP contained only three proteins, each corresponding in electrophoretic mobility to standard plasma IgG, IgA or IgM. The major positively and negatively charged protein antigens (PSMAg and NSMAg) isolated from S. mutans by electrophoresis and ion exchange chromatography respectively were recognized sugar-reversibly by the anti-β-glucan antibody (ABG) and though less avidly, by the dextran-binding immunoglobulin (DIg) in normal plasma. NSMAg addition resulted in near doubling of IC-bound immunoglobulins in immunoglobulin-rich fraction of plasma. IC isolated from above fraction after NSMAg addition had substantially more IgA and IgM content than total plasma immunoglobulins. IC formation by NSMAg was significantly inhibited by ABG- and DIg-specific sugars or by selective withdrawal of ABG or DIg from plasma. ABG and DIg being relatively high titer plasma antibodies IC formation with them suggested a possible route for vascular adhesion and damage by S. mutans and its antigens. Further, high IgA content of these ICs indicated their susceptibility to tissue uptake through cell surface galectin-1 for which IgA is the lone immunoglobulin ligand.

二甲基亚砜辅助分离酵母细胞壁中β-葡聚糖的工艺探索

酵母β-葡聚糖(yeastβ-glucan)是一种难溶于水、酸、碱等常用溶剂的多糖,因传统的制备工艺复杂、烦琐且产品产量低或纯度不高,导致其产业化困难。作者用碱法结合二甲基亚砜(DMSO)辅助分离对酵母β-葡聚糖的生产制备工艺进行了探索和优化。结果显示:在0.7 g/dL NaOH中80℃处理2.6 h进行碱法除杂,除杂率最大为71.84%;在料液比为30 mg∶1 mL、体积分数80%的DMSO、80℃下分离纯化β-葡聚糖30 min,得到的β-葡聚糖产品纯度达到95.84%。通过薄层色谱和傅里叶红外光谱对产品进行鉴定,表明此产品是由葡萄糖单体聚合而成,呈β构型;抗炎试验表明,此产品具有一定的生物活性。该研究旨在简化生产工艺、扩大生产规模、提高产品质量,以期为工业化生产提供依据。

高压酸水解-离子交换色谱法测定乳粉中的酵母β-葡聚糖

目的:采用高压酸水解-离子交换色谱法建立乳粉中酵母β-葡聚糖含量的分析方法。方法:先对乳粉中的酵母β-葡聚糖进行富集,富集得到的酵母β-葡聚糖利用高压酸水解成葡萄糖后利用离子色谱法检测分析,最后通过公式换算计算出酵母β-葡聚糖的含量。结果:葡萄糖在2~200 mg/L质量浓度范围内的线性关系良好,相关系数r为0.9998。酵母β-葡聚糖的定量限为11.1 mg/100 g。在20,50,100 mg/100 g加标水平下,酵母β-葡聚糖的加标回收率为81.5%~99.8%,相对标准偏差小于5%。结论:该方法简便高效、灵敏度高、准确性好,适用于乳粉中酵母β-葡聚糖的定量检测。

酵母β-葡聚糖对受免异育银鲫免疫应答的增强作用

在饲料中添加定量的酵母 β -葡聚糖 ,投喂经注射接种福尔马林灭活的嗜水气单胞菌 (Aeromonashydrophila)菌苗的异育银鲫 (Carassiusauratusgibelio) 2 8d后 ,通过测定供试鱼的增重量、血清中凝集抗体效价、溶菌酶活性、谷丙转氨酶活性 (SGPT)、血清总蛋白含量、白细胞吞噬活性以及活菌攻毒后的免疫保护率 (RPS) ,探讨了酵母 β -葡聚糖对受免异育银鲫免疫应答的增强作用。结果表明 ,投喂添加 2 0 0 .0mg/ (kg·d)酵母 β -葡聚糖的饲料 ,不仅可以提高受免异育银鲫对灭活嗜水气单胞菌的免疫应答水平 ,增强抵抗嗜水气单胞菌人工感染的能力 ,而且还具有一定的促进生长和改善肝功能的作用。