Background Salmonella typhimurium(S.T),as an important foodborne bacterial pathogen,can cause diarrhea and gastroenteritis in humans and animals.Numerous studies have confirmed that exopolysaccharides(EPSs)have variou...Background Salmonella typhimurium(S.T),as an important foodborne bacterial pathogen,can cause diarrhea and gastroenteritis in humans and animals.Numerous studies have confirmed that exopolysaccharides(EPSs)have various biological functions,but the mechanism through which EPSs improve the immunity of animals against the invasion of pathogenic bacteria is unclear.Here,we explored the protective effect of EPSs of Lactobacillus rhamnosus GG(LGG)on the S.T-infected intestine.Methods Mice received adequate food and drinking water for one week before the start of the experiment.After 7 d of prefeeding,2×108 CFU/mL S.T solution and an equivalent volume of saline(control group)were given orally for 1 d.On the fourth day,the mice were treated with 0.5 mg/mL EPSs,1.0 mg/mL EPSs,2.0 mg/mL EPSs,or 2.0 mg/mL penicillin for 7 d.Finally,the body and relative organ weight,histological staining,and the levels of antioxidant enzyme activity and inflammatory cytokines were determined.Results The S.T-infected mice exhibited symptoms of decreased appetite,somnolence,diarrhea and flagging spirit.Treatment with EPSs and penicillin improved the weight loss of the mice,and the high dose of EPSs showed the best therapeutic effect.EPSs significantly ameliorated S.T-induced ileal injury in mice.High-dose EPSs were more effective than penicillin for alleviating ileal oxidative damage induced by S.T.The mRNA levels of inflammatory cytokines in the ileum of mice showed that the regulatory effects of EPSs on inflammatory cytokines were better than those of penicillin.EPSs could inhibit the expression and activation of key proteins of the TLR4/NF-κB/MAPK pathway and thereby suppress the level of S.T-induced ileal inflammation.Conclusions EPSs attenuate S.T-induced immune responses by inhibiting the expression of key proteins in the TLR4/NF-κB/MAPK signaling pathway.Moreover,EPSs could promote bacterial aggregation into clusters,which may be a potential strategy for reducing the bacterial invasion of intestinal epithelial cells.展开更多
Objective: To evaluate in-vitro antioxidant, anti-inflammatory and antitumor abilities against human breast adenocarcinoma(MCF7) and human prostate cancer(PC3) as well as the suppressor effect of bacterial exopolysacc...Objective: To evaluate in-vitro antioxidant, anti-inflammatory and antitumor abilities against human breast adenocarcinoma(MCF7) and human prostate cancer(PC3) as well as the suppressor effect of bacterial exopolysaccharide(BAEPS) on Ehrlich ascites carcinoma(EAC). Methods: In-vitro antioxidants characters of BAEPS were determined using various methods, while anti-inflammatory activity was estimated against cyclooxygenase(COX-1 and COX-2). In-vitro study, anticancer against MCF7 and PC3 were assessed by the mitochondrial dependent reduction of yellow MTT. In in-vivo study against EAC progression, mice were inoculated with EAC cells and then were orally administered BAEPS at 200 mg/kg after 24 h(equals to 0.10 of determined LD50)/10 d. Results: BAEPS was acidic exopolysaccharide contained uronic acid(12.3%) and sulfate(22.8%) with constitution of glucose, galactose and glucuronic acid in a molar ratio1.6: 1.0: 0.9, respectively, with a molecular mass of 3.76伊104 g/mol. BAEPS appeared potent antioxidant characters as free radical scavenging, oxygen reactive species scavenging and metal chelation, while its reducing power was low. BAEPS showed selective anti-inflammatory activity against COX-2 than COX-1, COX-2 selective. BAEPS exhibited potent and selective effect to breast cell cancer MCF7, the death percentage was 65.20% with IC_(50)=70 μg/m L and IC_(90)=127.40 μg/m L. BAEPS decreased counted viable EAC cells and induced non-viable cells. BAEPS improved all assessed hematological parameters. These improvements were reflected in the increasing median survival time and significant increment(P<0.05) in life span. Conclusions: BAEPS has anti-tumor activity with a good margin of safety. The anti-tumor activity of BAEPS may be due to its content from sulfated groups and uronic acids and they have antioxidant and anti-inflammatory properties.展开更多
A strain with high production of exopolysaccharide(EPS) was isolated from dried milk cake(a traditional fermented food from Inner Mongolia). The strain was called N21 and later identified as Leuconostoc citreum( Leu. ...A strain with high production of exopolysaccharide(EPS) was isolated from dried milk cake(a traditional fermented food from Inner Mongolia). The strain was called N21 and later identified as Leuconostoc citreum( Leu. citreum). The strain was cultured in Man-Rogosa-Sharpe medium containing 50 g/L of sucrose for 48 h at 30 °C and the EPS purified, with a yield of 24.5 g/L. An average molecular weight of 6.07 × 10~6 g/mol was determined by high-performance size-exclusion chromatography. The structure of the purified EPS was investigated through gas chromatography, ~1H and ^(13)C nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. The results demonstrated a polysaccharide composed of D-glucopyranose units in a linear chain with consecutive α(1 → 6) linkages. No branching was found in the structure of the exopolysaccharide. The purified EPS showed high water solubility and emulsibility. Based on the thermogravimetric curve, the degradation temperature of the EPS was 308.47 °C, which suggested that the dextran in the study exhibited high thermal stability. The results indicated that Leu. citreum N21 could be widely used to produce linear EPS and that the EPS has potential applications in food science and processing as a food additive.展开更多
The interaction between sucrose, yeast extract and initial pH was investigated to optimize critical medium components for mycelium biomass and production of exopolysaccharide (EPS) of Lentinus squarrosulus using Respo...The interaction between sucrose, yeast extract and initial pH was investigated to optimize critical medium components for mycelium biomass and production of exopolysaccharide (EPS) of Lentinus squarrosulus using Response Surface Methodology (RSM). A central composite design (CCD) was applied and a polynomial regression model with quadratic term was used to analyse the experimental data using analysis of variance (ANOVA). ANOVA analysis showed that the model was very significant (p Lentinus squarrosulus are as follows: sucrose concentration 114.61 g/L, yeast extract 1.62 g/L and initial pH of 5.81;sucrose concentration 115.8 g/L, yeast extract of 3.39 g/L and initial pH of 6.44 respectively.展开更多
This paper deals with adsorption of Pb and Hg on the exopolysaccharide produced by Azotobacter chroococcum XU1. The adsorption of metal ions was significantly affected by the pH of metal solutions (Pb(NO3)2 and Hg(NO3...This paper deals with adsorption of Pb and Hg on the exopolysaccharide produced by Azotobacter chroococcum XU1. The adsorption of metal ions was significantly affected by the pH of metal solutions (Pb(NO3)2 and Hg(NO3)2), metal ions concentration and exopolysaccharide concentrations. At optimum pH the uptakes of the metals were 40.48% and 47.87% respectively. The metal ions biosorption was high at 4, 5-5.展开更多
The bacteriophage P13 that infects Klebsiella serotype K13 contains a heat-stable depolymerase capable of effective degradation of exopolysaccharide(EPS) produced by this microorganism. In this study, the titer of pha...The bacteriophage P13 that infects Klebsiella serotype K13 contains a heat-stable depolymerase capable of effective degradation of exopolysaccharide(EPS) produced by this microorganism. In this study, the titer of phage P13, initially 2.0 × 107 pfu mL-1, was found increasing 20 min after infection and reached 5.0 × 109 pfu mL-1 in 60 min. Accordingly, the enzyme activity of depolymerase approached the maximum 60 min after infection. Treatment at 70℃ for 30 min inactivated all the phage, but retained over 90% of the depolymerase activity. Addition of acetone into the crude phage lysate led to precipitation of the protein, with a marked increase in bacterial EPS degradation activity and a rapid drop in the titer of phage. After partial purification by acetone precipitation and ultrafiltration centrifugation, the enzyme was separated from the phage particles, showing two components with enzyme activity on Q-Sepharose Fast Flow. The soluble enzyme had an optimum degradation activity at 60℃ and pH 6.5. Transmission electron microscopy demonstrated that the phage P13 particles were spherical with a diameter of 50 nm and a short stumpy tail. It was a double-strand DNA virus consisting of a nucleic acid molecule of 45976 bp. This work provides an efficient purification operation including thermal treatment and ultrafiltration centrifugation, to dissociate depolymerase from phage particles. The characterization of phage P13 and associated EPS depolymerase is beneficial for further application of this enzyme.展开更多
Lactobacillus delbrueckii subsp. bulgaricus, which has been widely used as a fermented milk starter, is a type of probiotic, and certain strains are able to produce exopolysaccharide (EPS). EPS produced from L. bulgar...Lactobacillus delbrueckii subsp. bulgaricus, which has been widely used as a fermented milk starter, is a type of probiotic, and certain strains are able to produce exopolysaccharide (EPS). EPS produced from L. bulgaricus contributes to the physical and biological function of dairy products by regulating immune response, and this tendency seems to place EPS with acidic groups. To date, six types of chemical structure have been determined and are basically composed from glucose (Glc), galactose (Gal), and rhamnose (Rha). Eps clusters on chromosome DNA control the EPS synthesis and are transcribed as one mRNA 14 genes with 18kb on L. bulgaricus Lfi5. Furthermore, L. bulgaricus is able to utilize lactose (Lac) as carbohydrate source, repeating units of EPS are synthesized from Glc 6-phosphate, generated by an Embden-Meyerhof (EM) pathway in cellular carbohydrate assimilation. This review discusses EPS produced from L. bulgaricus.展开更多
<span style="line-height:1.5;"><span style="font-family:Verdana;">An antioxidant is a substance that inhibits the oxidation of other molecules caused by free radicals. The inbuilt antio...<span style="line-height:1.5;"><span style="font-family:Verdana;">An antioxidant is a substance that inhibits the oxidation of other molecules caused by free radicals. The inbuilt antioxidant systems possessed by living or</span><span style="font-family:Verdana;">g</span><span style="font-family:Verdana;">anisms are generally not enough to prevent them from oxidati</span><span style="font-family:Verdana;">ve damage</span><span style="font-family:Verdana;">s and the use</span></span><span style="line-height:1.5;font-family:Verdana;">s</span><span style="line-height:1.5;font-family:Verdana;"> of synthetic antioxidants also ha</span><span style="line-height:1.5;font-family:Verdana;">ve</span><span style="line-height:1.5;font-family:Verdana;"> some harmful effects. T</span><span style="line-height:1.5;"><span style="font-family:Verdana;">his study was aimed at evaluating the antioxidant activities of exopolysaccharides p</span><span style="font-family:Verdana;">roduced by lactic acid bacteria isolated from yoghurt. Lactic acid bac</span><span style="font-family:Verdana;">teria (LAB) were isolated from six different brands of commercially available yoghurt using deMan Rogosa Sharpe (MRS) agar. The LAB isolates were identified based on morphological and biochemical analyses and were screened for exopolysaccharide (EPS) production. The LAB isolates screened positive were used for EPS production in a liquid medium and the EPS produced were purified and quantified using standard methods. Antioxidant activities of the E</span><span style="font-family:Verdana;">PS were evaluated by determining the 1,1-dip</span><span style="font-family:Verdana;">henyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, ferric ion reducing power, and total phenolic contents. Data obtained were analysed using Analysis of Variance. Total lactic acid bacterial count obtained from the yoghurt samples ranged from 0 - 3.9 × 10</span><sup><span style="font-family:Verdana;">4</span></sup><span style="font-family:Verdana;"> CFU/mL with sample A (Fan Yoghurt) having the highest LAB count (3.9 × 10</span><sup><span style="font-family:Verdana;">4</span></sup><span style="font-family:Verdana;"> CFU/mL). The isolated LAB and their incidence rate were </span><i><span style="font-family:Verdana;">Lactobacillus plantarum </span></i><span style="font-family:Verdana;">(25.49%),</span><i><span style="font-family:Verdana;"> L. delbrueckii </span></i><span style="font-family:Verdana;">(19.61%),</span><i><span style="font-family:Verdana;"> L. fermentum </span></i><span style="font-family:Verdana;">(15.69%),</span><i><span style="font-family:Verdana;"> L. acidophilus </span></i><span style="font-family:Verdana;">(13.73%), </span><i><span style="font-family:Verdana;">Leuconostoc mesenteroides </span></i><span style="font-family:Verdana;">(11.76%),</span><i><span style="font-family:Verdana;"> Lactococcus lactis </span></i><span style="font-family:Verdana;">(7.84%), and </span><i><span style="font-family:Verdana;">Lactobacillus casei </span></i><span style="font-family:Verdana;">(5.88%). Fifty-one out of the 64 LAB isolates were screened positive for EPS production and only six were able to produce substantial quantity of EPS ranging from 127.4 - 208.5 mg/L. The exopolysaccharides produced by </span><i><span style="font-family:Verdana;">L. fermentum</span></i><span style="font-family:Verdana;"> had the highest DPPH radical scavenging activity (62.90%) while that of </span><i><span style="font-family:Verdana;">L. plantarum</span></i><span style="font-family:Verdana;"> had the lowest (23.10%) at a concentration of 1000 μg/mL. Also, the EPS produced by </span><i><span style="font-family:Verdana;">L. fermentum</span></i><span style="font-family:Verdana;"> recorded the highest ferric ion reducing power (12.89 mg AAE/mL) at 1000 μg/mL while that of </span><i><span style="font-family:Verdana;">L. plantarum</span></i><span style="font-family:Verdana;"> had the lowest (5.62 mg AAE/mL). At 1000 μg/mL, the total phenolic contents of the EPS samples ranged from 1.41 - 1.58 mg GAE/mL, and the EPS produced by </span><i><span style="font-family:Verdana;">L. fermentum </span></i><span style="font-family:Verdana;">had the highest (1.58 mg GAE/mL) while those produced by </span><i><span style="font-family:Verdana;">L. paracasei </span></i><span style="font-family:Verdana;">had the lowest (1.41 mg GAE/mL). This study revealed that the exopolysaccharides produced by the LAB isolates showed high antioxidant activities with respect to their DPPH free radical scavenging activity, ferric ion reducing power and total phenolic contents.展开更多
An exopolysaccharide(EPS) was isolated and purified from an Antarctic psychrophilic bacterium B-3,identified as Psychrobacter sp.,and the activation of RAW264.7 cells by B-3 EPS was investigated.The results show that ...An exopolysaccharide(EPS) was isolated and purified from an Antarctic psychrophilic bacterium B-3,identified as Psychrobacter sp.,and the activation of RAW264.7 cells by B-3 EPS was investigated.The results show that B-3 EPS,over a certain concentration range,promoted cell viability,nitric oxide production,tumor necrosis factor(TNF)a secretion,and phagocytic ability.Furthermore,TAK-242,an inhibitor of the toll-like receptor 4(TLR4) significantly reduced nitric oxide production by these cells after stimulation with B-3 EPS.Moreover,B-3 EPS induced p65 phosphorylation and IκBα degradation in these cells.In conclusion,B-3 EPS might have activated RAW264.7 cells by combining with TLR4 on cell surface and triggering activation of NF-κB signaling pathways,implying that this EPS could activate macrophages and regulate initial immune response.展开更多
The sterilization conditions between experiment and dairy industrial level are different and concern about influence on product’s qualities. In this study, the fermentation properties of Streptococcus thermophilus, a...The sterilization conditions between experiment and dairy industrial level are different and concern about influence on product’s qualities. In this study, the fermentation properties of Streptococcus thermophilus, alone and in combination with Lactobacillus delbrueckii subsp. bulgaricus, were evaluated in skim milk that had been subjected to distinct sterilization conditions. Growth, organic acid generation, and EPS production were determined using pasteurized or autoclaved milk. When S. thermophilus was cultivated in pasteurized skim milk, the growth was strain-dependent. On the other hand, growth of S. thermophilus was accelerated in autoclaved milk. Exocellular polysaccharide (EPS) production by L. bulgaricus was not affected by the combination of S. thermophilus strains. Thus, we observed that yogurt fermented by L. bulgaricus was minimally affected by the combination of S. thermophilus strains;growth of L. bulgaricus was maintained under the constant environment. These results should facilitate the development of fermented milk produced from L. bulgaricus in the dairy industry.展开更多
In the current study, in order to change the permeability of cell membrane and solve the problem of linked group of fungi mycelium, the method of adjusting osmotic pressure of medium and adding tween-80 was establishe...In the current study, in order to change the permeability of cell membrane and solve the problem of linked group of fungi mycelium, the method of adjusting osmotic pressure of medium and adding tween-80 was established. The utilized strain with relatively high exopolysaccharide (EPS) yield and low pigment level was obtained after the rejuvenation and sifting of long-preserved Aureobasidium pullulans strain. The optimal proportion of substrate was determined by means of orthogonal test. The transformation ratio of EPS was increased by 10% - 20% and the pigment content was greatly reduced. The fermenting liquor is between creamy white and pale yellow, and the white primary product can be gained without decolourization step. Furthermore, to magnify to 5 L bioreactor can get the similar result.展开更多
Biosorption of silver ions onto A. chroococcum XU1 biomass and exopolysaccharide (EPS) was investigated. It was found that the overall biosorption process was the best when cell biomass and EPS were used together. Met...Biosorption of silver ions onto A. chroococcum XU1 biomass and exopolysaccharide (EPS) was investigated. It was found that the overall biosorption process was the best when cell biomass and EPS were used together. Metal adsorption experiments showed that the final precipitate obtained by cell biomass and EPS, contained 7.85% of Ag. Based on the results presented in this study, the biomass and EPS of A. chroococcum XU1 indicated the possibility of application of them as biosorbent for removal of silver from waste waters.展开更多
Baking of sourdough is a common practice and has the advantage of improving the nutritional value, sensory qualities and increasing the shelf life of the bread. This study therefore focus on the antimicrobial and anti...Baking of sourdough is a common practice and has the advantage of improving the nutritional value, sensory qualities and increasing the shelf life of the bread. This study therefore focus on the antimicrobial and antioxidant capacity of exopolysaccharides form Lactic Acid Bacteria (LAB) and its application in sourdough production. The Lactobacillus delbrueckii LDYG2 and Weissella confusa WCFF1 were collected from the culture collection Centre and the LABs were maintained in De Man, Rogosa and Sharpe (MRS) broth. Modified Exopolysaccharide Selection Medium (mESM) was used to produce the EPS while the total sugar concentration was determined using phenol-sulfuric acid method. The antibacterial, antioxidant, proximate, physical, organoleptic properties and the shelf life of the SDB produced were also evaluated. The quantity of EPS produced by LDYG2 and WCFF1 ranged from 4743.75 - 5090.03 g/L. Eight different sugars were present in both EPSLD and EPSWC with high antibacterial activity (24 mm and 23 mm) against B. cereus and S. aureus respectively. EPSLD and EPSWC had antioxidant capacity increased in a dose dependent (0.5 - 10 mg/mL) manner. EPSWCSDB had the highest proximate content except for moisture content. There was a significantly different (P ≤ 0.05) in the shelf life extension of the sourdough bread. WCEPSSDB was generally accepted in terms of colour, aroma, taste, texture and palatability. EPS produced by L. delbrueckii (EPSLD) and W. confusa (EPSWC) has antimicrobial and antioxidant capacity and can be used in production of nutraceutical sourdough bread with an improved shelf life and high consumer acceptability.展开更多
The main objective of this study was to determine effect of exopolysaccharide (EPS) from bacteria on formation of milk gel. Milk gel was made from 10%, 15% and 20% Reconstituted Skim Milk (RSM). EPS at different conce...The main objective of this study was to determine effect of exopolysaccharide (EPS) from bacteria on formation of milk gel. Milk gel was made from 10%, 15% and 20% Reconstituted Skim Milk (RSM). EPS at different concentrations (0%, 0.2%, 0.4%, 0.6%, 0.8% and 1.0% according to our previous study) were added to RSM, heated at 60°C for 30 minute and 85°C for 30 second and cooled to 5°C before viscosity and pH were examined using viscometer and pH-meter. Viscosity was dependent on the concentrations of skim milk, increasing as the concentration of RSM increased. Lower concentration of EPS, viscosity showed a slight increase, but at 0.4% EPS, viscosity of milk gel increased rapidly and continued to increase up to 1%. Microstructure was determined using scanning electron microscope to evaluated milk gel formation. Interaction between milk protein and EPS was showed as network aggregate one and another. EPS function as binding agent between one molecule of casein and another. These results indicated that EPS could use to increase quality of milk gel.展开更多
Over-use or misuse of antibiotics in livestock and poultry production contributes to the rising threat of antibiotic resistance in animals and has negative ecological effects.Exopolysaccharides from lactic acid bacter...Over-use or misuse of antibiotics in livestock and poultry production contributes to the rising threat of antibiotic resistance in animals and has negative ecological effects.Exopolysaccharides from lactic acid bacteria(LAB-EPS)are a class of biological macromolecules which are secreted by lactic acid bacteria to the outside of the cell wall during their growth and metabolism.Numerous studies demonstrated that LAB-EPS have anti-inflammatory and antimicrobial activities and are able to regulate intestinal health and the immune system in livestock.They are biodegradable,nontoxic and bio-compatible,which are considered as ideal alternatives to antibiotics.This review aims to discuss and summarize recent research findings of LAB-EPS on regulation of intestinal health and the immune system in animals,and thus provide scientific justification for commercial applications of LAB-EPS in livestock.展开更多
Maize straw,an abundant agricultural residue,has potential as an eco-friendly resource.The aim of this study was to investigate the struc-ture and effect on Bifidobacterium longum of exopolysaccharide produced by Weis...Maize straw,an abundant agricultural residue,has potential as an eco-friendly resource.The aim of this study was to investigate the struc-ture and effect on Bifidobacterium longum of exopolysaccharide produced by Weissella cibaria using maize straw as a carbon source.In this work,an exopolysaccharide-producing strain was isolated from vegetable juice,which was identified as W.cibaria.Our results demonstrated that exopolysaccharide produced by W.cibaria is a linear glucan containing anα-1,6 glycosidic bond with a molecular weight of 9462 Da.In addition,scanning electron microscopy of exopolysaccharide from W.cibaria revealed the flake structures.In vitro assays showed that the exopolysaccharide from W.cibaria has the ability to stimulate the proliferation of B.longum strain and its metabolism to produce acetic acid.This work provides a scientific reference for the potential application of maize straw and a new insight into an eco-friendly carbon source to produce exopolysaccharide.展开更多
EPSAH is an exopolysaccharide from Aphanothece halophytica GR02. The present study was designed to evaluate its toxicity and adjuvant potential in the specific cellular and humoral immune responses in ovalbumin(OVA) i...EPSAH is an exopolysaccharide from Aphanothece halophytica GR02. The present study was designed to evaluate its toxicity and adjuvant potential in the specific cellular and humoral immune responses in ovalbumin(OVA) in mice. EPSAH did not cause any mortality and side effects when the mice were administered subcutaneously twice at the dose of 50 mg×kg^(–1). Hemolytic activity in vitro indicated that EPSAH was non-hemolytic. Splenocyte proliferation in vitro was assayed with different concentrations of EPSAH. The mice were immunized subcutaneously with OVA 0.1 mg alone or with OVA 0.1 mg dissolved in saline containing Alum(0.2 mg) or EPSAH(0.2, 0.4, or 0.8 mg) on Day 1 and 15. Two weeks later, splenocyte proliferation, natural killer(NK) cell activity, production of cytokines IL-2 from splenocytes, and serum OVA-specific antibody titers were measured. Phagocytic activity, production of pro-inflammatory cytokines IL-1 and IL-12 in mice peritoneal macrophages were also determined. EPSAH showed a dose-dependent stimulating effect on mitogen-induced proliferation. The Con A-, LPS-, and OVA-induced splenocyte proliferation and the serum OVA-specific IgG, IgG1, and IgG2 a antibody titers in the immunized mice were significantly enhanced. EPSAH also significantly promoted the production of Th1 cytokine IL-2. Besides, EPSAH remarkably increased the killing activities of NK cells from splenocytes in the immunized mice. In addition, EPSAH enhanced phagocytic activity and the generation of pro-inflammatory cytokines IL-1 and IL-12 in macrophages. These results indicated that EPSAH had a strong potential to increase both cellular and humoral immune responses, particularly promoting the development of Th1 polarization.展开更多
The aim of this research work was to enhance the fermentative production of exopolysaccharide(EPS)with mixed fruit waste as a key substrate.Xanothomonas campestries was isolated from spoiled orange and its EPS product...The aim of this research work was to enhance the fermentative production of exopolysaccharide(EPS)with mixed fruit waste as a key substrate.Xanothomonas campestries was isolated from spoiled orange and its EPS production efficiency was determined using EPS medium.Prior to optimisation,the production was 3.4 g/L,upon optimizing the medium the production improved to 9.2 g/L.The medium formulation was studied by sequential addition of medium components and replacement of sugar with mixed fruit waste.In formulated medium,the production enhanced to 11.1 g/L.For further optimisation,the response surface methodology was used,which resulted in the enhancement of production to 14.5 g/L.The scale-up study was undertaken in a 10 L shake flask and fermenter.In 10 L flask EPS,production was 14.45 g/L in 100 h,whereas in 10 L fermenter it was 21.10 g/L in 60h only.The optimisation studies gave nearly 500%(6.2fold)enhanced EPS production and dwindle in fermentation time.Replacement of sucrose with fruit waste extract made the process environment-friendly;omission of L-cystine and use of 50%reduced amount of sodium acetate in the medium lowered the production cost of EPS.The developed process resulted in the utilization of fruit waste and was also useful in solving the fruit waste disposal problem.展开更多
A yeast-like fungus strain B1 isolated from wild fungus Tremella aurantialba was identified and initially characterized. Two phylogenetic trees were generated based on the sequences of large subunit ribosomal RNA gene...A yeast-like fungus strain B1 isolated from wild fungus Tremella aurantialba was identified and initially characterized. Two phylogenetic trees were generated based on the sequences of large subunit ribosomal RNA gene D1/D2 regions and internal transcribed spacer (ITS) regions of related fungi, respectively. The analysis of D1/D2 regions and ITS sequences showed that fungus B1 was clustered together with T. aurantialba, T. aurantia and T. microspore in the phylogenetic trees. Both the morphological characteristic and phylogenetic analysis established that fungus B1 was one of the anamorph strains of T. aurantialba and belongs to Tremella genus. A fermentation medium for exopolysaccharides (EPS) production by T. aurantialba B1 . Plackett-Burmen design was used to evaluate the effects of different components in the culture medium. Glucose and yeast extract have significant influence on the EPS production. The concentrations of two factors were optimized subsequently using central composite design and response surface analysis. The results showed that 49.2 g/L glucose and 10.4 g/L yeast extract could lead to the maximum production of EPS (4.99 g/L). The optimized medium led to a 1.5-fold enhancement of the production of EPS by T. aurantialba B1 , as compared with that without optimization.展开更多
To investigate the growth conditions of white-rot fungus and simulate its metabolism kinetic models, the rules how the factors such as biomass, culture fluid, pH value, glucose consumption and exopolysaccharides gener...To investigate the growth conditions of white-rot fungus and simulate its metabolism kinetic models, the rules how the factors such as biomass, culture fluid, pH value, glucose consumption and exopolysaccharides generation, etc., changed during the batch culture process of white-rot fungi by using an air-lift fermenter, as well as metabolic kinetics of white-rot fungi were studied. Based on Logistic equation, Luedeking-Piret equation and experimental data, the correlation model parameters of mycelia biomass, glucose consumption and exopolysaccharide generation were obtained and found to be change with time in metabolism process. Detailedly, μm=0.071 8 h-1,α= 0.831 8 g/(g·h), β= 0.002 g/(g·h), b1=0.016 3 g/(g·h) and b2=3.023 3 g/(g·h). Hence the mycelial growth kinetic model, exopolysaccharide generation kinetic model and substrate consumption kinetic model which describe fermentation process of white-rot fungi were established. Meanwhile, the experimental data were verified by this model, and a good fitting result with an average relative error less than 10% between the data obtained from experiments and the model was yielded. The results show that these models can predict the growth and metabolic rules of white-rot fungus, the fermentation process of exopolysaccharides and the kinetic mechanism of white-rot fungus accurately.展开更多
基金supported by the National Natural Science Foundation of China(32030101,32272914)the National Key R&D Program of China(2022YFD1300700)the Heilongjiang Touyan Innovation Team Program。
文摘Background Salmonella typhimurium(S.T),as an important foodborne bacterial pathogen,can cause diarrhea and gastroenteritis in humans and animals.Numerous studies have confirmed that exopolysaccharides(EPSs)have various biological functions,but the mechanism through which EPSs improve the immunity of animals against the invasion of pathogenic bacteria is unclear.Here,we explored the protective effect of EPSs of Lactobacillus rhamnosus GG(LGG)on the S.T-infected intestine.Methods Mice received adequate food and drinking water for one week before the start of the experiment.After 7 d of prefeeding,2×108 CFU/mL S.T solution and an equivalent volume of saline(control group)were given orally for 1 d.On the fourth day,the mice were treated with 0.5 mg/mL EPSs,1.0 mg/mL EPSs,2.0 mg/mL EPSs,or 2.0 mg/mL penicillin for 7 d.Finally,the body and relative organ weight,histological staining,and the levels of antioxidant enzyme activity and inflammatory cytokines were determined.Results The S.T-infected mice exhibited symptoms of decreased appetite,somnolence,diarrhea and flagging spirit.Treatment with EPSs and penicillin improved the weight loss of the mice,and the high dose of EPSs showed the best therapeutic effect.EPSs significantly ameliorated S.T-induced ileal injury in mice.High-dose EPSs were more effective than penicillin for alleviating ileal oxidative damage induced by S.T.The mRNA levels of inflammatory cytokines in the ileum of mice showed that the regulatory effects of EPSs on inflammatory cytokines were better than those of penicillin.EPSs could inhibit the expression and activation of key proteins of the TLR4/NF-κB/MAPK pathway and thereby suppress the level of S.T-induced ileal inflammation.Conclusions EPSs attenuate S.T-induced immune responses by inhibiting the expression of key proteins in the TLR4/NF-κB/MAPK signaling pathway.Moreover,EPSs could promote bacterial aggregation into clusters,which may be a potential strategy for reducing the bacterial invasion of intestinal epithelial cells.
基金financially supported from National Research Centre,Egypt,through the Project No.10010103(2013-2016)
文摘Objective: To evaluate in-vitro antioxidant, anti-inflammatory and antitumor abilities against human breast adenocarcinoma(MCF7) and human prostate cancer(PC3) as well as the suppressor effect of bacterial exopolysaccharide(BAEPS) on Ehrlich ascites carcinoma(EAC). Methods: In-vitro antioxidants characters of BAEPS were determined using various methods, while anti-inflammatory activity was estimated against cyclooxygenase(COX-1 and COX-2). In-vitro study, anticancer against MCF7 and PC3 were assessed by the mitochondrial dependent reduction of yellow MTT. In in-vivo study against EAC progression, mice were inoculated with EAC cells and then were orally administered BAEPS at 200 mg/kg after 24 h(equals to 0.10 of determined LD50)/10 d. Results: BAEPS was acidic exopolysaccharide contained uronic acid(12.3%) and sulfate(22.8%) with constitution of glucose, galactose and glucuronic acid in a molar ratio1.6: 1.0: 0.9, respectively, with a molecular mass of 3.76伊104 g/mol. BAEPS appeared potent antioxidant characters as free radical scavenging, oxygen reactive species scavenging and metal chelation, while its reducing power was low. BAEPS showed selective anti-inflammatory activity against COX-2 than COX-1, COX-2 selective. BAEPS exhibited potent and selective effect to breast cell cancer MCF7, the death percentage was 65.20% with IC_(50)=70 μg/m L and IC_(90)=127.40 μg/m L. BAEPS decreased counted viable EAC cells and induced non-viable cells. BAEPS improved all assessed hematological parameters. These improvements were reflected in the increasing median survival time and significant increment(P<0.05) in life span. Conclusions: BAEPS has anti-tumor activity with a good margin of safety. The anti-tumor activity of BAEPS may be due to its content from sulfated groups and uronic acids and they have antioxidant and anti-inflammatory properties.
基金supported by the National Science and Technology Support Plan Project(No.2015BAD16B01)
文摘A strain with high production of exopolysaccharide(EPS) was isolated from dried milk cake(a traditional fermented food from Inner Mongolia). The strain was called N21 and later identified as Leuconostoc citreum( Leu. citreum). The strain was cultured in Man-Rogosa-Sharpe medium containing 50 g/L of sucrose for 48 h at 30 °C and the EPS purified, with a yield of 24.5 g/L. An average molecular weight of 6.07 × 10~6 g/mol was determined by high-performance size-exclusion chromatography. The structure of the purified EPS was investigated through gas chromatography, ~1H and ^(13)C nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. The results demonstrated a polysaccharide composed of D-glucopyranose units in a linear chain with consecutive α(1 → 6) linkages. No branching was found in the structure of the exopolysaccharide. The purified EPS showed high water solubility and emulsibility. Based on the thermogravimetric curve, the degradation temperature of the EPS was 308.47 °C, which suggested that the dextran in the study exhibited high thermal stability. The results indicated that Leu. citreum N21 could be widely used to produce linear EPS and that the EPS has potential applications in food science and processing as a food additive.
文摘The interaction between sucrose, yeast extract and initial pH was investigated to optimize critical medium components for mycelium biomass and production of exopolysaccharide (EPS) of Lentinus squarrosulus using Response Surface Methodology (RSM). A central composite design (CCD) was applied and a polynomial regression model with quadratic term was used to analyse the experimental data using analysis of variance (ANOVA). ANOVA analysis showed that the model was very significant (p Lentinus squarrosulus are as follows: sucrose concentration 114.61 g/L, yeast extract 1.62 g/L and initial pH of 5.81;sucrose concentration 115.8 g/L, yeast extract of 3.39 g/L and initial pH of 6.44 respectively.
文摘This paper deals with adsorption of Pb and Hg on the exopolysaccharide produced by Azotobacter chroococcum XU1. The adsorption of metal ions was significantly affected by the pH of metal solutions (Pb(NO3)2 and Hg(NO3)2), metal ions concentration and exopolysaccharide concentrations. At optimum pH the uptakes of the metals were 40.48% and 47.87% respectively. The metal ions biosorption was high at 4, 5-5.
基金supported by the National Natural Science Foundation of China(No.41076087)
文摘The bacteriophage P13 that infects Klebsiella serotype K13 contains a heat-stable depolymerase capable of effective degradation of exopolysaccharide(EPS) produced by this microorganism. In this study, the titer of phage P13, initially 2.0 × 107 pfu mL-1, was found increasing 20 min after infection and reached 5.0 × 109 pfu mL-1 in 60 min. Accordingly, the enzyme activity of depolymerase approached the maximum 60 min after infection. Treatment at 70℃ for 30 min inactivated all the phage, but retained over 90% of the depolymerase activity. Addition of acetone into the crude phage lysate led to precipitation of the protein, with a marked increase in bacterial EPS degradation activity and a rapid drop in the titer of phage. After partial purification by acetone precipitation and ultrafiltration centrifugation, the enzyme was separated from the phage particles, showing two components with enzyme activity on Q-Sepharose Fast Flow. The soluble enzyme had an optimum degradation activity at 60℃ and pH 6.5. Transmission electron microscopy demonstrated that the phage P13 particles were spherical with a diameter of 50 nm and a short stumpy tail. It was a double-strand DNA virus consisting of a nucleic acid molecule of 45976 bp. This work provides an efficient purification operation including thermal treatment and ultrafiltration centrifugation, to dissociate depolymerase from phage particles. The characterization of phage P13 and associated EPS depolymerase is beneficial for further application of this enzyme.
文摘Lactobacillus delbrueckii subsp. bulgaricus, which has been widely used as a fermented milk starter, is a type of probiotic, and certain strains are able to produce exopolysaccharide (EPS). EPS produced from L. bulgaricus contributes to the physical and biological function of dairy products by regulating immune response, and this tendency seems to place EPS with acidic groups. To date, six types of chemical structure have been determined and are basically composed from glucose (Glc), galactose (Gal), and rhamnose (Rha). Eps clusters on chromosome DNA control the EPS synthesis and are transcribed as one mRNA 14 genes with 18kb on L. bulgaricus Lfi5. Furthermore, L. bulgaricus is able to utilize lactose (Lac) as carbohydrate source, repeating units of EPS are synthesized from Glc 6-phosphate, generated by an Embden-Meyerhof (EM) pathway in cellular carbohydrate assimilation. This review discusses EPS produced from L. bulgaricus.
文摘<span style="line-height:1.5;"><span style="font-family:Verdana;">An antioxidant is a substance that inhibits the oxidation of other molecules caused by free radicals. The inbuilt antioxidant systems possessed by living or</span><span style="font-family:Verdana;">g</span><span style="font-family:Verdana;">anisms are generally not enough to prevent them from oxidati</span><span style="font-family:Verdana;">ve damage</span><span style="font-family:Verdana;">s and the use</span></span><span style="line-height:1.5;font-family:Verdana;">s</span><span style="line-height:1.5;font-family:Verdana;"> of synthetic antioxidants also ha</span><span style="line-height:1.5;font-family:Verdana;">ve</span><span style="line-height:1.5;font-family:Verdana;"> some harmful effects. T</span><span style="line-height:1.5;"><span style="font-family:Verdana;">his study was aimed at evaluating the antioxidant activities of exopolysaccharides p</span><span style="font-family:Verdana;">roduced by lactic acid bacteria isolated from yoghurt. Lactic acid bac</span><span style="font-family:Verdana;">teria (LAB) were isolated from six different brands of commercially available yoghurt using deMan Rogosa Sharpe (MRS) agar. The LAB isolates were identified based on morphological and biochemical analyses and were screened for exopolysaccharide (EPS) production. The LAB isolates screened positive were used for EPS production in a liquid medium and the EPS produced were purified and quantified using standard methods. Antioxidant activities of the E</span><span style="font-family:Verdana;">PS were evaluated by determining the 1,1-dip</span><span style="font-family:Verdana;">henyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, ferric ion reducing power, and total phenolic contents. Data obtained were analysed using Analysis of Variance. Total lactic acid bacterial count obtained from the yoghurt samples ranged from 0 - 3.9 × 10</span><sup><span style="font-family:Verdana;">4</span></sup><span style="font-family:Verdana;"> CFU/mL with sample A (Fan Yoghurt) having the highest LAB count (3.9 × 10</span><sup><span style="font-family:Verdana;">4</span></sup><span style="font-family:Verdana;"> CFU/mL). The isolated LAB and their incidence rate were </span><i><span style="font-family:Verdana;">Lactobacillus plantarum </span></i><span style="font-family:Verdana;">(25.49%),</span><i><span style="font-family:Verdana;"> L. delbrueckii </span></i><span style="font-family:Verdana;">(19.61%),</span><i><span style="font-family:Verdana;"> L. fermentum </span></i><span style="font-family:Verdana;">(15.69%),</span><i><span style="font-family:Verdana;"> L. acidophilus </span></i><span style="font-family:Verdana;">(13.73%), </span><i><span style="font-family:Verdana;">Leuconostoc mesenteroides </span></i><span style="font-family:Verdana;">(11.76%),</span><i><span style="font-family:Verdana;"> Lactococcus lactis </span></i><span style="font-family:Verdana;">(7.84%), and </span><i><span style="font-family:Verdana;">Lactobacillus casei </span></i><span style="font-family:Verdana;">(5.88%). Fifty-one out of the 64 LAB isolates were screened positive for EPS production and only six were able to produce substantial quantity of EPS ranging from 127.4 - 208.5 mg/L. The exopolysaccharides produced by </span><i><span style="font-family:Verdana;">L. fermentum</span></i><span style="font-family:Verdana;"> had the highest DPPH radical scavenging activity (62.90%) while that of </span><i><span style="font-family:Verdana;">L. plantarum</span></i><span style="font-family:Verdana;"> had the lowest (23.10%) at a concentration of 1000 μg/mL. Also, the EPS produced by </span><i><span style="font-family:Verdana;">L. fermentum</span></i><span style="font-family:Verdana;"> recorded the highest ferric ion reducing power (12.89 mg AAE/mL) at 1000 μg/mL while that of </span><i><span style="font-family:Verdana;">L. plantarum</span></i><span style="font-family:Verdana;"> had the lowest (5.62 mg AAE/mL). At 1000 μg/mL, the total phenolic contents of the EPS samples ranged from 1.41 - 1.58 mg GAE/mL, and the EPS produced by </span><i><span style="font-family:Verdana;">L. fermentum </span></i><span style="font-family:Verdana;">had the highest (1.58 mg GAE/mL) while those produced by </span><i><span style="font-family:Verdana;">L. paracasei </span></i><span style="font-family:Verdana;">had the lowest (1.41 mg GAE/mL). This study revealed that the exopolysaccharides produced by the LAB isolates showed high antioxidant activities with respect to their DPPH free radical scavenging activity, ferric ion reducing power and total phenolic contents.
基金Supported by the Chinese Polar Environment Comprehensive Investigation&Assessment Programs(No.CHINARE2013-01-05)the National Science&Technology Major Project(No.2011ZX8001-003)+1 种基金the Hebei Province Science&Technology Support Program(No.12220407D)the National Natural Science Foundation of China(No.31100715)
文摘An exopolysaccharide(EPS) was isolated and purified from an Antarctic psychrophilic bacterium B-3,identified as Psychrobacter sp.,and the activation of RAW264.7 cells by B-3 EPS was investigated.The results show that B-3 EPS,over a certain concentration range,promoted cell viability,nitric oxide production,tumor necrosis factor(TNF)a secretion,and phagocytic ability.Furthermore,TAK-242,an inhibitor of the toll-like receptor 4(TLR4) significantly reduced nitric oxide production by these cells after stimulation with B-3 EPS.Moreover,B-3 EPS induced p65 phosphorylation and IκBα degradation in these cells.In conclusion,B-3 EPS might have activated RAW264.7 cells by combining with TLR4 on cell surface and triggering activation of NF-κB signaling pathways,implying that this EPS could activate macrophages and regulate initial immune response.
文摘The sterilization conditions between experiment and dairy industrial level are different and concern about influence on product’s qualities. In this study, the fermentation properties of Streptococcus thermophilus, alone and in combination with Lactobacillus delbrueckii subsp. bulgaricus, were evaluated in skim milk that had been subjected to distinct sterilization conditions. Growth, organic acid generation, and EPS production were determined using pasteurized or autoclaved milk. When S. thermophilus was cultivated in pasteurized skim milk, the growth was strain-dependent. On the other hand, growth of S. thermophilus was accelerated in autoclaved milk. Exocellular polysaccharide (EPS) production by L. bulgaricus was not affected by the combination of S. thermophilus strains. Thus, we observed that yogurt fermented by L. bulgaricus was minimally affected by the combination of S. thermophilus strains;growth of L. bulgaricus was maintained under the constant environment. These results should facilitate the development of fermented milk produced from L. bulgaricus in the dairy industry.
文摘In the current study, in order to change the permeability of cell membrane and solve the problem of linked group of fungi mycelium, the method of adjusting osmotic pressure of medium and adding tween-80 was established. The utilized strain with relatively high exopolysaccharide (EPS) yield and low pigment level was obtained after the rejuvenation and sifting of long-preserved Aureobasidium pullulans strain. The optimal proportion of substrate was determined by means of orthogonal test. The transformation ratio of EPS was increased by 10% - 20% and the pigment content was greatly reduced. The fermenting liquor is between creamy white and pale yellow, and the white primary product can be gained without decolourization step. Furthermore, to magnify to 5 L bioreactor can get the similar result.
文摘Biosorption of silver ions onto A. chroococcum XU1 biomass and exopolysaccharide (EPS) was investigated. It was found that the overall biosorption process was the best when cell biomass and EPS were used together. Metal adsorption experiments showed that the final precipitate obtained by cell biomass and EPS, contained 7.85% of Ag. Based on the results presented in this study, the biomass and EPS of A. chroococcum XU1 indicated the possibility of application of them as biosorbent for removal of silver from waste waters.
文摘Baking of sourdough is a common practice and has the advantage of improving the nutritional value, sensory qualities and increasing the shelf life of the bread. This study therefore focus on the antimicrobial and antioxidant capacity of exopolysaccharides form Lactic Acid Bacteria (LAB) and its application in sourdough production. The Lactobacillus delbrueckii LDYG2 and Weissella confusa WCFF1 were collected from the culture collection Centre and the LABs were maintained in De Man, Rogosa and Sharpe (MRS) broth. Modified Exopolysaccharide Selection Medium (mESM) was used to produce the EPS while the total sugar concentration was determined using phenol-sulfuric acid method. The antibacterial, antioxidant, proximate, physical, organoleptic properties and the shelf life of the SDB produced were also evaluated. The quantity of EPS produced by LDYG2 and WCFF1 ranged from 4743.75 - 5090.03 g/L. Eight different sugars were present in both EPSLD and EPSWC with high antibacterial activity (24 mm and 23 mm) against B. cereus and S. aureus respectively. EPSLD and EPSWC had antioxidant capacity increased in a dose dependent (0.5 - 10 mg/mL) manner. EPSWCSDB had the highest proximate content except for moisture content. There was a significantly different (P ≤ 0.05) in the shelf life extension of the sourdough bread. WCEPSSDB was generally accepted in terms of colour, aroma, taste, texture and palatability. EPS produced by L. delbrueckii (EPSLD) and W. confusa (EPSWC) has antimicrobial and antioxidant capacity and can be used in production of nutraceutical sourdough bread with an improved shelf life and high consumer acceptability.
文摘The main objective of this study was to determine effect of exopolysaccharide (EPS) from bacteria on formation of milk gel. Milk gel was made from 10%, 15% and 20% Reconstituted Skim Milk (RSM). EPS at different concentrations (0%, 0.2%, 0.4%, 0.6%, 0.8% and 1.0% according to our previous study) were added to RSM, heated at 60°C for 30 minute and 85°C for 30 second and cooled to 5°C before viscosity and pH were examined using viscometer and pH-meter. Viscosity was dependent on the concentrations of skim milk, increasing as the concentration of RSM increased. Lower concentration of EPS, viscosity showed a slight increase, but at 0.4% EPS, viscosity of milk gel increased rapidly and continued to increase up to 1%. Microstructure was determined using scanning electron microscope to evaluated milk gel formation. Interaction between milk protein and EPS was showed as network aggregate one and another. EPS function as binding agent between one molecule of casein and another. These results indicated that EPS could use to increase quality of milk gel.
基金supported by the National Natural Science Foundation of China(NSFC No.32072773)the International Post-doctoral Exchange Fellowship Program of China and the Chinese Academy of Agricultural Sciences Postdoctoral YouNong Program of China.
文摘Over-use or misuse of antibiotics in livestock and poultry production contributes to the rising threat of antibiotic resistance in animals and has negative ecological effects.Exopolysaccharides from lactic acid bacteria(LAB-EPS)are a class of biological macromolecules which are secreted by lactic acid bacteria to the outside of the cell wall during their growth and metabolism.Numerous studies demonstrated that LAB-EPS have anti-inflammatory and antimicrobial activities and are able to regulate intestinal health and the immune system in livestock.They are biodegradable,nontoxic and bio-compatible,which are considered as ideal alternatives to antibiotics.This review aims to discuss and summarize recent research findings of LAB-EPS on regulation of intestinal health and the immune system in animals,and thus provide scientific justification for commercial applications of LAB-EPS in livestock.
基金supported by Fujian Agriculture and Forestry University(No.72202200901),China.
文摘Maize straw,an abundant agricultural residue,has potential as an eco-friendly resource.The aim of this study was to investigate the struc-ture and effect on Bifidobacterium longum of exopolysaccharide produced by Weissella cibaria using maize straw as a carbon source.In this work,an exopolysaccharide-producing strain was isolated from vegetable juice,which was identified as W.cibaria.Our results demonstrated that exopolysaccharide produced by W.cibaria is a linear glucan containing anα-1,6 glycosidic bond with a molecular weight of 9462 Da.In addition,scanning electron microscopy of exopolysaccharide from W.cibaria revealed the flake structures.In vitro assays showed that the exopolysaccharide from W.cibaria has the ability to stimulate the proliferation of B.longum strain and its metabolism to produce acetic acid.This work provides a scientific reference for the potential application of maize straw and a new insight into an eco-friendly carbon source to produce exopolysaccharide.
基金supported by College Students Innovation Project for the R&D of Novel Drugs(J1030830)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘EPSAH is an exopolysaccharide from Aphanothece halophytica GR02. The present study was designed to evaluate its toxicity and adjuvant potential in the specific cellular and humoral immune responses in ovalbumin(OVA) in mice. EPSAH did not cause any mortality and side effects when the mice were administered subcutaneously twice at the dose of 50 mg×kg^(–1). Hemolytic activity in vitro indicated that EPSAH was non-hemolytic. Splenocyte proliferation in vitro was assayed with different concentrations of EPSAH. The mice were immunized subcutaneously with OVA 0.1 mg alone or with OVA 0.1 mg dissolved in saline containing Alum(0.2 mg) or EPSAH(0.2, 0.4, or 0.8 mg) on Day 1 and 15. Two weeks later, splenocyte proliferation, natural killer(NK) cell activity, production of cytokines IL-2 from splenocytes, and serum OVA-specific antibody titers were measured. Phagocytic activity, production of pro-inflammatory cytokines IL-1 and IL-12 in mice peritoneal macrophages were also determined. EPSAH showed a dose-dependent stimulating effect on mitogen-induced proliferation. The Con A-, LPS-, and OVA-induced splenocyte proliferation and the serum OVA-specific IgG, IgG1, and IgG2 a antibody titers in the immunized mice were significantly enhanced. EPSAH also significantly promoted the production of Th1 cytokine IL-2. Besides, EPSAH remarkably increased the killing activities of NK cells from splenocytes in the immunized mice. In addition, EPSAH enhanced phagocytic activity and the generation of pro-inflammatory cytokines IL-1 and IL-12 in macrophages. These results indicated that EPSAH had a strong potential to increase both cellular and humoral immune responses, particularly promoting the development of Th1 polarization.
基金We are grateful to the Department of Science and Technology(DST),New Delhi,India awarding INSPIRE Fellowship to Dr.Kinjal.H.Upadhyay.Dr Bhargav C Patel for correction of text and plagiarism check.
文摘The aim of this research work was to enhance the fermentative production of exopolysaccharide(EPS)with mixed fruit waste as a key substrate.Xanothomonas campestries was isolated from spoiled orange and its EPS production efficiency was determined using EPS medium.Prior to optimisation,the production was 3.4 g/L,upon optimizing the medium the production improved to 9.2 g/L.The medium formulation was studied by sequential addition of medium components and replacement of sugar with mixed fruit waste.In formulated medium,the production enhanced to 11.1 g/L.For further optimisation,the response surface methodology was used,which resulted in the enhancement of production to 14.5 g/L.The scale-up study was undertaken in a 10 L shake flask and fermenter.In 10 L flask EPS,production was 14.45 g/L in 100 h,whereas in 10 L fermenter it was 21.10 g/L in 60h only.The optimisation studies gave nearly 500%(6.2fold)enhanced EPS production and dwindle in fermentation time.Replacement of sucrose with fruit waste extract made the process environment-friendly;omission of L-cystine and use of 50%reduced amount of sodium acetate in the medium lowered the production cost of EPS.The developed process resulted in the utilization of fruit waste and was also useful in solving the fruit waste disposal problem.
基金Supported by the Key Project of National 9th Five-Year Plan Program (No.96-C02-03-06)
文摘A yeast-like fungus strain B1 isolated from wild fungus Tremella aurantialba was identified and initially characterized. Two phylogenetic trees were generated based on the sequences of large subunit ribosomal RNA gene D1/D2 regions and internal transcribed spacer (ITS) regions of related fungi, respectively. The analysis of D1/D2 regions and ITS sequences showed that fungus B1 was clustered together with T. aurantialba, T. aurantia and T. microspore in the phylogenetic trees. Both the morphological characteristic and phylogenetic analysis established that fungus B1 was one of the anamorph strains of T. aurantialba and belongs to Tremella genus. A fermentation medium for exopolysaccharides (EPS) production by T. aurantialba B1 . Plackett-Burmen design was used to evaluate the effects of different components in the culture medium. Glucose and yeast extract have significant influence on the EPS production. The concentrations of two factors were optimized subsequently using central composite design and response surface analysis. The results showed that 49.2 g/L glucose and 10.4 g/L yeast extract could lead to the maximum production of EPS (4.99 g/L). The optimized medium led to a 1.5-fold enhancement of the production of EPS by T. aurantialba B1 , as compared with that without optimization.
基金Supported by National Natural Sciences Foundation of China(40373044)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(05KJD610209)~~
文摘To investigate the growth conditions of white-rot fungus and simulate its metabolism kinetic models, the rules how the factors such as biomass, culture fluid, pH value, glucose consumption and exopolysaccharides generation, etc., changed during the batch culture process of white-rot fungi by using an air-lift fermenter, as well as metabolic kinetics of white-rot fungi were studied. Based on Logistic equation, Luedeking-Piret equation and experimental data, the correlation model parameters of mycelia biomass, glucose consumption and exopolysaccharide generation were obtained and found to be change with time in metabolism process. Detailedly, μm=0.071 8 h-1,α= 0.831 8 g/(g·h), β= 0.002 g/(g·h), b1=0.016 3 g/(g·h) and b2=3.023 3 g/(g·h). Hence the mycelial growth kinetic model, exopolysaccharide generation kinetic model and substrate consumption kinetic model which describe fermentation process of white-rot fungi were established. Meanwhile, the experimental data were verified by this model, and a good fitting result with an average relative error less than 10% between the data obtained from experiments and the model was yielded. The results show that these models can predict the growth and metabolic rules of white-rot fungus, the fermentation process of exopolysaccharides and the kinetic mechanism of white-rot fungus accurately.
