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Extracellular Polysaccharide (extracellular + polysaccharide)

Distribution by Scientific Domains

Life Sciences	53%
Chemistry	30%
Medical Sciences	15%

Selected Abstracts

NUDIST COLONIES: A REVEALING GLIMPSE OF CYANOBACTERIAL EXTRACELLULAR POLYSACCHARIDE

JOURNAL OF PHYCOLOGY, Issue 1 2004
Malcolm Potts
No abstract is available for this article. [source]

NOSTOC (CYANOPHYCEAE) GOES NUDE: EXTRACELLULAR POLYSACCHARIDES SERVE AS A SINK FOR REDUCING POWER UNDER UNBALANCED C/N METABOLISM,

JOURNAL OF PHYCOLOGY, Issue 1 2004
Ana Otero
Many species of the filamentous N2 -fixing heterocyst-forming Cyanobacteria of the genus Nostoc produce large amounts of extracellular polymeric substances (EPS), but hitherto no general model has been proposed of the factors that control their synthesis. Previously, we demonstrated a strong correlation between the presence of a glycocalyx (or EPS capsule) and diazotrophic growth in the genus Nostoc. When grown with nitrate, nude morphotypes lacking a glycocalyx were obtained for all the capsulated strains tested. CO2 availability was pro-posed as a key factor that controls the synthesis of the capsule. To test this hypothesis, Nostoc PCC 7936 was cultured diazotrophically (N2) or with nitrate with different CO2 supplies. By tuning the pH and the supply of CO2, capsulated or nude mor-photypes were obtained irrespective of the source of nitrogen. Exocellular polysaccharides were synthesized only when the fixed carbon exceeded the amount of nitrogen available. The glycocalyx is not needed for the optimal functioning of nitrogenase because diazotrophic cultures grew equally well, irrespective of whether they were capsulated or nude. Capsulated cultures possessed protein to carbohydrate ratios that ranged between 1 and 1.5, whereas in nude cultures the ratio ranged between 2 and 2.5. Low protein to carbohydrate ratios were indicative for either nitrogen-limited or carbon-oversaturated cultures. The results demonstrate that in Nostoc EPS serve as a sink for the excess fixed carbon under unbalanced C/N metabolism. [source]

Structure of an Extracellular Polysaccharide from a Strain of Lactic Acid Bacteria

CHINESE JOURNAL OF CHEMISTRY, Issue 12 2003
Xiao-Mei Gu
Abstract A new extracellular polysaccharide (EPS-I) isolated and purified from Z222, a strain of Lactic acid bacteria has been investigated. Sugar composition analysis, methylation analysis and 1H NMR and 13C NMR spectroscopy reveal that the EPS-I is composed of a pentasaccharide repeating unit. The sequence of sugar residue was determined by using two-dimensional NMR spectroscopy, including heteronuclear multiple-bond correlation (HMBC) and nuclear overhauser effect spectroscopy (NOESY). [source]

CHANGES IN THE MORPHOLOGY AND POLYSACCHARIDE CONTENT OF MICROCYSTIS AERUGINOSA (CYANOBACTERIA) DURING FLAGELLATE GRAZING,

JOURNAL OF PHYCOLOGY, Issue 3 2008
Zhou Yang
To investigate the changes in the morphology and polysaccharide content of Microcystis aeruginosa (Kütz.) Kütz. during flagellate grazing, cultures of M. aeruginosa were exposed to grazing Ochromonas sp. for a period of 9 d under controlled laboratory conditions. M. aeruginosa responded actively to flagellate grazing and formed colonies, most of which were made up of several or dozens of cells, suggesting that flagellate grazing may be one of the biotic factors responsible for colony formation in M. aeruginosa. When colonies were formed, the cell surface ultrastructure changed, and the polysaccharide layer on the surface of the cell wall became thicker. This change indicated that synthesis and secretion of extracellular polysaccharide (EPS) of M. aeruginosa cells increased under flagellate grazing pressure. The contents of soluble extracellular polysaccharide (sEPS), bound extracellular polysaccharide (bEPS), and total polysaccharide (TPS) in colonial cells of M. aeruginosa increased significantly compared with those in single cells. This finding suggested that the increased amount of EPS on the cell surface may play a role in keeping M. aeruginosa cells together to form colonies. [source]

Effect of medium molecular weight xanthan gum in rheology and stability of oil-in-water emulsion stabilized with legume proteins

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2005
Evdoxia M Papalamprou
Abstract Xanthan gum is a water-soluble extracellular polysaccharide that has gained widespread commercial use because of its strong pseudoplasticity and tolerance to high ionic strength, which bring unique rheological properties to solutions. This study compares and evaluates the emulsifying properties of oil-in-water (30:70 v/v) emulsions stabilized with lupin and soya protein isolates and medium molecular weight xanthan gum. The protein was obtained by an isoelectric precipitation method and the polysaccharide was produced by Xanthomonas campestris ATCC 1395 in batch culture in a laboratory fermenter (LBG medium) without pH control. The addition of xanthan gum in the emulsion formulation enhances emulsion stability through the phenomenon of thermodynamic incompatibility with the legume protein, resulting in an increase of the adsorbed protein at the interface. The emulsion stability is also enhanced by a network structure built by the polysaccharide in the bulk phase. Copyright © 2005 Society of Chemical Industry [source]

Isolation and characterization of the cell-surface polysaccharides of Porphyromonas gingivalis ATCC 53978

MOLECULAR ORAL MICROBIOLOGY, Issue 3 2000
S. I. Farquharson
The cell-surface carbohydrates of Porphyromonas gingivalis strain ATCC 53978 were isolated and partially characterized. Three separate polysaccharides were found to be present: an extracellular polysaccharide, capsular polysaccharide and lipopolysaccharide. The capsular polysaccharide, which had peculiar, gel-like viscoelastic properties, was found to be comprised of mannuronic acid, glucuronic acid, galacturonic acid, galactose, and 2-acetamido-2-deoxy- d -glucose in relative molar ratios of 0.6:0.9:0.5:0.5:1.0, respectively. The extracellular polysaccharide was found to contain mannose, rhamnose, glucose, galactose, and 2-acetamido-2-deoxy- d -glucose in relative molar ratios of 13.5:1.4:1.0:2.0:1.0, respectively. The lipopolysaccharide was found to contain an O -antigen with a regular tetrasaccharide repeat unit comprised of 4-linked ,- l -rhamnopyranosyl, 6-linked ,- d -glucopyranosyl, 3-linked ,- d -galactopyranosyl, and 4-linked 2-acetamido-2-deoxy-,- d -glucopyranosyl residues in equimolar proportions. [source]

Microbiota analysis of Caspian Sea yogurt, a ropy fermented milk circulated in Japan

ANIMAL SCIENCE JOURNAL, Issue 2 2009
Kenji UCHIDA
ABSTRACT We analyzed the microbiota of domestic ropy fermented milk, Caspian Sea yogurt (or ,kasupikai yohguruto' in Japanese), circulated in Japan. We collected six varieties from five localities. Lactococcus (L) lactis ssp. cremoris was isolated from all samples as the dominant strain at levels of 108,109 CFU/g. We show this strain produces an extracellular polysaccharide (EPS) that causes the unique characteristic viscosity of the product. From analysis of the RAPD pattern of 60 bacterial isolates from the six samples, we found that 59 strains from a total of 60 isolates were identical and produced this viscosity. Furthermore, PFGE analysis of representative strains from each sample indicated that the isolates could be classified into four subgroups. This suggests these L. lactis ssp. cremoris strains found in Caspian Sea yogurt may have been slightly mutated during subculture in Japan. In addition, Lactobacillus (L.) sakei ssp. sakei were isolated from three samples; L. plantarum, Gluconoacetobacter sacchari and Acetobacter aceti were isolated from two samples; and L. paracasei, L. kefiri, Leuconostoc (Leu.) mesenteroides were isolated from one sample. [source]

Structure of an Extracellular Polysaccharide from a Strain of Lactic Acid Bacteria

Effects of clinical isolates of Pseudomonas aeruginosa on Staphylococcus epidermidis biofilm formation

FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2010
Maria Pihl
Abstract Pseudomonas aeruginosa is often found in chronic infections, including cystic fibrosis lung infections and those related to chronic wounds and venous ulcers. At the latter sites, P. aeruginosa can be isolated together with Staphylococcus epidermidis, and we have therefore explored the effect of clinical isolates and laboratory strains of P. aeruginosa strains on colonization by S. epidermidis in dual-species biofilms. Biofilm formation was assayed using 16S rRNA FISH and confocal laser scanning microscopy. Among the six P. aeruginosa strains tested, one particular strain, denoted 14:2, exerted a significant inhibitory effect, and even after 6 h, S. epidermidis levels in dual-species biofilms were reduced by >85% compared with those without P. aeruginosa. Interestingly, strain 14:2 was found to be negative for classical virulence determinants including pyocyanin, elastase and alkaline protease. Therefore, we suggest that less virulent phenotypes of P. aeruginosa, which may develop over time in chronic infections, could counteract colonization by S. epidermidis, ensuring persistence and dominance by P. aeruginosa in the host micro-habitat. Further studies are required to explain the inhibitory effect on S. epidermidis, although extracellular polysaccharides produced by P. aeruginosa might play a role in this phenomenon. [source]

The structure of the lipid anchor of Campylobacter jejuni polysaccharide

FEMS MICROBIOLOGY LETTERS, Issue 2 2006
Adrian T. Corcoran
Abstract Campylobacter jejuni is a leading cause of gastroenteritis in humans. Campylobacter jejuni produces extracellular polysaccharides that have been characterized structurally and shown to be independent of lipopolysaccharides. Furthermore, it has been suggested that these C. jejuni polysaccharides are capsular in nature, although their lipid anchor has not been identified. In this report, the occurrence of a lipid-linked capsular-like polysaccharide in C. jejuni is conclusively shown, and the lipid anchor identified as dipalmitoyl-glycerophosphate. [source]

Proteomic and transcriptomic analysis for streptozotocin-induced diabetic rat pancreas in response to fungal polysaccharide treatments

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 11 2008
Sang Woo Kim
Abstract In an attempt to search for novel biomarkers for monitoring diabetes prognosis, we examined the influence of the hypoglycemic fungal extracellular polysaccharides (EPS) on the differential change in pancreatic proteome and transcriptome in streptozotocin (STZ)-induced diabetic rats using 2-DE-based protein mapping and oligonucleotide microarray analysis. The 2-DE system separated more than 2000 individual spots, demonstrating that 34 proteins out of about 500 matched spots were differentially expressed. A total of 22 overexpressed and 12 underexpressed proteins in 2-DE map were observed (p<0.05) between the healthy and diabetic rats, of which 26 spots were identified by PMF analysis. Of these, significant down regulation of carbonyl reductase (Cbr), hydroxymethylglutaryl-CoA synthase (HMGCS), and putative human mitogen-activated protein kinase activator with WD repeats-binding protein (MAWDBP) in diabetic pancreas were reported for the first time in this study. When treated with EPS, all these four proteins were reverted to normal levels. The microarray analysis revealed that 96 out of 1272 genes were down- or up-regulated in the diabetic rats and the altered transcript levels of many of these genes were reversed after EPS treatment. In particular, ROS generation in rat islets was significantly increased after STZ treatment, thereafter EPS treatment was likely to play a preventive role in ,-cell destruction mediated by STZ. Taken together, EPS may act as a potent regulator of gene expression for a wide variety of genes in diabetic rats, particularly in antioxidative stress, insulin biosynthesis, and cell proliferation. [source]

Improvement of ganoderic acid and Ganoderma polysaccharide biosynthesis by Ganoderma lucidum fermentation under the inducement of Cu2+

BIOTECHNOLOGY PROGRESS, Issue 2 2010
Ya-Jie Tang
Abstract The cell growth and total accumulation of bioactive metabolites were significantly improved by Cu2+ addition during the submerged fermentation of medicinal mushroom Ganoderma lucidum. A mathematical model, constructed by response surface methodology combination with full factorial design, was applied to study the synergic effect of Cu2+ addition concentration and addition time. The optimal Cu2+ inducement strategy for the cell growth were different from those for the biosynthesis of ganoderic acid (GA) and Ganoderma polysaccharide. A multiple additions strategy of Cu2+ by adding each 1 mM Cu2+ on day 2, 6, 8 and 2 mM Cu2+ on day 4 was developed to enhance total accumulation of GA and extracellular polysaccharides. The highest GA content reached 3.0 ± 0.1 mg per 100 mg DW, which was increased by 76.5% and 33.9% compared with the control without Cu2+ addition and the peak value predicted by the constructed mathematical model, respectively. While, relatively higher addition concentration of Cu2+ (i.e., 5 mM) on the culture of day 4 led to higher content and total production of intracellular polysaccharides. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source]