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1.
Streptococcus thermophilus EU20 when grown on skimmed milk secretes a high-molecular-weight exopolysaccharide that is composed of glucose, galactose and rhamnose in a molar ratio of 2:3:2. Using chemical techniques and 1D and 2D-NMR spectroscopy (1H and 13C) the polysaccharide has been shown to possess a heptasaccharide repeating unit having the following structure: [chemical structure: see text]. Treatment of the polysaccharide with mild acid (0.5 M TFA, 100 degrees C for 1 h) liberates two oligosaccharides; the components correspond to the repeating unit and a hexasaccharide equivalent to the repeating unit minus the terminal alpha-L-Rhap. 相似文献
2.
The exopolysaccharide of Streptococcus thermophilus S3, produced in skimmed milk, is composed of D-galactose and L-rhamnose in a molar ratio of 2:1. The polysaccharide contains 0.4 equiv of O-acetyl groups per repeating unit. Linkage analysis and 1D/2D NMR (1H and 13C) studies on native and O-deacetylated EPS together with nanoES-CID tandem mass spectrometry studies on oligosaccharides generated by a periodate oxidation protocol, show the polysaccharide to have the following structure: [structure: see text]. 相似文献
3.
Isolation and characterization of the exopolysaccharide produced by Streptococcus thermophilus SFi20
Navarini L Abatangelo A Bertocchi C Conti E Bosco M Picotti F 《International journal of biological macromolecules》2001,28(3):219-226
This paper reports isolation, structural characterization and some physico-chemical properties in aqueous solution of the exopolysaccharide (EPS) produced by Streptococcus thermophilus strain SFi20. The yield of the purified EPS was found to be reproducible and close to the average value of 143 mg/l. The chemical structure, previously suggested, has been confirmed on the basis of NMR data. Viscometric, chiro-optical and rheological measurements have been carried out with the aim of characterizing the conformational state of the polysaccharide in aqueous solution. All the data reported indicate that the EPS does not undergo a cooperative conformational transition under the investigated experimental conditions. Furthermore, the viscosity data and the viscoelastic behaviour suggest that the polymer is rather flexible and adopts a random coil conformation in aqueous solution. 相似文献
4.
Elisabeth J Faber Daan J Van Haaster Johannis P Kamerling Johannes F G Vliegenthart 《European journal of biochemistry》2002,269(22):5590-5598
The exopolysaccharide produced by Streptococcus thermophilus 8S in reconstituted skimmed milk is a heteropolysaccharide containing d-galactose, d-glucose, d-ribose, and N-acetyl-d-galactosamine in a molar ratio of 2 : 1 : 1 : 1. Furthermore, the polysaccharide contains one equivalent of a novel open chain nononic acid constituent, 3,9-dideoxy-d-threo-d-altro-nononic acid, ether-linked via C-2 to C-6 of an additional d-glucose per repeating unit. Methylation analysis and 1D/2D NMR studies (1H and 13C) performed on the native polysaccharide, and mass spectrometric and NMR analyses of the oligosaccharide obtained from the polysaccharide by de-N-acetylation followed by deamination and reduction demonstrated the 'hepta'saccharide repeating unit to be: -->4)-alpha-D-Galp-(1-->2)-beta-D-Ribf-(1-->4)-beta-D-Galp-(1-->4)-beta-D-Glcp-(1--7')-Sub-(1-->4)-beta-D-GalpNAc-(1--> in which Sug is 6-O-(3',9'-dideoxy-d-threo-d-altro-nononic acid-2'-yl)-alpha-d-glucopyranose. 相似文献
5.
T Doco J M Wieruszeski B Fournet D Carcano P Ramos A Loones 《Carbohydrate research》1990,198(2):313-321
Streptococcus thermophilus strains grown on skimmed milk produced a viscosifying, exocellular, and water-soluble polysaccharide which contains D-glucose, D-galactose, and N-acetyl-D-galactosamine in the ratio of 1:2:1. Methylation analysis identified the glycosidic linkages in the tetrasaccharidic repeating-unit, and Smith degradation and nitrous deamination after N-deacetylation gave the sequence of monosaccharides in the repeating-unit. The anomeric configurations of the sugar residues were determined by oxidation of the peracetylated polysaccharide with chromium trioxide and by 1H- and 13C-n.m.r. spectroscopy. The following structure was assigned to the repeating unit of the polysaccharide,----3)-beta-D-Galp-(1----3)-[alpha-D-Galp-(1----6)]-beta- D- Glcp-(1----3)-alpha-D-GalpNAc-(1----. 相似文献
6.
Enhanced exopolysaccharide production by metabolic engineering of Streptococcus thermophilus 总被引:7,自引:0,他引:7
It is possible that the low levels of production of exopolysaccharides (EPSs) by lactic acid bacteria could be improved by altering the levels of enzymes in the central metabolism that influence the production of precursor nucleotide sugars. To test this hypothesis, we identified and cloned the galU gene, which codes for UDP glucose pyrophosphorylase (GalU) in Streptococcus thermophilus LY03. Homologous overexpression of the gene led to a 10-fold increase in GalU activity but did not have any effect on the EPS yield when lactose was the carbon source. However, when galU was overexpressed in combination with pgmA, which encodes phosphoglucomutase (PGM), the EPS yield increased from 0.17 to 0.31 g/mol of carbon from lactose. A galactose-fermenting LY03 mutant (Gal(+)) with increased activities of the Leloir enzymes was also found to have a higher EPS yield (0.24 g/mol of carbon) than the parent strain. The EPS yield was further improved to 0.27 g/mol of carbon by overexpressing galU in this strain. However, the highest EPS yield, 0.36 g/mol of carbon, was obtained when pgmA was knocked out in the Gal(+) strain. Measurements of the levels of intracellular metabolites in the cultures revealed that the Gal(+) strains had considerably higher glucose 1-phosphate levels than the other strains, and the strain lacking PGM activity had threefold-higher levels of glucose 1-phosphate than the other Gal(+) strains. These results show that it is possible to increase EPS production by altering the levels of enzymes in the central carbohydrate metabolism. 相似文献
7.
The primary structure of an emulsion-stabilizing exopolysaccharide from the adhesive, hydrophobic Rhodococcus strain No. 33 was elucidated by NMR spectroscopy, methylation analyses, periodate oxidation and oligosaccharide analyses. The polysaccharide PS-33 consisted of rhamnose, galactose, glucose and glucuronic acid in molar ratios of 2:1:1:1. The main chain contained 3-substituted alpha-D-glucuronic acid linked to the 3-position at alpha-L-rhamnose, in addition to 3-substituted residues of beta-D-galactose and alpha-D-glucose. The alpha-L-rhamnose of the side chain was linked to position 4 of the galactose. In addition, the polysaccharide was O-acetylated, corresponding to one acetyl group per repeating unit. From the results two structural possibilities could be suggested. As the polysaccharide carries hydrophobic groups (methyl of rhamnose/O-acetyl), it is very likely that these are of general significance for the emulsifying activity of polysaccharides. It also seems to be possible that this polysaccharide is at least partially responsible for the hydrophobic cell surface properties of the Rhodococcus strain No. 33 and it may be involved in hydrophobic interactions when adhering to hydrophobic interfaces. 相似文献
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9.
Roger O Kervarec N Ratiskol J Colliec-Jouault S Chevolot L 《Carbohydrate research》2004,339(14):2371-2380
The structure of the extracellular polysaccharide produced by the mesophilic species, Alteromonas infernus, found in deep-sea hydrothermal vents and grown under laboratory conditions, has been investigated using partial depolymerization, methylation analysis, mass spectrometry and NMR spectroscopy. The repeating units of this polysaccharide is a nonasaccharide with the following structure: [carbohydrate: see text]. 相似文献
10.
Structural features and hypoglycaemic activity of an exopolysaccharide produced by Sorangium cellulosum 总被引:2,自引:0,他引:2
AIMS: To investigate the structural features and hypoglycaemic activity of an exopolysaccharide (EPS) produced by Sorangium cellulosum NUST06. METHODS AND RESULTS: The chemical structure of the EPS from S. cellulosum NUST06 was determined by gas-liquid chromatography, gas chromatography (GC), GC-mass spectrometry and nuclear magnetic resonance. The EPS was composed of a beta-D-(1-->4)-glucose backbone with alpha-D-(1-->6)-mannose side chains. The molecular weight of the EPS was approx. 2x10(5) Da. Healthy and alloxan-induced diabetic mice were used in the study. Blood glucose levels of the experimental animals during the trial period were analysed by a glucose test kit based on the glucose oxidase method. When 100 and 200 mg kg(-1) day(-1) of purified EPS was orally administered for 7 days, the serum glucose in alloxan-induced diabetic mice was reduced by 35.9 and 41.4% (P<0.01), and the serum glucose in healthy mice was reduced by 27.3 and 30.1% (P<0.05), respectively. CONCLUSIONS: The EPS produced by S. cellulosum NUST06 decreased blood glucose levels distinctly in both healthy and alloxan-induced diabetic mice. SIGNIFICANCE AND IMPACT OF THE STUDY: To elucidated the chemical structure of the EPS from S. cellulosum NUST06 and exploited the anti-diabetic potential of the EPS. 相似文献
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12.
This paper describes the structure of neutral exopolysaccharide (EPS) produced by Lactobacillus johnsonii 142, strain of the lactic acid bacteria isolated from the intestine of mice with experimentally induced inflammatory bowel disease (IBD). Sugar and methylation analyses along with 1H and 13C NMR spectroscopy, including two-dimensional 1H,1H COSY, TOCSY, NOESY, and 1H,13C HSQC experiments revealed that the repeating unit of the EPS is a pentasaccharide:→3)-α-d-Galp-(1→3)-β-d-Glcp-(1→5)-β-d-Galf-(1→3)-α-d-Galp-(1→3)-α-d-Galp-(1→The rabbit antiserum raised against whole cells of L. johnsonii 142 reacted with homologous EPS, and cross-reacted with exopolysaccharide from Lactobacillus animalis/murinus 148 isolated also from mice with IBD, but not reacted with EPS of L. johnsonii 151 from healthy mice. 相似文献
13.
A pH-dependent adsorption/desorption technique was used to screen Streptococcus thermophilus strains for the production of bacteriocins. Agar-diffusion tests with S. thermophilus strains as targets identified 13 out of 41 strains as producers of antibacterial activity. Thermophilin A, the bacteriocin-like substance present in the culture supernatant of S.thermophilus ST134 was purified to homogeneity by ammonium sulfate precipitation and ion-exchange chromatography, followed by ultrafiltration. Thermophilin A is a relatively heat-stable and apparently glycosylated bacteriocin with a bactericidal mode of action against sensitive cells. 相似文献
14.
Structural characterization of the exocellular polysaccharides produced by Streptococcus thermophilus SFi39 and SFi12. 总被引:1,自引:0,他引:1 下载免费PDF全文
J Lemoine F Chirat J M Wieruszeski G Strecker N Favre J R Neeser 《Applied microbiology》1997,63(9):3512-3518
We investigated the structures of the exopolysaccharides (EPSs) produced by Streptococcus thermophilus SFi39 and SFi12. Both polymers were found to have molecular masses of greater than 2 x 10(6) Da. The SFi39 EPS consisted of D-glucose and D-galactose in a molar ratio of 1:1, whereas the SFi12 EPS was composed of D-galactose, L-rhamnose, and D-glucose in a molar ratio of 3:2:1. Methylation analysis of and nuclear magnetic resonance spectra recorded from the native polysaccharide, as well as oligosaccharides released by partial acid hydrolysis, allowed the complete structural determination of the SFi39 EPS, which consists of the following tetrasaccharide repeating unit: [formula: see text] Similar spectra recorded only from the native polysaccharide were sufficient to allow the structural determination of the SFi12 EPS, which consists of the following hexasaccharide repeating unit: [formula: see text] This study shows that the texturizing properties of different S. thermophilus ropy strains are based on the production of EPSs exhibiting chemical similarities but structural differences. 相似文献
15.
Structural studies of the exopolysaccharide produced by Lactobacillus rhamnosus strain GG (ATCC 53103) 总被引:1,自引:0,他引:1
The structure of the extracellular polysaccharide (EPS) from Lactobacillus rhamnosus strain GG has been investigated. In combination with component analysis, NMR spectroscopy shows that the polysaccharide is composed of hexasaccharide repeating units. Sequential information was obtained by two-dimensional (1)H,(1)H-NOESY, and (1)H,(13)C-HMBC NMR techniques. The structure of the repeating unit of the EPS from Lactobacillus rhamnosus strain GG was determined as: [carbohydrate structure: see text] 相似文献
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17.
Structural studies of a novel exopolysaccharide produced by a mutant of Rhizobium meliloti strain Rm1021 总被引:4,自引:0,他引:4
The structure of a novel expolysaccharide obtained from a mutant of Rhizobium meliloti strain Rm1021 was elucidated by a combination of enzymic, chemical, and spectroscopic methods. The polysaccharide is composed of a disaccharide repeating-unit, beta-D-Glcp-(1----3)-alpha-D-Galp-(1----3), having a 6-O-acetyl group attached to most D-glucose residues and a 4,6-O-(1-carboxyethylidene) group attached to every D-galactose residue. 相似文献
18.
Structure and properties of the exopolysaccharide produced by Streptococcus macedonicus Sc136 总被引:3,自引:0,他引:3
Streptococcus macedonicus is a Gram positive lactic acid bacterium that is part of the starter flora present in Greek sheep and goat cheeses. The S. macedonicus Sc136 strain produces a high-molecular-mass, highly texturizing exopolysaccharide composed of D-glucose, D-galactose, and N-acetyl-D-glucosamine in the molar ratio of 3:2:1. The structure of the exopolysaccharide produced by S. macedonicus Sc136 was determined by chemical analysis, mass spectrometry, and nuclear magnetic resonance spectroscopy. The repeating unit was shown to be: (see text) The polysaccharide sidechain beta-D-Galf-(1-->6)-beta-D-Glcp-(1-->6)-beta-D-GlcpNAc is a key factor in the highly texturizing properties of the S.macedonicus Sc136 exopolysaccharide. Finally, the trisaccharide sequence beta-D-GlcpNAc-(1-->3)-beta-D-Galp-(1-->4)-beta-D-Glcp corresponds to the internal backbone of the lacto-N-tetraose and lacto-N-neotetraose units, which serve as a structural basis for the large majority of human milk oligosaccharides, an additional property offering an important potential for the development of improved infant nutrition products. 相似文献
19.
Requirement for phosphoglucomutase in exopolysaccharide biosynthesis in glucose- and lactose-utilizing Streptococcus thermophilus 总被引:2,自引:0,他引:2
To study the influence of phosphoglucomutase (PGM) activity on exopolysaccharide (EPS) synthesis in glucose- and lactose-growing Streptococcus thermophilus, a knockout PGM mutant and a strain with elevated PGM activity were constructed. The pgmA gene, encoding PGM in S. thermophilus LY03, was identified and cloned. The gene was functional in Escherichia coli and was shown to be expressed from its own promoter. The pgmA-deficient mutant was unable to grow on glucose, while the mutation did not affect growth on lactose. Overexpression of pgmA had no significant effect on EPS production in glucose-growing cells. Neither deletion nor overexpression of pgmA changed the growth or EPS production on lactose. Thus, the EPS precursors in lactose-utilizing S. thermophilus are most probably formed from the galactose moiety of lactose via the Leloir pathway, which circumvents the need for a functional PGM. 相似文献
20.
Cellulomonas flavigena KU produces large quantities of an insoluble exopolysaccharide (EPS) under certain growth conditions. The EPS has previously
been shown to be a glucose polymer and to have solubility properties similar to curdlan, a β-1,3-D-glucan produced by Alcaligenes faecalis var. myxogenes 10C3K. Furthermore, EPS purified by alkaline extraction stains with aniline blue, a dye specific for curdlan-type polysaccharides.
However, EPS-producing colonies of C. flavigena KU do not stain on aniline blue agar as do those of curdlan-producing bacteria. These facts prompted a more thorough structural
analysis of the EPS. Here we report that purified EPS is indeed identical to curdlan in primary structure, but that the native
form of the EPS may differ from curdlan in physical conformation. Journal of Industrial Microbiology & Biotechnology (2002) 29, 200–203 doi:10.1038/sj.jim.7000277
Received 19 February 2002/ Accepted in revised form 20 May 2002 相似文献