Found 11 publications. Displayed publications from 1 to 11
Expand all publications       Show all as text (SweetDB notation)
1. (Article ID: 530)
 
Ridout M, Cairns P, Brownsey G, Morris V
Synergistic interactions between the genetically modified bacterial polysaccharide P2 and carob or konjac mannan
Carbohydrate Research 339(13) (2004) 2233-2239
 

Rheological studies have confirmed that the bacterial polysaccharide P2, a genetically modified variant of the Acetobacter xylinum polysaccharide acetan, undergoes synergistic gelation with either of the plant polysaccharides carob or konjac mannan. X-ray fibre diffraction data shows that P2 can form a 5-fold helical structure of pitch 4.7nm and an axial rise per disaccharide repeat of 0.92nm. Optical rotation data demonstrate that P2 undergoes a coil-helix transition in solution and that deacylation enhances the stability of the helical structure in solution. Studies made on mixtures prepared at different temperatures and ionic strengths suggest that denaturation of the P2 helix favours interaction and gelation. Deacetylation of P2 enhances gelation. X-ray diffraction data for oriented fibres prepared from deacetylated P2-konjac mannan mixed films reveal a 6-fold helical structure of pitch 5.54nm with an axial rise per disaccharide repeat also of 0.92nm. This mixed helix provides direct evidence for binding between the two polysaccharides. P2 contains two sites of acetylation: one on the backbone and one on the sidechain. The former site of acetylation inhibits helix formation for P2. It is suggested that this site of acetylation also inhibits formation of the mixed helix, explaining the enhanced gelation of mixtures on deacetylation.

Bacterial polysaccharide, Rheology, Konjac mannan, Mixtures, Carob

The publication contains the following compound(s):
 

Expand this publication
2. (Article ID: 1696)
 
Couso RO, Ielpi L, Garcia RC, Dankert MA
Synthesis of mannosyl cellobiose diphosphate prenol in Acetobacter xylinum
Archives of Biochemistry and Biophysics 204 (1980) 434-443
 
The publication contains the following compound(s):
 

Expand this publication
3. (Article ID: 1940)
 
Christensen BE, Smidsrød O, Stokke BT
The role of side-chains in the CR3+-induced gelation of xanthan and xylinan (acetan) variants
Carbohydrate Polymers 25 (1994) 25-29
 

The effect of the length and chemical composition of the side-chains in comb-like branched polysaccharides on gelation with trivalent metal ions has been studied using xanthan and xylinan (acetan) with intact and truncated side-chains. Partial or complete removal of the terminal β-d-mannose, or removal of up to 22% of the trisaccharide side-chains of xanthan using partial acid hydrolysis, has only small effects on the Cr3+-induced gelation. In contrast, replacement of β-d-mannose by the trisaccharide [structure] to yield the polysaccharide xylinan totally inhibits the gelation with Cr3+ ions. Removal of the trisaccharide by partial acid hydrolysis, which leads to a series of polymers with structures converging towards the partially hydrolysed xanthans, restores the gelling ability with Cr3+ ions. These observations seem to support the gelation model where Cr3+-glucuronic acid interactions are involved in the cross-linking of chains. It is further suggested that this interaction can be suppressed due to steric hindrance caused by the bulky side-chains in xylinan.

The publication contains the following compound(s):
 

Expand this publication
4. (Article ID: 2262)
 
Jansson PE, Lindberg J, Wimalasiri KMS, Dankert MA
Structural studies of acetan, an exopolysaccharide elaborated by Acetobacter xylinum
Carbohydrate Research 245 (1993) 303-310
 

The exopolysaccharide acetan, elaborated by Acetobacter xylinum, has been investigated. The polysaccharide and a heptasaccharide, obtained on enzymic hydrolysis, corresponding to the repeating unit were characterised by sugar and methylation analysis and by NMR spectroscopy and MS. It is concluded that the polysaccharide is composed of repeating units with the following structure. [formula: see text] The polysaccharide further contains approximately two O-acetyl groups per repeating unit, which have not been assigned, but it appears that they are on primary locations.

The publication contains the following compound(s):
 

Expand this publication
5. (Article ID: 2573)
 
MacCormick CA, Harris JE, Gunning AP, Morris VJ
Characterization of a variant of the polysaccharide acetan produced by a mutant of Acetobacter xylinum strain CR1/4
Journal of Applied Bacteriology 74 (1993) 196-199
 
The publication contains the following compound(s):
 

Expand this publication
6. (Article ID: 2701)
 
Couso RO, Ielpi L, Dankert MA
A xanthan-gum-like polysaccharide from Acetobacter xylinum
Journal of General Microbiology 133(8) (1987) 2123-2135
 

A new exopolysaccharide, secreted in addition to cellulose, has been isolated from the culture medium of Acetobacter xylinum NRRL B42. This polysaccharide, for which the name acetan is proposed, contains glucose, mannose, glucuronic acid and rhamnose in a molar ratio of 4:1:1:1. On the basis of methylation, thin-layer, paper and gas-liquid chromatography, paper electrophoresis and mass spectrometry studies of the degradation products obtained by total and partial hydrolysis and acetolysis of acetan, the following structure is proposed for its repeating unit. Since our previous work with this strain demonstrated the in vitro synthesis of a lipid-linked heptasaccharide with the same structure, the possibility of acetan being the result of its polymerization is discussed. One to two O-acetyl residues per repeating unit are also present in positions not yet determined.

The publication contains the following compound(s):
 

Expand this publication
7. (Article ID: 2702)
 
De Iannino NI, Couso RO, Dankert MA
Lipid-linked intermediates and the synthesis of acetan in Acetobacter xylinum
Journal of General Microbiology 134(6) (1988) 1731-1736
 

Several strains of Acetobacter xylinum were screened for in vivo cellulose and acetan production, and for in vitro synthesis of a prenyl-diphosphate-hexasaccharide, using UDP-Glc, UDP-GlcA and GDP-Man as sugar donors. The lipid-bound saccharide was synthesized only by acetan-producing strains. Previous work has shown that the in vitro-synthesized lipid-linked saccharides have the same structure as the acetan repeating unit. The present results strongly suggest a precursor-product relationship. The strains that produced acetan lost their ability to do so by ageing of the culture.

The publication contains the following compound(s):
 

Expand this publication
8. (Article ID: 2975)
 
Couso RO, Ielpi L, Garcia RC, Dankert MA
Biosynthesis of polysaccharides in Acetobacter xylinum. Sequential synthesis of a heptasaccharide diphosphate prenol
European Journal of Biochemistry 123 (1982) 617-627
 

The sequential synthesis in vitro of a heptasaccharide diphosphate prenol, containing glucose, mannose, glucuronic acid and rhamnose in the ratio 4:1:1:1 is described. The enzyme preparation consisted of EDTA-treated Acetobacter xylinum cells and UDP-glucose, GDP-mannose, UDP-glucuronic acid and TDP-rhamnose were employed as sugar donors. The compounds soluble in chloroform/methanol/water (1:2:0.3) formed from incubations carried out under different conditions in the presence of a variety of combinations of the donors labeled with 14C, 3H or 32P were analysed by DEAE-cellulose column chromatography, gel filtration, partial acid hydrolysis, acetolysis, periodate oxidation, etc. The following structure is proposed for the most complex compound characterized: rhamnosyl-(1→6)-β-glucosyl-(1→6)-α-glucosyl-(1→4)-β-glucuronyl-(1→6)-β-mannosyl-(1→3)-β-glucosyl-(1→4)-α-glucosyl diphosphate prenol. The smaller oligosaccharide diphosphate prenols formed as intermediate steps are also characterized in this or in previous work [Garcia, R. C., Recondo, E. and Dankert, M. A. (1974) Eur. J. Biochem. 43, 93-105; Couso, R. O., Ielpi, L., and Dankert, M. A. (1980) Arch. Biochem. Biophys. 204, 434-443]. The role of these compounds in the biosynthesis of a complex exopolysaccharide that this microorganism forms in addition to cellulose is discussed.

The publication contains the following compound(s):
 

Expand this publication
9. (Article ID: 3005)
 
Gilkes NR, Kilburn DG, Miller RC, Warren RAJ, Sugiyama J, Chanzy H, Henrissat B
Visualization of the adsorption of a bacterial endo-a-1,4-glucanaseand its isolated cellulose-binding domain to crystalline cellulose
International Journal of Biological Macromolecules 15 (1993) 347-351
 

Endo-β-1,4-glucanase A (CenA), a cellulase from the bacterium Cellulomonas fimi, is composed of two domains: a catalytic domain and a cellulose-binding domain. Adsorption of CenA and its isolated cellulose-binding domain (CBD.PTCenA) to Valonia cellulose microcrystals was examined by transmission electron microscopy using an antibody sandwich technique (CenA/CBD.PTCenA-α CenA IgG-protein A-gold conjugate). Adsorption of both CenA and CBD.PTCenA occurred along the lengths of the microcrystals, with an apparent preference for certain crystal faces or edges. CenA or CBD.PTCenA, but not the isolated catalytic domain, were shown to prevent the flocculation of microcrystalline bacterial cellulose. The cellulose-binding domain may assist crystalline cellulose hydrolysis in vitro by promoting substrate dispersion.

The publication contains the following compound(s):
 

Expand this publication
10. (Article ID: 4966)
 
Xu L, Zhang J
Bacterial glucans: production, properties, and applications
Applied Microbiology and Biotechnology 100(21) (2016) 9023-9036
 

Bacterial glucans have aroused increasing interest in commercial applications in the food and pharmaceutical sectors. A number of bacterial glucans have been reported over recent decades, and their structure, production, and functional properties have been extensively studied. In this paper, we review recent researches on bacterial glucans, with emphasis on the production, physical and chemical properties, and the new developments in food, biomedical, pharmaceutical, and other industrial applications.

food, property, production, pharmaceutical, Bacterial glucans, Biomedical

The publication contains the following compound(s):
 

Expand this publication
11. (Article ID: 5492)
 
Schmid J, Sieber V, Rehm B
Bacterial exopolysaccharides: biosynthesis pathways and engineering strategies
Frontiers in Microbiology 6 (2015) 496
 

Bacteria produce a wide range of exopolysaccharides which are synthesized via different biosynthesis pathways. The genes responsible for synthesis are often clustered within the genome of the respective production organism. A better understanding of the fundamental processes involved in exopolysaccharide biosynthesis and the regulation of these processes is critical toward genetic, metabolic and protein-engineering approaches to produce tailor-made polymers. These designer polymers will exhibit superior material properties targeting medical and industrial applications. Exploiting the natural design space for production of a variety of biopolymer will open up a range of new applications. Here, we summarize the key aspects of microbial exopolysaccharide biosynthesis and highlight the latest engineering approaches toward the production of tailor-made variants with the potential to be used as valuable renewable and high-performance products for medical and industrial applications.

biosynthesis, gene clusters, Bacterial exopolysaccharides, polysaccharide engineering, tailor-made exopolysaccharides

The publication contains the following compound(s):
 

Expand this publication

Resort publications by:

New query Export IDs Home Help

Execution: 1 sec