Structural studies of acetan, an exopolysaccharide elaborated by Acetobacter xylinum

Jansson, Per‐Erik; Lindberg, J. Johan; Wimalasiri, K. M. S.; Dankert, Marcelo A.

doi:10.1016/0008-6215(93)80079-t

Cited by 65 publications

(25 citation statements)

References 11 publications

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“…The incorporation of [14C]acetyl residues into lipidlinked precursors, already detected employing EDTAtreated cells (R. 0. Couso and M. A. Dankert, unpublished observations), as well as into acetan, confirmed previous observations (Jansson et al, 1993).…”

Section: Introductionsupporting

confidence: 90%

“…Work from this laboratory has shown that, in addition, some strains of this organism are also able to produce a complex exopolysaccharide, acetan, that contains glucose (Glc), mannose (Man), glucuronic acid (GlcA) and rhamnose (Rha) in a 4: 1 : 1 : 1 molar ratio ( Couso et al, 1987;Jansson et al, 1993). The proposed structure can be considered a substituted cellulose, of the type assigned to xanthan (Jansson et al, 1975), in which pentasaccharide side chains are linked to alternate glucoses of the p-( 1 + 4)-glucose main chain (Fig.…”

Section: Introductionmentioning

confidence: 99%

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In vitro biosynthesis of acetan using electroporated Acetobacter xylinum cells as enzyme preparations

Semino

Dankert

1993

Journal of General Microbiology

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Acetobacter xylinum strain NRRL B42 and its derivative RCGrl produce a complex exopolysaccharide, acetan, containing glucose, mannose, glucuronic acid and rhamnose in a 4: 1 : 1 : 1 molar ratio. The in vitro synthesis of acetan, employing electroporated cells as the enzyme system and the respective l4C-1abelled sugar nucleotide precursors, is described. The synthesis of the prenyl-linked heptasaccharide repeat unit, already observed in EDTA-treated cells, was confirmed, as well as the formation of other saccharides not related to acetan biosynthesis, including a high molecular mass glucan. The acetan formed was characterized by gel filtration, specific radioactive labelling with each precursor and permethylation analysis. It was also shown that acetan contains acetyl residues and that using [14C]acetyl CoA as donor, radioactivity was detected both at the polysaccharide and at the prenyl-linked oligosaccharide stage.

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Section: Introductionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

In vitro biosynthesis of acetan using electroporated Acetobacter xylinum cells as enzyme preparations

Semino

Dankert

1993

Journal of General Microbiology

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“…It has been shown that G. xylinus produces a soluble EPS composed of rhamnose, glucose, mannose, and glucuronic acid (P. Duboc, M. Fischer, and S. Vincent, submitted for publication). Its composition is related to acetan, which is produced by some Acetobacter xylinus strains (16). This new EPS, named gluconacetan by Duboc et al (submitted), may be a promising candidate as a thickening agent in food formulation.…”

mentioning

confidence: 97%

Influence of Nutritional Factors on the Nature, Yield, and Composition of Exopolysaccharides Produced by Gluconacetobacter xylinus I-2281

Kornmann

Duboc

Marison

et al. 2003

Appl Environ Microbiol

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The influence of substrate composition on the yield, nature, and composition of exopolysaccharides (EPS) produced by the food-grade strain Gluconacetobacter xylinus I-2281 was investigated during controlled cultivations on mixed substrates containing acetate and either glucose, sucrose, or fructose. Enzymatic activity analysis and acid hydrolysis revealed that two EPS, gluconacetan and levan, were produced by G. xylinus. In contrast to other acetic acid strains, no exocellulose formation has been measured. Considerable differences in metabolite yields have been observed with regard to the carbohydrate source. It was shown that glucose was inadequate for EPS production since most of this substrate (0.84 C-mol/C-mol) was oxidized into gluconic acid, 2-ketogluconic acid, and 5-ketogluconic acid. In contrast, sucrose and fructose supported a 0.35 C-mol/C-mol gluconacetan yield. In addition, growing G. xylinus on sucrose produced a 0.07 C-mol/C-mol levan yield. The composition of EPS remained unchanged during the course of the fermentations. Levan sucrase activity was found to be mainly membrane associated. In addition to levan production, an analysis of levan sucrase's activity also explained the formation of glucose oxides during fermentation on sucrose through the release of glucose. The biosynthetic pathway of gluconacetan synthesis has also been explored. Although the activity of key enzymes showed large differences to be a function of the carbon source, the ratio of their activities remained similar from one carbon source to another and corresponded to the ratio of precursor needs as deduced from the gluconacetan composition.

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“…In addition, the pyruvate content of the EPS produced in vivo by 2444(pGB108.2) was 60% of that of xanthan produced by wild-type strain B-1459 (data not shown). Acetan produced by A. xylinum B42 contains no pyruvyl side groups (7,27).…”

Section: Resultsmentioning

confidence: 99%

“…In acetan, the side chain is the pentasaccharide Rha␣1-6Glc␤1-6Glc␣1-4GlcUA␤1-2Man␣1-, while in xanthan, the side chain is the trisaccharide Man␤1-4GlcUA␤1-2Man␣1-. In addition, acetyl groups are present in both EPS (7,26,27,47). Pyruvyl groups which are present in xanthan have not been found in acetan (7,27).…”

mentioning

confidence: 99%

Isolation and nucleotide sequence of the GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase gene from Acetobacter xylinum

Petroni

Ielpi

1996

J Bacteriol

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A genetic locus from Acetobacter xylinum involved in acetan polysaccharide synthesis has been characterized. The chromosomal region was identified by screening a genomic library of A. xylinum in a Xanthomonas campestris mutant defective in xanthan polysaccharide synthesis. The A. xylinum cosmid clone can functionally complement a xanthan-negative mutant. The polymer produced by the recombinant strain was found to be indistinguishable from xanthan. Insertion mutagenesis and subcloning of the cosmid clone combined with complementation studies allowed the identification of a 2.3-kb fragment of A. xylinum chromosomal DNA. The nucleotide sequence of this fragment was analyzed and found to contain an open reading frame (aceA) of 1,182 bp encoding a protein of 43.2 kDa. Results from biochemical and genetic analyses strongly suggest that the aceA gene encodes the GDP-mannose:cellobiosyl-diphosphopolyprenol ␣-mannosyltransferase enzyme, which is responsible for the transfer of an ␣-mannosyl residue from GDP-Man to cellobiosyl-diphosphopolyprenol. A search for similarities with other known mannosyltransferases revealed that all bacterial ␣-mannosyltransferases have a short COOH-terminal amino acid sequence in common.

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Structural studies of acetan, an exopolysaccharide elaborated by Acetobacter xylinum

Cited by 65 publications

References 11 publications

In vitro biosynthesis of acetan using electroporated Acetobacter xylinum cells as enzyme preparations

In vitro biosynthesis of acetan using electroporated Acetobacter xylinum cells as enzyme preparations

Influence of Nutritional Factors on the Nature, Yield, and Composition of Exopolysaccharides Produced by Gluconacetobacter xylinus I-2281

Isolation and nucleotide sequence of the GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase gene from Acetobacter xylinum

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