The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Victor J Morris - One of the best experts on this subject based on the ideXlab platform.
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identification cloning and sequencing the acea gene involved in acetan biosynthesis in Acetobacter Xylinum
Fems Microbiology Letters, 1996Co-Authors: Annette Griffin, Victor J Morris, M. J. GassonAbstract:The aceA gene from Acetobacter Xylinum was identified and cloned from a genomic DNA library. The complete DNA sequence was determined and computer analysis of the translated gene sequence revealed homology with the deduced amino acid sequence of gumD from Xanthomonas campestris. Therefore aceA is likely to encode the phosphate-prenyl glucose I -phosphate transferase catalyzing the first step in acetan biosynthesis in A. Xylinum.
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Genetic analysis of the acetan biosynthetic pathway in Acetobacter Xylinum
International Journal of Biological Macromolecules, 1994Co-Authors: Annette M. Griffin, Victor J Morris, M. J. GassonAbstract:We have identified, cloned and sequenced an 8422 base pair fragment of Acetobacter Xylinum genomic DNA containing part of the acetan biosynthetic gene cluster. Computer analysis of the nucleotide sequence data generated revealed the presence of six open reading frames. Comparison of the translated sequences of putative genes to the amino acid sequences of genes from other organisms was used to assign functions to the aceA, aceC and manB genes. These genes were predicted to encode a UDP-glycosyl transferase, a GDP-mannosyl transferase and a phosphomannose isomerase/GDP-mannose pyrophosphorylase, respectively.
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characterization of a variant of the polysaccharide acetan produced by a mutant of Acetobacter Xylinum strain cr1 4
Journal of Applied Microbiology, 1993Co-Authors: C A Maccormick, J E Harris, A P Gunning, Victor J MorrisAbstract:: Acetobacter Xylinum NRRL B42 (NCIB 40123) produces both cellulose and a complex anionic branched heteropolysaccharide called acetan. Chemical mutagenesis was used to isolate stable cellulose-minus Acetobacter Xylinum mutants. Further chemical mutagenesis of these cellulose-minus A. Xylinum bacteria was used to select mutants which secrete polysaccharides which are variants of the acetan structure. Preparation, purification and characterization of these polysaccharides are described. Methylation analysis of the polysaccharide structure CR1/4 suggests that the polysaccharide has an acetan structure with a truncated sidechain terminating in glucuronic acid.
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Characterization of a variant of the polysaccharide acetan produced by a mutant of Acetobacter Xylinum strain CR1/4
Journal of Applied Microbiology, 1993Co-Authors: C A Maccormick, J E Harris, A P Gunning, Victor J MorrisAbstract:: Acetobacter Xylinum NRRL B42 (NCIB 40123) produces both cellulose and a complex anionic branched heteropolysaccharide called acetan. Chemical mutagenesis was used to isolate stable cellulose-minus Acetobacter Xylinum mutants. Further chemical mutagenesis of these cellulose-minus A. Xylinum bacteria was used to select mutants which secrete polysaccharides which are variants of the acetan structure. Preparation, purification and characterization of these polysaccharides are described. Methylation analysis of the polysaccharide structure CR1/4 suggests that the polysaccharide has an acetan structure with a truncated sidechain terminating in glucuronic acid.
Moshe Benziman - One of the best experts on this subject based on the ideXlab platform.
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Complementation of cellulose-negative mutants of Acetobacter Xylinum by the cloned structural gene for phosphoglucomutase
Fems Microbiology Letters, 2006Co-Authors: Espen Fjærvik, Svein Valla, Kirsten Frydenlund, Yasser Huggirat, Moshe BenzimanAbstract:Eleven cellulose-negative mutants of Acetobacter Xylinum were analysed with respect to the activities of the enzymes known to be involved in cellulose biosynthesis. The analysis showed that all the mutants were deficient in phosphoglucomutase. All 11 mutants were complemented with a recombinant cosmid from a gene bank of wild type A. Xylinum DNA. A subcloned 3.8-kb DNA fragment from the cosmid insert expressed high levels of phosphoglucumutase in Escherichia coli. Electrophoretic analysis showed that the introduced A. Xylinum activity could be separated from the endogenous phosphoglucomutase present in E. coli. The experiments thus demonstrated that the cloned DNA fragment contained the A. Xylinum structural gene for phosphoglucomutase.
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c di gmp binding protein a new factor regulating cellulose synthesis in Acetobacter Xylinum
FEBS Letters, 1997Co-Authors: Haim Weinhouse, Shai Sapir, D Amikam, Yehudit Shilo, Gail Volman, Patricia Ohana, Moshe BenzimanAbstract:A protein which specifically binds cyclic diguanylic acid (c-di-GMP), the reversible allosteric activator of the membrane-bound cellulose synthase system of Acetobacter Xylinum, has been identified in membrane preparations of this organism. c-di-GMP binding is of high affinity (KD 20 nM), saturable and reversible. The equilibrium of the reaction is markedly and specifically shifted towards the binding direction by K+. The c-di-GMP binding protein, structurally associated with the cellulose synthase, appears to play a major role in modulating the intracellular concentration of free c-di-GMP and thus may constitute an essential factor in regulating cellulose synthesis in vivo.
V V Klechkovskaya - One of the best experts on this subject based on the ideXlab platform.
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TEM investigation ofSe nanostructures in/on Acetobacter Xylinum cellulose gel-film
EMC 2008 14th European Microscopy Congress 1–5 September 2008 Aachen Germany, 2020Co-Authors: Natalya A. Arkharova, V V Klechkovskaya, Elena I SuvorovaAbstract:Acetobacter Xylinum cellulose (A X-BC) and its composites with some mineral and organic additives are the perspective materials for healing the heavy and complicated wounds. The Se/Ag/A X-BC composite is expected to have some antiphlogistic and immunostimulating properties [1].
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network model of Acetobacter Xylinum cellulose intercalated by drug nanoparticles
namb, 2008Co-Authors: V V Klechkovskaya, Yu G Baklagina, A K Khripunov, V V Volkov, E V Shtykova, Natalia A Arkharova, Ruslan Yu Smyslov, L N Borovikova, A A TkachenkoAbstract:It was shown that Acetobacter Xylinum cellulose gel-films can sorb silver and selenium nanoparticles stabilized by N-poly(vinyl-2-pirrolidone). The structure of original cellulose matrix, isolated nanoparticles and cellulose with sorbed nanoparticles was characterized by electron diffraction, electron microscopy, small- and wide-angle x-ray scattering methods, and atomic force microscopy. It was found that in static culture Acetobacter Xylinum bacterium (strain VKM B-880) may synthesize high-molecular cellulose with narrow molecular weight distribution and a considerable number of carbon sources. The structures of cellulose microfibrilles and ribbons correspond mainly to polymorphous Iβ modification. We concluded from structural studies that textured cellulose films were formed. The sorption conditions of poly(vinylpyrrolidone)-Se° and poly(vinylpyrrolidone)-Ag° nanoparticles were optimized to obtain a cellulose template that can be used in medical practice.
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formation of a composite from se0 nanoparticles stabilized with polyvinylpyrrolidone and Acetobacter Xylinum cellulose gel films
Russian Journal of Applied Chemistry, 2007Co-Authors: A K Khripunov, V V Klechkovskaya, Yu G Baklagina, A A Tkachenko, L N Borovikova, V K Nilova, Yu R Smyslov, N A Matveeva, Ya A Volkov, V K LavrentevAbstract:Formation of a composite from Se0 nanoparticles stabilized with polyvinylpyrrolidone and Acetobacter Xylinum cellulose gel films was studied. The optimal sorption parameters at which the amorphous form of the selenium complex is preserved in the composite were suggested.
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structure of cellulose Acetobacter Xylinum
Crystallography Reports, 2003Co-Authors: V V Klechkovskaya, Yu G Baklagina, N D Stepina, A K Khripunov, P A Buffat, Elena I Suvorova, I S Zanaveskina, A A Tkachenko, S V GladchenkoAbstract:The data are presented on optimization of cellulose synthesis by Acetobacter Xylinum (strain VKM V-880) and the structural characteristics of A. Xylinum cellulose gel film synthesized during static cultivation. The structural changes caused by the removal of water from gel films are established and the structural organization of macromolecular chains in cellulose A. Xylinum is studied.
Makoto Shoda - One of the best experts on this subject based on the ideXlab platform.
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effects of acetan on production of bacterial cellulose by Acetobacter Xylinum
Bioscience Biotechnology and Biochemistry, 2002Co-Authors: Takehiko Ishida, Yasushi Sugano, Tomonori Nakai, Makoto ShodaAbstract:Acetan is a water-soluble polysaccharide produced by a bacterial cellulose (BC) producer, Acetobacter Xylinum. An acetan-nonproducing mutant, EP1, was generated from wild-type A. Xylinum BPR2001 by the disruption of aceA, which may act to catalyze the first step of the acetan biosynthetic pathway in this bacterium. EP1 produced less BC than the wild-type strain. However, when EP1 was cultured in a medium containing acetan, BC production was stimulated and the final yield of BC was equivalent to that of BPR2001. The culture broth containing acetan was more viscous and the free cell number was higher than that of the broth without the polysaccharide, so acetan may hinder the coagulation of BC in the broth. The addition of 1.5 g/l agar also increased BC production; we concluded that acetan and BC syntheses were not directly related on the genetic level.
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novel glycosyltransferase genes involved in the acetan biosynthesis of Acetobacter Xylinum
Biochemical and Biophysical Research Communications, 2002Co-Authors: Takehiko Ishida, Yasushi Sugano, Makoto ShodaAbstract:Abstract Novel aceQ and aceR genes involved in the acetan biosynthesis of Acetobacter Xylinum were newly isolated. The homology search with DNA Data Bank of Japan indicated that aceQ and aceR were glycosyltransferases. Their gene-disrupted mutants were obtained by homologous recombination using the tetracycline resistance gene and the electroporation method. By NMR and ESI-MS analyses, aceQ-disrupted mutant DQ was found to secrete a water-soluble polysaccharide harboring the -Man-GlcUA side chain and the aceR-disrupted mutant DR was found to secrete an acetan analog, lacking the terminal Rha residue. These results suggested that aceQ and aceR encode a glucosyltransferase and a rhamnosyltransferase, respectively. It was indicated that acetan analogs harboring various side chains can be generated easily by genetic engineering.
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production of bacterial cellulose by Acetobacter Xylinum with an air lift reactor
Biotechnology Techniques, 1997Co-Authors: Yaping Chao, Yasushi Sugano, T Kouda, Fumihiro Yoshinaga, Makoto ShodaAbstract:Bacterial cellulose was produced by Acetobacter Xylinum subsp. surcrofermentans BPR2001 in a 50 liter air-lift reactor using fructose as the main carbon source. When air was supplied, the production of the cellulose was only 2.3 g/l in 80 h but when O -fortified air was supplied, the cellulose concentration increased to 5.63 g/l in 28 h and the productivity of the cellulose in an air-lift reactor with O -fortified air supply was comparable to that in a mechanically agitated jar fermenter.
Minoru Ameyama - One of the best experts on this subject based on the ideXlab platform.
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production of cellulose from d mannitol by Acetobacter Xylinum ku 1
Bioscience Biotechnology and Biochemistry, 1995Co-Authors: Tadao Oikawa, Toshiyuki Ohtori, Minoru AmeyamaAbstract:We found that Acetobacter Xylinum KU-1 produced cellulose from D-arabitol. The maximum cellulose production was obtained when it was grown in a medium containing 2.0% D-arabitol, 1.0% tryptone, and 1.0% yeast extract (pH 5) at 30°C for 96h statically. The productivity was more than 6 times as much as that of D-glucose [productivity (mg/ml-medium): from D-arabitol, 12.4; from D-glucose, 2.0].
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Detection of Carboxymethyl Cellulase Activity in Acetobacter Xylinum KU-1
Bioscience Biotechnology and Biochemistry, 1994Co-Authors: Tadao Oikawa, Miho Takagi, Minoru AmeyamaAbstract:We detected carboxymethyl cellulase activity in a crude extract of Acetobacter Xylinum KU-1. The enzyme activity was detected when glycerol, d-fructose, d-mannitol, d-glucose, d-arabitol, d-sorbitol, or carboxymethyl cellulose was used as a carbon source. The optimum pH was found to be 4.0, while the optimum temperature was 50°C. The enzyme activity was inhibited characteristically by the addition of Hg2+.
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Detection of Dye-linked D-Mannitol Dehydrogenase Activity in Acetobacter Xylinum KU-1
Bioscience Biotechnology and Biochemistry, 1993Co-Authors: Tadao Oikawa, Minoru AmeyamaAbstract:We detected dye-linked D-mannitol dehydrogenase activity in the crude extract of Acetobacter Xylinum KU-1. The enzyme activity was specific for D-mannitol, and not pyridine nucleotide (NAD+, NADP+)-dependent. The optimal pH was found to be 5.0, while the optimal temperature was at 50°C. The enzyme activity was inhibited by p-quinone noncompetitively.
