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Showing papers on "Arabitol published in 2001"


Journal ArticleDOI
TL;DR: The survival as well as the subsequent growth of yeast cells was largely unaffected after hypo-osmotic shock and the kinetics and patterns of osmolyte export suggest the involvement of channel proteins, but the molecular nature of this export pathway in yeasts, with exception of S. cerevisiae, remains to be established.
Abstract: In response to fluctuations in environmental osmolarity, yeast cells adjust their intracellular solute concentrations in order to maintain a constant turgor pressure and ensure continuation of cellular activity. In this study, the effect of hypo-osmotic stress on osmolyte content of osmotolerant yeasts Zygosaccharomyces rouxii and Pichia sorbitophila and the less tolerant Saccharomyes cerevisiae was investigated. All these yeasts released glycerol upon hypo-osmotic shock. However, Z. rouxii also released arabitol, whereas P. sorbitophila released erythritol in addition to arabitol and glycerol. Osmolyte release was very rapid and specific and was neither affected by reduced temperatures nor inhibited by the channel blocker gadolinium or the protonophore carbonyl cyanide m-chlorophenyl hydrazone. Extracellular osmolyte levels increased drastically suggesting that osmolytes were not metabolised but mainly released upon exposure to hypotonic conditions. The export process is well controlled, and the amount of osmolyte released was proportional to the shock intensity. Osmolyte release occurred with little cell lysis and thus the survival as well as the subsequent growth of yeast cells was largely unaffected after hypo-osmotic shock. The kinetics and patterns of osmolyte export suggest the involvement of channel proteins, but the molecular nature of this export pathway in yeasts, with exception of S. cerevisiae, remains to be established.

65 citations


Journal ArticleDOI
TL;DR: Overproduction of XKIA did not reduce the size of the intracellular arabitol and xylitol pools, and therefore had no effect on expression of genes encoding xylan and arabinan degrading enzymes nor on the activity of the enzymes of the catabolic pathway, which supports the suggestion that l-arabitol may be the specific low molecular mass inducer of the genes involved inArabinan degradation.
Abstract: The Aspergillus nigerd-xylulose kinase encoding gene has been cloned by complementation of a strain deficient in d-xylulose kinase activity. Expression of xkiA was observed in the presence of l-arabinose, l-arabitol and d-xylose. Expression of xkiA is not mediated by XLNR, the xylose-dependent positively-acting xylanolytic regulator. Although the expression of xkiA is subject to carbon catabolite repression, the wide domain regulator CREA is not directly involved. The A. nigerd-xylulose kinase was purified to homogeneity, and the molecular mass determined using electrospray ionization mass spectrometry agreed with the calculated molecular mass of 62816.6 Da. The activity of XKIA is highly specific for d-xylulose. Kinetic parameters were determined as Km(d-xylulose) = 0.76 mm and Km(ATP) = 0.061 mm. Increased transcript levels of the genes encoding arabinan and xylan degrading enzymes, observed in the xylulose kinase deficient strain, correlate with increased accumulation of l-arabitol and xylitol, respectively. This result supports the suggestion that l-arabitol may be the specific low molecular mass inducer of the genes involved in arabinan degradation. It also suggests a possible role for xylitol in the induction of xylanolytic genes. Conversely, overproduction of XKIA did not reduce the size of the intracellular arabitol and xylitol pools, and therefore had no effect on expression of genes encoding xylan and arabinan degrading enzymes nor on the activity of the enzymes of the catabolic pathway.

60 citations


Journal ArticleDOI
TL;DR: Both xylitol yield and volumetric productivity remarkably increased with the number of adaptations, demonstrating that the more adapted the cells, the better the capacity of the yeast to reduce xylose toxylitol in hemicellulose hydrolysates.
Abstract: Batch xylitol production from concentrated sugarcane bagasse hydrolysate by Candida guilliermondii was performed by progressively adapting the cells to the medium. Samples were analyzed to monitor sugar and acetic acid consumption, xylitol, arabitol, ethanol, and carbon dioxide production, as well as cell growth. Both xylitol yield and volumetric productivity remarkably increased with the number of adaptations, demonstrating that the more adapted the cells, the better the capacity of the yeast to reduce xylose to xylitol in hemicellulose hydrolysates. Substrate and product concentrations were used in carbon material balances to study in which way the different carbon sources were utilized by this yeast under microaerobic conditions, as well as to shed light on the effect of the progressive adaptation to the medium on its fermentative activity. Such a theoretical means allowed estimation for the first time of the relative contribution of each medium component to the formation of the main products of this fermentation system.

45 citations


Journal ArticleDOI
TL;DR: In this paper, Pichia methanolica and Gluconobacter oxydans were immobilized on chromatographic paper and fixed on an Clark type oxygen electrode.

39 citations


Journal ArticleDOI
TL;DR: Glycerol and arabitol were the main solutes accumulated by C. sake cells in response to lowered a(w), and intracellular concentration of these polyols depended more on the solute used to adjust the a-w than on the a(W) itself.
Abstract: The biocontrol agent Candida sake was cultured on either an unmodified molasses-based medium (water activity, aw 0.996) or on water stressed media produced by the addition of glycerol, glucose, NaCl, sorbitol, or proline to 0.98, and 0.96 aw for 24, 48, and 72 h, to study their impact on subsequent cell viability, and on concentrations of endogenous sugars (trehalose and glucose) and polyols (glycerol, erythritol, arabitol, and mannitol). The viability of cells of different ages cultured on these media was evaluated on NYDA medium with freely available water (aw 0.995), and on medium modified with polyethylene glycol to aw 0.95. Regardless of solute used, viable counts of cells grown on molasses-based medium (aw 0.98) were equal to or higher than those obtained from the medium with water freely available. The amino acid proline stimulated growth at 10% concentration. In contrast, water stress induced by addition of NaCl, glucose, or sorbitol at aw 0.96 caused a significant reduction in viable counts. Olde...

34 citations


Journal ArticleDOI
TL;DR: Overall, partially esterified pectins are specifically cleaved to generate a series of oligogalacturonic acids bearing an arabitol residue as aglycone, which discloses the pattern of contiguous nonesterification in a variety of pectin of differing degrees of esterification.

20 citations


Patent
07 Mar 2001
TL;DR: In this article, a process for culturing yeast cells and preparing D-arabitol by transforming D-glycose with said yeast cells is discolsed, which has high transformation efficiency up to 55-60%.
Abstract: A process for culturing yeast cells and preparing D-arabitol by transforming D-glycose with said yeast cells is discolsed. Its advantages are high transformation efficiency up to 55-60%, simple equipment and operation, and convenient extraction.

9 citations


Journal ArticleDOI
TL;DR: Aqueous solutions of arabinonic acid in equilibrium with the corresponding lactone and δ-lactone were hydrogenated to arabitol in a batch reactor in the presence of an active carbon-supported ruthenium catalyst as discussed by the authors.

8 citations


Patent
03 Jul 2001
TL;DR: In this paper, an alcohol-containing glucidic seasoning is characterized by comprising one or more kinds of polyhydric alcohols selected from glycerol, erythritol, arabitol, xylitol and mannitol in an amount of 3-20 wt/vol.
Abstract: PROBLEM TO BE SOLVED: To obtain art alcohol-containing glucidic seasoning such as a Mirin (sweet sake), a fermented seasoning or a Mirin-like seasoning excellent in functions on a cooking process such as a prevention of breaking into pieces in the cooking process of foods. SOLUTION: This alcohol-containing glucidic seasoning is characterized by comprising one or more kinds of polyhydric alcohols selected from glycerol, erythritol, arabitol, xylitol and mannitol in an amount of 3-20 wt./vol.% expressed in terms of total concentration.

4 citations


Patent
08 Mar 2001
TL;DR: In this article, the authors proposed a positive selection method for selecting transgenic cells that involves conferring to cells the ability to metabolize certain compounds, preferably arabitol, ribitol, raffinose, sucrose, mannitol or combinations thereof.
Abstract: Disclosed herein are novel methods and materials for selecting transgenic cells. Specifically exemplified herein are positive selection methods that involve conferring to cells the ability to metabolize certain compounds, preferably arabitol, ribitol, raffinose, sucrose, mannitol or combinations thereof. Accordingly, transformed cells can be selected by simply subjecting them to a medium containing such compounds. The subject invention alleviates the disadvantages and concerns of negative selection methods, such as the unnecessary killing of transformed cells and the dispersal of potentially harmful genes (e.g., antibiotic or herbicide resistant genes) into the environment. Furthermore, novel nucleotide sequences relating to the E. coli rtl operon and arabitol dehydrogenase gene, and amino acid sequences relating to the gene products thereof are disclosed.

3 citations


Journal Article
TL;DR: The partial genomic library of Acetobacter suboxydans was constructed using Yeast-E.
Abstract: The partial genomic library of Acetobacter suboxydans was constructed using Yeast-E. coli shuttle plasmid YEp352 as vector. Two positive transformants, designated as DH5 alpha(pAD91) and DH5 alpha(pAD98), were obtained by screening the growth of transformants on the agar plate in which D-arabitol was used as the sole carbon source. The results of Southern blot and restriction endonuclease analysis showed that the two recombinants are identical. The insert is about 2.3 kb. Arabitol dehydrogenase activity assay indicated that the transformants could produce D-xylulose-forming D-arabitol dehydrogenase. Hence, the gene encoding D-arabitol dehydrogenase exists in the cloned DNA fragment.

Patent
31 Jul 2001
TL;DR: In this paper, a method of producing arabitol by continuous fermentation of at least one sugar by micro-organisms is described, where the fermentation medium obtained from the second fermentation area is separated into a fraction concentrated in microorganisms and another, soluble fraction enriched in arabbitol.
Abstract: A method of producing arabitol by continuous fermentation of at least one sugar by micro-organisms producing arabitol, characterised in that arabitol is produced in a first fermentation area including at least one fermenter in such a manner that some of the sugar introduced into the fermentation medium is consumed by said micro-organisms, some of the fermentation medium obtained in this way is transferred into a second fermentation area including at least one fermenter, the volume being maintained constant in the first fermentation area by adding sugar, production of arabitol continues in said second fermentation area in such a manner as to consume the residual sugar of the fermentation medium, the fermentation medium thus obtained from said second fermentation area is separated a continuously into a fraction concentrated in micro-organisms and another, soluble fraction enriched in arabitol, and the arabitol thus obtained is collected.


Journal Article
TL;DR: It was found that the various yeasts of non glycerol producing type could produce a considerable amount of glycerols in the medium containing 9% of NaCl, which suggested that the metabolic pathways of yeasts might be markedly altered by the high concentration of salts.
Abstract: Candida OS-300 was an excellent polylol producer .Glycerol could be produced alone in the medium containing 18% of NaCl, although the yeast could produce three kinds of polylol:glycerol, arabitol and erythritol in the medium containing 30% of glucose. It was also found that the various yeasts of non glycerol producing type could produce a considerable amount of glycerol in the medium containing 9% of NaCl. This phenomenon suggested that the metabolic pathways of yeasts might be markedly altered by the high concentration of salts.

Patent
15 Jun 2001
TL;DR: In this article, a method for efficiently producing D-arabitol and xylitol using a microorganism was proposed, which is based on the genus Metschnikowia.
Abstract: PURPOSE: To provide a method for efficiently producing D-arabitol, and a method for producing D-xylulose and xylitol using the method. CONSTITUTION: The method for producing xylitol comprises the steps of: producing D-arabitol in a medium by culturing a microorganism which belongs to the genus Metschnikowia, and can produce D-arabitol (e.g. M pulcherrima, M reukaufii, M bicuspidata, M. lutana, and M. zobellii) aerobically in a medium containing saccharide(s) as the main carbon source(s) to form D-arabitol in the medium, inoculating/culturing a microorganism which has an ability of producing D-xylulose from D-arabitol to form D-xylulose in the broth, and inoculating/culturing a microorganism which has an ability of transforming D-xylulose to xylitol to the broth containing D-xylulose to collect xylitol formed.

Patent
25 Apr 2001
TL;DR: In this paper, a method for enhancing enzymatic activity at high temperatures comprises including, in a reaction liquid containing a relevant enzyme, substance(s) having chaperonic action, e.g. saccharide(s), such as trehalose, sorbitol and arabitol, amino acid(s such as betaine and/or sarcosine, chapenonin-like protein.
Abstract: PROBLEM TO BE SOLVED: To provide a method for more easily and effectively improving the heat resistance of an enzyme and thereby manifesting high enzymatic activity at high temperatures. SOLUTION: This method for enhancing enzymatic activity at high temperatures comprises including, in a reaction liquid containing a relevant enzyme, substance(s) having chaperonic action, e.g. saccharide(s) such as trehalose, sorbitol and/or arabitol, amino acid(s) such as betaine and/or sarcosine, chapenonin-like protein.

Journal ArticleDOI
TL;DR: The 23Na NMR quadrupolar relaxation in NaDNA aqueous solutions has been investigated in the presence of D(+) and L(-) arabitol and quite different results were produced by the enantiomers.

Patent
13 Mar 2001
TL;DR: In this paper, the physicochemical properties of a sorbitol dehydrogenase were investigated, and it was shown that it has excellent substrate affinity and substrate specificity, and that it is possible to obtain microorganisms capable of producing the enzyme.
Abstract: PROBLEM TO BE SOLVED: To obtain a sorbitol dehydrogenase excellent in substrate affinity and substrate specificity, to obtain microorganisms capable of producing the enzyme, and to provide a method for producing the enzyme. SOLUTION: This sorbitol dehydrogenase has the physicochemical properties as follows: (1) action: dehydrogenically oxidizing D-sorbitol in the presence of NAD+ to form D-fructose; by the reaction reverse to the above, reducing D-fructose in the presence of NADH to form D-sorbitol and NAD+; (2) substrate specificity: when the Vmax/Km for D-sorbitol is assumed to be 100, the Vmax/Km for galactitol is about <=37, being about <=3 for L-iditol, and inert to D- arabitol, D-mannitol, xylitol and D-glucose; and (3) the Km for sorbitol is <=5.9 mM.