Showing papers on "Arabitol published in 1990"

Intramolecular esterification by lipase powder in microaqueous benzene: Factors affecting activity of pure enzyme

Abstract: Various factors affecting the catalytic activity of pure lipase of Pseudomonas fluorescens in microaqueous benzene were investigated with respect to lactonization of 15-hydroxypentadecanoic acid. Without deposition of the enzyme or of the enzyme plus activity enhancer (additive) on celite powder, the pure enzyme was very poorly dispersed in the microaqueous benzene, resulting in very low activity. The enzyme immobilized on celite powder exhibited the highest activity at a free water content of ca. 0.083%. When a sugar alcohol such as erythritol, arabitol, or sorbitol was added before lyophilization with approximate proportion of 3 g/g enzyme, marked increases in the enzyme activity were observed at a shifted optimal free water content, i.e., 0.04%. Inclusion of phosphotidylcholine resulted in a somewhat higher activity than in the system of enzyme plus celite only. Addition of lactose, bovine serum albumin, casein, dextran, polyvinyl alcohol, phosphate, or NaCl all caused a decrease in the enzyme activity. From the effects of the additives examined, it is deduced that the following three factors are required for a pure enzyme to exhibit its full activity in a water-immiscible organic solvent: (1) optimum moisture content, (2) disperser (support particles having enough surface area on which the enzyme is thinly deposited), and (3) activity enhancer (additive) at optimum concentration The importance of noting the purity of the enzyme preparation is emphasized when its catalysis in an organic solvent is investigated.

Intermediary Metabolite Concentrations in Xylulose- and Glucose-Fermenting Saccharomyces cerevisiae Cells.

Abstract: Glucose and xylulose fermentation and product formation by Saccharomyces cerevisiae were compared in batch culture under anaerobic conditions. In both cases the main product was ethanol, with glycerol, xylitol, and arabitol produced as by-products. During glucose and xylulose fermentation, 0.74 and 0.37 g of cell mass liter−1, respectively, were formed. In glucose-fermenting cells, the carbon balance could be closed, whereas in xylulose-fermenting cells, about 25% of the consumed sugar carbon could not be accounted for. The rate of sugar consumption was 3.94 mmol g of initial biomass−1 h−1 for glucose and 0.39 mmol g of initial biomass−1 h−1 for xylulose. Concentrations of the intermediary metabolites fructose-1,6-diphosphate (FDP), pyruvate (PYR), sedoheptulose 7-phosphate (S7P), erytrose 4-phosphate, citrate (CIT), fumarate, and malate were compared for both types of cells. Levels of FDP, PYR, and CIT were lower, and levels of S7P were higher in xylulose-fermenting cells. After normalization to the carbon consumption rate, the levels of FDP were approximately the same, whereas there was a significant accumulation of S7P, PYR, CIT, and malate, especially of S7P, in xylulose-fermenting cells compared with in glucose-fermenting cells. In the presence of 15 μM iodoacetate, an inhibitor of the enzyme glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12), FDP levels increased and S7P levels decreased in xylulose-assimilating cells compared with in the absence of the inhibitor, whereas fermentation was slightly slowed down. The specific activity of transaldolase (EC 2.2.1.2), the pentose phosphate pathway enzyme reacting with S7P and glyceraldehyde-3-phosphate, was essentially the same for both glucose- and xylulose-fermenting cells. It was, however, several orders of magnitude lower than that reported for a Torula yeast and Candida utilis. The presence of iodoacetate did not influence the activity of transaldolase in xylulose-fermenting cells. The results are discussed in terms of a competition between the pentose phosphate pathway and glycolysis for the common metabolite, glyceraldehyde-3-phosphate, which would explain the low rates of xylulose assimilation and ethanol production from xylulose by S. cerevisiae.

Carbohydrate Storage in the Entomopathogenic Fungus Beauveria bassiana.

Abstract: The entomopathogenic fungus Beauveria bassiana was grown in 1% (wt/vol) gelatin-liquid media singly supplemented with a monosaccharide (glucose or fructose), a disaccharide (maltose or trehalose), a polyol (glycerol, mannitol, or sorbitol), or the amino sugar N-acetyl-d-glucosamine The relative contributions of the carbohydrate, protein, and water contents in the fungal biomass were determined Carbohydrates composed 18 to 42% of the mycelial dry weight, and this value was lowest in unsupplemented medium and highest in medium supplemented with glucose, glycerol, or trehalose Biomass production was highest in liquid cultures supplemented with trehalose When liquid cultures were grown in medium supplemented with 0 to 1% (wt/vol) glucose, trehalose, or N-acetyl-d-glucosamine, there was an increase in the biomass production and the contribution of carbohydrate to mycelial dry weight Regardless of the glucose concentration in the culture, water content of the mycelia remained about 775% (wt/wt) Mycelial storage carbohydrates were determined by capillary gas chromatography In gelatin-liquid medium supplemented with 1% (wt/vol) glucose, B bassiana stored glycogen (120%, wt/dry wt) and the polyols mannitol (22%), erythritol (16%), glycerol (04%), and arabitol (01%) Without glucose, B bassiana stored glycogen (54%), mannitol (08%), glycerol (06%), and erythritol (06%) but not arabitol To our knowledge, this is the first report of carbohydrate storage in an entomopathogenic fungus, and the results are discussed in relation to other fungi and the potential implications to commercial formulation and insect-fungus interactions

Chemical composition and characterization of a galactomannoglucan from Gliocladium viride wall material

Abstract: The following fractions were obtained from the wall material of Gliocladium viride : F1 (27.5%), a glucan, containing xylose, mannose and galactose, coluble in 1 M NaOH at 20°C; F2 (6.7%), a β-glucan-chitin complex, solubilized with 1 M NaOH at 20°C from the previous residue left overnight at −20°C; F3 (8.1%), a glucan, containing mannose and galactose solubilized with 1 M NaOH at 70°C; and F4, the insoluble residue, a β-glucan-chitin complex similar to F2, amounting to 31.3% of the wall material. F1 was extracted with distilled water. The soluble material (F1S) was a galactomannoglucan (54.7%) and the inscluble (F1P) a glucan (45.3%). Periodate oxidation revealed the presence of glycerol, erythritol, threitol, ribitol, arabitol, mannose, galactose and glucose in F1S, and glycerol and glucose as the main components in F1P. The fractions obtained when F1S was purified through Sepharose CL6B, were methylated.

Water relations of polyol accumulation by Zygosaccharomyces rouxii in continuous culture

Abstract: Glycerol and arabitol were the main polyols accumulated by Zygosaccharomyces rouxii in continuous culture but the intracellular and extracellular concentrations of the polyols varied with the dilution rate and osmoticum used to adjust the water activity (aw) to 0.960. When the aw was adjusted with NaCl, glycerol was the main polyol accumulated intracellularly whereas glycerol and arabitol were accumulated when polyethylene glycol (PEG) 400 was used. The extracellular glycerol and arabitol concentrations at 0.960 aw (NaCl or PEG 400) were similar or decreased relative to cultures at 0.998 aw. Compared to steady-state cultivation at 0.998 aw, the yeast retained at 0.960 aw (NaCl or PEG 400) a greater proportion of the total glycerol intracellularly against an increased concentration ratio without significantly greater production of glycerol. Arabitol was only significant in osmoregulation when cultivated at 0.960 aw (PEG 400). The intracellular glycerol concentration was insufficient to balance the aw across the membrane, but an equilibrium could be achieved under certain conditions if arabitol was also osmotically active.

Adaptation ofZygosaccharomyces rouxii to changes in water activity in transient continuous culture

Abstract: The polyols glycerol and arabitol were accumulated against an increasing concentration ratio in response to aW reduction. Glycerol was the main osmoregulatory solute accumulated and arabitol accumulation only occurred during the initial transitory phase. The polyols were accumulated to concentrations less than that required to maintain equilibrium across the membrane.

Food for desert

Abstract: PURPOSE:To optimize gelidium jelly to dessert food product or health food product without adverse effect on shape retention by filling vessels with a seasoning solution containing gelidium jelly and sugar alcohol. CONSTITUTION:Agar agar extract or agar agar solution is cooled down into gel and the gel and a seasoning solution containing sugar alcohol is charged in vessels to give the dessert food products. The sugar alcohol is, e.g., hydrogenated starch hydrolysate, hydrogenated maltose syrup, maltitol, maltoilitol, D- sorbitol, D-mannitol, D-xylitol, arabitol, or erythritol. The amount of the sugar alcohol added, and the solid ratio of the gel to the seasoning are more than 1w/v%, when the shape retention of the gel is taken into consideration, while higher than 3w/v% and 1:1 to 6:1, preferably 2:1, when texture and flavor are taken into consideration.

Production of arabitol by microorganism of genus rahnella

Abstract: PURPOSE:To easily produce D-arabinose in a mass at a low cost by culturing a microbial strain of genus Rahnella under aerobic condition in a medium containing D-arabinose. CONSTITUTION:A precultured Rahnella aquatilis (JCM-1683) is inoculated in a medium containing 1-20wt.% of D-arabinose, a nitrogen compound such as peptone, an inorganic salt such as Mg, etc., and cultured at 20-37 deg.C for 1-10 days under aerobic condition to produce arabitol in the medium. As necessary, the above microorganism of genus Rahnella is cultured in a medium containing monosaccharide (e.g., arabinose), organic acid (e.g., gluconic acid), nitrogen compound (e.g., peptone), etc., to obtain microbial cells. The microbial cells or treated cell such as extract of the cell are added to a solution of D-arabinose having a concentration of 1-40wt.% and reacted to produce arabitol in the reaction liquid.

Urinary Polyol Profiles in Patients with Chronic Liver Diseases and Their Correlation with Severity, as Obtained by Capillary Gas Chromatography

Abstract: A capillary gas chromatographic method for urinary polyol profiling analysis was applied to a study of urinary polyols in patients with chronic liver diseases. There was no statistically significant difference in any urinary polyols between the groups with and without glucose infusion. Ribitol, xylitol and sorbitol in patients significantly increased, and arabitol significantly decreased compared with the amounts from normal subjects. It is striking that the decrease of arabitol and the increased abnormal incidence of mannitol and sorbitol were well correlated with the severity of chronic liver diseases according to the Child-Turcott Classification. Urinary polyol profiling analysis may be useful in assessment of hepatic functional reserve.