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Malic Acid (malic + acid)
Selected AbstractsDegradation of malic acid in wine by immobilized Issatchenkia orientalis cells with oriental oak charcoal and alginateLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2010S.K. Hong Abstract Aims:, To test degradation of malic acid content in wine by immobilized Issatchenkia orientalis KMBL 5774 cells recently isolated from Korean wine pomace as a malic acid-degrading yeast. Methods and Results:,I. orientalis KMBL 5774 cells were immobilized using a mixture of oriental oak (Quercus variabilis) charcoal with sodium alginate. When the immobilized yeast cells were observed on a scanning electron microscope, cells were efficiently immobilized on the surface area of the charcoal. A Korean wine containing a high level of malic acid was treated with the immobilized yeast cells. The HPLC analysis of the malic acid content in the treated wine showed the malic acid content was reduced to 0·75 mg ml,1 after treatment from the original content of 8·96 mg ml,1, representing 91·6% of the malic acid was degraded during the treatment. Conclusions:, The immobilization of the malic acid-degrading yeasts with oriental oak charcoal and sodium alginate is useful for degradation of malic acid in wines containing a high level of malic acid with no significant increase in other acids. Significance and Impact of the study:, Malic acid is sometimes detrimental to the quality of wines when present at high concentrations in some varieties. The immobilized I. orientalis KMBL5774 cells appear to be a promising candidate in view of developing biotechnological methods for reduction of malic acid contents in wine. [source] Assimilate transport in grapevines -effect of phloem disruptionAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 3 2001J.J.(KOBUS) HUNTER Abstract Assimilate translocation in mature grapevines (cv. Gewürztraminer and cv. Harslevelü) under field conditions was investigated during the growth season by quantifying individual sugars and organic acids in mature leaves, shoot bark and berries, as affected by girdling the shoot just above the bunches. Tissue was sampled at berry set, pea size, veraison and ripeness stages of the vine. Invertase activity was determined in the shoot bark at ripeness. In the leaves, malic acid concentrations reached lowest levels at pea size, but increased thereafter. Tartaric acid decreased after peaking at pea size stage. Tartaric acid concentrations increased with girdling. Despite the increase in leaf age, sucrose concentrations remained virtually stable during the season, emphasising the importance of mature leaves for nourishing bunches. Girdling resulted in a build-up of sucrose in the leaves. In the bark, malic and tartaric acid stayed more or less the same during the growth period, but increased above the girdle. As a result of phloem disruption, sucrose also increased. The increase in glucose and tartaric acid is believed to result from catabolic cleavage of sucrose by invertase. Invertase activity was evident in the bark (of mature Harslevelü vines) at ripeness, which may indicate involvement in osmotic adjustments and gradients in the bark/phloem structure. In the berries, malic and tartaric acids reached peak concentrations at pea size. The volume increase during the ripening period, and in the case of malic acid also respiratory loss, resulted in a decrease in organic acid concentration. Malic acid continued to decrease after the initial decline, whereas tartaric acid stayed virtually stable. Girdling had no marked effect on organic acid accumulation in the berries. Sucrose concentrations were low during the first part of the season, but increased thereafter. Sucrose concentrations during ripening increased with girdling, which may represent a concentration effect and/or import from the rest of the vine. Sucrose concentrations (in mature Harslevelü vines) were indeed lower below than above the girdle. Comparison of sucrose concentrations in the leaves, bark and berries showed the existence of a decreasing concentration gradient, in line with the source:sink transport concept. An equally prominent decrease in sucrose:glucose ratio in the berries from the start of the ripening period indicates that vacuolar integrity (compartmentation) was affected in the ripening berry, most probably allowing hydrolysis of sucrose by invertase and decreasing osmotic potential within the berry. The results provide further evidence for the hypothesis of an osmotic gradient driven transport to the berry. [source] Apoptolidinone A: Synthesis of the Apoptolidin A AglyconeCHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2006Julia Schuppan Dr. Abstract An efficient stereocontrolled synthesis of apoptolidinone A, the aglycone of apoptolidin A is described. The synthetic strategy relies on a cross coupling between C11/C12 of a northern half (C1,C11) and a southern part (C12,C28) followed by a ring-size selective macrolactonization. Key steps for the introduction of the southern half stereocenters are a stereoselective aldol reaction, a substrate controlled dihydroxylation and a chelation-controlled Grignard/aldehyde addition. The conjugated triene of the northern half was built up successively by E -selective Wittig reactions. L -Malic acid was chosen as the chiral pool source for the C8/C9 stereocenters. The final cleavage of the silyl ethers and the conversion of the C21 methyl ketal into the hemiketal was achieved by HF,pyridine. [source] Nucleophilic Additions to Cyclic Nitrones en Route to Iminocyclitols , Total Syntheses of DMDP, 6-deoxy-DMDP, DAB-1, CYB-3, Nectrisine, and Radicamine BEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2008Pedro Merino Abstract Highly diastereoselective nucleophilic additions to cyclic nitrones derived from L -malic acid and D -arabinose have been used for the construction of enantiomerically pure polyhydroxylated pyrrolidines. The synthetic strategy adopted was based on an oxidation/reduction protocol involving hydroxylamine/nitrone pairs and demonstrates the use of reagent- and substrate-derived stereocontrol. In most cases reactions took place with total diastereoselectivity and in quantitative yield, with no purification being necessary. By this strategy, 2-(hydroxymethyl)-, 2-(aminomethyl)-, and 2-aryl-substituted polyhydroxylated pyrrolidines have been prepared with abundant configurational diversity. The use of appropriate substrates and reagents allowed for approaches to DMDP, 6-deoxy-DMDP, DAB-1, CYB-3, nectrisine and radicamine B. Several analogues of these compounds with inverted configuration at one or more stereocenters were also prepared.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Molecular analysis of Oenococcus oeni population dynamics and the effect of aeration and temperature during alcoholic fermentation on malolactic fermentationINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2005Cristina Reguant Summary The effects of aeration and temperature during alcoholic fermentation (AF) on spontaneous and inoculated malolactic fermentation (MLF) of wine have been analysed by following the population dynamics of Oenococcus oeni strains with multiplex random amplified polymorphic DNA-polymerase chain reaction. It has enabled us to follow precisely the proportion of different autochthonous strains and the starter strain through fermentations. Lack of aeration led to delays in AF, which meant that autochthonous lactic acid bacteria could develop earlier and prevented the starter strain from developing correctly. Temperature was not found to lead to any differences. Two strains were isolated in the same spontaneous MLF, suggesting that, in some cases, multiple strains might be responsible for the degradation of malic acid in wine. It can be concluded that delays in the AF can negatively affect the control of MLF and that this can be studied by following the development of the different strains of O. oeni. [source] Coimmobilization of malic enzyme and alanine dehydrogenase on organic,inorganic hybrid gel fibers and the production of L -alanine from malic acid using the fibers with coenzyme regenerationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Koji Nakane Abstract Malic enzyme (EC 1.1.1.39) and alanine dehydrogenase (EC 1.4.1.1) were entrap-immobilized on hybrid gel fibers of cellulose acetate (CA) and zirconium (Zr) alkoxide by air-gap wet spinning. The production of L -alanine from malic acid with coenzyme regeneration was examined with the enzymes immobilized on the fibers. The productivity of L -alanine of the immobilized enzymes decreased to approximately one-fifth of that of free enzymes, but the CA,Zr-fiber-immobilized enzymes retained a high level of productivity after repeated use. Reduced form of nicotinamide adenine dinucleotide (NADH) recycling also occurred effectively for the enzymes immobilized on the fiber. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Unexpected fluorescence emission of poly(,,,- L -malic acid) in aqueous mediumJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Yaofeng Fan Abstract Unexpected fluorescence of poly(,,,- L -malic acid) (,,,-PMA) without traditional fluorophore was observed firstly. This fluorescent polymer was synthesized via melt polycondensation of L -malic acid. The polymer was characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermogravimetry (TG), Fourier transform infrared spectroscopy (IR), Fourier transform Raman spectroscopy (Raman), and X-ray powder diffractometry (XRD). The high molecular weight ,,,-PMA was synthesized by the optimum polycondensation at 130°C for 15 h, followed by fractional precipitation with diethyl ether and petroleum ether. The degree of branching of ,,,-PMA was from 10% to 20% according to the reaction condition. Terminal group of ,,,-PMA was mainly hydroxycarboxylic group companied with a few CHCHCOOH groups owing to dehydration of a normal terminal during the melt polycondensation. A fluorescence emission maximum of ,,,-PMA in water appeared at 420 nm when it was excited at 340 nm. Further study indicated that the fluorescence intensity was concentration-dependent, pH-dependent, and molecular-weight-dependent. The fluorescence formation may result from multichain aggregations, which was formed readily in aqueous solution due to intermolecular hydrogen bonds between branched ,,,-PMA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Organic acids: old metabolites, new themesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2006Israel Goldberg Abstract Fumaric, L -malic and citric acids are intermediates of the oxidative tricarboxylic acid (TCA) cycle which in eukaryotes is localized in mitochondria. These organic acids are synthesized and accumulated in the medium to very high concentrations by filamentous fungi such as Aspergillus spp. and Rhizopus sp. This article reviews basic research on the unusual acid production capability and the associated metabolic pathways operating under defined stress conditions in these specific fungi. In particular, we describe and discuss the importance of the cytosolic reductive TCA pathway, which includes the cytosolic activities of pyruvate carboxylase, malate dehydrogenase and fumarase, for production of fumaric and L -malic acids. This article also describes the differences between fumaric acid, L -malic acid and citric acid production by different organisms (filamentous fungi, yeast, and higher eukaryotes), and the possible application of novel technologies (genetic engineering and bioinformatics) to fungal systems which may offer new industrial potential of filamentous fungi for the production of valuable metabolites. Copyright © 2006 Society of Chemical Industry [source] Wine is Bactericidal to Foodborne PathogensJOURNAL OF FOOD SCIENCE, Issue 9 2004T. Møretrø ABSTRACT: Red and white wines without added sulfite were tested for antibacterial activity against stationary-phase grown cells of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, and Staphylococcus aureus. The wines had bactericidal activity against all strains, with the red wine being most potent. S. Typhimurium was most sensitive, with 6 log reduction after 10 min exposure to wine, whereas S. aureus appeared least sensitive to the wines. Mutants having the gene encoding the alternative sigma factor disrupted were generally more sensitive to wine than their wild-type counterparts. When different combinations of ethanol, organic acids, and acidity were tested against the pathogens, it was found that a composition of 0.15% malic acid, 0.6% tartaric acid, 15% ethanol, and pH 3.0 had a strong bactericidal effect. The compounds in the mixture seemed to act synergistically against the pathogens. The pathogens grew in 25% to 40% white wine diluted in brain hearth infusion broth, with S. aureus being able to grow at the highest concentration of wine. Preincubation of the bacteria in sublethal concentrations of wine and ethanol and pH 4.5 did not increase their tolerance against wine or against the mixture of organic acids and ethanol. In conclusion, wine had an antibacterial effect against the pathogens tested. The synergistic effect of organic acids, ethanol, and low pH seems to be responsible for a major part of the antibacterial effect of wine. The alternative sigma factors seemed to be involved in protection of the bacteria against wine. [source] Malolactic Activity of Lactic Acid Bacteria during Sauerkraut FermentationJOURNAL OF FOOD SCIENCE, Issue 8 2004S.D. Johanningsmeier ABSTRACT: The frequency of lactic acid bacteria (LAB) involved in sauerkraut fermentation with (MDC+) or without (MDC - ) the ability to decarboxylate malic acid was determined. The MDC+ phenotype was found in > 99% of homofermentative LAB isolated from commercial fermentations. In contrast, heterofermentative LAB isolates from 0.25, 3, 7, and 10 d had only 53%, 54%, 15%, and 11% MDC+ phenotype, respectively, indicating that more than 1 strain or species was involved. The malolactic reaction was demonstrated in cabbage juice with known strains of Leuconostoc mesenteroides, raising the question of desirability of such activity in cultures selected for the controlled fermentation of cabbage. [source] Synthesis and Investigation of Submicrometer Spherical Indium Oxide ParticlesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2008Sung-En Lin Spherical indium (In) oxide in submicrometer size is considered as a practical material in photonic bandgap applications. To obtain narrow size distribution, systematic studies of different conditions such as precursor concentration, reaction temperature, and other parameters have been carried out and are reported here. Tri- or dicarboxylic acid of citric acid (CA), malic acid, and tartaric acid were introduced into the reaction system and In-precipitates of spherical shape were produced. The particle size and internal morphology were observed by scanning electron microscopy and transmission electron microscopy. X-ray diffraction and thermal analysis were performed. The reaction kinetics analysis shows that the reaction rate depends on the reaction temperature, urea, and In concentration rather than on CA. [source] Effect of nitrogen source in the fertilizing solution on nutritional quality of three members of the Portulaca oleracea aggregateJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2010Gabriella Szalai Abstract BACKGROUND:Portulaca oleracea (purslane) is nutritious but, in addition to the essential ,-linolenic acid, vitamin C and tocopherols, it contains undesirable oxalic acid. Knowing the effects of nitrate and ammonium on oxalate accumulation, we tested the agronomic potential of three members of the P. oleracea aggregate under various nitrogen fertilization conditions, by measuring biomass production and accumulation of fatty acids, organic acids and tocopherol in the commercial P. sativa (Pos) and two natural members: P. nitida (Pon) and P. papillato-stellulata (Pop). RESULTS:With nitrate as the sole N source, we measured differences between Pon and Pos in concentrations of the essential ,-3 fatty acid ,-linolenic acid. Pos also gained less dry biomass under these conditions, implying a higher agronomical and nutritional value for Pon. Increasing the fertilizer ammonium concentration and reducing that of nitrate significantly decreased oxalic acid by factors of up to 1.7, 2.6 and 3.4 in Pos, Pop and Pon, respectively, significantly increased concentrations of tocopherol and malic acid, had no effect on fatty acids or ascorbic acid, but reduced biomass. CONCLUSION:In spite of the recumbent growth habit of Pon, the present findings indicate its agronomic potential. Because early flowering and seed production may be the limiting factors in purslane agriculture, growing Pon in nitrate-poor conditions might be agriculturally favorable. Copyright © 2010 Society of Chemical Industry [source] Metabolic response to two hydrocooling temperatures in sweet cherries cv Lapins and cv SunburstJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2006Rafael Alique Abstract Physiological and metabolic characterisation and analysis of response to two hydrocooling temperatures in cv Sunburst (early season) and cv Lapins (mid-season) cherries during post-harvest life has been studied. Samples were hydrocooled with water at 1 °C to reach 6 °C inside the fruit (HC-6C) and 2 °C (HC-2C) inside the fruit. After harvesting, Sunburst samples presented higher respiration rates and lower malic acid and sorbitol contents than Lapins. Glucose and fructose contents were similar in the two varieties. Sunburst control exhibited a higher respiration rate than Lapins and a higher rate of conversion from sorbitol to fructose. The change of glucose and malic acid consumption over 4 days at 20 °C was similar for the two varieties. Hydrocooling reduced respiration and the consumption of respiratory substrates. The residual effect of hydrocooling was especially significant in cherries of both varieties that had been pre-cooled to 2 °C. Hydrocooling delayed loss of skin and pulp firmness, and reduced loss of titratable acid and soluble solid contents over 4 days at 20 °C in both varieties. Hydrocooling to 2 °C checked loss of quality with respect to controls for both varieties after 4 days at 20 °C. Lapins showed better conservation properties than Sunburst under all the experimental storage conditions. Hydrocooling reduced total losses in both varieties, especially in cherries pre-cooled to 2 °C. Hydrocooling also had several residual effects: reduction of the respiration rate and consumption of respiratory substrates, and slowing of loss of quality, particularly for Lapins. Copyright © 2006 Society of Chemical Industry [source] Degradation of malic acid in wine by immobilized Issatchenkia orientalis cells with oriental oak charcoal and alginateLETTERS IN APPLIED MICROBIOLOGY, Issue 5 2010S.K. Hong Abstract Aims:, To test degradation of malic acid content in wine by immobilized Issatchenkia orientalis KMBL 5774 cells recently isolated from Korean wine pomace as a malic acid-degrading yeast. Methods and Results:,I. orientalis KMBL 5774 cells were immobilized using a mixture of oriental oak (Quercus variabilis) charcoal with sodium alginate. When the immobilized yeast cells were observed on a scanning electron microscope, cells were efficiently immobilized on the surface area of the charcoal. A Korean wine containing a high level of malic acid was treated with the immobilized yeast cells. The HPLC analysis of the malic acid content in the treated wine showed the malic acid content was reduced to 0·75 mg ml,1 after treatment from the original content of 8·96 mg ml,1, representing 91·6% of the malic acid was degraded during the treatment. Conclusions:, The immobilization of the malic acid-degrading yeasts with oriental oak charcoal and sodium alginate is useful for degradation of malic acid in wines containing a high level of malic acid with no significant increase in other acids. Significance and Impact of the study:, Malic acid is sometimes detrimental to the quality of wines when present at high concentrations in some varieties. The immobilized I. orientalis KMBL5774 cells appear to be a promising candidate in view of developing biotechnological methods for reduction of malic acid contents in wine. [source] Low-Molecular-Weight Poly(, -methyl ,,L -malate) of Microbial Origin: Synthesis and CrystallizationMACROMOLECULAR BIOSCIENCE, Issue 2 2005Carlos E. Fernández Abstract Summary: Low-molecular-weight poly(, -methyl ,,L -malate) made of approximately 25,30 units was prepared from microbial poly(,,L -malic acid) by treatment with diazomethane. The thermal characterization of the polymalate methyl ester was carried out and its crystalline structure was preliminary examined. Its ability to crystallize both from solution and from the melt was comparatively evaluated. Poly(, -methyl ,,L -malate) spherulitic film cast from CHCl3. [source] Plastidic metabolite transporters and their physiological functions in the inducible crassulacean acid metabolism plant Mesembryanthemum crystallinumTHE PLANT JOURNAL, Issue 3 2000Rainer E. Häusler Summary The inducible crassulacean acid metabolism (CAM) plant Mesembryanthemum crystallinum accumulates malic acid during the night and converts it to starch during the day via a pathway that, because it is located in different subcellular compartments, depends on specific metabolite transport across membranes. The chloroplast glucose transporter (pGlcT) and three members of the phosphate translocator (PT) family were isolated. After induction of CAM, transcript amounts of the phosphoenolpyruvate (PEP) phosphate translocator (PPT) and the glucose-6-phosphate (Glc6P) phosphate translocator (GPT) genes were increased drastically, while triose phosphate (TP) phosphate translocator (TPT) and the pGlcT transcripts remained unchanged. PPT- and GPT-specific transcripts and transporter activities exhibited a pronounced diurnal variation, displaying the highest amplitude in the light. pGlcT transcripts were elevated towards the end of the light period and at the beginning of the dark period. These findings, combined with diurnal variations of enzyme activities and metabolite contents, helped to elucidate the roles of the PPT, GPT, TPT and pGlcT in CAM. The main function of the PPT is the daytime export from the stroma of PEP generated by pyruvate orthophosphate:dikinase (PPDK). The increased transport activity of GPT in the light suggests a higher requirement for Glc6P import for starch synthesis rather than starch mobilization. Most likely, Glc6P rather than 3-phosphoglycerate or triose phosphates is the main substrate for daytime starch biosynthesis in M. crystallinum plants in which CAM has been induced (CAM-induced), similar to non-green plastids. In the dark, starch is mobilized both phosphorylytically and amylolytically and the products are exported by the GPT, TPT and pGlcT. The transport activities of all three phosphate translocators and the transcript amounts of the pGlcT adapt to changing transport requirements in order to maintain high metabolic fluxes during the diurnal CAM cycle. [source] Chiral versus racemic building blocks in supramolecular chemistry: malate salts of organic diaminesACTA CRYSTALLOGRAPHICA SECTION B, Issue 3-2 2002Dorcas M. M. Farrell (S)-Malic acid forms a salt with N,N,-dimethylpiperazine, [MeN(CH2CH2)2NMe]H22+·2C4H5O5, (1) (triclinic, P1, Z, = 1), in which the cations link pairs of hydrogen-bonded anion chains to form a molecular ladder. With 4,4,-bipyridyl, (S)-malic acid forms a 1:1 adduct which crystallizes from methanol to yield two polymorphs, (2) (triclinic, P1, Z, = 1) and (3) (monoclinic, C2, Z, = 1), while racemic malic acid with 4,4,-bipyridyl also forms a 1:1 adduct, (4) (monoclinic, P21/c, Z, = 1). In each of (2), (3) and (4) the components are linked by O,H,N and N,H,O into chains of alternating bipyridyl and malate units, which are linked into sheets by O,H,O hydrogen bonds. In each of the 1:1 adducts (5) and (6), formed by, respectively, (S)-malic acid and racemic malic acid with 1,2-bis(4,-pyridyl)ethene, the diamine is disordered over two sets of sites, related by a 180° rotation about the N,N vector. In (5), (C12H10N2)H+·C4H5O5, (triclinic, P1, Z, = 1), the components are again linked by a combination of N,H,O and O,H,O hydrogen bonds into sheets, while in (6) (triclinic, P, Z, = 0.5) there is only partial transfer of the H atom from O to N and the malate component is disordered across a centre of inversion. With 1,4-diazabicyclo[2.2.2]octane, racemic malic acid forms a 1:2 salt, [(C6H12N2)H2]2+·2C4H5O5, (7) (monoclinic, P21/c, Z, = 2), while (S)-malic acid forms a 1:1 adduct, (8) (monoclinic, P21, Z, = 3). There are thus six independent molecular components in each. In (7) the ions are linked by an extensive series of N,H,O and O,H,O hydrogen bonds into a three-dimensional framework, but in (8) there is extensive disorder involving all six components, and no refinement proved to be feasible. [source] Bis[2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium] dl -malateACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009S. Franklin Racemic malic acid and trimethoprim [5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diamine] form a 1:2 salt (monoclinic, P21/c), 2C14H19N4O3+·C4H4O52,, in which the malate component is disordered across a centre of inversion. The crystal structure of the salt consists of protonated trimethoprim residues and a malate dianion. The carboxylate group of the malate ion interacts with the trimethoprim cation in a linear fashion through pairs of N,H...O hydrogen bonds to form a cyclic hydrogen-bonded motif. This is similar to the carboxylate,trimethoprim cation interaction observed earlier in the complex of dihydrofolate reductase with trimethoprim. The structure of the salt of trimethoprim with racemic dl -malic acid reported here is the first of its kind. The present study investigates the conformations and the hydrogen-bonding interactions, which are very important for biological functions. The pyrimidine plane makes a dihedral angle of 78.08,(7)° with the benzene ring of the trimethoprim cation. The cyclic hydrogen-bonded motif observed in this structure is self-organized, leading to novel types of hydrogen-bonding motifs in supramolecular patterns. [source] Organic and inorganic anions in Shiraz and Chardonnay grape berries and wine as affected by rootstock under saline conditionsAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 1 2010H. GONG Abstract Background and Aims:, Rootstocks influence the inorganic ion and organic acid composition of grapes of the scion variety. The aim was to investigate the impact of rootstocks on the inter-relationship of inorganic ions and organic acid anions in the skin and pulp of grapes and in resultant wine. Methods and Results:, Vines were irrigated with water having electrical conductivities in the range 1.6,2.1 dS/m. Chloride, sodium, potassium, malic and tartaric acid concentrations were higher in almost all cases in skin than in pulp. Significant positive correlations existed between chloride and sodium concentrations in both pulp and skin. A significant negative linear regression existed between malic acid and both chloride and sodium concentrations in skin of Chardonnay berries. There were positive linear regressions in chloride concentration between berry (pulp and skin) and resultant wine chloride in both Chardonnay and Shiraz. Conclusion:, The higher malic acid and lower chloride concentrations in skin of most grafted Chardonnay and Shiraz vines, and vice versa for own rooted vines, may indicate competition for similar transporter proteins involved in loading into skins. Alternatively, higher salt concentrations in skins may be associated with accelerated malic acid catabolism. Significance of the Study:, Chloride-excluding rootstocks demonstrated advantages through reduced chloride (but not sodium) in pulp and skin of grape berries and in resultant wines. Where rootstocks reduced chloride concentrations in skin of grape berries, there is potential for higher malic acid in skin and in the resultant red wines. [source] Assimilate transport in grapevines -effect of phloem disruptionAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 3 2001J.J.(KOBUS) HUNTER Abstract Assimilate translocation in mature grapevines (cv. Gewürztraminer and cv. Harslevelü) under field conditions was investigated during the growth season by quantifying individual sugars and organic acids in mature leaves, shoot bark and berries, as affected by girdling the shoot just above the bunches. Tissue was sampled at berry set, pea size, veraison and ripeness stages of the vine. Invertase activity was determined in the shoot bark at ripeness. In the leaves, malic acid concentrations reached lowest levels at pea size, but increased thereafter. Tartaric acid decreased after peaking at pea size stage. Tartaric acid concentrations increased with girdling. Despite the increase in leaf age, sucrose concentrations remained virtually stable during the season, emphasising the importance of mature leaves for nourishing bunches. Girdling resulted in a build-up of sucrose in the leaves. In the bark, malic and tartaric acid stayed more or less the same during the growth period, but increased above the girdle. As a result of phloem disruption, sucrose also increased. The increase in glucose and tartaric acid is believed to result from catabolic cleavage of sucrose by invertase. Invertase activity was evident in the bark (of mature Harslevelü vines) at ripeness, which may indicate involvement in osmotic adjustments and gradients in the bark/phloem structure. In the berries, malic and tartaric acids reached peak concentrations at pea size. The volume increase during the ripening period, and in the case of malic acid also respiratory loss, resulted in a decrease in organic acid concentration. Malic acid continued to decrease after the initial decline, whereas tartaric acid stayed virtually stable. Girdling had no marked effect on organic acid accumulation in the berries. Sucrose concentrations were low during the first part of the season, but increased thereafter. Sucrose concentrations during ripening increased with girdling, which may represent a concentration effect and/or import from the rest of the vine. Sucrose concentrations (in mature Harslevelü vines) were indeed lower below than above the girdle. Comparison of sucrose concentrations in the leaves, bark and berries showed the existence of a decreasing concentration gradient, in line with the source:sink transport concept. An equally prominent decrease in sucrose:glucose ratio in the berries from the start of the ripening period indicates that vacuolar integrity (compartmentation) was affected in the ripening berry, most probably allowing hydrolysis of sucrose by invertase and decreasing osmotic potential within the berry. The results provide further evidence for the hypothesis of an osmotic gradient driven transport to the berry. [source] Direct chiral resolution of tartaric acid by ion-pair capillary electrophoresis using an aqueous background electrolyte with (1R,2R)-(,)-1,2-diaminocyclohexane as a chiral counterionELECTROPHORESIS, Issue 15 2003Shuji Kodama Abstract Chiral resolution of native DL -tartaric acid was achieved by ion-pair capillary electrophoresis (CE) using an aqueous-ethanol background electrolyte with (1R,2R)-(,)-1,2-diaminocyclohexane (R -DACH) as a chiral counterion. Factors affecting chiral resolution and migration time of tartaric acid were studied. By increasing the viscosity of the background electrolyte and the ion-pair formation, using organic solvents with a lower relative dielectric constant, resulted in a longer migration time. The optimum conditions for both high resolution and short migration time of tartaric acid were found to be a mixture of 65% v/v ethanol and 35% v/v aqueous solution containing 30 mMR -DACH and 75 mM phosphoric acid (pH 5.1) with an applied voltage of ,30 kV at 25°C, using direct detection at 200 nm. By using this system, the resolution (Rs) of racemic tartaric acid was approximately 1. The electrophoretic patterns of tartaric and malic acids suggest that two carboxyl groups and two hydroxyl groups of tartaric acid are associated with the enantioseparation of tartaric acid by the proposed CE method. [source] Chemotactic response of plant-growth-promoting bacteria towards roots of vesicular-arbuscular mycorrhizal tomato plantsFEMS MICROBIOLOGY ECOLOGY, Issue 3 2003Sushma Gupta Sood Abstract The chemotactic responses of the plant-growth-promoting rhizobacteria Azotobacter chroococcum and Pseudomonas fluorescens to roots of vesicular-arbuscular mycorrhizal (Glomus fasciculatum) tomato plants were determined. A significantly (P=0.05) greater number of bacterial cells of wild strains were attracted towards vesicular-arbuscular mycorrhizal tomato roots compared to non-vesicular-arbuscular mycorrhizal tomato roots. Substances exuded by roots served as chemoattractants for these bacteria. P. fluorescens was strongly attracted towards citric and malic acids, which were predominant constituents in root exudates of tomato plants. A. chroococcum showed a stronger response towards sugars than amino acids, but the response was weakest towards organic acids. The effects of temperature, pH, and soil water matric potential on bacterial chemotaxis towards roots were also investigated. In general, significantly (P=0.05) greater chemotactic responses of bacteria were observed at higher water matric potentials (0, ,1, and ,5 kPa), slightly acidic to neutral pH (6, 6.5 and 7), and at 20,30°C (depending on the bacterium) than in other environmental conditions. It is suggested that chemotaxis of P. fluorescens and A. chroococcum towards roots and their exudates is one of the several steps in the interaction process between bacteria and vesicular-arbuscular mycorrhizal roots. [source] Physiological behaviour of Hanseniaspora guilliermondii in aerobic glucose-limited continuous culturesFEMS YEAST RESEARCH, Issue 2 2003Helena Albergaria Abstract The physiology of Hanseniaspora guilliermondii was studied under aerobic glucose-limited conditions using the accelerostat procedure (continuous acceleration of dilution rate) and classical chemostat cultures. By both cultivation techniques this yeast was found to be Crabtree-positive. Up to a dilution rate of 0.25 h,1, glucose was completely metabolised into biomass, glycerol and carbon dioxide. Above this value, an increase in the dilution rate was accompanied by the production of other metabolites like ethanol, acetic and malic acids. Biomass yield during the purely oxidative growth was 0.49 g g,1 and decreased to 0.26 g g,1 for D=0.34 h,1. A maximal specific ethanol production rate of 1.36 mmol g,1 h,1 and a maximal ethanol yield of 0.05 g g,1 were achieved at D=0.34 h,1. [source] Organic acids: old metabolites, new themesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2006Israel Goldberg Abstract Fumaric, L -malic and citric acids are intermediates of the oxidative tricarboxylic acid (TCA) cycle which in eukaryotes is localized in mitochondria. These organic acids are synthesized and accumulated in the medium to very high concentrations by filamentous fungi such as Aspergillus spp. and Rhizopus sp. This article reviews basic research on the unusual acid production capability and the associated metabolic pathways operating under defined stress conditions in these specific fungi. In particular, we describe and discuss the importance of the cytosolic reductive TCA pathway, which includes the cytosolic activities of pyruvate carboxylase, malate dehydrogenase and fumarase, for production of fumaric and L -malic acids. This article also describes the differences between fumaric acid, L -malic acid and citric acid production by different organisms (filamentous fungi, yeast, and higher eukaryotes), and the possible application of novel technologies (genetic engineering and bioinformatics) to fungal systems which may offer new industrial potential of filamentous fungi for the production of valuable metabolites. Copyright © 2006 Society of Chemical Industry [source] Loss of TIP1;1 aquaporin in Arabidopsis leads to cell and plant deathTHE PLANT JOURNAL, Issue 6 2004Shisong Ma Summary Arabidopsis TIP1;1 (,TIP) is a member of the tonoplast family of aquaporins (AQP). Using RNA interference (RNAi) we reduced TIP1;1 to different extent in various lines. When most severely affected, miniature plants died, a phenotype partially complemented by the TIP1;1 homolog McMIP-F. Less severely affected lines produced small plants, early senescence, and showed lesion formation. The relative water content in TIP1;1 RNAi plants was not significantly affected. Global expression profiling suggested a disturbance in carbon metabolism in RNAi lines with upregulated transcripts for functions in carbon acquisition and respiration, vesicle transport, signaling and transcription, and radical oxygen stress. Metabolite profiles showed low glucose, fructose, inositol, and threonic, succinic, fumaric, and malic acids, but sucrose levels were similar to WT. Increased amounts were found for raffinose and several unknown compounds. TIP1;1 RNAi plants also contained high starch and apoplastic carbohydrate increased. A GFP-TIP1;1 fusion protein indicated tonoplast location in spongy mesophyll cells, and high signal intensity in palisade mesophyll associated with vesicles near plastids. Signals in vascular tissues were strongest not only in vesicle-like structures but also outlined large vacuoles. Compromised routing of carbohydrate and lack of sucrose provision for cell-autonomous functions seems to characterize this RNAi phenotype. We suggest a function for TIP1;1 in vesicle-based metabolite routing through or between pre-vacuolar compartments and the central vacuole. Phenotype and expression characteristics support a view of TIP1;1 functioning as a marker for vesicles that are targeted to the central vacuole. [source] A method for determination of fruit-derived ascorbic, tartaric, oxalic and malic acids, and its application to the study of ascorbic acid catabolism in grapevinesAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 3 2009V.J. MELINO Abstract Background and Aims:, The majority of the acidity of a grapevine (Vitis vinifera L.) berry is a result of the accumulation of l -tartaric (TA) and l -malic acids (MA). TA is synthesised from l -ascorbic acid (Asc, vitamin C), the metabolism of which is poorly characterised in grapevines. In a distinct pathway, oxalic acid (OA) is also formed from Asc degradation. The aim of this study was to develop a single method whereby the distribution of Asc and its catabolites from fruit and vegetative sources could be determined. Methods and Results:, Effective recoveries of total Asc, TA, OA and MA were achieved with this extraction method, while chromatographic separation was accomplished with reversed-phase high-performance liquid chromatography (RP-HPLC). These results demonstrate that Asc and its catabolites TA and OA rapidly accumulate in immature berries, and that the Asc to dehydroascorbate ratio increases with berry maturity. Conclusions:, A method for the simultaneous analysis of Asc, TA, OA and MA in fruits is provided; moreover, we have demonstrated its use to study their distribution in fruits, rachis, leaves and roots. Significance of the Study:, This method enables accurate monitoring of the accumulation of Asc, permitting further research towards understanding acid metabolism during berry ripening. [source] | ||||||||||||||||||||||||||||