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PubMed1993

Inulin formation of penicillin producing industrial Penicillium chrysogenum strains.

Conidia of certain penicillin producing Penicillium chrysogenum industrial strains produced polyfructose. Two types of polyfructoses were formed by conidia of P. chrysogenum B10 from sucrose and with less yield from raffinose. Ten percent of fructans were in water insoluble form attached to the outer wall of conidia. The other, ethanol precipitable fructan formed a colloid opalescent solution. The latter had inulin type beta (2-->1) bonds--identified by 13C NMR spectroscopy--between fructose molecules and had a molecular weight of 217,000 Daltons. The KM value of sucrose hydrolysis--the first step of inulin production--was 0.86 M. The invertase hydrolysed about 70% of sucrose on the second day. Optimal conditions for inulin formation were: pH 6.0, 25-45 degrees C, 100 mg/ml sucrose, 10(7) spore/ml. The maximum conversion rate of fructose from sucrose into precipitable inulin was about 10% after 48 h incubation. The inulin production could be inhibited by glucose.

Carbohydrate Sequence↗

PubMed1998

Prevention of colon cancer by pre- and probiotics: evidence from laboratory studies.

Oligofructose and inulin, selective fermentable chicory fructans, have been shown to stimulate the growth of bifidobacteria which are regarded as beneficial strains in the colon. Studies were designed to evaluate inulin (Raftiline) and oligofructose (Raftilose), for their potential inhibitory properties against aberrant crypt foci (ACF) formation in the colon of rats. ACF are putative preneoplastic lesions from which adenomas and carcinomas may develop. The results of this study demonstrate that dietary administration of oligofructose and inulin inhibits the formation of preneoplastic lesions in the colon suggesting the potential colon tumour inhibitory properties of chicory fructans. Since these prebiotics selectively stimulate the growth of bifidobacteria, tumour inhibitory activity of lyophilized cultures of Bifidobacterium longum (BL) against azoxymethane (AOM)-induced colon carcinogenesis in rats and modulating effect of these cultures on colonic tumour cell proliferation, ornithine decarboxylase (ODC) activity, and ras-p21 oncoprotein expression were investigated. Dietary administration of lyophilized cultures of BL strongly suppressed AOM-induced colon tumour development. Inhibition of colon carcinogenesis was associated with a decrease in colonic mucosal cell proliferation and colonic mucosal and tumour ODC and ras-p21 activities.

Animals↗

PubMedDate not supplied

Oligofructose modulates lipid metabolism alterations induced by a fat-rich diet in rats.

The aim of this study was to test the hypothesis that non-digestible fructans, namely oligofructose (OFS), are able to decrease post-prandial lipaemia in rats fed a high-fat diet composed of 10% lard, 4% corn oil and 0.15% cholesterol. Male Wistar rats were divided into three groups: group 1 was fed a standard low-fat diet (AO4), group 2 received the high-fat diet (HF) and group 3 received 10% (w/w) OFS in the HF diet (HF-OFS) for 3 weeks. The OFS supplementation reduced post-prandial triglyceridaemia by more than 50%, compared to both AO4 and HF groups. It also protected rats against the increase in free cholesterol serum level induced by the HF diet. The OFS did not prevent the HF-induced hepatic accumulation of triglycerides, phospholipids and cholesterol; however, histochemical analysis showed smaller lipid droplets in the liver of HF-OFS rats as compared to HF rats. Our results suggest that, when given in HF diet, OFS decreases serum triglycerides through an extra-hepatic event, namely by enhancing triglyceride-rich lipoprotein catabolism.

Animals↗

PubMed2005

Sugar signalling and gene expression in relation to carbohydrate metabolism under abiotic stresses in plants.

Sucrose is required for plant growth and development. The sugar status of plant cells is sensed by sensor proteins. The signal generated by signal transduction cascades, which could involve mitogen-activated protein kinases, protein phosphatases, Ca 2+ and calmodulins, results in appropriate gene expression. A variety of genes are either induced or repressed depending upon the status of soluble sugars. Abiotic stresses to plants result in major alterations in sugar status and hence affect the expression of various genes by down- and up-regulating their expression. Hexokinase-dependent and hexokinase-independent pathways are involved in sugar sensing. Sucrose also acts as a signal molecule as it affects the activity of a proton-sucrose symporter. The sucrose trans-porter acts as a sucrose sensor and is involved in phloem loading. Fructokinase may represent an additional sensor that bypasses hexokinase phosphorylation especially when sucrose synthase is dominant. Mutants isolated on the basis of response of germination and seedling growth to sugars and reporter-based screening protocols are being used to study the response of altered sugar status on gene expression. Common cis-acting elements in sugar signalling pathways have been identified. Transgenic plants with elevated levels of sugars/sugar alcohols like fructans, raffinose series oligosaccharides, trehalose and mannitol are tolerant to different stresses but have usually impaired growth. Efforts need to be made to have transgenic plants in which abiotic stress responsive genes are expressed only at the time of adverse environmental conditions instead of being constitutively synthesized.

Carbohydrate Metabolism↗

PubMed1981

Extracellular polysaccharide synthesized by the oral bacterium Streptococcus mutans of serotype a to e in vitro.

Extracellular polysaccharide (EPS) synthesized in vitro by Streptococcus mutans belonging to serotypes a, b, c, d and e was shown to consist mainly of glucan. Only strains of type b and e regularly produced substantial amounts of fructan, too. Strains of type d synthesized significantly higher quantities of glucan than strains of the other types per gram of bacterial mass. The percentage of insoluble glucan was lowest in samples from strains of type a and c, and highest in samples from strains of type d. In contrast to the insoluble glucan, the linkage pattern of the soluble glucan of the five types showed only small differences. The percentage of alpha-1,3-linked glucose units was highest in the insoluble glucan from strains of type d and e, and lowest in glucan from type c. The differences were significant. Incubation of Strep. mutans under various culture conditions showed that the quantities and composition of EPS formed depend on the culture condition used. The effect of culture conditions, however, was similar for all strains. Therefore the differences found with respect to the quantities and composition of EPS synthesized in vitro by Strep. mutans of different types are apparently type-dependent.

Culture Media↗

PubMed1990

Immunochemical studies on levans from several strains of Actinomyces viscosus.

High molecular-weight levans elaborated by 8 separate strains of Actinomyces viscosus were purified: the inteactions of these levans with concanavalin A and anti-fructan myeloma immunoglobulins UPC-10 and J606 were examined by the quantitative precipitin method. Oligosaccharides released from the levans by partial acid hydrolysis were separated by partition chromatography on paper and characterized in situ by selective spray reagents. The liberated oligomers were compared with oligomers of known structure released from levans of Aerobacter levanicum and Leuconostoc mesenteriodes B512 as well as with plant inulin. The fragmentation analysis indicated a structure for Actinomyces levans comprising chains of beta (2----6)-linked fructofuranosyl units joined through multiple (1,2,6)-linked fructosyl branch units.

Actinomyces↗

PubMed1984

Analysis of the linkage positions in D-fructofuranosyl residues by the reductive-cleavage method.

The suitability of the reductive-cleavage method for analysis of the linkage positions in D-fructofuranosyl residues of D-fructans was examined by using sucrose, chicory-root inulin, and Aerobacter levanicum levan as models. Permethylation, and reductive cleavage with triethylsilane in the presence of either boron trifluoride etherate or trimethylsilyl trifluoromethanesulfonate, gave the expected methylated derivatives of 2,5-anhydro-D-mannitol and 2,5-anhydro-D-glucitol. With either catalyst, nonreducing (terminal) D-fructofuranosyl groups and D-fructofuranosyl residues linked at O-1 gave derivatives having the manno configuration as the major product, whereas D-fructofuranosyl residues linked at O-6, and at both O-1 and O-6, gave derivatives having the gluco configuration as the major product. The independent synthesis, and n.m.r.- and mass-spectral characterization, of the methylated 2,5-anhydro-D-mannitol and 2,5-anhydro-D-glucitol derivatives formed from these residues by reductive cleavage are reported.

Chemical Phenomena↗

PubMed1992

Fructo-oligosaccharides from the stems of Triticum aestivum.

Fructo-oligosaccharides, extracted with hot water from wheat stems before flowering, were fractionated by gel-permeation chromatography on Biogel P2. The tri-/tetra- and penta-saccharide fractions were purified by HPLC and analysed by the reductive cleavage method. The trisaccharides 1-kestose and 6-kestose, the branched tetrasaccharide bifurcose, and the (2-->6)-linked pentasaccharide were identified. The fractions of higher molecular weight were also investigated and confirmed the branched-levan structure of this fructan.

Carbohydrate Conformation↗

PubMed1995

Protective effect of dietary fructo-oligosaccharide in young rats against exocrine pancreas atrophy induced by high fructose and partial copper deficiency.

The objective of this investigation was to protect rats against exocrine pancreatic atrophy by adding 22% fructo-oligosaccharide (FOS), a natural fructan obtained from inulin, to the 50% copper-deficient diets containing qualitatively and quantitatively different carbohydrates. Young male Wistar rats were maintained on these diets for 10 wk, being weighed weekly then killed and autopsied. Major organs were weighed and histologically examined. Copper content in the diets was measured by flame atomic absorption spectroscopy. Incomplete (50%) copper deficiency avoided precocious mortality due to cardiovascular lesions and enabled another pathological condition to develop, consisting of the induction of exocrine pancreas atrophy. Introduction of gradually increasing percentages of fructose in diets at the level of 22, 42 and 62% induced a gradual increase in the copper-deficiency-mediated pathology in rats, expressed by an increase in exocrine pancreatic atrophy. 22% FOS introduced to the diet prevented the pathology induced by both fructose and partial copper deficiency better than starch added to diet at the level of 20 or 40%.

Animals↗

PubMed2004

Transgenic tobacco plants accumulating osmolytes show reduced oxidative damage under freezing stress.

We studied the reaction to the oxidative component of freezing in several tobacco lines, transformed with genes coding for enzymes involved in the synthesis of osmoprotectants (proline, fructan or glycine betaine) along with their wild type. The levels of some oxidative stress markers (leakage of electrolytes, hydrogen peroxide and malondialdehyde) as well as the activity of antioxidative enzymes catalase (EC 1.11.1.6.) and guaiacol peroxidase (EC 1.11.1.7.) have been followed at acclimation, 12 and 24 h freezing and at recovery. Freezing for 24 h resulted in severe damages for the wild type. A corresponding increase of electrolyte leakage, hydrogen peroxide and malondialdehyde contents, a rise of peroxidase activity and inhibition of catalase activity occurred in the non-transformants. Similar, but significantly lower trend of the same parameters has been found for the transgenic lines. Moreover, the oxidative markers returned to their normal levels when the transformants were able to recover from freezing. It could be speculated that transfer of genes, coding for accumulation of osmoprotectants, is related to reduced intensity of freezing-induced oxidative processes. Our lines and model system could serve as a good prerequisite for additional studies to gain further insights into the complex role of osmoprotectants in freezing tolerance.

Acclimatization↗

PubMed2003

Acid diffusion through extracellular polysaccharides produced by various mutants of Streptococcus mutans.

Mutants of Streptococcus mutans V403, constructed by allelic exchange and altered in their capacity to produce enzymes involved in the production of extracellular polysaccharides from sucrose, were used to study the role of glucans and fructans in the diffusion of ions through cell concentrates. A 4.0mm diameter, 0.75 mm deep diffusion chamber with an ion-sensitive field-effect transistor electrode positioned at the base was used to monitor the diffusion of hydronium ions from a sodium lactate buffer using cell concentrates prepared from bacteria grown in various concentrations of sucrose and glucose. The wild-type strain V403 produced at least seven times as much water-insoluble glucan (ISG) from sucrose as mutants deficient in various combinations of glucosyltransferase B (GTF B), GTF C, GTF D and fructosyltransferase. The fastest diffusion of hydronium ions occurred with sucrose-grown cell concentrates of strain V403, and the time of diffusion to the bottom of the chamber was approximately 2.3 times longer when this strain was grown in glucose. The speed of diffusion with glucose-grown V403 was similar to that obtained with each of the mutants. When cells of strain V403 grown in sucrose and glucose were mixed, increases in diffusion speed were found to be directly related to the proportion of sucrose-grown cells. The mixing of ISG with several strains of S. mutans revealed that increases in diffusion speed were directly related to the quantity of ISG added.

Acids↗

PubMed1978

Immunochemical studies on dextran-specific and levan-specific myeloma proteins from NZB mice.

Two dextran-specific (PC 3858 and PC 3936) and one levan-specific (PC 3660) NZB myeloma proteins were studied by quantitative precipitin and precipitin-inhibition assays. Both myeloma antidextrans were alphaD-(1 leads to 6) specific and precipitated strongly with a synthetic, linear dextran, molecular weight 35,500, and with other dextrans. The two myeloma antidextrans differed with respect to their relative reactivities with dextrans containing various proportions of alpha-D-(1 leads to 6), alpha-D-(1 leads to 4)-like, and alpha-D-(1 leads to 3)-like linkages. In inhibition assays, the two antidextran myeloma proteins behaved differently from each other, from alpha-D-(1 leads to 6)-specific BALB/c myeloma antidextrans, and from the human antidextrans previously studied. Isomalto-oligosaccharides IM3, IM4, and IM5 were all equal in inhibitory power but were only about 60% as potent as IM6 and IM7, which also inhibited equally on a molar basis. Although precipitation with linear dextran suggests that both may have groove-type sites, as previously inferred for QUPC 52, the size of their combining sites is uncertain. It is not clear whether the sites are only as big as three glucose residues with the increased inhibition by six and seven glucose residues being attributable to partial bivalence and to their ability to combine in several ways along the chain, or whether the site is as big as six glucose residues with the increment in binding by the fourth and fifth glucose residues being minimal and the sixth contributing considerable additional binding-energy. The fructan-specific myeloma protein did not react with inulin, but reacted with many levans and with perennial rye-grass levan containing only beta-D-(2 leads to 6) links. The levan-antilevan reaction was not inhibited by beta-D-(2 leads to 1)- linked oligosaccharides. The findings suggest that PC 3660 has a specificity for (2 leads to 6)-linked chains.

Animals↗

PubMed1997

Integration of inulin determination in the AOAC method for measurement of total dietary fibre.

A suitable modification of the standard AOAC method for the measurement of dietary fibre is proposed to quantitatively include beta-fructans in the determination of the soluble dietary fibre fraction and as a consequence in the related total dietary fibre fraction. The standard AOAC method is modified by including a preheated commercial inulinase, Novozym SP 230, to the amyloglucosidase incubation step. It was previously outlined that this commercial inulinase contains some pectolytic activity. It is now demonstrated that a heat pretreatment of this enzyme preparation at 60 degrees C for 2 h eliminates this pectolytic activity while keeping sufficient activity to hydrolyse all the inulin from the soluble fibre fraction.

Dietary Fiber↗

PubMed1998

Lactic acid fermentation and storage of blanched garlic.

The controlled fermentation of peeled, blanched garlic, using a starter culture of Lactobacillus plantarum, was studied and compared with that of unblanched garlic. Blanching was carried out in hot water (90 degrees C) for 15 min. The starter grew abundantly in the case of blanched garlic, producing mainly lactic acid and reaching a pH of 3.8 after 7 days, but its growth was inhibited in unblanched garlic. Ethanol and fructose, coming from enzymatic activities of the garlic, and a green pigment were formed during the fermentation of unblanched garlic, but not of blanched garlic. The blanched garlic fermented by L. plantarum, even without a preservation treatment (pasteurization), was microbiologically stable during storage at 30 degrees C in an acidified brine (approximately 3% (w/w) NaCl and pH 3.5 at equilibrium), but fructans were hydrolyzed. The packed fermented product and that obtained by direct packing without fermentation were not significantly different with regard to flavour.

Carbohydrates↗

PubMed2001

Purification of a novel fructosyltransferase from Lactobacillus reuteri strain 121 and characterization of the levan produced.

Fructosyltransferase (FTF) enzymes have been characterized from various Gram-positive bacteria, but not from Lactobacillus sp. In a screening of 182 lactobacilli for polysaccharide production only one strain, Lactobacillus reuteri strain 121, was found to produce a fructan being a levan. Here we report the first-time identification and biochemical characterization of a Lactobacillus FTF enzyme. When incubated with sucrose the enzyme produced a levan that is identical to that produced by Lb. reuteri strain 121 cells.

Amino Acid Sequence↗

PubMed2004

Evaluation of carbohydrates in Pukekohe Longkeeper and Grano cultivars of Allium cepa.

The storage, soluble, and structural carbohydrates of two onion cultivars, the hard, pungent Pukekohe Longkeeper (PLK) and the softer, milder Houston Grano, were analyzed to determine differences that might be related to their response to sulfur nutrition received during growth as well as their postharvest attributes and end-use suitability. PLK tissue contained 1.37 times more dry matter than Grano and was composed of more fructan and sucrose and less glucose and fructose than Grano [corrected] There were also differences in neutral sugar content, especially galactose, and the amount, size, and content of pectin fractions soluble in chelator and weak alkali. These two onion cultivars differed in their capacity to take up sulfur, but there was no statistical association between sulfur supply and any measured dry matter component.

Carbohydrates↗

PubMed2000

Cloning and functional analysis of chicory root fructan1-exohydrolase I (1-FEH I): a vacuolar enzyme derivedfrom a cell-wall invertase ancestor? Mass fingerprint of the 1-FEH I enzyme.

This paper describes the cloning and functional analysis of chicory (Cichorium intybus L.) fructan 1-exohydrolase I cDNA (1-FEH I). To our knowledge it is the first plant FEH cloned. Full-length cDNA was obtained by a combination of RT-PCR, 5' and 3' RACE using primers based on N-terminal and conserved amino acid sequences. Electrophoretically purified 1-FEH I enzyme was further analyzed by in-gel trypsin digestion followed by matrix-assisted laser desorption ionization and electrospray time-of-flight tandem mass spectrometry. Functionality of the cDNA was demonstrated by heterologous expression in potato tubers. 1-FEH I takes a new, distinct position in the phylogenetic tree of plant glycosyl hydrolases being more homologous to cell-wall invertases (44-53%) than to vacuolar invertases (38-41%) and fructosyl transferases (33-38%). The 1-FEH I enzyme could not be purified from the apoplastic fluid at significantly higher levels than can be explained by cellular leakage. These and other data suggest a vacuolar localization for 1-FEH I. Also, the pI of the enzyme (6.5) is lower than expected from a typical cell-wall invertase. Unlike plant fructosyl transferases that are believed to have evolved from a vacuolar invertase, 1-FEH I might have evolved from a cell-wall invertase-like ancestor gene that later obtained a vacuolar targeting signal. 1-FEH I mRNA quantities increase in the roots throughout autumn, and especially when roots are stored at low temperature.

Amino Acid Sequence↗

PubMed2004

The impact of altitude and simulated herbivory on the growth and carbohydrate storage of Petasites albus.

We tested the hypothesis that higher respiratory losses caused by higher temperatures in the lowlands, compared to montane sites, prevent growth of the montane hemicryptophyte Petasites albus (Asteraceae). In addition, we tested whether increased levels of herbivory enhanced carbon losses at lower elevations. Rhizomes of Petasites albus were transplanted to a montane and a lowland site. In the subsequent three growing seasons the plants were artificially defoliated to simulate mollusc herbivory. Whereas there were no altitudinal differences in the leaf number per plant, the leaf area was higher at the montane site. At the montane site, the leaf number and leaf area decreased with increasing damage, and the rhizome dry weight in the third year was much higher in the undamaged plants. In contrast, fructan concentrations in the rhizomes that were harvested at the end and at the beginning of the growing seasons were generally higher at the lowland site. No clear defoliation effects were observed on most harvest dates. The results indicate that the lower altitudinal limit of Petasites albus cannot be explained by the negative effects of higher temperatures or more leaf damage by herbivores in the lowlands, either alone or in combination. An explanation will require consideration of other site factors such as competition and possibly interactions with herbivory and carbohydrate storage.

Altitude↗