Co-administration of the prebiotic 1-kestose and the paraprobiotic Lactiplantibacillus plantarum FM8 in magellanic penguins promotes the activity of intestinal Lactobacillaceae and reduces the plc gene levels encoding Clostridium perfringens toxin

Despite the well-known potential health benefits of prebiotics and non-viable probiotics (paraprobiotics) in various animal species, research regarding their use in penguins is scarce. Our study aimed to investigate the impact of a combined administration of prebiotics and paraprobiotics (referred to here as "parasynbiotics") on the gut microbiome and overall health of Magellanic penguins (Spheniscus magellanicus). The parasynbiotics consisted of 1-kestose, which is a fructooligosaccharide comprising sucrose and fructose, and heat-killed Lactiplantibacillus plantarum FM8, isolated from pickled vegetables. It was administered to eight penguins aged <3 years (Young-group) and nine penguins aged >17 years (Adult-group) for 8 weeks. Results from 16S rRNA sequencing revealed that compared to baseline, parasynbiotic administration significantly decreased the relative abundance of intestinal Clostridiaceae_222000 in both groups and significantly increased that of Lactobacillaceae in the Young-group. Quantitative real-time polymerase chain reaction revealed a significant decrease in the plc gene levels encoding alpha-toxin of Clostridium perfringens in the Young-group after parasynbiotic administration (P=0.0078). In the Young-group, parasynbiotic administration significantly increased the plasma levels of total alpha-globulin (P=0.0234), which is associated with inflammatory responses. Furthermore, exposure of dendritic cells to heat-killed L. plantarum FM8 promoted the secretion of interleukin 10, a major anti-inflammatory cytokine. Overall, parasynbiotic administration enhanced the activity of gut Lactobacillaceae, decreased the levels of C. perfringens and its toxin encoding plc gene, and reduced inflammatory response in penguins. These results provide novel insights into the potential benefits of parasynbiotics for improving penguin health.

Dietary supplementation with 1-kestose induces altered locomotor activity and increased striatal dopamine levels with a change in gut microbiota in male mice

1-Kestose (KES), a dietary fiber and prebiotic carbohydrate, benefits various physiological functions. This study aimed to examine whether diets supplemented with KES over three consecutive generations could significantly affect some host physiological aspects, including behavioral phenotypes and gut microbial ecology. Mice that received KES-supplemented diets for three generations demonstrated increased activity compared with those fed diets lacking KES. Furthermore, the KES group showed increased striatal dopamine (DA) and serotonin (5-HT) levels. The observed increase in DA levels within the striatum was positively correlated with locomotor activity in the KES group but not in the control (CON) group. The α-diversities were significantly lower in the KES group compared to the CON group. The three-dimensional principal coordinate analysis revealed a substantial distinction between the KES and CON groups across each generation. At the genus level, most gut microbiota genera exhibited lower abundances in the KES group than in the CON group, except for Bifidobacteria and Akkermansia. Spearman's rank-order analysis indicated significant negative correlations between the striatal DA levels and α-diversity values. These findings suggest that prolonged supplementation with KES may stimulate increased locomotor activity along with elevated striatal DA levels, which are potentially associated with KES-induced alterations in the gut microbiota.

longum in conventional mice through the feeding of raffinose or 1-kestose

How bifidobacteria colonize and survive in the intestine is not fully understood. The administration of bifidobacteria to conventional mice can be used to evaluate their ability to colonize the intestine in the presence of endogenous gut microbiota. However, human-derived bifidobacteria do not readily colonize the intestines of conventional mice, and although colonization by Bifidobacterium breve UCC2003 has been achieved, the viability of such populations requires improvement. Therefore, we aimed to establish a colonization system with human-derived bifidobacteria of high viability in conventional mice using Bifidobacterium longum subsp. longum 105-A. Lactose, raffinose, and 1-kestose were identified as the preferred carbohydrate sources for the growth of this strain in culture. The administration of B. longum 105-A to conventional BALB/c mice fed these carbohydrates showed that diets containing 6% (w/w) raffinose or 1-kestose facilitated colonization with >108 colony-forming units/g feces for 2 weeks. The population of this strain was more stable in the raffinose-fed group than in the 1-kestose-fed group. The ingestion of these prebiotics had a greater impact on the composition of the microbiota than the administration of B. longum 105-A. The ingestion of these prebiotics also increased the fecal concentrations of organic acids, which was indicative of greater intestinal fermentation. Collectively, we established a colonization system for B. longum 105-A with high viability in conventional mice by feeding the mice raffinose or 1-kestose. This system should be useful for elucidation of the mechanisms of colonization and survival of bifidobacteria in the intestines in the presence of the endogenous gut microbiota.

Characterization and alteration of product specificity of Beijerinckia indica subsp. indica β-fructosyltransferase

The trisaccharide 1-kestose, a major constituent of fructooligosaccharide, has strong prebiotic effects. We used high-performance liquid chromatography and 1H nuclear magnetic resonance spectroscopy to show that BiBftA, a β-fructosyltransferase belonging to glycoside hydrolase family 68, from Beijerinckia indica subsp. indica catalyzes transfructosylation of sucrose to produce mostly 1-kestose and levan polysaccharides. We substituted His395 and Phe473 in BiBftA with Arg and Tyr, respectively, and analyzed the reactions of the mutant enzymes with 180 g/L sucrose. The ratio of the molar concentrations of glucose and 1-kestose in the reaction mixture with wild-type BiBftA was 100:8.1, whereas that in the reaction mixture with the variant H395R/F473Y was 100:45.5, indicating that H395R/F473Y predominantly accumulated 1-kestose from sucrose. The X-ray crystal structure of H395R/F473Y suggests that its catalytic pocket is unfavorable for binding of sucrose while favorable for transfructosylation.

A Double-Blind, Randomized, Placebo-Controlled Trial of the Effect of 1-Kestose on Defecation Habits in Constipated Kindergarten Children: A Pilot Study

Constipation is common in children and can significantly affect quality of life. Prebiotics are reportedly helpful for constipation in adults, but few studies have examined their use in young children. In this study, the effect of 1-kestose (kestose), which has excellent bifidobacterial growth properties, on constipation in kindergarten children (n = 11) was compared with that of maltose (n = 12) in a randomized, double-blind study. Three grams of kestose per day for 8 weeks did not affect stool properties, but significantly increased the number of defecations per week (Median; 3 → 4 times/week, p = 0.017, effect size = 0.53). A significant decrease in Intestinibacter, a trend toward increased bifidobacteria, and a trend toward decreased Clostridium sensu stricto were observed after kestose ingestion, while concentrations of short-chain fatty acids in stools were unchanged.

Efficacy of 1-kestose supplementation in patients with mild to moderate ulcerative colitis: A randomised, double-blind, placebo-controlled pilot study

BACKGROUND

Ulcerative colitis involves an excessive immune response to intestinal bacteria. Whether administering prebiotic 1-kestose is effective for active ulcerative colitis remains controversial.

AIMS

This randomised, double-blind, placebo-controlled pilot trial investigated the efficacy of 1-kestose against active ulcerative colitis.

METHODS

Forty patients with mild to moderate active ulcerative colitis were randomly treated with 1-kestose (N = 20) or placebo (maltose, N = 20) orally for 8 weeks in addition to the standard treatment. The Lichtiger clinical activity index and Ulcerative Colitis Endoscopic Index of Severity were determined. Faecal samples were analysed to evaluate the gut microbiome and metabolites.

RESULTS

The clinical activity index at week 8 was significantly lower in the 1-kestose group than in the placebo group (3.8 ± 2.7 vs. 5.6 ± 2.1, p = 0.026). Clinical remission and response rates were higher in the 1-kestose group than in the placebo group (remission: 55% vs. 20%, p = 0.048; response: 60% vs. 25%, p = 0.054). The Ulcerative Colitis Endoscopic Index of Severity at week 8 was not significantly different (2.8 ± 1.6 vs. 3.5 ± 1.6, p = 0.145). Faecal analysis showed significantly reduced alpha-diversity in the 1-kestose group, with a decreased relative abundance of several bacteria, including Ruminococcus gnavus group. The short-chain fatty acid levels were not significantly different between the groups. The incidence of adverse events was comparable between the groups.

DISCUSSION

Oral 1-kestose is well tolerated and provides clinical improvement for patients with mild to moderate ulcerative colitis through modulation of the gut microbiome.

Consumption of 1-Kestose Upregulates MicroRNA-200 and -192/215 Families in Lamina Propria Leukocytes of the Murine Large Intestine

By comparing germ-free mice and specific pathogen-free mice, we recently demonstrated that the presence of gut commensals upregulates microRNA-200 family members in lamina propria leukocytes (LPL) of the murine large intestine. The present study tested whether the consumption of 1-kestose (KES), an indigestible oligosaccharide that alters gut microbiota composition, influences the microRNA expression in the LPL. Supplementation of KES (4%) in drinking water for 2 wk increased the levels of miR-182-5p, -205-5p, -290a-5p, miR-200 family members (miR-141-3p, -200a-3p, -200b-3p, -200c-3p, and -429-3p) as well as miR-192/215 family members (miR-192-5p, -194-5p, and -215-5p) as determined by microarray analysis in large intestinal LPL of C57BL/6 mice. Quantitative reverse transcription-PCR further confirmed the increase in miR-192-5p, -194-5p, -200a-3p, -200b-3p, -200c-3p, -205-5p, and 215-5p. KES consumption significantly increased Bifidobacterium pseudolongum in the cecal contents. In a separate experiment, intragastric administration of B. pseudolongum (10⁹ CFU/d) for 7 d increased the levels of miR-182-5p, -194-5p, and -200a-3p and tended to increase the levels of miR-200b-3p, -215-5p, and -429-3p. These results suggest that dietary KES influences miRNA expression in the large intestinal LPL, which may be associated with the increased population of B. pseudolongum.

Separation of Fructosyl Oligosaccharides in Maple Syrup by Using Charged Aerosol Detection

Fructosyl oligosaccharides, including fructo-oligosaccharide (FOS), are gaining popularity as functional oligosaccharides and have been found in various natural products. Our previous study suggested that maple syrup contains an unidentified fructosyl oligosaccharide. Because these saccharides cannot be detected with high sensitivity using derivatization methods, they must be detected directly. As a result, an analytical method based on charged aerosol detection (CAD) that can detect saccharides directly was optimized in order to avoid relying on these structures and physical properties to clarify the profile of fructosyl oligosaccharides in maple syrup. This analytical method is simple and can analyze up to hepta-saccharides in 30 min. This analytical method was also reliable and reproducible with high validation values. It was used to determine the content of saccharides in maple syrup, which revealed that it contained not only fructose, glucose, and sucrose but also FOS such as 1-kestose and nystose. Furthermore, we discovered a fructosyl oligosaccharide called neokestose in maple syrup, which has only been found in a few natural foods. These findings help to shed light on the saccharides profile of maple syrup.

Synergistic enzyme cocktail between levansucrase and inulosucrase for superb levan-type fructooligosaccharide synthesis

Inulosucrase (ISC) and levansucrase (LSC) utilise sucrose and produce inulin- and levan-type fructans, respectively. This study aims to propose a new strategy to improve levan-type fructooligosaccharide (L-FOS) production. The effect of ISC/ LSC -mixed reaction was elucidated on L-FOS production. The presence of ISC in the LSC reaction significantly leads to the higher production of L-FOSs as the main products. Furthermore, the different ratios between ISC and LSC affected the distribution of L-FOSs. A greater amount of ISC compared to LSC promoted the synthesis of short-chain L-FOSs. Conversely, when LSC was increased, the synthesis of longer-chain L-FOSs was enhanced. The addition of trisaccharide mixtures obtained from either a single ISC or LSC reaction could enhance L-FOSs synthesis in the LSC reaction. Analysis of these trisaccharides revealed that most species of the oligosaccharides were similar, with 1-kestose being the major one. The supplement of only 1-kestose in the LSC reaction showed similar results to those of the reaction in the presence of trisaccharide mixtures. Moreover, the results were supported by molecular dynamics simulations. This work not only provides an improvement in L-FOS production but also revealed and supported some insights into the mechanism of fructansucrases.

Investigation of Yacon Leaves (Smallanthus sonchifolius) for α-Glucosidase Inhibitors Using Metabolomics and In Silico Approach

Yacon (Smallanthus sonchifolius (Poepp.) H. Robinson) leaves is traditionally consumed as herbal tea in many countries including Indonesia. This plant's antidiabetic properties have been extensively researched, but studies on the responsible active compound identification are scarce. Information on the active compounds is critical for the consistency of Yacon herbal tea quality. The aim of this study was to identify α-glucosidase inhibitors in Indonesian Yacon leaves grown in two different locations using FTIR- and LC-MS/MS-based metabolomics in combination with in silico technique. Yacon leaves ethanol (50 and 95%) and water extracts were tested for α-glucosidase inhibitory activity, with the 95% ethanol extract being the most active. Geographical origins were found to have no major impact on the activity. In parallel, chemical profile of Yacon leaves extract was determined using FTIR and LC-MS/MS. Orthogonal Projection to Latent Structure (OPLS) was used to analyze both sets of data. OPLS analysis of FTIR data showed that compounds associated to α-glucosidase inhibitor activity included those with functional groups -OH, stretched CH, carbonyl, and alkene. It was consistent with the result of OPLS analysis of LC-MS/MS data, which revealed that based on their VIP and Y-related coefficient value, nystose, 1-kestose, luteolin-3'-7-di-O-glucoside, and 1,3-O-dicaffeoilquinic acid isomers, strongly linked to Yacon's α-glucosidase inhibitor activity. In silico study supported these findings, revealing that the four compounds were potent α-glucosidase inhibitors with docking score in the range of - 100.216 to - 115.657 kcal/mol, which are similar to acarbose (- 115.774 kcal/mol) as a reference drug.

Consumption of indigestible saccharides and administration of Bifidobacterium pseudolongum reduce mucosal serotonin in murine colonic mucosa

SCFA increase serotonin (5-hydroxytryptamine, 5-HT) synthesis and content in the colon in vitro and ex vivo, but little is known in vivo. We tested whether dietary indigestible saccharides, utilised as a substrate to produce SCFA by gut microbiota, would increase colonic 5-HT content in mice. Male C57BL/6J mice were fed a purified diet and water supplemented with 4 % (w/v) 1-kestose (KES) for 2 weeks. Colonic 5-HT content and enterochromaffin (EC) cell numbers were lower in mice supplemented with KES than those without supplementation, while monoamine oxidase A activity and mRNA levels of tryptophan hydroxylase 1 (Tph1), chromogranin A (Chga), Slc6a4 and monoamine oxidase A (Maoa) genes in the colonic mucosa, serum 5-HT concentration and total 5-HT content in the colonic contents did not differ between groups. Caecal acetate concentration and Bifidobacterium pseudolongum population were higher in KES-supplemented mice. Similar trends were observed in mice supplemented with other indigestible saccharides, that is, fructo-oligosaccharides, inulin and raffinose. Intragastric administration of live B. pseudolongum (108 colony-forming units/d) for 2 weeks reduced colonic 5-HT content and EC cell numbers. These results suggest that changes in synthesis, reuptake, catabolism and overflow of 5-HT in the colonic mucosa are not involved in the reduction of colonic 5-HT content by dietary indigestible saccharides in mice. We propose that gut microbes including B. pseudolongum could contribute to the reduction of 5-HT content in the colonic mucosa via diminishing EC cells.

Increase in muscle mass associated with the prebiotic effects of 1-kestose in super-elderly patients with sarcopenia

Sarcopenia causes functional disorders and decreases the quality of life. Thus, it has attracted substantial attention in the aging modern world. Dysbiosis of the intestinal microbiota is associated with sarcopenia; however, it remains unclear whether prebiotics change the microbiota composition and result in the subsequent recovery of muscle atrophy in elderly patients with sarcopenia. This study aimed to assess the effects of prebiotics in super-elderly patients with sarcopenia. We analyzed the effects of 1-kestose on the changes in the intestinal microbiota and body composition using a next-generation sequencer and a multi-frequency bioimpedance analysis device. The Bifidobacterium longum population was significantly increased in the intestine after 1-kestose administration. In addition, in all six patients after 12 weeks of 1-kestose administration, the skeletal muscle mass index was greater, and the body fat percentage was lower. This is the first study to show that administration of a prebiotic increased the population of B. longum in the intestinal microbiota and caused recovery of muscle atrophy in super-elderly patients with sarcopenia.

Supercritical CO2 Processing of a Functional Beverage Containing Apple Juice and Aqueous Extract of Pfaffia glomerata Roots: Fructooligosaccharides Chemical Stability after Non-Thermal and Thermal Treatments

The effects of supercritical CO₂ processing on the chemical stability of fructooligosaccharides (FOS) and other functional and nutritional compounds were evaluated employing non-thermal and thermal approaches. Apple juice was enriched with Pfaffia glomerata roots aqueous extract due to its high content of short-chain FOS and then subjected to different levels of temperature (40 and 60 °C), pressure (8 and 21 MPa), and CO₂ volume ratio (20 and 50%). The percentage of CO₂ volume was evaluated concerning the total volume of the high-pressure reactor. Also, the functional beverage was thermally treated at 105 °C for 10 min. Physicochemical properties (pH and soluble solid content), beta-ecdysone, sugars (glucose, fructose, and sucrose), and FOS (1-kestose, nystose, and fructofuranosylnystose) content were determined. The pH and soluble solid content did not modify after all treatments. The pressure and CO₂ volume ratio did not influence the FOS content and their chemical profile, however, the temperature increase from 40 to 60 °C increased the nystose and fructofuranosylnystose content. High-temperature thermal processing favored the hydrolysis of 1-kestose and reduced the sucrose content. Regarding beta-ecdysone, its content remained constant after all stabilization treatments demonstrating thus its high chemical stability. Our results demonstrated that supercritical CO₂ technology is a promising technique for the stabilization of FOS-rich beverages since the molecular structures of these fructans were preserved, thus maintaining their prebiotic functionality.

Activation of butyrate-producing bacteria as well as bifidobacteria in the cat intestinal microbiota by the administration of 1-kestose, the smallest component of fructo-oligosaccharide

1-kestose is a structural component of fructo-oligosaccharides and is composed of 2 fructose residues bound to sucrose through β2-1 bonds. In the present study, the influence of the ingestion of 1-kestose on the intestinal microbiota was investigated in cats. Six healthy cats were administered 1 g/day of 1-kestose for 8 weeks followed by a 2-week wash-out period. Fecal samples were collected from cats after 0, 4, 8, and 10 weeks. The intestinal microbiota was examined by a 16S rRNA gene metagenomic analysis and real-time PCR. Short-chain fatty acids were measured by GC/MS. The results suggested that the intestinal bacterial community structure in feline assigned to this study was divided into 2 types: one group mainly composed of the genus Lactobacillus (GA) and the other mainly composed of the genus Blautia with very few bacteria of Lactobacillus (GB). Furthermore, the number of Bifidobacterium slightly increased after the administration of 1-kestose (at 4 and 8 weeks) (P<0.1). The administration of 1-kestose also increased the abundance of Megasphaera, the butyric acid-producing bacteria, at 4 and 8 weeks (P<0.1). Furthermore, an increase in butyric acid levels was observed after the administration of 1-kestose for 4 weeks (P<0.1). These results suggest that 1-kestose activated butyrate-producing bacteria as well as bifidobacteria and propose its potential as a new generation prebiotic.

Experimental Determination of the Threshold Dose for Bifidogenic Activity of Dietary 1-Kestose in Rats

1-Kestose is a non-digestible oligosaccharide consisting of glucose linked to two fructose units. While 1-kestose is not digested in the small intestine of mammals, it is fermented in the ceca and colon, where the growth of bifidobacteria is promoted. In the present study, we assessed the threshold dose of dietary 1-kestose that increased cecal bifidobacterial levels in rats. Rats were fed experimental diets containing 0% to 0.3% 1-kestose for four weeks. The levels of the genus Bifidobacterium and total gut bacteria were significantly increased in cecal samples of rats fed the 0.3% 1-kestose diet. Further, a significant correlation between the dose of 1-kestose and the levels of cecal Bifidobacterium and total gut bacteria was observed. The minimum dose of dietary 1-kestose to induce significant bifidogenic activity in rats was 0.3% by weight in the diet.

1-Kestose, the Smallest Fructooligosaccharide Component, Which Efficiently Stimulates Faecalibacterium prausnitzii as Well as Bifidobacteria in Humans

The concept of prebiotics was established more than 30 years ago. While the prebiotic concept has now expanded thus includes non-carbohydrate substances and diverse categories other than foods, fructooligosaccharides (FOS) have still predominantly been used as pebiotics, because the effects of FOS exclusively act through the enrichment of Bifidobacterium and Lactobacillus spp., which have been classified as beneficial intestinal commensals so far. Now the commercially available FOS products are synthetic mixture of several kinds of FOS components including 1-kestose (GF₂), nystose (GF₃) and GF₄. In our previous studies, superiority of 1-kestose to the longer-chain FOS components such as nystose with regard to bifidogenic activity was clearly demonstrated. Recently, a broader range of beneficial bacteria including butyrate-producing indigenous bacteria have been recognized and expected to be new probiotic strains. Among them, resident Faecalibacterium prausnitzii is a butyrate producer with a significant anti-inflammatory effect thus expected to be useful as a next-generation probiotic. However, this bacterium is extremely oxygen-sensitive thus can be difficult to grow industrially. On the other hand, we have clearly demonstrated a significant prebiotic effect of 1-kestose, which is the smallest component of FOS, on F. prausnitzii in the gut of humans. These findings suggest that 1-kestose has impressive potential as a new prebiotic targeting F. prausnitzii, a next-generation probiotic strain, as well as bifidobacteria.

1-Kestose consumption during pregnancy and lactation increases the levels of IgA in the milk of lactating mice

To examine the effect of dietary supplementation with 1-kestose on the IgA levels in milk, BALB/c mice were fed diets with or without 5% 1-kestose during pregnancy and lactation. The total and specific IgA levels in the milk were measured at 7 and 14 days after delivery. A two-way ANOVA with repeated measures resulted in a significant effect of 1-kestose-supplementation on total IgA concentrations (p < 0.05) and the level of anti-Bacteroides IgA (p < 0.05). A significant positive correlation was found between the mean count of Bacteroides spp. in maternal feces and the total IgA concentration in maternal milk (r = 0.55, p < 0.05), suggesting a potential link between the gut and mammary gland immune system. In conclusion, this study demonstrated the effects of dietary prebiotics on milk IgA production.

Carbohydrate composition and invertase activity of the leafy liverwort Porella platyphylla

The major soluble carbohydrates in the desiccation-tolerant leafy liverwort Porella platyphylla (L.) Lindb. are sucrose and a homologous series of fructans including the trisaccharide 1-kestose. Exogenous glucose and fructose (10 mol m^-3 ) did not affect the composition of the soluble carbohydrate pool. Sucrose caused an increase in the fructan pool. Sucrose also inhibited photosynthetic oxygen evolution and respiration. The fructan pool was maintained in preference to sucrose during dark starvation. Low temperature and low water potential increased the fructan pool whereas desiccation increased the proportion of high molecular weight fructan. Acid invertase activity was detected in a taxonomically diverse range of liverworts but was very low or undetectable in a range of mosses. The invertase activity from P. platyphylla was partially purified by ammonium sulphate precipitation. The reaction products of the partially purified enzyme were equimolar glucose and fructose. Kestose and higher DP fructans were not detected suggesting that, at least under the assay conditions used, the enzyme does not have sucrose∶sucrose fructosyl transferase activity. The pH optimum was 4·5-5 and the K_m for sucrose was 1·7 mol m^-3 . Pyridoxal hydrochloride (5 mol m^-3 ) caused 50% inhibition. The coexistence of sucrose and invertase suggests that either the invertase is inactive in vivo or is in a different subcellular compartment from sucrose. The pH response shows that it would have very low activity at cytosolic pH. A large acidic vacuole was detected in P. platyphylla leaf cells by neutral-red staining in which either invertase or sucrose could be sequestered. Rehydrating desiccated P. platyphylla for 10 min resulted in a 60% loss of extractable invertase activity. By contrast, extractable malate dehydrogenase activity increased during rehydration. Rehydrating desiccated leaves caused an increase in glucose and fructose suggesting that the sucrose pool was susceptible to invertase at this time. It is suggested that the partial inactivation of invertase during rehydration minimizes sucrose hydrolysis while membrane structure and subcellular compartmentation are re-established.

Fructan synthesis in oat: I. Oligomer accumulation in stems during cold hardening and their in vitro synthesis in a crude enzyme extract

The accumulation of fructan oligomers in cold hardened oat stems was compared to oligomer synthesis in a crude enzyme extract. Water-soluble carbohydrates were quantified at specified time intervals in three oat cultivars which had been hardened for a total of 5 wk at 2 °C. A crude enzyme extract was prepared from stems of one cultivar hardened for 6 d at 2 °C and incubated at 30 °C with 200 mM sucrose. 1-Kestose was the first oligomer to accumulate in vitro but neokestose rapidly increased after 3 h of incubation and eventually surpassed the level of 1 -kestose. Neokestose and 1-kestose accumulated at similar rates in vivo in the first week of hardening but after 1 week, 1-kestose began to decrease while neokestose remained relatively constant. The same phenomenon was observed in vitro but after only 3 h. 6-Kestose was not observed in vivo or in vitro, except for a trace before hardening began. The first tetramer to increase was 1&6^G -kestotetraose but it subsequently decreased and its concentration was surpassed by that of 6^G ,6-kestotetraose. Similarities and differences between in vivo and in vitro patterns of fructan synthesis are discussed.

Rate of accumulation of fructan oligomers in wheat seedlings (Triticum aestivum L.) during the early stages of chilling treatment

The accumulation of soluble carbohydrates was studied during chilling of 2-week-old wheat (Triticum aestivum L.) seedlings. The extracts were analysed using a C18 HPLC method separating hexoses, sucrose and a wide range of oligofructan. Isomers were recognized and their content determined. The amounts of hexoses, sucrose and the trisaccharides 1-kestose and 6-kestose increased at the beginning of the treatment. The accumulation rate of 1-kestose, the trisaccharide generally considered to be the precursor of fructan, increased ten fold with some delay. Heavier fructan accumulated even later. In leaf blades, 1-3 molecular species with a degree of polymerization from 4 to 8 were detected. Five of these accounted for 90% of this pool at day 5. In leaf bases the amount of carbohydrates was lower but more species of fructan were detected. The sequence of accumulation was the same as in the blades. These results are discussed in relation to current models ot fructan synthesis.