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PubMed2006

Supplemental dietary inulin affects the bioavailability of iron in corn and soybean meal to young pigs.

Iron deficiency represents one of the most common global nutritional disorders in humans. Our objective was to determine whether and how supplemental inulin improved utilization of iron intrinsically present in a corn and soybean meal diet by young pigs for hemoglobin repletion. In Expt. 1, 3 groups (n = 8/group) of pigs were fed a corn and soybean meal-based diet (BD, without inorganic iron addition) or BD + 2 or 4% inulin (Synergy 1: a mixture of oligofructose and long-chain inulin HP, Orafti) for 5 wk. Final blood hemoglobin concentrations and the overall hemoglobin repletion efficiency of pigs were positively (r = 0.55 and 0.69, P < 0.01) correlated with dietary inulin concentrations. Compared with pigs fed the BD, those fed 4% inulin demonstrated a 28% improvement (P < 0.01) in hemoglobin repletion efficiency and 15% (P < 0.01) improvement in the final blood hemoglobin concentration. In Expt. 2, 12 weanling pigs (n = 6/group) were fed the BD or the BD + 4% inulin for 6 wk. Pigs fed 4% inulin had higher (P < 0.05) soluble Fe concentrations in the digesta of the proximal, mid, and distal colon, and lower (P < 0.05) sulfide concentrations in the digesta of the distal colon. Supplemental inulin had virtually no effect on pH or phytase activity of digesta from any of the tested segments. In conclusion, supplementing 4% inulin improved utilization of intrinsic iron in the corn and soybean meal diet by young pigs, and this benefit was associated with soluble Fe and sulfide concentrations but not pH or phytase activity in the digesta.

Animal Feed↗

PubMed2000

Enteral inulin does not affect epithelial gene expression and cell turnover within the ileoanal pouch.

PURPOSE: This study evaluates the effects of enteral inulin on ileoanal pouch functioning by studying epithelial gene expression, cell turnover, and mucosal morphology. METHODS: Twenty patients with an ileoanal pouch received 24 g of inulin daily for three weeks, then a four-week wash-out period, and a placebo for three weeks. In this randomized, double-blind, crossover study, biopsy specimens of pouch mucosa were taken after each test period. Mucosal morphology, inflammation, epithelial proliferation, and cell death were assessed histologically. Expressions of proapoptotic and antiapoptotic regulators, intestinal fatty acid-binding protein, and mucin were quantified by Western blotting or enzyme-linked immunosorbent assay. The number of intestinal fatty acid-binding protein expressing cells was histologically assessed and a high iron diamine/Alcian blue staining was performed to discriminate between sulfated and nonsulfated acidic mucins. RESULTS: Inulin supplementation neither altered mucosal morphology nor influenced inflammation, epithelial cell proliferation, or cell death. The ratio between the proapoptotic and antiapoptotic regulators did not change after inulin supplementation. The number of intestinal fatty acid-binding protein-producing enterocytes and the intestinal fatty acid-binding protein expression level increased after inulin treatment, but did not reach statistical significance. The intestinal fatty acidbinding protein expression level correlated with the Pouchitis Disease Activity Index, which was at the brink of significance (P = 0.06). Mucin expression and the ratio between sulfated and nonsulfated acidic mucins were not altered by inulin supplementation. CONCLUSION: In this prospective study, inulin supplementation did not significantly alter pouch mucosal functioning because neither epithelial homeostasis nor epithelial gene expression was significantly altered by enteral inulin.

Adult↗

PubMed2004

Stimulatory effect of inulin on intestinal absorption of calcium and magnesium in rats is modulated by dietary calcium intakes short- and long-term balance studies.

Previous studies have shown that short-term intake of fermentable oligosaccharides (OS), including inulin, can increase mineral intestinal absorption in humans and animals. While the stimulatory effect of these substances on intestinal magnesium (Mg) absorption is generally high and consistent, their effect on calcium (Ca) seems to depend on experimental conditions, particularly the duration of fermentable OS intake. The aim of this study was to determine how the short- and long-term dietary Ca intake may modulate the effect of inulin on Ca absorption. Sixty male Wistar rats, weighing 275 g, were randomized into two groups to receive or not 10% of inulin in their diet. Each group was divided into three sub-groups to receive one of the following dietary Ca levels 0.25%, 0.50% and 0.75% in their food. The animals were fed fresh food and water ad libitum for 40 days. Apparent intestinal absorptions of Ca and Mg were determined at D13 and D36 of the experiment. As expected, inulin feeding increased Ca and Mg absorption in both periods at all dietary Ca levels. However, the effect of inulin on intestinal Ca absorption was dependent on dietary Ca levels and on experiment duration. In the short-term period, the inulin effect was prominent in the groups receiving high or low Ca levels, but in long-term period inulin improved intestinal Ca absorption much more in the group receiving the low Ca level. In addition, efficiency of intestinal absorption of Ca and Mg (%) was negatively affected by Ca intake levels. These results show that the beneficial effect of inulin on intestinal Ca absorption may be more marked in cases where the Ca intake is low or where the organism's Ca requirement is high. Further studies are required to confirm these results in humans.

Animals↗

PubMed1999

The effect of the daily intake of inulin on fasting lipid, insulin and glucose concentrations in middle-aged men and women.

The present study was carried out to examine the effect of the daily intake of 10 g inulin on fasting blood lipid, glucose and insulin levels in healthy middle-aged men and women with moderately raised total plasma cholesterol (TC) and triacylglycerol (TAG) levels. This study was a double-blind randomized placebo-controlled parallel study in which fifty-four middle-aged subjects received either inulin or placebo for a period of 8 weeks. Fasting blood samples were collected before the supplementation period (baseline samples 1 and 2, separated by 1 week) and at weeks 4 and 8, with a follow-up at week 12. Compared with baseline values, insulin concentrations were significantly lower at 4 weeks (P < 0.01) in the inulin group. There was a trend for TAG values, compared with baseline, to be lower in the inulin group at 8 weeks (P < 0.08) returning to baseline concentrations at week 12. On comparison of the inulin and placebo groups, the fasting TAG responses over the 8-week test period were shown to be significantly different (P < 0.05, repeated measures ANOVA), which was largely due to lower plasma TAG levels in the inulin group at week 8. The percentage change in TAG levels in the inulin group during the 8-week study was shown to correlate with the initial TAG level of the subjects (rs -0.499, P = 0.004). We therefore conclude that the daily addition of 10 g inulin to the diet significantly reduced fasting insulin concentrations during the 8-week test period and resulted in lower plasma TAG levels, particularly in subjects in whom fasting TAG levels were greater than 1.5 mmol/l. These data support findings from animal studies that fructans influence the formation and/or degradation of TAG-rich lipoprotein particles, and the insulin data are also consistent with recent studies showing attenuation of insulin levels in fructan-treated rats.

Adult↗

PubMed1999

Effects of inulin on faecal bifidobacteria in human subjects.

A controlled study with eight healthy free-living subjects was carried out, in which energy intake was adjusted to the individual energy requirements. On administration of inulin, blood lipids, the faecal microflora, short-chain fatty acids and accompanying gastrointestinal symptoms were characterized in order to investigate the long-term effect of inulin. During the run-in phase (8 d), subjects received a typical Western diet providing 45% energy as fat and 40% energy as carbohydrate. Subsequently, the subjects consumed a fat-reduced diet which provided 30% energy as fat and 55% energy as carbohydrate for a period of 64 d using inulin as a fat replacer. The amounts of inulin consumed by the subjects (up to 34 g/d) were based on individual energy requirements with the aim to keep the diet isoenergetic with that used in the run-in period. To assess the effects of inulin administration, a control study (run-in and intervention) was carried out in which subjects consumed the same diet but devoid of inulin during the whole course of the study. To investigate the effect of inulin on faecal flora composition total bacteria and bifidobacteria in the faeces were enumerated by in situ hybridization with 16S rRNA targeted oligonucleotide probes. Inulin significantly increased bifidobacteria from 9.8 to 11.0 log10/g dry faeces and caused a moderate increase in gastrointestinal symptoms such as flatulence and bloatedness, whereas blood lipids and short-chain fatty acids remained essentially unaffected.

Adult↗

PubMed2004

Enrichment of higher molecular weight fractions in inulin.

Inulin (general formulas GFn and Fm, with G = anhydroglucose and F = anhydrofructose) naturally occurs as a homologous series of oligo- and polysaccharides with different chain lengths. For reasons of growing interest in the food and pet food industries, the short chain inulins have to be separated from their long chain analogues because their properties (digestibility, prebiotic activity and health promoting potential, caloric value, sweetening power, water binding capacity, etc.) differ substantially. To study these properties in relation to the number average degree of polymerization (DPn), ultrafiltration, specific crystallization from aqueous solution, and precipitation from solvent/water mixtures were used to enrich native chicory and dahlia inulin in the higher molecular weight fractions. Depending on the membrane module used, the DPn of chicory inulin (DPn = 8.1) and dahlia inulin (DPn = 29) could be increased by ultrafiltration to a maximum value of, respectively, 22 and 43. With crystallization from aqueous solutions (25 degrees C), similar results were obtained but at a much higher yield. Finally, long chain inulin could be precipitated from aqueous solutions in the presence of high concentrations of methanol, ethanol, and acetone. Acetone demonstrated to be the best solvent system to increase the DPn, followed by ethanol and methanol. However, for safety reasons and food purposes, ethanol was evaluated to be the best choice. With ethanol, the DPn could be raised to 25 for chicory inulin and up to 40 for dahlia inulin.

Chemical Precipitation↗

PubMed2004

Inulin effects on bioavailability of soy isoflavones and their calcium absorption enhancing ability.

The effect of inulin on isoflavone absorption and the effect of isoflavones and synergy with inulin on calcium absorption in rats was investigated. Rats (n = 48) were divided into three groups and fed inulin (50 mg/g), isoflavone (8 mg/g) or inulin + isoflavone (50 mg/g + 8 mg/g) diets for 21 days. After a 2-h fast, rats were given (45)Ca orally or intraperitoneally, together with 25 mg of calcium as calcium acetate. Blood and femurs were collected 4 days later. Sera were analyzed for isoflavones using HPLC-MS, femurs for (45)Ca by beta-scintillation counting, and total femoral calcium by atomic absorption spectroscopy. Both groups fed isoflavones had similar and significantly higher weight-adjusted total femoral calcium content compared to the inulin-fed group (p < 0.0001). (45)Ca absorption was significantly higher (p < 0.01) when isoflavones were added to the diet, and serum equol was significantly lower (p < 0.01) when inulin was added to the diet containing isoflavones. We conclude that isoflavones enhance calcium absorption, without synergy from inulin, and that inulin decreases equol production.

Absorption↗

PubMed1993

The renal clearance and infusion clearance of inulin are similar, but not identical.

Thirty-eight simultaneous renal (R-Cin) and infusion (INF-Cin) clearances of inulin were done. The equilibration period preceding the clearance studies was of at least two hours duration. The R-Cin on each subject was based on two clearance periods during which the plasma inulin concentration ([P(in)]) varied by 1.0 mg/dl or less and the rate of inulin excretion by less than 10%. There was excellent correlation between the R-Cin and the INF-Cin (r = 0.976), but the INF-Cin consistently exceeded the R-Cin (mean difference = 13.8 +/- 8.8 ml/min/1.73 m2, t = 9.7163 and P = < 0.001). Complete equilibration of inulin in body fluids has been assumed when [P(in)] levels were relatively constant (variation < 10%). However, complete equilibration of inulin would not be present, even with relatively constant P(in) levels, if the rate of infusion of inulin were equal to the rate of excretion plus the rate of penetration of inulin into less permeable components of the extracellular fluid compartment (that is, dense connective tissue solids). Estimation of glomerular filtration rate using the INF-Cin requires complete equilibration of inulin in body fluids, a process probably requiring 12 to 15 hours or longer.

Adolescent↗

PubMed1997

Inulin and oligofructose do not influence the absorption of cholesterol, or the excretion of cholesterol, Ca, Mg, Zn, Fe, or bile acids but increases energy excretion in ileostomy subjects.

OBJECTIVE: To investigate the effects of inulin and oligofructose on cholesterol absorption and excretion of cholesterol, bile acids, energy, nitrogen and minerals in man. DESIGN: Double-blind cross-over study. SETTING: Metabolic kitchen with policlinic visits, Sahlgrenska Hospital, Göteborg, Sweden. SUBJECTS: Patients with conventional ileostomy because of ulcerative colitis. INTERVENTIONS: 7 g of inulin, 17 g of oligofructose and 7 g of sucrose were added to a controlled diet during three experimental periods of three days each. Ileostomy effluents were collected and analysed. Differences between experimental and control diet were investigated with the Wilcoxon's sign and values test. RESULTS: Inulin and oligofructose were recovered in the ileostomy effluent to 88% (95% CI, 76-100%) and 89% (64-114%) respectively. Dry solid excretion increased by 14.4 g (11.3-17.5) on inulin, and by 14.7 g (13.0-16.4 g) on oligofructose and energy excretion increased 245 kJ (190-307 kJ) on inulin and 230 kJ (214-315 kJ) on oligofructose compared to control diet (P < 0.05). Cholesterol absorption, excretion of cholesterol, bile acids, nitrogen, fat, calcium, magnesium, zinc and iron were not affected by inulin and oligofructose. CONCLUSIONS: Inulin and oligofructose are not digested in the small intestine. They do not affect mineral excretion and hence hardly mineral absorption. They do not increase fat or nitrogen excretion from the small intestine. Any physiological effect of inulin and oligofructose is probably mediated through other mechanisms than altered excretion from the small intestine.

Adult↗

PubMed2006

Dietary inulin intake and age can affect intestinal absorption of zinc and copper in rats.

Nondigestible inulin-type fructan intake can stimulate intestinal mineral absorption in both humans and animals. However, this stimulatory effect may depend on experimental conditions such as the duration of the experience, mineral levels in the diet, and the animal's physiological status. The aim of this study was to determine the effect of inulin intake on Zn and Cu absorption in rats at different ages. Male Wistar rats (n = 80) of 4 different ages (2,5, 10, and 20 mo) were randomly assigned to a control group or a group administered 3.75% inulin in their diet for 4 d followed by 7.5% inulin for 26 d. Absorption of Zn67 and Cu65 was determined on d 21 of the experiment by fecal monitoring using Zn67 and Cu65 isotopes. Zn and Cu status was also assessed. Absorption of Zn67 and Cu65 was significantly lower in 11- and 21-mo-old rats than in 3- and 6 mo-old-rats. Moreover, inulin intake significantly increased Zn67 and Cu65 absorption. In conclusion, age and dietary inulin intake can significantly affect intestinal absorption of zinc and copper in rats. Further studies are required to explore this effect over longer periods of inulin intake and to test the effects of inulin in humans.

Aging↗

PubMed1983

Inulin single injection clearance. Microsample technique useful in children for determination of glomerular filtration rate.

The agreement between single injection inulin (polyfructosan) clearance and two reference methods for glomerular filtration rate (GFR) determination, namely standard inulin constant infusion clearance and 51-Cr-EDTA single injection clearance, was investigated. Studies were also made to see whether different results were obtained when capillary and venous blood samples were used in the single injection clearance method. The investigation was made in children from one year of age, adult patients and volunteers. For the single injection technique with inulin or 51-Cr-EDTA, five to seven blood samples were taken in a period of up to 180 min after injection. A bi-exponential plasma disappearance curve was used for calculations of single injection clearances. Good agreement was obtained between venous inulin single injection clearance on the one hand, and standard inulin clearance (correlation coefficient r = 0.86) and 51-Cr-EDTA single injection clearance on the other (r = 0.85). With use of capillary blood samples in inulin single injection clearance, similar good agreement was obtained both with venous 51-Cr-EDTA and with venous inulin single injection clearance (r = 0.85 and r = 0.89 respectively). From these results we conclude that inulin single injection clearance is a reliable method for GFR determinations. This method is recommended, especially in children, as capillary blood samples can be used.

Adolescent↗

PubMed1993

Production of high concentrations of ethanol from inulin by simultaneous saccharification and fermentation using Aspergillus niger and Saccharomyces cerevisiae.

Pure nonhydrolyzed inulin was directly converted to ethanol in a simultaneous saccharification and fermentation process. An inulinase-hyperproducing mutant, Aspergillus niger 817, was grown in a submerged culture at 30 degrees C for 5 days. The inulin-digestive liquid culture (150 ml) was supplemented with 45 g of inulin, 0.45 g of (NH4)2SO4, and 0.15 g of KH2PO4. The medium (pH 5.0) was inoculated with an ethanol-tolerant strain, Saccharomyces cerevisiae 1200, and fermentation was conducted at 30 degrees C. An additional 20 g of inulin was added to the culture after 15 h of fermentation. S. cerevisiae 1200 utilized 99% of the 65 g of inulin during the fermentation, and produced 20.4 and 21.0% (vol/vol) ethanol from chicory and dahlia inulins, respectively, within 3 days of fermentation. The maximum volumetric productivities of ethanol were 6.2 and 6.0 g/liter/h for chicory and dahlia inulins, respectively. The conversion efficiency of inulin to ethanol was 83 to 84% of the theoretical ethanol yield.

Aspergillus niger↗

PubMed2005

Fermentation of fructooligosaccharides and inulin by bifidobacteria: a comparative study of pure and fecal cultures.

The utilization of fructooligosaccharides (FOS) and inulin by 55 Bifidobacterium strains was investigated. Whereas FOS were fermented by most strains, only eight grew when inulin was used as the carbon source. Residual carbohydrates were analyzed by high-performance anion-exchange chromatography with pulsed amperometric detection after batch fermentation. A strain-dependent capability to degrade fructans of different lengths was observed. During batch fermentation on inulin, the short fructans disappeared first, and then the longer ones were gradually consumed. However, growth occurred through a single uninterrupted exponential phase without exhibiting polyauxic behavior in relation to the chain length. Cellular beta-fructofuranosidases were found in all of the 21 Bifidobacterium strains tested. Four strains were tested for extracellular hydrolytic activity against fructans, and only the two strains which ferment inulin showed this activity. Batch cultures inoculated with human fecal slurries confirmed the bifidogenic effect of both FOS and inulin and indicated that other intestinal microbial groups also grow on these carbon sources. We observed that bifidobacteria grew by cross-feeding on mono- and oligosaccharides produced by primary inulin intestinal degraders, as evidenced by the high hydrolytic activity of fecal supernatants. FOS and inulin greatly affected the production of short-chain fatty acids in fecal cultures; butyrate was the major fermentation product on inulin, whereas mostly acetate and lactate were produced on FOS.

Bifidobacterium↗

PubMed1999

A simple, nonradioactive method for evaluating single-nephron filtration rate using FITC-inulin.

The determination of inulin concentration in nanoliter fluid samples is fundamental to micropuncture investigations of renal function, and this is generally accomplished through the use of radioisotopes. We report here a simple and reliable alternative to the use of radioisotopes that employs FITC-labeled inulin. Samples containing FITC-inulin are stored between oil columns in constant-bore microcapillary tubes, which are then used as cuvettes to determine fluorescence on a microscope fluorometer. Standard curves were generated and found to be linear, with correlation coefficients (R) exceeding 0.99 in every case. Although the fluorescence of FITC-inulin was found to be pH dependent, the pH and fluorescence of each 20- to 40-nl sample could be normalized by the addition of 1 nl of 0.5 M HEPES at pH 7.5. In mice prepared for standard micropuncture, simultaneous measurements of tubular fluid-to-plasma ratios (TF/P) using FITC-inulin and [125I]iothalamate were highly correlated (slope = 0.95, y-intercept = 0.01, R = 0.942), as were whole kidney measurements of glomerular filtration rate (GFR) (slope = 1.25, y-intercept = -53.5 microliter/min, R = 0.99). Micropuncture determinations of late-proximal samples from mice before and after treatment with acetazolamide showed expected changes: TF/P of FITC-inulin decreased from 1.89 +/- 0.07 to 1.48 +/- 0.10; single-nephron GFR (SNGFR) decreased from 9.64 +/- 1.1 to 6.65 +/- 1. 0 nl/min; and fractional fluid reabsorption decreased from 45.3 +/- 1.9 to 26.8 +/- 5.2%. Measurements of TF/P of FITC-inulin, volume, and SNGFR using this technique were stable for at least 2 wk when samples were stored in the dark at 4 degreesC. These data demonstrate that this simple method for determining inulin clearance represents a viable and accurate alternative to radioactive methods. This approach has the added benefits of being relatively inexpensive and leaving the micropuncture sample intact.

Absorption↗

PubMed1985

Inulin space studies in fetal sheep.

Extracellular volume was estimated in fetal sheep by measuring the 14C inulin space in 6 in situ unanesthetized fetal lambs at gestational ages ranging from 120 to 145 days (term = 150 days). The total inulin space ranged from 979 to 1,510 ml. A positive correlation between total inulin space and gestational age (r = 0.65) was noted, such that fetal lambs of 120 days gestation had a predicted inulin space of 1,072 ml and fetal lambs near term at 145 days gestation had an inulin space of 1,422 ml. However, since fetal weight increases with gestation, inulin space expressed as a percent of body weight actually decreased with gestational age (r = -0.80), so that at 120 days gestation the fetus would have an estimated inulin space of 59% of body weight and at 145 days the fetus would have an inulin space of only 34% of body weight.

Animals↗

PubMed2005

Dietary inulin intake and age can significantly affect intestinal absorption of calcium and magnesium in rats: a stable isotope approach.

BACKGROUND: previous studies have shown that non-digestible inulin-type fructan intake can increase intestinal mineral absorption in both humans and animals. However, this stimulatory effect on intestinal absorption may depend on experimental conditions such as duration of fermentable fiber intake, mineral diet levels and animals' physiological status, in particular their age. OBJECTIVES: the aim of this study was to determine the effect of inulin intake on Ca and Mg absorption in rats at different age stages. METHODS: eighty male Wistar rats of four different ages (2, 5, 10 and 20 months) were randomized into either a control group or a group receiving 3.75% inulin in their diet for 4 days and then 7.5% inulin for three weeks. The animals were fed fresh food and water ad libitum for the duration of the experiment. Intestinal absorption of Ca and Mg was determined by fecal monitoring using stable isotopic tracers. Ca and Mg status was also assessed. RESULTS: absorption of Ca and Mg was significantly lower in the aged rats (10 and 20 mo) than in the young and adult rat groups. As expected, inulin intake increased Ca and Mg absorption in all four rat groups. However, inulin had a numerically greater effect on Ca absorption in aged rats than in younger rats whereas its effect on Mg absorption remained similar across all four rat age groups. CONCLUSION: the extent of the stimulatory effect of inulin on absorption of Ca may differ according to animal ages. Further studies are required to explore this effect over longer inulin intake periods, and to confirm these results in humans.

Aging↗

PubMed2003

A dose-response experiment evaluating the effects of oligofructose and inulin on nutrient digestibility, stool quality, and fecal protein catabolites in healthy adult dogs.

In this experiment, three concentrations (0.3, 0.6, and 0.9% of diet, as-fed basis) of two fructans, oligofructose (OF) and inulin, were tested against a 0% supplemental fructan control. Seven ileal-cannulated adult female dogs were fed a meat-based, kibbled diet and assigned to treatments in a 7 x 7 Latin square design. Dietary supplementation of fructans had no effect on nutrient intakes or ileal digestibilities. Total-tract digestibilities of DM, OM, and CP decreased (P < 0.05) as a result of dietary OF and inulin supplementation. Dogs fed the control diet had a DM total-tract digestibility of 83.0%. The percentages of fecal DM for dogs fed the control and 0.3, 0.6, and 0.9% OF were 36.6, 33.3, 32.8, and 31.7%, respectively. When compared with the control, OF (P < 0.01) and inulin (P < 0.01) supplementation increased fecal ammonia concentrations. Higher fecal short-chain fatty acid (SCFA; P < 0.10) and isovalerate concentrations (P < 0.01) were noted for dogs fed both fructans. Total fecal SCFA for dogs fed the control diet and 0.3, 0.6, and 0.9% OF were 406.4, 529.9, 538.3, and 568.8 micromol/g of feces (DM basis), respectively. Dogs fed 0.3, 0.6, and 0.9% inulin had total fecal SCFA of 472.2, 468.8, and 471.5 micromol/g of feces (DM basis), respectively. Linear increases were observed in putrescine (P < 0.11), cadaverine (P < 0.07), spermidine (P < 0.12), and total amines (P < 0.05) in feces of dogs fed OF. Lower fecal phenol (P < 0.08) and total phenol (P < 0.04) concentrations occurred in dogs fed inulin, along with a linear decrease (P < 0.08) in total phenols with OF supplementation. Total fecal phenols for dogs fed the control, 0.3, 0.6, and 0.9% inulin were 3.03, 1.86, 1.97, and 2.23 micromol/g of feces (DM basis), respectively. Low-level dietary inclusion of inulin and OF positively affected indices known to be associated with gut health of the dog without seriously compromising nutrient digestibility or stool quality. Overall, the 0.9% OF treatment resulted in the best responses, including no adverse effect on nutrient intakes, ileal digestibilities, or stool quality, as well as increased fecal SCFA and decreased fecal phenols. The biological responses due to inulin were more variable.

Ammonia↗

PubMedDate not supplied

Cell-wall structure and composition of Penicillium janczewskii as affected by inulin.

Penicillium janczewskii, a filamentous fungus isolated from the rhizosphere of Vernonia herbacea (Asteraceae), grows rapidly on media containing either sucrose or inulin as carbon sources. Maintenance of P. janczewskii on inulin medium induces secretion of proteins with high inulinase activity but results in a mycelium that easily collapses and breaks. We evaluated the influence of inulin on fungal growth and colony morphology and on cell-wall structure and composition in comparison with growth and wall characteristics on sucrose-containing medium. P. janczewskii grown on Czapek medium with agar containing 1% (w/v) sucrose or inulin showed differences in the color and morphology of the colonies, although growth rates were similar on both carbon sources. Scanning-electron microscopy revealed that the hyphae from fungus grown on inulin-containing medium are much thinner than those from fungus cultivated on sucrose. Ultrastructural analysis of 5 d old cultures using transmission-electron microscopy indicated significant differences in the cell-wall thickness between hyphae grown on inulin or sucrose media. No differences were detected in the overall carbohydrate and protein contents of cell walls isolated from cultures grown on the two carbon sources. Glycosyl composition analyses showed glucose and galactose as the predominant neutral monosaccharides in the walls but showed no differences attributable to the carbon source. Glycosyl linkage composition analyses indicated a predominance of 3-linked glucopyranosyl in the hyphal walls when P. janczewskii was grown on inulin-containing medium. Our results suggest that growth on inulin as the sole carbon source results in structural changes in the mycelia of P. janczewskii that lead to mycelial walls with altered physical and biological properties.

Carbohydrates↗