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PubMed1992

Comparison of the effects of ispaghula and wheat bran on rat caecal and colonic fermentation.

The effects of ispaghula and wheat bran on the contents of the caecum and proximal and distal colon of the rat were investigated to identify any differences that might account for their effects on colonic motility. Rats fed diets supplemented with 5% ispaghula and 10% wheat bran for 28 days were killed and the contents of the gut collected. Caecal and colonic content wet and dry weight and short chain fatty acid (SCFA) content were measured. In additional in vitro fermentations in batch cultures of mixed rat caecal bacteria with ispaghula and bran, SCFA production was monitored over 24 hours. Both ispaghula and wheat bran increased faecal weight but ispaghula was more effective. Ispaghula resulted in greater and more liquid contents, with a characteristic pattern of SCFA production (higher propionic acid) maintained throughout the colon. In contrast, wheat bran affected only the caecum and faeces. SCFA content and wet and dry weight in the proximal and distal colon were unaffected by wheat bran. Caecal butyrate was characteristically higher in wheat bran fed rats but ispaghula produced higher butyrate in the distal colon. In contrast, ispaghula seemed to be fermented more quickly in vitro than wheat bran. Thus, wheat bran has a portion that is rapidly fermented and an inert residue that may stimulate motility. Ispaghula seems to be fermented throughout the colon but maintains a high water content which dilutes the luminal contents.

Animals↗

PubMed2002

The degree of methylation influences the degradation of pectin in the intestinal tract of rats and in vitro.

We investigated the degradation, metabolism, fate, and selected effects of pectin in the intestinal tract of rats. Conventional and germfree rats were fed for 3 wk diets containing 6.5% pectin (degree of methylation 34.5, 70.8 and 92.6%, respectively) or pectin-free diets. Pectin passes the small intestine as a macromolecule. The molecular weight distribution of pectins isolated from intestinal contents of germfree rats were unaffected by diet. No or very little galacturonan was found in cecum, colon or feces of most of the conventional rats. In colon contents of some conventional rats, di- and trigalacturonic acid were present. Total anaerobic and Bacteroides counts were greater in groups fed pectin. The concentration of short-chain fatty acids (SCFA) was higher in cecum and feces in all pectin-fed groups. With increasing degree of methylation, the formation rate of SCFA decreased in the cecum of conventional rats. During in vitro fermentation of pectin with fecal flora from rats, unsaturated oligogalacturonic acids appeared as intermediate products. Low-methoxyl pectin was fermented faster than high-methoxyl pectins in vivo and in vitro. Pectin-fed rats had greater ileum, cecum and colon weights. We conclude that structural parameters of pectin influence its microbial degradation in the intestinal tract.

Animals↗

PubMed1998

The bifidogenic nature of chicory inulin and its hydrolysis products.

Research data on the bifidogenic effect of beta(2-1)fructans, which at present are commercialized in the U.S., Japan and Europe as food ingredients, are presented. These food ingredients originate from two different sources. Short-chain fructo-oligosaccharides are synthesized from sucrose and are composed of GFn [n beta(2-1) linked fructose moieties bound to a glucose molecule; 2 </= n </= 4]. The longer chain length molecule inulin is extracted with hot water from chicory roots (Cichorium intybus) and is also composed of GFn molecules (with 2 < n < 60). Oligofructose is a partial hydrolysate of inulin and is composed of GFn and Fm molecules (n and m indicate the number of fructose moieties with 2 </= n, m </= 7). All types of beta(2-1)fructans are well fermented by intestinal bacteria. For a given chain length, there is no difference in fermentation rate between GFn- and Fm-type beta-fructans. In vitro fermentation of inulin revealed that molecules with a chain length (degree of polymerization or DP) > 10 are fermented on average half as quickly as molecules with a DP < 10. All beta(2-1)fructans are bifidogenic and classified as biobiotics.

Bifidobacterium↗

PubMed2001

Initial pH as a determinant of cellulose digestion rate by mixed ruminal microorganisms in vitro.

In vitro fermentations of pure cellulose by mixed ruminal microorganisms were conducted under conditions in which pH declined within ranges similar to those observed in the rumen. At low cellulose concentrations (12.5 g/L), the first-order rate constants (k) of cellulose disappearance were successively lower at initial pH values of 6.86, 6.56, and 6.02, but in each case the value of k was maintained over a pH range of 0.3 to 1.2 units, as the fermentation progressed. Plots of k versus initial pH were linear, and k displayed a relative decrease of approximately 7% per 0.1 unit decrease in pH. At high cellulose concentration (50 g/L) and an initial pH of 6.8, cellulose digestion was initially zero order, the absolute rate of digestion declined with pH and digestion essentially ceased at pH 5.3 after only 30% of the added cellulose was digested. Further incubation resulted in a loss of bound N and P, suggesting that at low pH cells lysed or detached from the undigested fibers. Pure cultures of ruminal cellulolytic bacteria also were able to ferment cellulose to a minimum pH of 5.1 to 5.3, but the extent of fermentation was increased by coculture with noncellulolytic bacteria. A model is proposed in which the first-order rate constant of cellulose digestion is determined by the pH at which the fermentation is initiated, and end product ratios reflect greater activity of the noncellulolytic population as pH declines.

Animals↗

PubMedDate not supplied

Effects of Lavandula officinalis and Equisetum arvense dry extracts and isoquercitrin on the fermentation of diets varying in forage contents by rumen microorganisms in batch culture.

The short-term actions of Lavandula officinalis and Equisetum arvense dry extracts, and of isoquercitrin, flavonoid present in Equisetum arvense, on in vitro fermentation by rumen microbes were studied in batch culture. The orchard grass hay:barley ratios in the three experimental diets were 100:0, 75:25, 50:50 on a DM basis. The production rates of all volatile fatty acids except isobutyrate were strongly influenced by the composition of the diet and to a lesser extent, by plant extracts, with significant interactions between both factors. When hay was the only substrate, the addition of L. officinalis and E. arvense enhanced the fermentation rate by 50%, through an increased release of acetate and propionate. On the contrary, with the two other diets, the fermentation rate was strongly lowered by isoquercitrin. Gas outputs were not significantly influenced by plant extracts.

Animal Feed↗

PubMed1976

Synthesis of ruminal microbial protein and volatile fatty acid production in vitro.

Growth of a mixed ruminal population taken from a sheep on a protein-free (all urea) purified diet was estimated by an in vitro fermentation technique including precipitation of microbial protein by trichloracetic acid. Volatile fatty acid production in vitro was determined, and the associated a denosine triphosphate was estimated as moles volatile fatty acids X 2.4. On this basis, the quantity of microbial protein synthesized per mole of adenosine triphosphate increased at higher microbial growth rates.

Adenosine Triphosphate↗

PubMed1982

Effects of alternating high and medium concentrate diets on fermentation in a semi-continuous rumen culture system.

A semi-continuous culture system was used to determine effects of percent dietary concentrate and method of feeding on in vitro fermentation. Treatments consisted of four feeding regimens 1) 85% concentrate: 85% concentrate diet fed at 0700 and 1900 h; 2) alternate: 85% concentrate diet fed at 0700 h and 55% concentrate fed at 1900 h; 3) 70% concentrate: equal mixture of the 85 and 55% concentrate diets fed at 0700 and 1900 h, and 4) 55% concentrate: 55% concentrate diet fed at 0700 and 1900 h. Total volatile fatty acid concentrations and molar proportions of propionate were highest for the 85% concentrate regimen with no differences among other treatments. Acetate (molar proportion) was lower for the high concentrate diet than for other treatments. Concentrations of fermentation liquor ammonia were 13.4, 11.7, 12.6, and 9.8 mg/100 ml for 85% concentrate, alternate, 70% and 55% concentrate groups. Culture pH was similar for all treatments. Apparent organic matter digestibilities were 41.0, 40.1, 396., and 34.6% and true organic matter digestibilities were 46.3, 45.4, 44.4 and 39.5% for 85% concentrate, alternate, 70%, and 55% concentrate regimens. Bacterial numbers were 1.06, 1.33, .86, and .85 X 10(9) per ml.

Ammonia↗

PubMed1981

Effects of the antibiotic monensin and an inhibitor of methanogenesis on in vitro continuous rumen fermentations.

1. The effects of a methane inhibitor, ICI 111075, and a propionate enhancer, monensin, were studied using in vitro continuous fermenters. 2. Both compounds increased the yield of substrate energy, carbon and hydrogen in volatile fatty acids (VFA). This was mainly due to an increase in the molar proportion of propionic acid. 3. Improved yields of VFA were accompanied by reductions in methane production and microbial yield. 4. Since published information showed that monensin reduced rumen dilution rate in vivo an analogous in vitro system was proposed in which a high dilution rate control fermenter was compared with a monensin treated fermenter set to run at a low dilution rate. 5. Results showed that the general intrinsic microbial activity of the chemical manipulators was not affected by changes in dilution rate. Changing dilution rate in addition to chemical treatment however resulted in substantial modifications in the net effect on the fermentation. 6. The practical implications of reducing rumen dilution rate as a side effect of chemically manipulating the rumen fermentation could involve changes in food intake, increased importance of secondary fermentations and a reduced effect of nutrients not degraded in the rumen.

Animals↗

PubMed1999

The presence of salt and a curing agent reduces bacteriocin production by Lactobacillus sakei CTC 494, a potential starter culture for sausage fermentation.

The specific conditions in the batter of raw fermented sausages may reduce the efficiency of bacteriocin-producing starter cultures. In this work, using in vitro fermentation, we found that sodium chloride and sodium nitrite interfere with the growth of Lactobacillus sakei CTC 494, an organism which produces the antilisterial bacteriocin sakacin K. Because sakacin K production follows primary metabolite kinetics, a decrease in cell formation resulted in a decrease in sakacin K production as well. Sodium chloride dramatically influenced bacteriocin production by decreasing both biomass production and specific bacteriocin production. Sodium nitrite, however, had no effect on specific bacteriocin production and decreased bacteriocin production only because of its effect on cell growth. Moreover, sodium nitrite enhanced the toxic effect of lactic acid on bacterial growth.

Bacteriocins↗

PubMed1975

Fungal cellulase and hemicellulase prediction of forage digestibility.

An enzymatic procedure using Trichoderma viride carbohydrases, a fungal hemicellulase, and pepsin was developed to provide a laboratory method for predicting forage digestibility. The amount of forage dry matter solubilized by enzymes and incubation buffer was less than that in vivo or by in vitro fermentation by rumen microorganisms. Total forage dry matter solubilized by the enzymatic procedure was correlated (.92) with in vitro digestibility. Simple correlation coefficients between in vivo true digestibility of 18 forages and total dry matter solubilized by enzymes and buffer was .87; that soluble in the buffer only, .65; and that solubilized by the enzymes, .82. Correlation coefficients with in vivo true digestible amount of cell-wall and protein were greater when the forage species were considered separately than when pooled together. With this restriction, the enzymatic procedure can be a useful method for predicting forage digestibility. Fermentations with rumen inoculum however, provided more accurate predictions of in vivo digestibility in a variety of forage species.

Animal Feed↗

PubMed2005

Effects of the nematode Gyrinicola batrachiensis on development, gut morphology, and fermentation in bullfrog tadpoles (Rana catesbeiana): a novel mutualism.

We describe a novel mutualism between bullfrog tadpoles (Rana catesbeiana) and a tadpole-specific gastrointestinal nematode (Gyrinicola batrachiensis). Groups of tadpoles were inoculated with viable or nonviable nematode eggs, and development, morphology, and gut fermentation activity were compared between nematode-infected and uninfected tadpoles. Nematode infection accelerated tadpole development; the mean time to metamorphosis was 16 d shorter and the range of times to metamorphosis was narrower in nematode-infected tadpoles than in uninfected tadpoles. At metamorphosis, infected and uninfected bullfrogs did not differ in body size or condition. Colon width, wet mass of colon contents, and concentrations of most fermentation byproducts (short-chain fatty acids: SCFAs) in the hindgut were greater in infected tadpoles. Furthermore, in vitro fermentation yields for all SCFAs combined were over twice as high in infected tadpoles than in uninfected tadpoles. One explanation for accelerated development in infected tadpoles is the altered hindgut fermentation associated with the nematodes. Energetic contributions of fermentation were estimated to be 20% and 9% of the total daily energy requirement for infected and uninfected tadpoles, respectively. Infection by G. batrachiensis nematodes potentially confers major ecological and evolutionary advantages to R. catesbeiana tadpoles. The mutualism between these species broadens our understanding of the taxonomic diversity and physiological contributions of fermentative gut symbionts and suggests that nematodes inhabiting the gut regions of other ectothermic herbivores might have beneficial effects in those hosts.

Animals↗

PubMed2005

Dietary sesamin is converted to enterolactone in humans.

Sesamin, a major sesame seed lignan, has many biological actions. The specific mechanisms for most of these actions as well as the full metabolic pathway of sesamin in humans are unclear. Two experiments were carried out to determine whether postprandial plasma enterolactone is related to sesamin concentration in sesame seeds and whether enterolactone is the major product of the in vitro fermentation of sesamin. Four subjects (3 women, 1 man) were given a single dose of sesame seeds after they consumed a low-lignan diet for 1 wk. Blood was collected at baseline and at time intervals after intake and plasma was analyzed for plant and mammalian lignan concentrations. Additionally, pure sesamin standard was incubated in vitro with human fecal inoculum to mimic the fermentation process in human gut. We calculated individual pharmacokinetic variables and found high interindividual variation in the plasma plant lignan concentrations. The mammalian lignan appearance rate in plasma shows that sesamin is a major precursor of enterolactone in vivo. In the in vitro experiment, enterolactone was the major metabolite and 3 intermediates were identified, allowing the elucidation of sesamin metabolism in humans. Enterolactone was the major metabolite of sesamin both in vivo and in vitro. The abundance of sesamin in sesame seeds indicates that they are a major food source of enterolactone precursors.

4-Butyrolactone↗

PubMed1989

Effects of halogenated hydrocarbons on rumen microorganisms.

Halogenated hydrocarbons such as polychlorinated biphenyls (PCB's), heptachlor (HEP), 1,1,1-trichloro-2,2-bis(p-chlorophenyl)-ethane (DDT), and pentachlorophenol (PCP) are environmental contaminants and, at times, can bioaccumulate in the food chain. Cattle have been contaminated in a variety of ways, but generally it is believed that they are only affected by high concentrations of the chemicals. Rumen microorganisms, however, may be affected at lower doses, thus possibly affecting the cow's growth and milk production. Polychlorinated biphenyls, HEP, DDT, and PCP were tested by a 1-stage in vitro fermentation procedure. Substrate utilization was determined by measuring percent dry matter disappearance. Four concentrations (0, 10, 50, and 100 ppm) were studied, and in vitro incubations were conducted for 24 and 48 hr. Samples were removed from 48-hr incubations to determine if the chlorinated hydrocarbons were metabolized during fermentation. Dry matter disappearance proved to be a reliable method to determine microbial activity in the presence of chemicals. Substrate dry matter disappearance for controls and all concentrations of PCB's, HEP, and DDT was approximately 50 and 80% at 24 and 48 hr, respectively. The PCP significantly (P less than 0.05) depressed the percent dry matter disappearance in 50- and 100-ppm cultures to 45 and 30% at 24 hr and 70 and 50% at 48 hr, respectively. Metabolic changes in the test chemicals were not detected by gas chromatographic analysis.

Animals↗

PubMed1997

Consequences of biofilm and sessile growth in the large intestine.

The human colonic ecosystem is an extremely complex environment comprised of several hundred different strains of bacteria. Studies were undertaken to determine whether these organisms formed metabolic or genotypically distinct assemblages in the gut microbiota in relation to polysaccharide fermentation. Measurements of depolymerizing enzymes (4 polysac-charidases, 6 glycosidases) showed that specific amylase and pectinase activities were comparable in bacteria desorbed from the surfaces of food particles and in non-particulate organisms. However, xylanase, beta-xylosidase, arabinogalac-tanase, alpha-arabinofuranosidase, and beta-galacturonidase activities were always significantly greater in particulate bacteria. Short-term in vitro fermentations with both groups of bacteria showed marked differences in relative rates of starch, arabinogalactan, and mucin metabolism, while rates of fermentation product formation with pectin and xylan were broadly comparable. Significant differences were observed with respect to formation of individual fermentation products, especially when mucin or pectin were substrates, where particulate bacteria produced proportionally higher amounts of acetate. Bacteriological studies showed that communities of polymer-degrading bacteria and other groups of intestinal anaerobes growing on particulate matter were essentially similar to those occurring elsewhere in the gut lumen, at genus and species levels. In vitro colonization experiments demonstrated that a variety of polysaccharide-fermenting bifidobacteria and bacteroides--together with other cross-feeding organisms such as peptostreptococci, fusobacteria, and coliforms--rapidly attached to particulate intestinal materials.

Bacteria, Anaerobic↗

PubMed1993

Colonic fermentation of complex carbohydrates in patients with familial adenomatous polyposis.

Decreased production of butyric acid by colonic carbohydrate fermentation may predispose to colonic carcinogenesis, with the implicit assumption that the decrease in faecal butyrate found predates the development of the tumour. The influence of the genetic predisposition to colonic tumours and the presence of colonic polyps on in vitro fermentation of carbohydrates was examined. Stool samples from 11 normal controls and 20 patients with familial adenomatous polyposis (FAP) were incubated anaerobically with a range of carbohydrates. Fermentation patterns were similar for glucose and raffinose. These sugars produced different short chain fatty acid (SCFA) patterns from the two polysaccharides, starch and arabinogalactan, which differed one from the other. The FAP gene carriers with polyps produced less butyrate than normal controls (p < 0.005) and gene carriers without polyps (p < 0.05). There were corresponding decreases in the molar ratios of butyrate. Gene carriers without polyps produced less absolute amounts of acetate than normal controls (p < 0.05) and slightly less total SCFAs (p < 0.05) but were otherwise not significantly different. The decreased production of butyrate noted by other workers may be secondary to the tumours rather than a contributory cause.

Adenomatous Polyposis Coli↗

PubMed2000

Effect of oral antibiotics on intestinal production of propionic acid.

BACKGROUND: Propionic acid derived from colonic bacterial fermentation contributes substantially to overall propionate load in children with disorders of propionate metabolism, and its reduction is important for adequate metabolic control. AIMS: To evaluate the in vitro and in vivo effects of antibiotic treatment on propionate production by colonic bacteria, and plasma propionate concentrations in a child with propionic acidaemia. METHODS: In vitro fermentation techniques were used to study the effects of addition of antibiotics (metronidazole, clindamycin, erythromycin, and vancomycin) on net faecal production of short chain fatty acids including propionic acid. Courses of oral antibiotics of 7 days duration were used to assess the in vivo effects on faecal propionate production and metabolic control including plasma propionate concentrations. RESULTS: Metronidazole produced the largest and most consistent reduction (77-84%) in the production in vitro of propionate from faecal homogenates. Oral administration of metronidazole reduced faecal propionate production by 43% within 24 hours of treatment; a 7 day course virtually eliminated it for the next 3 weeks. These reductions were accompanied by substantially lowered plasma propionate concentrations during the same period. CONCLUSIONS: Intermittent courses of oral metronidazole might be as effective as continuous treatment in reducing gut propionate production in children with disorders of propionate metabolism.

Amino Acid Metabolism, Inborn Errors↗

PubMed1988

Influence of forage type on ruminal bacterial populations and subsequent in vitro fiber digestion.

Adaptation of the rumen fibrolytic bacteria to legume, C3 grass, and C4 grass forages was examined in a 3 X 3 Latin square. Fistulated steers were fed alfalfa, smooth bromegrass, and switchgrass hays for 6 wk at 1.8% of body weight. Rumen samples were collected weekly after an overnight fast. Bacterial counts were conducted on rumen samples and all rumen samples were used in an in vitro fiber digestion study with three stages of maturity each for alfalfa, smooth bromegrass, and switchgrass as the substrates. Consumption of alfalfa hay resulted in the highest total viable counts of rumen bacteria but a lower proportion of fibrolytic counts than seen on the grass diets. Use of filter paper as the isolation substrate gave higher fibrolytic counts than seen with NDF of the forage fed as the isolation substrate. Fifty percent or more of the fibrolytic bacteria were Bacteriodes succinogenes, and the switchgrass diet resulted in higher proportions of this organism in the fibrolytic population than seen for alfalfa and smooth bromegrass hays. The rumen inoculum from animals fed alfalfa degraded the fiber fractions of all substrate forages best. Improved in vitro digestibility of a forage was not observed due to feeding the same forage to the donor animals. Volatile fatty acid concentrations and proportions in the in vitro fermentations were related more to forage substrate than diet source. The results indicate that adaptation of the rumen population to diet forage composition occurred, but in vitro digestibility was unrelated to fibrolytic bacterial numbers or proportions.

Adaptation, Biological↗

PubMed1993

Microbial delignification with white rot fungi improves forage digestibility.

Three wild-type white rot fungi and two cellulase-less mutants developed from Phanerochaete chrysosporium K-3 (formerly Sporotrichum pulverulentum) were tested for their ability to delignify grass cell walls and improve biodegradation by rumen microorganisms. Fungal-treated and control stems of Bermuda grass were analyzed for their content of ester- and ether-linked aromatics by using alkali extraction and gas chromatography, for in vitro dry weight digestion and production of volatile fatty acids in in vitro fermentations with mixed ruminal microorganisms, for loss of lignin and other aromatics from specific cell wall types by using microspectrophotometry, and for structural changes before and after in vitro degradation by rumen microorganisms by using transmission electron microscopy. P. chrysosporium K-3 and Ceriporiopsis subvermispora FP 90031-sp produced the greatest losses in lignin and improved the biodegradation of Bermuda grass over that of untreated control substrate. However, C. subvermispora removed the most lignin and significantly improved biodegradation over all other treatments. Phellinus pini RAB-83-19 and cellulase-less mutants 3113 and 85118 developed from P. chrysosporium K-3 did not improve the biodegradation of Bermuda grass lignocellulose. Results indicated that C. subvermispora extensively removed ester-linked p-coumaric and ferulic acids and also removed the greatest amount of non-ester-linked aromatics from plant cell walls. Microscopic observations further indicated that C. subvermispora removed esters from parenchyma cell walls as well as esters and lignin from the more recalcitrant cell walls (i.e., sclerenchyma and vascular tissues). C. subvermispora improved in vitro digestion and volatile fatty acid production by ruminal microorganisms by about 80%, while dry matter loss due to fungi was about 20% greater than loss in untreated control stems. The chemical and structural studies used identified sites of specific fungal attack and suggested mechanisms whereby improvement occurred.

Journal Article↗