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PubMed1998

Fermentable dietary fiber increases GLP-1 secretion and improves glucose homeostasis despite increased intestinal glucose transport capacity in healthy dogs.

Ileal proglucagon gene expression and postprandial plasma concentrations of proglucagon-derived peptides are reported to change with the type and quantity of dietary fiber ingested by rats. Within the intestine, proglucagon encodes several proglucagon-derived peptides known to modulate intestinal absorption capacity and pancreatic insulin secretion. To determine whether the chronic ingestion of fermentable dietary fiber regulates the expression and synthesis of proglucagon-derived peptides in the distal intestine to modulate glucose homeostasis, the following study was conducted: 16 adult dogs (23 +/- 2 kg) were fed isoenergetic, isonitrogenous diets containing a mixture of high fermentable dietary fibers (HFF) or low fermentable (LFF) wood cellulose for 14 d in a randomized cross-over design. Food was withheld for 16 h before an oral glucose tolerance test was conducted supplying 2 g of glucose/kg body wt, and peripheral blood was collected via a hind-leg catheter at 0, 15, 30, 45, 60, 90 and 120 min for plasma glucose, insulin and glucagon-like peptide-1(7-36)NH2 (GLP-1) analyses. Intestinal samples were collected after the second dietary treatment. Ileal proglucagon mRNA, intestinal (GLP-1) concentrations and the integrated area under the curves (AUC) for plasma GLP-1 and insulin were greater and plasma glucose AUC was reduced when dogs were fed the HFF diet compared to the LFF diet (P < 0.05). Intestinal villi heights, brush border and basolateral glucose transporter protein abundance and jejunal transport capacities were significantly greater when dogs were fed the HFF diet than when fed the LFF diet. In conclusion, improvements in glucose homeostasis are observed in healthy dogs when they ingest fermentable fibers.

Animals↗
PubMed2000

Glucose-based oligosaccharides exhibit different in vitro fermentation patterns and affect in vivo apparent nutrient digestibility and microbial populations in dogs.

To evaluate the potential of indigestible oligosaccharides (OS) to serve as "dietary fiber-like" ingredients, it is necessary to determine their extent of indigestibility. In vitro fermentation characteristics of two novel OS, alpha-glucooligosaccharides (GOS) and a maltodextrin-like OS (MD), were compared to those of fructooligosaccharides (FOS), gum arabic (GA), guar gum (GG) and guar hydrolysate (GH). Total short-chain fatty acid (SCFA) production (micromol/g dry matter) as a result of MD fermentation was higher initially compared with GA (P<0.01), but GA was more extensively fermented at 24 h (P<0.01). Total SCFA production for GOS was similar to that for FOS, GG, GH and GA. In the second experiment, GOS and MD were added at 6% to an enteral formula control diet (Control) and fed to ileal-cannulated dogs in a 3x3 replicated Latin-square design. Ileal digestibility of glucose was lower (P<0.05) and carbohydrate (CHO) numerically lower (P = 0.08) for both GOS and MD compared with the Control. Total tract digestibility of CHO and glucose was lower only for MD (P<0.01) compared with the Control. Total fecal weights were higher (P<0.01) for both GOS and MD treatments. Fecal concentration of bifidobacteria was numerically increased by GOS and MD supplementation (P = 0.13 and 0.23, respectively). Thus, GOS and MD are indigestible yet fermentable OS, and may act as "dietary fiber-like" ingredients.

Animals↗
PubMed2002

A poorly fermented gel from psyllium seed husk increases excreta moisture and bile acid excretion in rats.

Psyllium seed husk (PSH) increases stool output and lowers blood cholesterol levels in humans. PSH and three fractions isolated from it were meal-fed to colectomized rats and fermented in vitro to test the hypothesis that viscous, gel-forming fraction B was responsible for these physiological actions. Control rats were fed 50 g/kg cellulose. The concentration of each PSH fraction in the test meals was equivalent to its concentration in PSH. Yields of the fractions were: A, 171; B, 575; and C, 129 g/kg of PSH. The wet weight and moisture content of ileal excreta (IE) from rats fed test meals containing PSH or fraction B were greater than those measured in excreta from rats fed meals containing cellulose or the other two PSH fractions. Total bile acids in IE did not differ between rats fed PSH or fraction B and were greater in these groups than in the other groups. Fraction A was not fermented during 3 d of incubation; fraction B was poorly fermented, with approximately 30% of the constituent sugars disappearing; and fraction C was rapidly and nearly completely fermented. These results indicate that the gel-forming fraction we isolated from PSH is the physiologically active component of the husks.

Animals↗
PubMed2004

A combined 13CO2/H2 breath test can be used to assess starch digestion and fermentation in humans.

Ingestion of starch from corn (naturally enriched with (13)C) should produce (13)CO(2) after small intestinal digestion and (13)CO(2) and H(2) from colonic fermentation. This study used a combined (13)CO(2)/H(2) breath test to assess the digestion and fermentation of resistant starch and to show that the test could detect changes in digestibility due to cooking. Volunteers consumed 40 g digestible cornstarch with water (n = 8), or 40 g resistant cornstarch in liquid (n = 12) or cooked into a pancake (n = 4). Interval breath sampling was performed and analyzed for (13)CO(2) and H(2). Ingestion of resistant starch produced a double-peaked (13)CO(2) excretion curve. The first increase in (13)CO(2) occurred at the same time as excretion from digestible starch (55 +/- 9 and 68 +/- 9 min, respectively), which was due to small intestinal digestion. The second increase in (13)CO(2) was accompanied by an increase in H(2) excretion (432 +/- 15 and 428 +/- 48 min, respectively), which was indicative of colonic bacterial fermentation. Cooking resistant starch increased its degree of digestion from 36 to 72%. The (13)CO(2)/H(2) breath test can be used to estimate digestion and fermentation of starches in different physiologic and pathologic conditions.

Adult↗
PubMed2004

The fermentation of different dietary fibers is associated with fecal clostridia levels in men.

Only a few reports have compared the fermentation of pectin and cellulose using the hydrogen-breath test, and no studies have examined the relation between the hydrogen breathing pattern and colonic microflora. Using breath-hydrogen measurements, we investigated whether different dietary fibers (DFs) were fermented differently and whether there were individual differences after ingestion of the same DF; we also examined the relation between individual fecal microflora and the fermentation of DF. Results of hydrogen tests in 14 men were compared after they had ingested 20 g of pectin, 20 g of cellulose, or 6 g of lactulose (a DF-like substance). We examined the relation between the breath hydrogen results and the subjects' fecal microflora. We defined significant fermentation (i.e., positive cases) as a continuous rise in hydrogen in the expiratory air of >19 ppm. The subjects were divided into 3 groups according to their hydrogen breath test pattern, i.e., positive for lactulose and pectin (Group LP, n = 4); positive for lactulose alone (Group L, n = 7); and negative for pectin, cellulose, and lactulose (Group N, n = 3). Individual differences were noted in subjects from Group LP and Group L. The detection frequency of lecithinase-negative clostridia was higher in Group LP than in the other groups (P < 0.05), and the detection frequency and the number of lecithinase-positive clostridia were higher in Groups LP and L than in Group N (P < 0.05). These findings suggest that the Clostridium species are associated with hydrogen production. The hydrogen breath test results of DFs depend on both the type of DF and the individual colonic microflora. The amount and constitution of colonic microflora might be predicted by the hydrogen-breath test using different DFs.

Adult↗
PubMed1982

The fermentation of lactulose by colonic bacteria.

Sixty-four strains of intestinal bacteria were cultured under anaerobic conditions in lactulose-containing media to assess their ability to ferment lactulose. Some organisms were unable to metabolize the disaccharide, while others, e.g. clostridia and lactobacilli, metabolized lactulose extensively. Quantitative analyses of the fermentation products indicated that the major non-gaseous metabolites were acetic, lactic and butyric acids. Hydrogen and carbon dioxide were the only gases detected. Fermentation products were estimated for selected species throughout their growth cycles. The products of fermentation of lactulose by stool cultures varied with incubation conditions such as pH, but correlated well with those produced by pure cultures. These results are discussed in relation to the therapeutic uses of lactulose.

Bacteria↗
PubMed2004

Crotonyl-coenzyme A reductase provides methylmalonyl-CoA precursors for monensin biosynthesis by Streptomyces cinnamonensis in an oil-based extended fermentation.

It is demonstrated that crotonyl-CoA reductase (CCR) plays a significant role in providing methylmalonyl-CoA for monensin biosynthesis in oil-based 10-day fermentations of Streptomyces cinnamonensis. Under these conditions S. cinnamonensis L1, a derivative of a high-titre producing industrial strain C730.1 in which ccr has been insertionally inactivated, produces only 15 % of the monensin yield. Labelling of the coenzyme A pools using [3H]-beta-alanine and analysis of intracellular acyl-CoAs in the L1 and C730.1 strains demonstrated that loss of ccr led to lower levels of the monensin precursor methymalonyl-CoA, relative to coenzyme A. Expression of a heterologous ccr gene from Streptomyces collinus fully restored monensin production to the L1 mutant. Using C730.1 and an oil-based extended fermentation an exceptionally efficient and comparably intact incorporation of ethyl [3,4-13C2]acetoacetate into both the ethylmalonyl-CoA- and methylmalonyl-CoA-derived positions of monensin was observed. No labelling of the malonyl-CoA-derived positions was observed. The opposite result was observed when the incorporation study was carried out with the L1 strain, demonstrating that ccr insertional inactivation has led to a reversal of carbon flux from an acetoacetyl-CoA intermediate. These results dramatically contrast similar analyses of the L1 mutant in glucose-soybean medium which indicate a role in providing ethylmalonyl-CoA but not methylmalonyl-CoA, thus causing a change in the ratio of monensin A and monensin B analogues, but not the overall monensin titre. These results demonstrate that the relative contributions of different pathways and enzymes to providing polyketide precursors are thus dependent upon the fermentation conditions. Furthermore, the generally accepted pathways for providing methylmalonyl-CoA for polyketide production may not be significant for the S. cinnamonensis high-titre monensin producer in oil-based extended fermentations. An alternative pathway, leading from the fatty acid catabolite acetyl-CoA, via the CCR-catalysed reaction is proposed.

Acyl-CoA Dehydrogenases↗
PubMed1982

Carbohydrate fermentation by Clostridium difficile.

Biochemical properties of Clostridium difficile were reinvestigated for the practical identification of the organism in clinical laboratories. Bacterial growth in 2% proteose peptone medium supplemented with 0.01% L-cysteine.HCl and 0.1% agar supported sufficient growth to read the fermentation results just as well as did pre-reduced anaerobically sterilized medium. Incubation for 2 days was long enough for determining the ability to ferment fructose, glucose, mannitol, mannose, melezitose, and sorbitol. All of the 82 strains liquefied 2% but not 10% gelatin. The significance of mannitol fermentation and gelatin liquefaction is stressed since C. difficile is the only species fermenting mannitol among the gelatin-liquefying species of clostridia having subterminal spores.

Carbohydrate Metabolism↗
PubMed1982

Variable sugar fermentation by clostridia.

Forty-two sugar fermentation characteristics recorded as "d" in the 8th edition of Bergey's Manual of Determinative Bacteriology were reinvestigated by using eight different peptone media and 205 strains of nine species of pathogenic clostridia. In the absence of sugar, the final pH of 7-day cultures in the basal medium varied widely depending on the peptone employed, the species tested, and even the strain of the species. In the presence of sugar, the final pH of 7-day cultures was markedly influenced by these factors. Since the sugars with reactions recorded as "d" were weakly fermented and, consequently, the fermentation reactions were easily affected by cultural variations resulting in strain instability, we employed the pH difference method (delta pH method) in which the pH difference of 0.5 between cultures with and without sugar was used as the critical level. Thirty-six (86%) of the 42 sugar reactions recorded as "d" were sorted into "+" or "-" by the delta pH method. Six sugars, however, still remained as "d" because of their extremely weak fermentation characters. The use of the delta pH method in any peptone medium not only minimizes incorrect evaluation but also can provide some distinct criteria for identification of clostridia.

Carbohydrate Metabolism↗
PubMed1997

Characteristics and pathogenicity of non-melibiose-fermenting strains of Yersinia pseudotuberculosis O3.

The biological properties of non-melibiose-fermenting (NMF) strains of Yersinia pseudotuberculosis O3 were investigated. These strains were clearly distinguished from representative melibiose-fermenting (MF) strains of Y. pseudotuberculosis O3 by their pathogenicity in mice, sensitivity to some phages, production of catalase, restriction endonuclease analysis of virulence plasmid DNA with BamHI, detection of specific yersinia outer-membrane proteins with SDS-PAGE, antigenicity of the outer-membrane proteins and neutrophil resistance to phagocytosis. The pathogenicity of NMF strains was clearly less than that of MF strains. In addition, the resistance of NMF strains to phagocytosis and catalase activity was evidently weaker than that of MF strains. These results suggested that the difference of pathogenicity was due to the ability of catalase production. Although the relationship between the above characteristics and melibiose-fermentation was not analysed, the pathogenicity of Y. pseudotuberculosis O3 strains can probably be predicted by testing melibiose-fermentation and catalase production.

Animals↗
PubMed1983

Sorbitol-fermenting bifidobacteria as specific indicators of human faecal pollution.

Bifidobacteria were consistently present in the faeces of both man and pigs but only occasionally in the faeces of cattle and sheep, and they were not isolated from faecal samples from other animals; total counts of bifidobacteria were obtained by membrane filtration with YN-17 medium, a modification of Resnick and Levin's YN-6 medium. Mannitol-fermenting strains of bifidobacteria were isolated from both human and animal faeces, but sorbitol-fermenting strains were obtained only from human samples. These sorbitol-fermenting strains were identified as either Bifidobacterium adolescentis or B. breve and their numbers were obtained by membrane filtration of Human Bifid Sorbitol agar (HBSA). Sorbitol-fermenting bifidobacteria are specific indicators of human faecal pollution of waters and wastewaters.

Animals↗
PubMed1983

Factors affecting the survival of Salmonella and Escherichia coli in anaerobically fermented pig waste.

The survival of Salmonella typhimurium was investigated in acidogenic, anaerobically fermented pig wastes and in synthetic media, each containing volatile fatty acids (VFA). Salm. typhimurium survived at pH 6.8, but not at pH 4.0, when incubated at 37 degrees C for 24 h in either fermented or synthetic medium containing VFA. The minimum inhibiting concentration of VFA for Salm. typhimurium after 48 h incubation at 30 degrees C at pH 4.0 was 0.03 mol/l and for Escherichia coli it was 0.09 mol/l. Fermented pig wastes in a digester, maintained at pH 5.9, were inoculated with Salm. typhimurium and then incubated at 37 degrees C for 24 h. The pH was adjusted to either 4.0 or 5.0 and after a further 48 h at 30 degrees C, Salm. typhimurium survived at pH 5.0 but not at pH 4.0. It was concluded that pH is critical in determining the survival of this organism in acidogenic anaerobically fermented pig waste.

Animals↗
PubMed1988

Fermentation products, amino acid utilization, maintenance energies and growth yields for the fibrillar Streptococcus salivarius HB and a non-fibrillar mutant HB-B grown in continuous culture under glucose limitation.

The fibrillar strain Streptococcus salivarius HB and a non-fibrillar mutant, strain HB-B, were grown in a defined medium under glucose limitation in a chemostat. Fermentation balances were produced for both strains in batch culture and at growth rates between 0.1/h and 1.1/h. In batch culture both strains fermented glucose to lactate, but in continuous culture glucose was fermented to formate, acetate and ethanol with increasing amounts of lactate as the growth rate was increased. Lactate never became the major fermentation product even at the highest growth rate. Amino acid analysis showed that only lysine was more than 50% utilized, while proline and tyrosine showed net production. The non-fibrillar strain HB-B showed, in general, a reduced utilization of amino acids compared with the fibrillar strain HB. Calculated growth yields and maintenance energies for the two strains showed that there was a reduction in the true growth yield and the maintenance energy coefficient of the non-fibrillar strain HB-B when compared with the fibrillar strain HB. The increase in the maintenance energy of the fibrillar strain HB (1.382 mmol/g/h) when compared with the non-fibrillar strain HB-B (0.546 mmol/g/h) of 153% is proposed to be the energy required for the maintenance of the fibrillar surface of the cell.

Amino Acids↗
PubMed1990

Microbiology of 'obiolor': a Nigerian fermented non-alcoholic beverage.

Obiolor is an acidic non-alcoholic beverage prepared by fermenting sorghum and millet malts. The traditional process for the production and microbiological characteristics of the beverage were investigated. Bacillus spp., Lactobacillus plantarum and Streptococcus lactis were the associated micro-organisms most actively involved. Yeasts were present in low numbers towards the end of the fermentation. Other micro-organisms isolated did not appear to play a role in the fermentation process. Variations in the important microbial groups involved and their metabolic products were studied. Titratable acidity increased gradually until the end of the fermentation while the total soluble solids and pH declined. Acetobacter spp. were probably responsible for the unacceptability of the product after 24 h.

Bacillus↗
PubMed1992

Survival of bacterial enteric pathogens in traditional fermented foods.

The survival of strains of bacterial enteric pathogens was investigated in two traditional fermented foods (mahewu and sour porridge) and in unfermented porridge. The foods were inoculated with cell suspensions of Salmonella, Shigella, Campylobacter, Aeromonas species and pathogenic Escherichia coli which had a final concentration of 10(6)-10(7) cfu/ml of food. None of the strains of Aeromonas and Campylobacter were detected in mahewu and sour porridge 20 min after inoculation. The salmonellas were not found 4 h after inoculation in either fermented foods but the shigellas and pathogenic E. coli strains were more tolerant to the low pH of the fermented foods. Some of the shigellas and pathogenic E. coli strains survived for 24 h after inoculation but showed a sharp decrease in numbers. All the strains of the enteric pathogens survived for 24 h in the unfermented porridge and increased in the numbers except for campylobacters, the numbers of which declined. These results suggest that the traditional fermented foods have bacteriostatic and bactericidal properties and are unlikely to play a major role in the transmission of bacterial enteric pathogens.

Aeromonas↗
PubMed1993

Molecular characterization of Lactobacillus curvatus and Lact. sake isolated from sauerkraut and their application in sausage fermentations.

Lactobacillus curvatus and Lact. sake are best adapted to meat fermentations and dominate the flora during the whole process. In fermenting sauerkraut, Leuconostoc mesenteroides subsp. mesenteroides is the major organism only during the early phase. In this environment Lact. curvatus and Lact. sake provide up to 50% of the microbial flora especially of the later phase, depending on the process conditions. Strains of Lact. curvatus and Lact. sake isolated from fermenting sauerkraut were identified by hybridization with species specific 23S rRNA-targeted oligonucleotide probes and further characterized. In 59 of 72 strains, plasmid DNA was detected. Small cryptic plasmids of 20 strains were found to be homologous with pLc2, a 2.6 kb plasmid from Lact. curvatus LTH683, which was originally isolated from meat. The ability to compete was investigated in fermenting sausages of two strains each of Lact. curvatus and Lact. sake isolated from sauerkraut. One strain each of Lact. curvatus and Lact. sake was found to outnumber the meat-borne flora and govern the process.

Brassica↗
PubMed1994

Fermentation of fructans by epiphytic lactic acid bacteria.

A total of 712 strains of lactic acid bacteria isolated from forage grasses were studied for their ability to ferment fructans of phlein- as well as inulin-type. Only 16 strains utilized phlein and eight of these also fermented inulin. They were identified as Lactobacillus paracasei subsp. paracasei, Lact. plantarum, Lact. brevis and Pediococcus pentosaceus. In the species Lact. paracasei subsp. paracasei, all strains gave positive results, whereas the other positive strains possessed unique properties within their own species. In all but two cases (strains of the species Lact. plantarum), the phlein was more intensively fermented than the inulin, as indicated by a lower pH and a higher lactic acid concentration. On the basis of the outcome of this study it seems worthwhile to inoculate grasses of low sugar content before ensiling with an active strain that can ferment fructans.

Fermentation↗
PubMed2004

Polyphasic study of the genetic diversity of lactobacilli associated with 'Almagro' eggplants spontaneous fermentation, based on combined numerical analysis of randomly amplified polymorphic DNA and pulsed-field gel electrophoresis patterns.

AIMS: The goal of this study was to assess the genetic diversity of lactic acid bacteria (LAB) from the complex natural ecosystem present in the spontaneous fermentation of 'Almagro' eggplants by a polyphasic approach based on molecular techniques. METHODS AND RESULTS: Randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) were applied to 149 Lactobacillus isolates obtained from that fermentation process. Two random primers, OPL-05 and ArgDei-For, and two rare-cutting enzymes, SfiI and SmaI, chosen after preliminary testing on the basis of band intensity and distribution, were used. RAPD and PFGE generated electrophoretic patterns suitable for strain discrimination, but further discrimination was achieved when combined numerical analysis of the results from both methods and the results previously obtained by SDS-PAGE whole cell protein analysis, was carried out. The findings indicated a considerable degree of genomic diversity in the LAB microbiota studied and especially in the Lactobacillus plantarum isolates. In terms of species assignment, the polyphasic study allowed a definite and well-founded identification of 98.7% of the isolates. CONCLUSIONS: The combined numerical analysis of RAPD and PFGE patterns represented a useful tool to discriminate the diversity of the Lactobacillus strains responsible for the spontaneous fermentation of this pickle. The species identification and strain typing results from the polyphasic study were regarded as the most exact compromise yielding the fewest contradictions based on the available data. SIGNIFICANCE AND IMPACT OF THE STUDY: Combined numerical analysis of RAPD-PCR and PFGE patterns has not yet been employed to study the genetic diversity of LAB from an ecosystem like that found in fermenting vegetables.

Cluster Analysis↗