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PubMed1986

Effect of glucose on fermentation heat in sheep rumen fluid in vitro.

1. Heat production rate (H) of rumen fluid was measured in a direct calorimeter. Basal H of samples of 15 ml rumen fluid mixed with 45 ml buffer was 0.4 mW/ml rumen fluid. 2. Addition of glucose (0.4-6.4 mg/sample) was followed by a dose-dependent increase in H. Maximal H was 1.1 mW/ml and lasted up to 5 min, returning thereafter to the basal level. 3. Expression of fermentation heat (Hf; kJ/mol substrate added) against glucose dose indicated an asymptotic dose response. 4. Maximal Hf (at infinite dilution) agreed with stoichiometric calculations whereas minimal Hf suggested a partial fermentation of the substrate at a high-glucose dose in the rumen environment.

Animals↗

PubMed1998

The ability of enteric diarrhoeal pathogens to ferment starch to short-chain fatty acids in vitro.

BACKGROUND: Short-chain fatty acids (SCFA), produced in the normal colon by bacterial fermentation, are decreased in acute diarrhoea. This may have deleterious effects on epithelial function in the colon. METHODS: The ability of several diarrhoeal pathogens to produce SCFA when incubated with starch in vitro was studied. Isolated pathogens were incubated for 24 h with either no added substrate, glucose, or starch under anaerobic conditions, and SCFA were quantitated by gas-liquid chromatography. RESULTS: Unlike the normal colonic flora, the pathogens produced acetate but not propionate or butyrate. D-Lactate was also produced by all the pathogens studied. When the pathogens were incubated in anaerobic medium containing starch, significantly greater amounts of acetate and significantly lesser amounts of lactate were produced. CONCLUSIONS: The inability of enteric pathogens to produce butyrate may impair epithelial cell function, whereas production of D-lactate may enhance mucosal damage in diarrhoeal disease. The presence of luminal starch may be helpful in shifting the fermentation profile to a more favourable pattern.

Butyrates↗

PubMedDate not supplied

In vitro and in vivo effects of three bismuth compounds on fermentation by colonic bacteria.

Three bismuth compounds (tripotassium dicitrate bismuthate, bismuth subsalicylate, and bismuth subnitrate) were tested in vitro and in vivo for their effect on fermentation by colonic bacteria. The studies in vitro were done with use of a technique designed to determine the effect of each one of the bismuth compounds on the fermentation of several stool samples that had been mixed with lactose as additional fermentable substrate (fermentation of lactose-enriched stools, FLES). The three bismuth compounds reduced FLES significantly in 47 (81%) of 58 of the stool samples used to test their effect. Bismuth subsalicylate, which reduced FLES in 10 of 10 stool samples, showed the greatest reduction (mean reduction, 74%; P less than .0001). The in vivo studies, done in six flatulent patients, showed significant reduction (P less than .01) of colonic fermentation of ingested raffinose by oral bismuth subnitrate given for 8 days.

Adolescent↗

PubMed1989

Nonabsorbed carbohydrate: effect on fecal pH in methane-excreting and nonexcreting individuals.

To determine whether the acidifying effect of malabsorbed carbohydrate on fecal pH differed between methane-excreting and nonexcreting individuals, we administered the poorly absorbed disaccharide lactulose to five CH4 excretors and six CH4 nonexcretors. Lactulose, 20 g twice daily for 1 wk, significantly lowered fecal pH among CH4 nonexcretors as compared with CH4-excreting individuals (5.38 +/- 0.66 vs 6.90 +/- 0.61, p less than 0.01). To determine whether this observation was due to differences in acid production from bacterial carbohydrate fermentation, feces from each subject were incubated with lactulose. There were no differences in in vitro acid or hydrogen production between groups. We conclude that malabsorbed carbohydrate fails to induce in vivo colonic acidification in CH4 excretors. In contrast, in vitro fecal carbohydrate fermentation is similar among CH4 excretors and nonexcretors. These results suggest differences between these two groups in the colonic absorption of fermentation products.

Adult↗

PubMed1981

Effect of nicotinic acid on microbial protein synthesis in vitro and on dairy cattle growth and milk production.

The effect of nicotinic acid (niacin) on microbial fermentation was tested in vitro. Microbial protein synthesis was greater with niacin and soybean meal than with niacin and urea. Otherwise, in most instances niacin decreased synthesis with urea. These responses to niacin with soybean meal occurred regardless of roughage type or ratio of roughage to concentration, except when the substrate contained 50% roughage from alfalfa; then the opposite was true. Adding niacin to urea-containing rations of heifers weighing 375 or 114 g failed to improve the heifers' weight gain or feed efficiency. In one of two lactation studies with cows in midlactation fed urea-containing rations, a slight increase in milk production was attributable to niacin; in the other, a slight improvement in milk protein production was attributable to niacin. In a third lactation study, but with fresh cows, milk production increased in cows receiving niacin and soybean meal but not in those receiving niacin and urea. In a fourth lactation study with fresh cows fed soybean meal, cows receiving niacin gave slightly more milk than did those receiving none. Response to niacin is greater in fresh cows than in those in midlactation and is greater in cows fed natural protein than in those fed urea.

Animal Feed↗

PubMed1990

In vitro study (Rusitec) of the action of abierixin, a new ionophore antibiotic, on the end products of fermentation and the degradation of nitrogen in the rumen.

We investigated the capacity of a new ionophore antibiotic, abierixin, to modify fermentations in the rumen using a semi-continuous fermenter (Rusitec). As in the studies carried out on a "batch" fermenter (HILLAIRE et al., 1989a), abierixin failed to alter volatile fatty acids and gas productions but, in contrast, it limited the degradation of dietary nitrogen without affecting microbial synthesis. This molecule which has a low level of toxicity and is capable of improving the use of dietary proteins by ruminants, was found to be more effective when used at very low dose levels.

Animals↗

PubMed2000

Influence of the novel urease inhibitor N-(n-butyl) thiophosphoric triamide on ruminant nitrogen metabolism: I. In vitro urea kinetics and substrate digestion.

Two in vitro digestion experiments were conducted to evaluate the influence of the novel urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) on in vitro urea kinetics, substrate digestion, and fermentation characteristics. In Exp. 1, in vitro incubations were conducted in 50-mL test tubes containing .25 g of ground fescue hay to which 0, 6.5, 13, 26, or 52 mg of NBPT in a buffered ruminal fluid innoculum was added. Tubes were incubated in triplicate at 39 degrees C and replicated on consecutive days, with NH3 N and urea concentrations measured at 0, 10, 30, 60, 120, 240, and 360 min. Samples for VFA analysis were collected at 6 h, and incubations were continued through 48 h to estimate true digestibility (based on NDF analysis). Increasing the dose of NBPT tended (P < .12) to linearly depress the rate of urea hydrolysis and decreased (P < .0004) subsequent NH3 N formation. Although total VFA concentration at 6 h increased linearly (P < .03), acetate:propionate and estimated true digestibility decreased (P < .01) with increasing NBPT concentration. In Exp. 2, we compared in vitro urea kinetics and digestion of forage-only or mixed forage-grain substrates in response to addition of NBPT. In vitro incubations were conducted in 50-mL test tubes containing either .5 g of ground fescue hay or .5 g of a ground fescue hay and ground corn mixture (50:50, DM basis) to which 0, 6.5, 13, 26, or 52 mg of NBPT in a buffered ruminal fluid innoculum was added. Tubes were incubated in triplicate at 39 degrees C and replicated on consecutive days, with NH3 N and urea concentrations measured at 0, .5, 1, 2, 4, 8, 12, 24, and 48 h. At 48 h, samples for VFA analysis were collected and true digestibility (based on NDF analysis) was estimated. No (P > .10) NBPT dose x substrate interactions were detected. Increasing the dose of NBPT depressed (P < .003) the rate of urea hydrolysis and subsequent NH3 N formation, regardless of substrate. Although total VFA concentration was unaffected (P > .10), the acetate:propionate and estimated true digestibility decreased (P < .002) with higher NBPT addition. In both experiments, the rate of urea degradation was not different (P > .20) from zero for the 26 and 52 mg NBPT treatments, indicating that nearly complete inhibition of urease had been achieved. We conclude that NBPT can be used to reduce the rate of NH3 N release from dietary urea and, thereby, offers the potential to improve nonprotein nitrogen utilization in ruminants.

Animal Feed↗

PubMed1999

Temperature and pH conditions that prevail during fermentation of sausages are optimal for production of the antilisterial bacteriocin sakacin K.

Sakacin K is an antilisterial bacteriocin produced by Lactobacillus sake CTC 494, a strain isolated from Spanish dry fermented sausages. The biokinetics of cell growth and bacteriocin production of L. sake CTC 494 in vitro during laboratory fermentations were investigated by making use of MRS broth. The data obtained from the fermentations was used to set up a predictive model to describe the influence of the physical factors temperature and pH on microbial behavior. The model was validated successfully for all components. However, the specific bacteriocin production rate seemed to have an upper limit. Both cell growth and bacteriocin activity were very much influenced by changes in temperature and pH. The production of biomass was closely related to bacteriocin activity, indicating primary metabolite kinetics, but was not the only factor of importance. Acidity dramatically influenced both the production and the inactivation of sakacin K; the optimal pH for cell growth did not correspond to the pH for maximal sakacin K activity. Furthermore, cells grew well at 35 degrees C but no bacteriocin production could be detected at this temperature. L. sake CTC 494 shows special promise for implementation as a novel bacteriocin-producing sausage starter culture with antilisterial properties, considering the fact that the temperature and acidity conditions that prevail during the fermentation process of dry fermented sausages are optimal for the production of sakacin K.

Bacteriocins↗

PubMed1999

Effect of supplementing a fibre basal diet with different nitrogen forms on ruminal fermentation and microbial growth in an in vitro semi-continuous culture system (RUSITEC)

Incubation trials were carried out with the rumen simulation technique (RUSITEC) to study the effects of four forms of N on the growth of ruminal micro-organisms and the fermentation variables when an all-fibre basal diet was incubated. The basal diet consisted of 10 g neutral-detergent fibre (NDF) from grass hay plus 2 g NDF from sugarbeet pulp. N forms were isolated soyabean protein, soyabean peptides, amino acids blended to profile soyabean protein and NH3 as NH4Cl. Half of the daily N supply was infused as NH4Cl and the other half was infused as each of the four treatments described. Non-NH3 N (NAN) forms increased NDF (P = 0.006), acid-detergent fibre (P = 0.003) and cellulose (P = 0.015) disappearance after 48 h incubation, CO2 (P < 0.001), CH4 (P = 0.002) and total volatile fatty acids production (P < 0.001), as well as the molar percentages of isobutyrate, isovalerate and valerate, which reflected the fermentation of amino acid C skeletons. NAN treatments also increased microbial N flow (P < 0.001) compared with NH3, with peptides and protein supporting more (P = 0.036) than amino acids. The proportion of microbial N derived from NH3 decreased successively (P < 0.05) with NH3 > amino acids > peptides > protein treatments, indicating preferential uptake of peptides without passage through the NH3 pool. Microbial efficiency (g microbial N/kg organic matter apparent disappearance) was greater (P = 0.002) for the NAN forms than for the NH3 treatment, with peptides and protein treatments supporting higher (P = 0.009) values than amino acid treatment. These results indicate that N forms other than NH3 are required for optimal fibre digestion and microbial growth.

Ammonia↗

PubMed1993

The effect of feeding xanthan gum on colonic function in man: correlation with in vitro determinants of bacterial breakdown.

Xanthan gum (15 g/d) was given for 10 d to eighteen normal volunteers. In vivo measurements of stool output, transit time, frequency of defaecation and flatulence were compared with a preceding control period of 10 d. At the end of the control and test periods fresh faecal homogenate from each subject was anaerobically incubated with xanthan gum and control solutions to assess the ability of the bacteria to break down the gum. Xanthan gum was found to be a highly efficient laxative agent causing significant increases in stool output (P < 0.01), frequency of defaecation (P < 0.05) and flatulence (P < 0.01) whilst having variable effects on transit time. Before feeding xanthan gum, faecal samples from twelve of the eighteen subjects could reduce the viscosity of the gum in vitro. This rose to sixteen of the eighteen with significantly greater amounts (P < 0.05) of hydrogen and short-chain fatty acids also being produced, indicating bacterial adaptation in the presence of the substrate. Correlations between the in vivo and in vitro findings did not substantiate claims that the in vivo effect of a given polysaccharide can be predicted from its fermentation characteristics in vitro.

Adult↗

PubMed2006

Fermentability of eastern gamagrass, big bluestem and sand bluestem grown across a wide variety of environments.

Plant biomass has attracted interest as a feedstock for biofuels production, but much of this work has been focused on relatively few plant species. In this study, three relatively-unstudied species of warm-season perennial grasses, grown at multiple locations in the eastern and central US and harvested over a three year period, were examined for fermentability via in vitro ruminal gas production and dry matter digestibility assays, and near-infrared reflectance calibrations were developed for these fermentation parameters. Big bluestem (Andropogon gerardii Vitman) displayed greater fermentability than did sand bluestem (Andropogon hallii Hack) or eastern gamagrass [Tripsacum dactyloides (L.) L.], but displayed lower biomass yields. The bluestems also displayed lower N contents and less variation in fermentability over different growth environments (geographic locations and harvest years), suggesting a more consistent biomass quality than for eastern gamagrass. Thus, in addition to their use as forage for ruminant animals, bluestems may be of particular interest as feedstocks for bioconversion to ethanol and other products via direct microbial fermentation (consolidated bioprocessing) schemes, and thus merit additional efforts to enhance biomass yield potential.

Agriculture↗

PubMed2006

Effect of total mixed ration composition on fermentation and efficiency of ruminal microbial crude protein synthesis in vitro.

The goal of this study was to identify dietary factors that affect fermentation and efficiency of microbial crude protein (CP(M)) synthesis in the rumen in vitro. We used 16 total mixed, dairy cow rations with known digestibilities that varied in ingredient composition and nutrient content. Each ration was incubated in a Rusitec (n = 3) for 15 d, and fermentation of different fractions was assessed. Observed extents of fermentation in 24 h were 35 to 47% for organic matter, 25 to 60% for crude protein, 3 to 28% for neutral detergent fiber, and 31 to 45% for gross energy. Organic matter fermentation depended on the content of crude protein and neutral detergent fiber in the ration. We studied net synthesis of CP(M) using an 15N dilution technique and found that 7 d of continuous 15N application are needed to achieve an 15N enrichment plateau in the N of isolated microbes in this type of study. The efficiency of CP(M) synthesis was 141 to 286 g/kg of fermented organic matter or 4.9 to 11.1 g/MJ of metabolizable energy, and these ranges agree with those found in the literature. Multiple regressions to predict the efficiency of CP(M) synthesis by diet data showed that crude protein was the only dietary chemical fraction that had a significant effect. Fat content and the inclusion rate of corn silage in the ration also tended to improve efficiency. We suggest that microbial need for preformed amino acids may explain the crude protein effect. A large part of the variation in efficiency of microbial activity still remains unexplained.

Animal Feed↗

PubMed1995

Fermentation of rice-bengal gram dhal blends with whey: changes in phytic acid content and in vitro digestibility of starch and protein.

Whey fermentation of various rice and bengal gram dhal blends prepared by mixing them in different proportions at 35 degrees C for 18 h brought about a significant decline in phytic acid content. Phytic acid content in various blends decreased to the extent of 23 to 36 per cent over the control values. Whey incorporation as well as fermentation improved the starch and protein digestibility (in vitro) of all the rice-bengal gram dhal mixtures. Improvement in starch and protein digestibility is related to the reduction in phytic acid content, as this antinutrient is known to inhibit amylolysis and proteolysis. A significant negative correlation found between phytic acid and digestibility of starch and protein strengthens our findings.

Animals↗

PubMed2006

Lactobacillus spp. with in vitro probiotic properties from human faeces and traditional fermented products.

Lactobacillus strains from traditional African fermented milk products, as well as human intestinal isolates were identified and investigated in vitro for their technological and functional characteristics as potential new probiotic strains. To test survival under gastrointestinal conditions, first the protective effect of milk and the effects of medium composition, lysozyme, pepsin, and pH of the medium on bacterial viability were assessed in vitro using the Plackett-Burman statistical model and the commercially used L. johnsonii LA1 probiotic strain. The use of either an artificial gastric electrolyte solution or MRS did not play a significant role in the viability of the cultures, while lysozyme, acidic conditions (pH 2.5), pepsin and the presence of milk significantly influenced the survival of the strain. Therefore, these parameters were selected as important test variables in a model stomach passage survival trial. Five strains identified as L. plantarum and two identified as L. johnsonii showed good survival under simulated gastrointestinal conditions. These selected strains also showed antimicrobial activity, probably due to production of organic acids. All strains exhibited bile salt hydrolase activity, while only the L. plantarum strains showed beta-galactosidase activity.

Antibiosis↗

PubMed1992

In vitro effects of the ionophore lysocellin on ruminal fermentation and microbial populations.

Batch and continuous culture techniques were used to evaluate the effect of the ionophore lysocellin on ruminal fermentation and microbial populations. In batch culture, .5 and 1 ppm (of the fluid) lysocellin markedly decreased (P less than .01) the acetate:propionate ratio without affecting fiber digestion, ammonia concentration, or culture pH. Greater concentrations of lysocellin had negative effects (P less than .05) on fiber digestion and increased (P less than .05) culture pH. In continuous culture, a low level of lysocellin (33 ppm of the diet DM or about .7 ppm of the fluid) decreased pH (P less than .05) and methane (P less than .05) production but had no effect on fiber digestion. Lysocellin tended to increase (P less than .05) OM digestion in corn-based diets but decreased OM digestion in barley-based diets (starch source x lysocellin interaction, P less than .05). In addition, the molar proportion of propionate was increased more in barley- than in corn-based diets. Total anaerobes and amylolytic and lactate-utilizing microorganisms were not affected by the ionophore. In continuous culture, cellulolytic and lactate-producing organisms were insensitive to lysocellin, but, in lysocellin-treated media, cellulolytic organisms were resistant, whereas lactic acid producers were sensitive to lysocellin at 4 ppm. In summary, the ionophore lysocellin alters ruminal fermentation by decreasing ruminal methane production and increasing the molar proportion of propionate; however, effects varied depending on whether corn or barley served as the primary starch source.

Ammonia↗

PubMed2003

Energy status and its control on embryogenesis of legumes. Embryo photosynthesis contributes to oxygen supply and is coupled to biosynthetic fluxes.

Legume seeds are heterotrophic and dependent on mitochondrial respiration. Due to the limited diffusional gas exchange, embryos grow in an environment of low oxygen. O(2) levels within embryo tissues were measured using microsensors and are lowest in early stages and during night, up to 0.4% of atmospheric O(2) concentration (1.1 micro M). Embryo respiration was more strongly inhibited by low O(2) during earlier than later stages. ATP content and adenylate energy charge were lowest in young embryos, whereas ethanol emission and alcohol dehydrogenase activity were high, indicating restricted ATP synthesis and fermentative metabolism. In vitro and in vivo experiments further revealed that embryo metabolism is O(2) limited. During maturation, ATP levels increased and fermentative metabolism disappeared. This indicates that embryos become adapted to the low O(2) and can adjust its energy state on a higher level. Embryos become green and photosynthetically active during differentiation. Photosynthetic O(2) production elevated the internal level up to approximately 50% of atmospheric O(2) concentration (135 micro M). Upon light conditions, embryos partitioned approximately 3-fold more [(14)C]sucrose into starch. The light-dependent increase of starch synthesis was developmentally regulated. However, steady-state levels of nucleotides, free amino acids, sugars, and glycolytic intermediates did not change upon light or dark conditions. Maturing embryos responded to low O(2) supply by adjusting metabolic fluxes rather than the steady-state levels of metabolites. We conclude that embryogenic photosynthesis increases biosynthetic fluxes probably by providing O(2) and energy that is readily used for biosynthesis and respiration.

Adenosine Triphosphate↗

PubMed1995

In-vitro production of ethanol in urine by fermentation.

Driving while under the influence of alcohol (DUI) can lead to serious injuries to the intoxicated driver and surrounding individuals, in addition to revocation or suspension of driving privileges. The accuracy and interpretation of the testing procedures may be compromised if an individual's urine contains sugar, and either bacteria or yeast. Under these conditions, ethanol can be produced in vitro, producing a result that may be erroneously indicative of DUI. In this study three yeast species and six bacterial species were added to a blank urine sample devoid of any alcohol or sugar. Samples were incubated at 0, 25, and 35 degrees C for 24, 48, and 144 hours in the presence of one of four different sugars. Ethanol concentrations were assayed using an enzymatic alcohol dehydrogenase assay. Results showed that when glucose was used as a substrate, all yeast species (Candida albicans, Candida parapsilosis, and Candida sp. not albicans) and three bacterial species (Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis) were capable of producing ethanol while the other three (Enterococcus sp., Staphylococcus sp. not aureus, and Pseudomonas aeruginosa) were not. The rate of ethanol production is temperature dependent and can be inhibited by storage of samples at 0 degrees C or the use of approximately 1% sodium fluoroide as an antimicrobial agent. Many of these species were also able to use other substrates (sucrose, fructose, and galactose) to produce ethanol by fermentation.

Candida↗

PubMedDate not supplied

Effect of sunflower, linseed and fish oils on the production of trans fatty acids in vitro.

In vitro anaerobic incubations were used to determine the effect of different oils (LO-linseed, SO-sunflower, FO-fish oil) on trans fatty acid production in rumen fluid and to test if combining of monensin (MON) with the oils affects the interactions on trans fatty acid concentrations in mixed cultures of ruminal microorganisms. Two different sources of rumen fluid were used; the inoculum from the sheep fed hay and barley (80:20%)--the inoculum A and the inoculum from the sheep fed alfalfa and barley (80:20 %)--the inoculum B. The analyses showed that inoculum B contained more short chain fatty acids (SCFA), medium chain fatty acids (MCFA) and saturated fatty acids (SFA) than inoculum A. In contrast, inoculum A contained more unsaturated fatty acids (UFA) than inoculum B. The results show, that the oils affected the biohydrogenation of fatty acids (FA) by increasing the concentration of C18:0 (3-7 times) and trans C18:1 isomers (2-9 times). The concentration of two main intermediates of FA biohydrogenation-- cis 9, trans 11 C18:2 (CLA) and trans 11C18:1 (TVA) were increased with the oils, but FO was more efficient than other plant oils on CLA and TVA production. The monensin treatment had similar effect on FA metabolism as the oil treatment in comparison to unincubated control. The interactions of monensin treatment with the oils were characterized with decrease (LO+MON, SO+MON) or increase (FO+MON) of the proportions of C18:0 and trans C18:1 isomers in comparison to oil treatment. The highest concentrations of two main isomers--CLA,TVA were found in the samples containing fish oil and monensin. In conclusion, fish oil treatment and monensin with fish oil treatment was more efficient than other plant oils in the effect on trans fatty acid production (mainly CLA and TVA) in fermentation fluid in vitro.

Animal Feed↗