Polysaccharide synthesis and degradation by rumen micro-organismsin vitro

1971 ◽  
Vol 76 (3) ◽  
pp. 423-432 ◽  
Author(s):  
J. K. Thompson ◽  
P. N. Hobson
Keyword(s):  
Volatile Fatty Acids ◽  
Starch Synthesis ◽  
Soluble Starch ◽  
Optimum Conditions ◽  
Polysaccharide Synthesis ◽  
Incubation Periods ◽  
Optimum Ph ◽  
Micro Organisms ◽  
Synthesis And Degradation

SUMMARYMicro-organisms from the rumen of a hay-fed sheep rapidly synthesized an intracellular polysaccharide (starch) when growing or resting suspensions of cells were incubatedin vitrowith easily metabolized sugars.In 30 min incubation periods the optimum pH for the synthesis of starch by resting cultures was about 6·0 when glucose or fructose were substrates. Relative to glucose (as 100%) in ability to form the polysaccharide were, fructose, 75%; sucrose, 80%; soluble starch, 18·6%; maltose, 6·9%; cellobiose, 4%; and xylose, 2·1%. No starch was formed from galacturonic, acetic, propionic, butyric, lactic or succinic acids. A bacterial fraction of the microbes was reponsible for about 80% of the starch formed from glucose, fructose or sucrose.In incubations of 24 h, resting cultures formed more starch per unit of microbial protein than growing cultures. The utilization of microbial starch and lactic acid, formation of which often accompanied starch synthesis, gave rise to volatile fatty acids. Acid production was maintained from these substrates at rates similar to those obtained from the fermentation of glucose. The acids were in molar proportions of 65–70% acetic, 20–27% propionic and 8–15% butyric. The maximum starch calculated to be synthesized by the microbes from 100 ml of rumen liquor, in media containing excess sugar, amounted to over 250 mg from glucose, 200 mg from fructose, 200 mg from cellobiose and 50 mg from xylose. It is calculated that under optimum conditions for synthesis about 25 g of starch would pass daily from the rumen of a sheep.

Heat Stress During Grain Filling in Maize: Effects on Carbohydrate Storage and Metabolism

1994 ◽  
Vol 21 (6) ◽  
pp. 829 ◽  
Author(s):  
GW Singletary ◽  
R Banisadr ◽  
PL Keeling
Keyword(s):  
Heat Stress ◽  
Seed Size ◽  
Starch Synthesis ◽  
Dry Weight ◽  
Grain Filling ◽  
Soluble Starch ◽  
Effect Of Temperature ◽  
Starch Accumulation ◽  
Maize Kernels

Heat stress during maize seed development can interfere with endosperm starch biosynthesis and reduce seed size, an important component of yield. Our objectives were to evaluate the direct influence of temperature during grain filling on kernel growth, carbohydrate accumulation, and corresponding endosperm metabolism. Kernels of maize were grown in vitro at 25�C until 15 or 16 days after pollination and then subjected to various temperatures for the remainder of their development. Mature kernel dry weight declined 45% in a linear fashion between 22 and 36�C. The rate of starch accumulation reached a maximum at approximately 32�C, and when measured at frequent intervals, declined only slightly with further temperature increase to 35�C. Reduced seed size resulted from an abbreviated duration of starch-related metabolism, which did not appear to be limited by endogenous sugars. Instead, a survey of 12 enzymes of sugar and starch metabolism indicated that ADP glucose pyrophosphorylase and soluble starch synthase were unique in displaying developmental peaks of activity which were compressed both in amount and time, similar to the effect of temperature on starch accumulation. We conclude that decreased starch synthesis in heat-stressed maize kernels results from a premature decline in the activity of these enzymes.

scholarly journals Excretion of purine derivatives by ruminants: recycling of allantoin into the rumen via saliva and its fate in the gut

1990 ◽  
Vol 63 (2) ◽  
pp. 197-205 ◽  
Author(s):  
X. B. Chen ◽  
F. D. DeB. Hovell ◽  
E. R. ØRskov
Keyword(s):  
Fatty Acids ◽  
Uric Acid ◽  
Urinary Excretion ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Purine Derivatives ◽  
Complete Destruction ◽  
Series Of Experiments ◽  
Micro Organisms

The saliva of sheep was shown to contain significant concentrations of uric acid (16 (sd) 4.5) μmol/l) and allantoin (120 (sd 16.4) μmol/l), sufficient to recycle purine derivatives equivalent to about 0.10 of the normal urinary excretion. When allantoin was incubated in vitro in rumen fluid, it was degraded at a rate sufficient to ensure complete destruction of recycled allantoin. In a series of experiments in which allantoin was infused into the rumen of sheep fed normally, or into the rumen or abomasum of sheep and the rumen of cattle completely nourished by intragastric infusion of volatile fatty acids and casein, no additional allantoin was recovered in the urine. These losses were probably due to the degradation of allantoin by micro-organisms associated with the digestive tract. It is concluded that all allantoin and uric acid recycled to the rumen via saliva will be similarly degraded. Therefore, the use of urinary excretion of purine derivatives as an estimator of the rumen microbial biomass available to ruminants will need to be corrected for such losses.

Purification and Properties of Potato Phosphorylase Isozymes

1976 ◽  
Vol 31 (7-8) ◽  
pp. 424-432 ◽  
Author(s):  
Kirumakki N. Shivaram
Keyword(s):  
Starch Synthesis ◽  
Soluble Starch ◽  
Potato Tubers ◽  
Multiple Forms ◽  
Ph Optimum ◽  
Molecular Weights ◽  
Purification And Properties ◽  
Glucan Phosphorylase ◽  
Sulfhydryl Compounds ◽  
Synthesis And Degradation

Abstract Two multiple forms of α-glucan phosphorylase which migrate about half way in polyacryl-amide-gel electrophoresis (named “slow“ and “fast” isozyme), were isolated by combined chromatography and preparative electrophoresis after freezing the tissue from freshly harvested and from sprouting potato tubers respectively. Depending on the primer used for the synthesis reaction their pH optimum varied between 5.2 and 6.0 and the optimum temperature was 30 and 35 °C. The isoelectric point for the slow isozyme was at pH 5.0±0.1 and for the fast isozyme, pH 5.5±0.1, the molecular weights were 209 000±10 000 and 165 000±5000 and for their subunits 104 000±4000 and 40 000±2000 respectively. Both isozymes were inhibited by Hg2+, Ag+ and p-chloromercuro-benzoate (p-CMB). Fe2+ ions inhibited them partially. Mg2+, Mn2+ and sulfhydryl compounds activated both. Km values for the slow and fast isozymes with glucose-l-phosphate in presence of soluble starch was 6.7 and 8.0 mM, of amylose 14.3 and 20.0 mм and of glycogen 22.2 and 40.0 mм respectively. The affinity of the primer for the slow and the fast isozymes were as follows: soluble starch 0.5 and 1.0 mм, amylose 2.6 and 3.8 mм, glycogen 6.2 and 7.7 mм respectively. Km values of phosphorolysis with soluble starch was 0.8 and 0.5 mм, with amylose was 3.1 and 1.1 mм, and with glycogen was 6.5 and 1.3 mм respectively. As substrate and primer the soluble starch was superior and the glycogen was inferior. Amylose was in between. Kinetic parameters suggested the existence of α-glucan phosphorylase isozymes with different specificities: the slow one being more active in the direction of starch synthesis and the fast isozyme degrading faster the polyglucans. These observations suggest that the polyglucan synthesis and degradation in potato tubers may be regulated by the change in the proportion of slow and fast isozymes.

scholarly journals Ruminal biohydrogenation as affected by tanninsin vitro

2008 ◽  
Vol 102 (1) ◽  
pp. 82-92 ◽  
Author(s):  
Valentina Vasta ◽  
Harinder P. S. Makkar ◽  
Marcello Mele ◽  
Alessandro Priolo
Keyword(s):  
Fatty Acids ◽  
Linoleic Acid ◽  
Volatile Fatty Acids ◽  
Vaccenic Acid ◽  
Acacia Cyanophylla ◽  
Total Conjugated Linoleic Acid ◽  
Branched Chain ◽  
Micro Organisms ◽  
Ruminal Biohydrogenation

The aim of the present work was to study the effects of tannins from carob (CT;Ceratonia siliqua), acacia leaves (AT;Acacia cyanophylla) and quebracho (QT;Schinopsis lorentzii) on ruminal biohydrogenationin vitro.The tannins extracted from CT, AT and QT were incubated for 12 h in glass syringes in cow buffered ruminal fluid (BRF) with hay or hay plus concentrate as a substrate. Within each feed, three concentrations of tannins were used (0·0, 0·6 and 1·0 mg/ml BRF). The branched-chain volatile fatty acids, the branched-chain fatty acids and the microbial protein concentration were reduced (P < 0·05) by tannins. In the tannin-containing fermenters, vaccenic acid was accumulated (+23 %,P < 0·01) while stearic acid was reduced ( − 16 %,P < 0·0005). The concentration of total conjugated linoleic acid (CLA) isomers in the BRF was not affected by tannins. The assay on linoleic acid isomerase (LA-I) showed that the enzyme activity (nmol CLA produced/min per mg protein) was unaffected by the inclusion of tannins in the fermenters. However, the CLA produced by LA-I (nmol/ml per min) was lower in the presence of tannins. These results suggest that tannins reduce ruminal biohydrogenation through the inhibition of the activity of ruminal micro-organisms.

The use of pivalic acid as a reference substance in measurements of production of volatile fatty acids by rumen micro-organisms in vitro

1976 ◽  
Vol 36 (2) ◽  
pp. 311-315 ◽  
Author(s):  
J. W. Czerkawski
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Pivalic Acid ◽  
Reference Substance ◽  
Micro Organisms

1. A procedure is described for using pivalic acid as an inert reference substance in determination of changes in concentrations of volatile fatty acids (VFA).2. Pivalic acid in concentrations of up to 80 mmol/l had no effect on production of methane or VFA by rumen contents.3. Pivalic acid was inert during incubation with rumen contents from sheep given different diets and with samples taken at different times with respect to feeding.

Utilization of urea by sheep

1964 ◽  
Vol 63 (3) ◽  
pp. 289-296 ◽  
Author(s):  
H. M. Schwartz ◽  
C. A. Schoeman ◽  
M. S. Färber
Keyword(s):  
Rumen Fluid ◽  
Soluble Starch ◽  
Large Numbers ◽  
Food Particles ◽  
Freely Suspended ◽  
Micro Organisms ◽  
Strained Material

1.The breakdown of urea, soluble starch and glucose was followed in the rumen of fistulated sheep and in artificial rumens containing rumen ingesta or strained rumen fluid.2. Carbohydrate remained in the rumen two to three times as long when starch was dosed in vivo as when glucose was given.3. The relative rates of breakdown of urea and carbohydrate by strained rumen fluid in vitro differed markedly from those in vivo. This was due to the fact that straining removed large numbers of starch- and glucose-utilizing micro-organisms which were attached to the larger food particles, while the concentration of the urea-splitting organisms which were freely suspended in the strained liquor was apparently the same as that obtained in the strained material. Strained rumen fluid should therefore not be used for studies of the utilization of urea in vitro.

Effect of melamine onin vitrorumen microbial growth, methane production and fermentation of Chinese wild rye hay and maize meal in binary mixtures

2013 ◽  
Vol 152 (4) ◽  
pp. 686-696 ◽  
Author(s):  
H. J. YANG ◽  
H. ZHUANG ◽  
X. K. MENG ◽  
D. F. ZHANG ◽  
B. H. CAO
Keyword(s):  
Volatile Fatty Acids ◽  
Ammonia Nitrogen ◽  
Rumen Fermentation ◽  
Gas Production ◽  
Hydrogen Gas ◽  
Batch Cultures ◽  
Branched Chain ◽  
Micro Organisms ◽  
High Forage

SUMMARYThe effects of melamine on gas production (GP) kinetics, methane (CH4) production and fermentation of diets differing in forage content (low-forage (LF) diet: 200 g/kg and high-forage (HF) diet: 800 g/kg) by rumen micro-organismsin vitrowere studied using batch cultures. Rumen contents were collected from three Simmental×Luxi crossbred beef cattle. Melamine was added to the incubation bottles to achieve final concentration of 0 (control), 2, 6, 18, 54, 162 and 484 mg/kg of each diet. Cumulative GP was continuously measured in an automated gas recording instrument during 72 h of incubation, while fermentation gas end-products were collected to determine molar proportions of carbon dioxide (CO2), CH4and hydrogen gas (H2) in manually operated batch cultures. Differences in GP kinetics and fermentation gases were observed in response to the nature of the diets incubated. Although melamine addition did not affect GP kinetics and fermentation gas pattern compared to the control, the increase of melamine addition stimulated the yield of CH4by decreasing CO2, especially during the fermentation of the HF diet. The concentrations of ammonia nitrogen (N), amino acid N and microbial N in culture fluids were greater in the fermentation of LF- than HF diets, and these concentrations were increased by the increase of melamine addition after 72-h fermentation. The concentrations of total volatile fatty acids (VFA) were greater in HF than LF diets. The addition of melamine decreased total VFA concentrations and this response was greater in HF than LF diet fermentations. Melamine addition did not affect molar proportions of acetate, butyrate, propionate and valerate compared with the control; however, branched-chain VFA production, which was lower in the HF than the LF diet, was increased by the melamine addition, especially in the HF diet fermentation. The ratio of non-glucogenic to glucogenic acids was lower in the HF than the LF diet, but it was not affected by melamine addition. In brief, the greater reduction in the rate and extent of rumen fermentation found for the HF diet in comparison with the LF diet suggested that rumen fermentation rate and extentin vitrodepended mainly on the nature of the incubated substrate, and that they could be further inhibited by the increase of melamine addition.

Radioimmunoassay for Clostridium perfringens Enterotoxin and Its Use in Screening Isolates Implicated in Food-Poisoning Outbreaks

1983 ◽  
Vol 46 (12) ◽  
pp. 1069-1073 ◽  
Author(s):  
GERARD N. STELMA ◽  
JOHN C. WIMSATT ◽  
PETER E. KAUFFMAN ◽  
DHIRENDRA B. SHAH
Keyword(s):  
Clostridium Perfringens ◽  
Food Poisoning ◽  
Soluble Starch ◽  
Optimum Conditions ◽  
Ileal Loop ◽  
Clostridium Perfringens Enterotoxin ◽  
Highly Active ◽  
Enterotoxin Production

Fourteen isolates of Clostridium perfringens obtained from food-poisoning outbreaks were screened for enterotoxigenicity using a radioimmunoassay (RIA) that detects 1.0 ng of enterotoxin/ml. Only four of the isolates produced enterotoxin in concentrations too low to be detected by counterimmunoelectrophoresis when grown in Duncan-Strong sporulation (D-S) medium. Substitution of raffinose for soluble starch or addition of theobromine to the medium stimulated enterotoxin production by three of the four enterotoxin-positive isolates. Raffinose and theobromine did not stimulate enterotoxin production by isolates that were enterotoxin-negative in D-S medium. Enterotoxin production by the RIA-positive strains correlated with the numbers of heat-resistant spores they produced. The RIA-negative isolates produced approximately the same numbers of spores/ml as the high enterotoxin producers, and more spores/ml than strain H8 produced under optimum conditions. Therefore, inability to sporulate is not the cause for failure of these isolates to produce enterotoxin. Rabbit ileal loop assays showed that the two isolates that were lowest enterotoxin producers in vitro were highly active in vivo.

Effect of malate on in vitro (RUSITEC) rumen fermentation

1998 ◽  
Vol 22 ◽  
pp. 303-305 ◽  
Author(s):  
M. D. Carro ◽  
S. Lopez ◽  
C. Valdes ◽  
F. J. Ovejero
Keyword(s):  
Volatile Fatty Acids ◽  
Artificial Saliva ◽  
Rumen Fermentation ◽  
Disodium Salt ◽  
Antibiotic Resistant ◽  
Selenomonas Ruminantium ◽  
Alfalfa Hay ◽  
Micro Organisms ◽  
Electron Sink

In the last few years there has been an increasing concern regarding the use of antibiotics in ruminant feeding and the potential for selection of antibiotic-resistant pathogen micro-organisms. Some authors (Martin and Streeter, 1995; Callaway and Martin, 1996) suggested that organic acids (aspartate, fumarate, malate) potentially provide an alternative to currently used antimicrobial compounds. Several in vitro studies (Martin and Streeter, 1995; Callaway and Martin, 1996) showed that incorporation of DL-malate into fermentations with both Selenomonas ruminantium HD4 and with mixed ruminal micro-organisms resulted in changes in final pH, methane and volatile fatty acids (VFA) that are analogous to ionophore effects. Nisbet and Martin (1993) hypothesized that malate acted as an electron sink for hydrogen. However, the mechanism of action is not well known. Malate is a key intermediate in the succinate-propionate pathway and therefore could stimulate propionate production. The objective of this study was to study the effects of DL-malate and propionate on the in vitro rumen fermentation of a 50:50 foragexoncentrate diet.The study was carried out using the rumen simulation technique (RUSITEC) following the general incubation procedure described by Czerkawski and Breckenridge (1977). The complete unit consisted of eight vessels with an effective volume of 700 ml each. The vessels inocula (solid and liquid) were obtained from three ruminally fistulated ewes given a diet consisting of 700 g alfalfa hay and 300 g concentrate per kg dry matter (DM) (Table 1) and transferred to the RUSITEC system within 30 min of the 1st day of the experiment. The flow through the vessels was maintained by continuous infusion of artificial saliva at a rate of 533 ml/day. Each vessel received daily a nylon bag containing 7 g alfalfa hay, 7 g concentrate and 0·10 g vitaminsminerals mix. From the 1st day of incubation three vessels received daily 5·62 mmol DL-malate (disodium salt; Sigma-Aldrich Quimica, S.A., Spain), three vessels received 5·62 mmol of propionate (monosodium salt; Sigma-Aldrich Quimica, S.A., Spain) and two vessels received no addition (control). DL-malate and propionate were weighed into the nylon bags and carefully mixed with the food.

Sign in / Sign up

Export Citation Format

Share Document