Indigenous bacteria and bacterial metabolic products in the gastrointestinal tract of broiler chickens

The gastrointestinal tract is a dynamic ecosystem containing a complex microbial community. In this paper, the indigenous intestinal bacteria and the microbial fermentation profile particularly short chain fatty acids (SCFA), lactate, and ammonia concentrations are reviewed. The intestinal bacterial composition changes with age. The bacterial density of the small intestine increases with age and comprises of lactobacilli, streptococci, enterobacteria, fusobacteria and eubacteria. Strict anaerobes (anaerobic gram-positive cocci, Eubacterium spp., Clostridium spp., Lactobacillus spp., Fusobacterium spp. and Bacteroides) are predominating caecal bacteria in young broilers. Data from culture-based studies showed that bifidobacteria could not be isolated from young birds, but were recovered from four-week-old broilers. Caecal lactobacilli accounted for 1.5-24% of the caecal bacteria. Gene sequencing of caecal DNA extracts showed that the majority of bacteria belonged to Clostridiaceae. Intestinal bacterial community is influenced by the dietary ingredients, nutrient levels and physical structure of feed. SCFA and other metabolic products are affected by diet formulation and age. Additional studies are required to know the bacterial metabolic activities together with the community analysis of the intestinal bacteria. Feed composition and processing have great potential to influence the activities of intestinal bacteria towards a desired direction in order to support animal health, well-being and microbial safety of broiler meat.     

Effect of condensed tannins addition on the astringency of red wines

Astringency has been defined as a group of sensations involving dryness, tightening, and shrinking of the oral surface. It has been accepted that astringency is due to the tannin-induced interaction and/or precipitation of the salivary proline-rich proteins (PRPs) in the oral cavity, as a result of the ingestion of food products rich in tannins, for example, red wine. The sensory evaluation of astringency is difficult, and the existence of fast and reliable methods to its study in vitro is scarce. So, in this work, the astringency of red wine supplemented with oligomeric procyanidins (condensed tannins), and the salivary proteins (SP) involved in its development were evaluated by high-performance liquid chromatography analysis of human saliva after its interaction with red wine and by sensorial evaluation. The results show that for low concentration of tannins, the decrease of acidic PRPs and statherin is correlated with astringency intensity, with these families having a high relative complexation and precipitation toward condensed tannins comparatively to the other SP. However, for higher concentrations of tannins, the relative astringency between wines seems to correlate's to the glycosylated PRPs changes. This work shows for the first time that the several families of SP could be involved in different stages of the astringency development.     

Nitrogenase diversity and activity in the gastrointestinal tract of the wood-eating catfish Panaque nigrolineatus

The Amazonian catfish, Panaque nigrolineatus, consume large amounts of wood in their diets. The nitrogen-fixing community within the gastrointestinal (GI) tract of these catfish was found to include nifH phylotypes that are closely related to Clostridium sp., Alpha and Gammaproteobacteria, and sequences associated with GI tracts of lower termites. Fish fed a diet of sterilized palm wood were found to contain nifH messenger RNA within their GI tracts, displaying high sequence similarity to the nitrogen-fixing Bradyrhizobium group. Nitrogenase activity, measured by acetylene reduction assays, could be detected in freshly dissected GI tract material and also from anaerobic enrichment cultures propagated in nitrogen-free enrichment media; nifH sequences retrieved from these cultures were dominated by Klebsiella- and Clostridium-like sequences. Microscopic examination using catalyzed reporter deposition-enhanced immunofluorescence revealed high densities of nitrogenase-containing cells colonizing the woody digesta within the GI tract, as well as cells residing within the intestinal mucous layer. Our findings suggest that the P. nigrolineatus GI tract provides a suitable environment for nitrogen fixation that may facilitate production of reduced nitrogen by the resident microbial population under nitrogen limiting conditions. Whether this community is providing reduced nitrogen to the host in an active or passive manner and whether it is present in a permanent or transient relationship remains to be determined. The intake of a cellulose rich diet and the presence of a suitable environment for nitrogen fixation suggest that the GI tract microbial community may allow a unique trophic niche for P. nigrolineatus among fish.     

Effect of age on bacterial translocation from the gastrointestinal tract in mice.

To clarify the effects of age on bacterial translocation from the gastrointestinal tract, mice at the age of 1, 2, 4, 6, 12, and 15 months were antibiotic-decontaminated for 4 days and then inoculated orally with streptomycin-resistant Escherichia coli C25. Mice treated with cyclophosphamide and untreated controls were tested for bacterial translocation to the mesenteric lymph nodes (MLN) 2 days later. The population levels of E. coli C25 in cyclophosphamide-treated and untreated mice were approximately 10(9.3) and 10(9.5) per gram of cecum, respectively, at each tested age. There were no significant differences in the incidence of translocation of E. coli C25 to MLN at any of the tested ages, whereas the number of E. coli C25 detected in MLN was higher in young mice than in aged mice in both the cyclophosphamide-treated and untreated groups. These findings suggest that bacterial translocation from the GI tract may be a more important problem in young animals than in aged animals.     

The digestion of dietary protein bound by condensed tannins in the gastro-intestinal tract of sheep

The digestion of dietary protein bound by condensed tannins (CTs) in ruminants was investigated by determining the extent of dissociation of insoluble ¹²⁵I-BSA + CT complexes administered to abomasally and intestinally fistulated sheep. The extent of dissociation was registered as the true digestibility of iodinated bovine serum albumin (¹²⁵I-BSA). The true digestibility of ¹²⁵I-BSA originally bound to Leucaena pallida CT (0.721) was lower (P<0.05) than that of ¹²⁵I-BSA originally bound to L. leucocephala CT (0.880) between the abomasum and terminal ileum. These results indicate that differences in the ability of CT to inhibit ¹²⁵I-BSA digestion in vivo matched the relative abilities of the same CT to bind BSA in vitro, indicating that the in vitro BSA-binding assay for ranking CT behaviour was biologically relevant in vivo. Furthermore, the true digestibility of CT-bound ¹²⁵I-BSA between the mouth and faeces permitted the prediction of the quantitative contribution that CT-bound dietary proteins make to improved nitrogen supply to the small intestines.     

Effect of gastrointestinal tract secretions on the anti-lysozyme activity of enterobacteria

The effect of the duodenal contents and its components on the antilysozyme activity (ALA) of enterobacteria was studied. Under the action of native bile and the preparation of dried bile the stimulation of the expression of ALA factor in 86.6-93.3% of enterobacteria was observed. Pancreatin increased the level of the secretion of ALA factor by 50% in comparison with the control. The preparation of egg lysozyme produced no changes in the frequency and level of the expression of ALA factor. The study revealed the dose-dependant character of the action of duodenal contents: in the native form, as well as at concentrations of 50% and 25%, duodenal contents stimulated the expression of the ALA factor of enterobacteria; at concentrations of 12.5% and lower, its effect could be stimulating, inhibitory or neutral.     

Mucosal dendritic cell diversity in the gastrointestinal tract

The discovery of dendritic cells (DCs) in skin by Paul Langerhans in 1868 identified a cell type which has since been recognized as a key link between innate and adaptive immunity. DCs originate from bone marrow and disseminate through blood to all tissues in the body, and distinct DC subpopulations have been identified in many different tissues. DC diversity is apparent throughout all mucosal surfaces of the body, but the focus of this review article is DC diversity throughout the gastro-intestinal tract (GIT). DC subpopulations have been well characterized in the oral cavity and small intestine, but DC characterization in other regions, such as the esophagus and stomach, is limited. Substantial research has focused on DC function during disease, but understanding the regulation of inflammation and the induction of acquired immune responses requires combined phenotypic and functional characterization of individual DC subpopulations. Furthermore, little is known regarding mucosal DC subpopulations in the GIT of the neonate and how these DC populations change following colonization by commensal microflora. The current review will highlight mucosal DC diversity and discuss factors that may influence mucosal DC differentiation.     

Effect of solar particle event radiation on gastrointestinal tract bacterial translocation and immune activation

Space flight conditions within the protection of Earth's gravitational field have been shown to alter immune responses, which could lead to potentially detrimental pathology. An additional risk of extended space travel outside the Earth's gravitational field is the effect of solar particle event (SPE) radiation exposure on the immune system. Organisms that could lead to infection include endogenous, latent viruses, colonizing pathogenics, and commensals, as well as exogenous microbes present in the spacecraft or other astronauts. In this report, the effect of SPE-like radiation on containment of commensal bacteria and the innate immune response induced by its breakdown was investigated at the radiation energies, doses and dose rates expected during an extravehicular excursion outside the Earth's gravitational field. A transient increase in serum lipopolysaccharide was observed 1 day after irradiation and was accompanied by an increase in acute-phase reactants and circulating proinflammatory cytokines, indicating immune activation. Baseline levels were reestablished by 5 days postirradiation. These findings suggest that astronauts exposed to SPE radiation could have impaired containment of colonizing bacteria and associated immune activation.     

Mutualistic fermentative digestion in the gastrointestinal tract: diversity and evolution

All animals, including humans, are adapted to life in a microbialworld. Anaerobic habitats have existed continuously throughoutthe history of the earth, the gastrointestinal tract being acontemporary microniche. Since microorganisms colonize and growrapidly under the favorable conditions in the gut they couldcompete for nutrients with the host. This microbial challengehas modified the course of evolution in animals, resulting inselection of complex animal-microbe relationships that varytremendously, ranging from competition to cooperation. The ecologicaland evolutionary interactions between herbivorous dinosaursand the first mammalian herbivores and their food plants arereconstructed using knowledge gained during the study of modernliving vertebrates, especially foregut and hindgut fermentingmammals. The ruminant is well adapted to achieve maximal digestionof roughage using the physiological mechanism at the reticulo-omasalorifice which selectively retains large particles in the reticulo-rumen.However, the most obvious feature of all ruminants is the regurgitation,rechewing and reswallowing of foregut digesta termed rumination.Foregut fermenting mammals also share interesting and uniquefeatures in two enzymes, stomach lysozyme and pancreatic ribonucleasewhich accompany and are adaptations to this mode of digestion.The microbial community inhabiting the gastrointestinal tractis represented by all major groups of microbes (bacteria, archaea,ciliate protozoa, anaerobic fungi and bacteriophage) and characterizedby its high population density, wide diversity and complexityof interactions. The development and application of molecularecology techniques promises to link distribution and identityof gastrointestinal microbes in their natural environment withtheir genetic potential and in situ activities.     

Assessment of mouse strain on bacterial translocation from the gastrointestinal tract

The translocation of indigenous bacteria from the gastrointestinal tract to the mesenteric lymphnodes was compared in ten strains of mice. Indigenous Escherichia coli were cultured from the mesenteric lymphnodes of only two of the six mouse strains examined. Thus, spontaneous translocation of indigenous enteric bacteria across the intestinal barrier did not occur to any significant extent in any of the mouse strains examined. Since bacterial overgrowth in the gastrointestinal tract promotes bacterial translocation, bacterial translocation was tested in ten mouse strains including B10 series after antibiotic-decontaminated and subsequent colonization with streptomycin-resistant E. coli C25. E. coli C25 populated the ceca of the mice at levels of 10(8) to 10(9) per gram and translocated to 90-100% of the mesenteric lymphnodes with mean of 10(1.13) to 10(1.86) per mesenteric lymphnode. However, there were no significant differences between mouse strains as to the translocation incidence or the numbers of viable E. coli C25 per mesenteric lymphnode. Thus, genetic differences between mouse strains did not influence bacterial translocation from the gastrointestinal tract to the mesenteric lymphnodes.     

Effect of lucerne saponins and Lotus condensed tannins on survival of grass grub,Costelytra zealandica

Abstract

Crude extracts of lucerne (Medicago sativa) and Lotus pedunculatus root were toxic when administered orally to third-instar Costelytra zealandica larvae. Purified saponins from lucerne root were alone found sufficiently toxic to account fully for the activity of the crude extract. Condensed tannins extracted from L. pedunculatus and L. corniculatus had no effect on larval survival when administered at levels equivalent to those present in crude extracts.     

Effect of CCK-8 on myoelectrical activity of the gastrointestinal tract in the conscious miniature pig

In conscious miniature pigs, with implanted electrodes in the wall of the antrum pylori, duodenum, jejunum, and ileum, the influence of IV infusions of CCK-8 (17.5 and 175 pM/kg/min) on gastrointestinal myoelectrical activity was measured. Although both doses under study induced a decrease in antral spike activity, only the higher dose resulted in an overall decrease in integrated myoelectrical activity. In the ileum both doses augmented spiking activity during the infusion, but inhibited electrical activity after the end of the infusion. No response was observed in the duodenum and jejunum. The experiments demonstrate the overall inhibitory effect of CCK-8 on antral electrical activity and its stimulatory influence on ileal smooth muscle.     

L-Carnitine dissimilation in the gastrointestinal tract of the rat

Results of previous studies in this laboratory and others have suggested that L-carnitine is degraded in the gastrointestinal tract of the rat, perhaps by the action of indigenous flora. L-[methyl-14C]Carnitine was administered to rats either orally or intravenously in doses of 86 nmol or 124 mumol, and expired air, 48-h urine and fecal collections, and selected tissues at 48 h after isotope administration were examined for radiolabeled carnitine and metabolites. Urine and feces of rats receiving oral L-[methyl-14C]carnitine consistently contained two radiolabeled metabolites which were identified as trimethylamine N-oxide (primarily in urine) and gamma-butyrobetaine (primarily in feces). In these rats, these metabolites accounted for up to 23% and 31% of the administered dose, respectively. By contrast, for rats receiving intravenous L-[methyl-14C]carnitine or germ-free rats receiving the isotope orally or intravenously, virtually all of the radioactivity recovered was in the form of carnitine. Analyses for 14CO2 and [14C]trimethylamine in expired air revealed little or no (less than 0.1% of dose) conversion to these compounds, regardless of size of dose or route of administration. Results of this study demonstrate conclusively that L-carnitine is degraded in the gastrointestinal tract of the rat and that indigenous flora are responsible for these transformations.     

Kallikrein-gene expression in the rat gastrointestinal tract.

The serine proteinase glandular kallikrein has been demonstrated in the gastrointestinal tract, although there is some doubt as to whether it is synthesized there or derives from exocrine-gland secretions. Using a rat pancreatic kallikrein cRNA probe we have demonstrated kallikrein-like gene expression in the corpus, duodenum, jejunum, ileum, caecum and colon, and compared the pattern of expression with that of the gastrointestinal peptides somatostatin, gastrin and glucagon. In addition, using a panel of oligonucleotide probes specific for various members of the rat kallikrein-gene family, we have shown that the kallikrein-like gene expressed appears to be expressed as true kallikrein.     

Postnatal development of bacterial population in the gastrointestinal tract of calves

Bacterial 16S rDNA from fecal samples of two calves were amplified by PCR and analyzed by denaturing gradient gel electrophoresis; selected bands were sequenced. Escherichia coli and Bifidobacterium animalis were the initial colonizers, followed by species closely related to the genera Bacteroides, Clostridium and Faecalibacterium. Change of diet was connected with shifts of bacterial population and with the occurrence of many bacterial species that have not been cultured up to now. The diet change corresponded with an alteration in a volatile-fatty-acid concentration in fecal samples.     

Effects of condensed tannins in conifer leaves on the composition and activity of the soil microbial community in a tropical montane forest

Background and aims

Condensed tannins, a dominant class of plant secondary metabolites, play potentially important roles in plant-soil feedbacks by influencing the soil microbial community. Effects of condensed tannins on the soil microbial community and activity were examined by a short-term tannin-addition experiment under field and laboratory conditions.

Methods

Condensed tannins were extracted from the leaves of a dominant conifer (Dacrydium gracilis) in a tropical montane forest on Mt. Kinabalu, Borneo. The extracted tannins were added to soils beneath the conifer and a dominant broadleaf (Lithocarpus clementianus) to evaluate the dependence of the response to tannin addition on the initial composition of the soil microbial community.

Results

Enzyme activities in the field tannin-addition treatment were lower than in the deionized-water treatment. Carbon and nitrogen mineralization were also inhibited by tannin-addition. The fungi-to-bacteria ratio after tannin-addition was higher compared with the distilled-water treatment in the laboratory experiment.

Conclusions

Based on our results, we suggest that the higher concentration of condensed tannins in the leaf tissues of Dacrydium than in those of Lithocarpus is a factor influencing the microbial community and activity. This may have influences on subsequent plant performance, which induces plant-soil feedback processes that can control dynamics of the tropical montane forest ecosystem.