Caecal Bacteria Research Articles

The effects of transgalactosylated oligosaccharides on gut flora metabolism in rats associated with a human faecal microflora

The effect on various caecal bacteria and their metabolic activities of feeding diet containing transgalactosylated oligosaccharides (TOS) with or without Bifidobacterium breve (administered in the drinking water) was investigated in rats colonized with a human faecal microflora. TOS (5% w/w in diet) or TOS plus B. breve, given for 4 weeks, induced increases in caecal concentration of total anaerobic bacteria, lactobacilli and bifidobacteria, and decreases in numbers of enterobacteria. Caecal pH was significantly reduced by feeding TOS, as were the activities of beta-glucuronidase and nitrate reductase. In contrast, beta-glucosidase activity was increased in TOS-fed rats. Dietary TOS was also associated with decreased conversion, by caecal contents, of the dietary carcinogen 2-amino-3-methyl-3H-imidazo[4,5-f] quinoline (IQ) to its genotoxic 7-hydroxy derivative.

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.

SPFマウス腸内菌叢の生産施設差

Specific pathogen free BALB/c mice from 3 commercial laboratory animal breeders in Japan were compared on the composition of caecal flora revealed by selective and nonselective cultivation as well as direct microscopical observation on smears, and relative caecal weight. Large differences were detected in viable counts of total bacteria and almost all bacterial groups, while direct microscopical counts which consisted mainly of fusiform bacteria were almost equal, resulting in diverse recovery rates among 3 breeders. Eubacterium and spiral shaped organisms were not detected from all breeders. There also existed variations within breeders, especially those in the number of Enterobacteriaceae. Relative caecal weight also differed among breeders, suggesting the participation of variety of caecal bacteria in determining this parameter. As these variations in bacteriological status of animals can influence experimental results, standardization of intestinal microbial flora is required.

Internal exposure of rats to benzidine derived from orally administered benzidine-based dyes after intestinal azo reduction

The role of the rat intestinal flora in the azo reduction of some benzidine-based dyes was studied in vitro and in vivo. The formation of benzidine was measured after anaerobic incubation of direct black 38, direct blue 6 and direct brown 95 in the presence of caecal bacteria in vitro. Benzidine was absorbed from the intestinal tract much better than the parent compounds. Oral administration of direct black 38 or direct brown 95 to Wistar rats results in the urinary excretion of mutagens. After oral administration of these dyes to germ-free Wistar rats no mutagenicity was observed in urine. The present results show that after oral administration, reduction by the intestinal flora should be considered as the first essential step in the biotoxification of benzidine-based dyes.

Virulence associated plasmids of Salmonella serotype typhimurium in experimental murine infection

The growth pattern of Salmonella enterica subsp. enterica serotype Typhimurium (Typhimurium) was studied in mice to examine the role of the 60-Mdal virulence-associated plasmid in the pathogenesis of mouse typhoid. After repeated subcultures at 45 degrees C, isogenic variants harbouring the virulence-associated plasmid (strains C52, TM122 and TM332) or having lost this large plasmid (strains C53, TM123 and TM333) were obtained from three parental strains (strains C5, TM12 and TM33, respectively). Plasmid pIP1350, present in strain C52, was tagged by Tn10 and transferred by successive conjugations to strains C53, TM123 and TM333. The behaviour of these three Typhimurium lines was studied in C57BL/6, DBA2, B6D2 (C57BL/6 X DBA2 F1 hybrid) and OF1 mice after oral infection, subcutaneous injection into the hind footpad or intravenous inoculation. The kinetics of organ colonization were followed at intervals after injection by enumeration of viable bacteria in caecum, mesenteric or popliteal lymph node, spleen, liver, kidney and lung depending on the route of infection. Strains harbouring virulence plasmid and their cured derivatives did not differ significantly in their ability to colonize caecal content and to translocate to draining lymph nodes. Elimination of the virulence plasmid was correlated with a significant reduction in the ability of cured variants to colonize spleen and liver. Reintroduction of the virulence plasmid into plasmidless variants restored the virulence to the level originally observed. These data demonstrate that a 60-Mdal plasmid in Typhimurium strains is necessary to ensure colonization of spleen and liver of experimentally infected mice.

Opportunistic bacteria isolated from the caecum of rabbits with mucoid enteritis

The caecal microflora of rabbits with mucoid enteritis was investigated by aerobic and anaerobic techniques. Escherichia coli was identified in the majority of faecal cultures from diseased rabbits and the following bacteria were occasionally identified either in the presence or absence of E. coli: Proteus mirabilis, Alcaligenes, Citrobacter, Acinetobacter, Bacillus sp. and Klebsiella. The E. coli and P. mirabilis isolated did not produce heat-stable or heat-labile toxins. None of the P. mirabilis but all E. coli isolates examined exhibited mannose-sensitive haem-agglutination of human and guinea-pig erythrocytes. There was no evidence of in-vitro attachment of E. coli or P. mirabilis to human intestinal epithelial cells. Light and electron microscopy examination of rabbits' caecal sections revealed bacteria closely associated with epithelial cells in only four of 22 mucoid enteritis cases studied. The E. coli were shown to be resistant to a sulphonamide drug at concentrations similar to those presently used in the rabbit breeding industry to control the disease. Re-inoculation of the E. coli or P. mirabilis failed to induce mucoid enteritis. The absence of amoeba, viruses, fungi, Chlamydia, Campylobacter, Clostridium perfringens and Clostridium difficile, and the heterogeneity of the caecal microflora in diseased animals raised the question whether a micro-organism was the primary aetiological agent. The caecal bacteria so often implicated appear to be opportunists.

Activités α- et β-Galactosidasiques des Fractions Protozoaires et Bactéries Isolées du Contenu du Caecum de Cheval

Leaf lipids have a high content of galactolipids localized in chloroplasts. Fractions of caecum bacteria and of caecum protozoa (which ingest and digest chloroplasts) possessed both α- and ß-galactosidase activities. It was found that cell-free extracts of these microorganisms hydrolyzed mono- and digalactosyldiglycerides, melibiose, and raffinose, and the activity of protozoa was greater than that of bacteria. Caecum fluid without any microorganisms had nearly no activity on these substrates.

Evaluation of treatment with defined and undefined mixtures of gut microorganisms for preventing Salmonella colonization in chicks and turkey poults

A defined mixture of 48 bacteria isolated from the chicken caecum and undefined, anaerobic cultures of the contents of the caecum of both chicken and turkey have been compared for their ability to prevent intestinal colonization of newly hatched chicks and turkey poults by Salmonella kedougou or S. typhimurium. Although treatment with undefined cultures from either type of bird confirmed previous observations that reciprocal protection against Salmonella can be obtained, the defined bacterial mixture protected chicks but not poults, even when a further 17 strains of different caecal bacteria were incorporated in the treatment mixture. The undefined culture from chicken was less protective for poults than the corresponding turkey culture.

The influence of media on the recovery of bacteria from the normal mouse caecum.

3 diluting fluids and 6 agar media were compared for the culture of caecal microflora of mice. The efficiency of the media in the growth of caecal bacteria was determined by comparing the quantitative recovery (expressed as percentage of the total microscopic count) from the specimens. Of the diluting fluids saline resulted in a low yield (11.47%). Addition of potassium salts increased the yield (23.25%). A broth medium resulted in the highest recovery (44.44%). The influence of storing the caecal microflora in 3 different diluting fluids on the yield was studied. In all diluents the viable count of caecal bacteria decreased with time, but did so least in broth medium. 6 solid agar media were tested. When saline was used as the diluting fluid, no significant differences in yields were found with all 6 media. When broth medium was used as diluting fluid and yields up to 60% were obtained, no significant differences were shown between the results with 5 media but one medium resulted in a lower yield (32.59%).

Dietary fibre, bacterial metabolism and toxicity of nitrate in the rat.

1. A semi-synthetic diet, the semi-synthetic diet plus pectin, and a stock diet were fed to rats, and three metabolic functions of the caecal bacteria (reduction of amaranth, p-nitrobenzoic acid and nitrate) were measured in vitro. 2. No consistent differences were noted between diets for the reduction of amaranth and p-nitrobenzoic acid. 3. No consistent differences in nitrate reductase activity were noted for rats maintained on a stock diet or a fibre-free diet. However, the addition of 5% pectin to the latter diet resulted in a several-fold increase in nitrite production. 4. This increased nitrite production in vitro was associated with methaemoglobinaemia following the oral administration of nitrate to rats fed the diet containing pectin. Animals receiving the basal fibre-free diet were unaffected by nitrate.

Ring-a reduction of medroxyprogesterone acetate [17α-acetoxy-6α-methyl-4-pregnene-3, 20-dione (MPA)] in biological systems

Medroxyprogesterone acetate [17-acetoxy-6α-methyl-4-pregnene-3,20-dione (MPA)] is readily reduced by cultures of human faecal bacteria and rat caecal bacteria incubated aerobically or anaerobically. Gas chromatographic-mass spectrometric evidence indicated formation of 5β-dihydro MPA (17α-acetoxy-6α-methyl-5β-pregnane-3,17-dione) and three tetrahydro MPA (17α-acetoxy-6α-methyl-3ζ-hydroxy-5ζ-pregnan-20-one) isomers by human faecal bacteria; rat caecal bacteria formed two tetrahydro MPA isomers. Megestrol acetate [17-acetoxy-6-methyl-4,6-pregnadiene-3,17-dione (MA)] was resistant to reduction by these bacterial systems. That ring A reduction of MPA is also a significant route of hepatic metabolism is indicated by the detection of similar tetrahydro MPA metabolites in liver, bile and faeces from dogs to which MPA was administered orally (or intramuscularly); a (3-hydroxy)dihydro MPA (17α-acetoxy-6α-methyl-3ζ-hydroxy-4-pregnene-20-one) glucuronide was also detected in bile. A tetrahydro MPA metabolite was also found, as a glucuronide, in significant quantities, in bile collected by T-tube drainage from a woman who was given MPA orally.

The effect of rumen and post-rumen feeding of carbohydrates on the caecal microflora of sheep.

Summary. When sheep were bottle‐fed with solutions of glucose, sucrose or maltose, so avoiding fermentation in the rumen, there was a marked increase in the number of caecal bacteria, with a higher percentage of viable bacteria, compared with caecal counts from sheep fed conventionally on carbohydrates. Bottle‐feeding also resulted in a redistribution of bacterial types, 40–46% of the flora comprising Gram positive rods and a significant increase in butyric acid and decrease in propionic acid in the caecal contents. Feeding cellulose suspensions by bottle or conventionally failed to produce significant differences in counts of cellulolytic caecal bacteria. When sucrose was infused in increasing amounts into the abomasum, Streptococcus bovis was the principal organism, isolated from faeces.

Degradation of riboflavin by alimentary bacteria of the ruminant and man: production of 7,8-dimethyl-10-carboxymethylisoalloxazine.

1. A new product of the bacterial degradation of riboflavin has been isolated from fermentations in vitro of mixtures of either rumen bacteria or caecal bacteria with excess of the vitamin.2. This product has been identified as 7,8-dimethyl-10-carboxymethylisoalloxazine and has also been shown to occur in the urine of ruminants and man.3. The bacterial formation of this compound is compared with the bacterial formation of other isoalloxazines previously identified in similar incubation mixtures, and is discussed in relation to the factors influencing the mode of degradation of riboflavin.

Intestinal Azo-reduction and Glucuronide Conjugation of Prontosil

1. The lipid-soluble azo-dye Prontosil was excreted in rat bile as an N-glucuronide, and in the urine, after azo-reduction, as free and N4-acetylated sulphanilamide.2. When everted sections of rat intestine were incubated with 35S-Prontosil, the dye was metabolized mostly to the glucuronide and partly to sulphanilamide by the intestinal wall.3. Both intravenously and intraduodenally administered 35S-Prontosil to biliary cannulated rats was recovered mainly in the bile as the N-glucuronide, whereas intracaecally administered 35S-Prontosil was recovered chiefly in the urine as the products of azo-reduction. Considerably more N-glucuronide was biliary excreted after intraduodenal than intravenous dosage. The results imply that the rat intestinal wall is a major site of glucuronide conjugation of orally administered Prontosil. It is also apparent that the caecal bacteria, and not the liver, is the prime site of azo-reduction of Prontosil, in vivo. Azo-reduction is probably also mediated to some extent by the intestinal wall.4. Urinary metabolites of 35S-Prontosil from mouse, hamster and guinea-pig were qualitatively the same as the rat, although there were some quantitative differences.

Factors affecting dimethylnitrosamine formation from simple precursors by rat intestinal bacteria

[ 14C]Dimethylamine and sodium nitrite incubated together in the molecular proportion 1:4 with the bacterial flora of the rat intestine under anaerobic conditions at pH 7·0 give rise to [ 14C]dimethylnitrosamine, which can be readily detected by thin-layer chromatography and estimated by scintillation counting. Glucose is required for the formation of dimethylnitrosamine from precursors dependent on the metabolic activity of the bacterial flora from the caecum, small intestine or large intestine. By omission of glucose from the system, or by the use of a boiled bacterial preparation, nitrosamine formation is suppressed but not completely abolished. [ 14C]Dimethylnitrosamine formation is also suppressed to a similar extent by inclusion of the antibiotic neomycin as a component of the standard incubation system. There appears to be a residual non-enzymatic formation of [ 14C]dimethylnitrosamine from its precursors under these circumstances, even though the reaction conditions at pH 7·0 are far from optimal for spontaneous interaction of dimethylamine and sodium nitrite. Enzymatic formation of dimethylnitrosamine can be enhanced when standard incubations are performed in the presence of riboflavin. Overall yields of nitrosamine can also be enhanced by increasing the nitrite levels in the system, but this tends predominantly to increase the non-enzymatic nitrosamine formation. Preformed [ 14C]dimethylnitrosamine incubated with caecal bacteria under standard conditions for 20 hr appears to be stable and is recoverable in 95% yield from incubation mixtures.

Intestinal azo reduction and glucuronide conjugation of prontosil.

Abstract1. The lipid-soluble azo-dye Prontosil was excreted in rat bile as an N-glucuronide, and in the urine, after azo-reduction, as free and N4-acetylated sulphanilamide.2. When everted sections of rat intestine were incubated with 35S-Prontosil, the dye was metabolized mostly to the glucuronide and partly to sulphanilamide by the intestinal wall.3. Both intravenously and intraduodenally administered 35S-Prontosil to biliary cannulated rats was recovered mainly in the bile as the N-glucuronide, whereas intracaecally administered 35S-Prontosil was recovered chiefly in the urine as the products of azo-reduction. Considerably more N-glucuronide was biliary excreted after intraduodenal than intravenous dosage. The results imply that the rat intestinal wall is a major site of glucuronide conjugation of orally administered Prontosil. It is also apparent that the caecal bacteria, and not the liver, is the prime site of azo-reduction of Prontosil, in vivo. Azo-reduction is probably also mediated to some extent...

Entamoeba histolytica: Encystation and cultivation of several isolates

Culture media consisting of Ringer extracts of colon contents or faecal material from man, including meconium from newborn babies, pig, horse, cow, dog, and fowl have, with addition of rice starch, supported isolation, maintenance, encystation, and excystation of Entamoeba histolytica. These media improve by one autoclave sterilization, but reautoclaving and Seitz filtration ruin their potency. Acriflavine eradicates some bacteria necessary for starch ingestion in these media. Individual cultures have been kept alive up to 50 days. Practically all strains isolated with bacteria from distal parts of the colon encyst spontaneously, commencing in the earliest cultural generations. Strains isolated with bacteria from proximal parts of the colon do not encyst spontaneously. Almost every well established strain can be induced to encyst by suitable methods. Two new methods have been successfully tried. One consists of adding acriflavine at inoculation to cultures in diphasic serum media with starch. In practically every such culture and in several subsequent cultures cysts appear. The second method consists of cooling cysts for several days, after which on reincubation fresh cysts appear in one or several subsequent cultures. This method was successful only with freshly isolated not old and well established strains. Reduced encystation capacity in two established strains was temporarily restored by addition of unmodified caecal bacteria. Viability of early, spontaneous cysts is short, but induced cysts are hatchable after several weeks in the refrigerator.

Steroids in germfree and conventional rats. Sulpho- and glucuronohydrolase activities of caecal contents from conventional rats.

Caecal contents from conventional rats has been shown to have steroid sulphatase and glucuronidase activities. Whereas the sulphatase activity was of microbial origin the glucuronidase activity was also present in caecal contents from germfree rats. In vitro incubations showed that sulphuric acid esters of the 3α‐, 3β‐, 17β‐ and 21‐hydroxyl groups were all hydrolyzed by the caecal bacteria. The ration between free and conjugated metabolites of [4‐14C]corticosterone administered to germfree and conventional rats was much higher in the conventional than in the germfree rats. This shows that microbial hydrolysis of steroid sulphates takes place also in vivo.

Bacterial symbiotes from the caeca of certain Heteroptera

does not appear. First page follows. Introduction Since the early years of the nineteenth century it has been known (e.g., see (Dufour, 1833)4 that the posterior end of the midgut in certain groups of Heteroptera is characterized by the presence of saclike appendages opening into it. These evaginations, called “gastric caeca” or simply “caeca,” apparently serve a purpose different from that of the so-called gastric caeca of the Acrididae, and they appear almost always to contain specific bacteria. The bacteria from different Heteroptera may vary in their morphology, but they are relatively constant for a given insect species. The caeca themselves also vary a great deal in their morphology according to species, showing simple to complex arrangements, and apparently reflect basic phylogenetic relationships. Although there have been a number of studies (e.g., those by (Forbes, 1892); (Glasgow, 1914); (Kuskop, 1924); (Rosenkranz, 1939); (Schneider, 1940) very little has been accomplished toward revealing the nature, kind, or function of the caecal bacteria. Of their function we are most ignorant; certainly it can be said that the role of the bacteria, and their relation to the host insect, are not clearly understood. (Glasgow (1914)) assumed that the caecal bacteria not only inhibited the development of “foreign” or adventitious bacteria but excluded them altogether. Others (e.g., (Kuskop, 1924) have thought they might play a nutritional role. In size and shape, the bacteria, as they occur in different species of Heteroptera, range from small coccuslike bacilli to large vermiform or spirochete-like forms. Attempts to cultivate the bacteria on ordinary bacteriological media have not met with much success. (Glasgow (1914)) reported the cultivation of the symbiote from the caeca of the squash bug, Anasa tristis (De Geer), and of certain other coreids, in nutrient broth and agar; and Steinhaus