Reconstitution of the gastrointestinal microflora of lactobacillus-free mice.

A colony of mice that do not harbor lactobacilli in their digestive tracts but whose intestinal microflora is otherwise functionally similar to that of conventional animals was derived. Methods used to reconstitute the intestinal microflora of the mice included inoculation of the animals with cultures of specific microbes, noncultivable microbes attached to epithelial cells, and cecal contents from conventional mice treated with chloramphenicol. Twenty-six microflora-associated characteristics were monitored by using relatively simple tests to determine the microflora status of the mice.     

Some aspects of the gastrointestinal microflora of germfree mice associated with cultured microfloras

Attempts are described to 'normalize' germfree mice by association with 3, 21 and 71 different intestinal bacterial cultures isolated from mice with an SPF flora. Germfree mice associated naturally with an SPF flora served as controls. Vital bacterial counts were determined by aerobic and anaerobic culture. Stomach and small intestine contained fewer bacteria per gram than caecum and large intestine. Aerobic vital counts from caecum and large intestine were higher in the experimental groups than in control mice. The aerobic and anaerobic flora in stomach and small intestine comprised mainly Gram-positive non-fusiform shaped rods. In the caecum and colon Gram-positive cocci predominated in the aerobic culture while in the anaerobic culture fusiform-shaped rods were prominent. Scanning electron microscopy of oesophagus, ileum, caecum and faeces demonstrated colonization of the oesophageal epithelium only after association with 71 bacterial strains; the filamentous bacteria present in the ileum of SPF mice were not found in the experimental groups and caecum and faeces contained mainly fusiform-shaped bacteria. Non-bacterial matter decreased in the caecum and faeces with increase in the complexity of the flora.     

Enumeration of anaerobic bacterial microflora of the equine gastrointestinal tract

Samples from the duodenum, jejunum, and ileum, as well as from the cecum and colon, were obtained from 11 mature grass-fed horses. Viable counts of total culturable and proteolytic bacteria were made on habitat-simulating media containing 40% clarified ruminal fluid. The mean pHs in the duodenum, jejunum, and ileum were 6.32, 7.10, and 7.47, respectively; the mean pH decreased to 6.7 in the hindgut. The acetate concentration increased along the length of the small intestine and was the only volatile fatty acid present in this gut segment. Molar proportions of acetate, propionate, and butyrate in the hindgut were 85:10:3. Differences in bacterial counts on habitat-simulating media containing equine cecal fluid or clarified ruminal fluid were negligible. Bacterial counts showed a substantial population in the duodenum (ca. 2.9 x 10(6) per g [wet weight] of sample), and this increased to 29.0 x 10(6) in the jejunum and 38.4 x 10(6) in the ileum. Proteolytic bacteria formed a high proportion of the total culturable bacteria, especially in duodenal samples. Counts of proteolytic bacteria per gram (wet weight) of sample were 3.0 x 10(6), 15.6 x 10(6), and 22.0 x 10(6) in the duodenum, jejunum, and ileum, respectively. There was a close relationship between lumenal and mucosal bacterial counts, although actual values were lower in mucosal samples. The mucosal bacterial population in the duodenum was high relative to the lumenal population. Although the comparison of bacterial populations in the hindgut of the horse and white rhino was limited to a single animal, the results were of interest. Counts were higher in the cecum than in the colon for both the horse and the white rhino.(ABSTRACT TRUNCATED AT 250 WORDS)     

反刍动物胃肠道微生物多样性研究进展

反刍动物胃肠道中庞大而复杂的微生物群落对饲料利用和宿主自身代谢有深远的影响。胃肠道微生物群落在亚种或菌株水平上表现出极大的多样性。研究反刍动物胃肠道微生物多样性有助于了解其结构、功能、影响因素以及可能的调控措施。但是,80%~90%的胃肠道微生物仍然无法培养,构成了反刍动物胃肠道微生物研究的瓶颈,分子生物学和生物信息学的快速发展为这个问题的解决提供了新的机遇。     

Enumeration of anaerobic bacterial microflora of the equine gastrointestinal tract.

Samples from the duodenum, jejunum, and ileum, as well as from the cecum and colon, were obtained from 11 mature grass-fed horses. Viable counts of total culturable and proteolytic bacteria were made on habitat-simulating media containing 40% clarified ruminal fluid. The mean pHs in the duodenum, jejunum, and ileum were 6.32, 7.10, and 7.47, respectively; the mean pH decreased to 6.7 in the hindgut. The acetate concentration increased along the length of the small intestine and was the only volatile fatty acid present in this gut segment. Molar proportions of acetate, propionate, and butyrate in the hindgut were 85:10:3. Differences in bacterial counts on habitat-simulating media containing equine cecal fluid or clarified ruminal fluid were negligible. Bacterial counts showed a substantial population in the duodenum (ca. 2.9 x 10(6) per g [wet weight] of sample), and this increased to 29.0 x 10(6) in the jejunum and 38.4 x 10(6) in the ileum. Proteolytic bacteria formed a high proportion of the total culturable bacteria, especially in duodenal samples. Counts of proteolytic bacteria per gram (wet weight) of sample were 3.0 x 10(6), 15.6 x 10(6), and 22.0 x 10(6) in the duodenum, jejunum, and ileum, respectively. There was a close relationship between lumenal and mucosal bacterial counts, although actual values were lower in mucosal samples. The mucosal bacterial population in the duodenum was high relative to the lumenal population. Although the comparison of bacterial populations in the hindgut of the horse and white rhino was limited to a single animal, the results were of interest. Counts were higher in the cecum than in the colon for both the horse and the white rhino.(ABSTRACT TRUNCATED AT 250 WORDS)     

Persistence of biologically active components of gastrointestinal tract microflora

The article is dedicated to examination and analysis of materials on translocation of microflora and its products from intestine to the internal environment of the macroorganism and persistence of biologically active substances of microflora in the bloodstream. High frequency of translocation and persistence of intestine microflora and its components in system bloodstream is shown. Persistent biologically active substances of endogenous microorganisms take part in human physiology and pathology.     

The experimental and clinical effect of ciprofloxacin on the microflora of the gastrointestinal tract

The study of the influence of cyprofloxacin on the microflora of the gastrointestinal tract has been made under experimental and clinical conditions. As revealed in this study, cyprofloxacin produces a corrective effect on the intestinal microflora; the action of this preparation, in contrast to that of other antimicrobial preparations, is retained for a long time. In patients having duodenal ulcer with bacteriosis caused by Campylobacter pylori and with intestinal dysbacteriosis the combination of cyprofloxacin and cimetidine yields a higher therapeutic effect than the use of cimetidine alone.     

Reconstitution of the thymus dependent area in the spleen of lethally irradiated mice

Cell and Tissue Research - To study the submicroscopical morphology of the microenvironment for T-lymphocytes in the spleen, mice were lethally X-irradiated and injected intravenously with...     

Colicinogenic activity of intestinal microflora as a sign of dysbacteriosis of the gastrointestinal tract

Clinical and bacteriological studies have revealed that the production of colicin by Escherichia coli forming a part of intestinal microbiocenosis is related to the clinical manifestations of inflammatory diseases of the gastrointestinal tract. During the exacerbation of chronic inflammatory processes of the digestive system the proportion of colicin producing E. coli increases (more than 45%) in comparison with that of E. coli fecal strains isolated in children and adolescents regarded as healthy (less than 15%). The possibility of using the colicin producing activity of intestinal microflora for the evaluation of the dysbiotic states of gastrointestinal tract is discussed.     

水溶性壳聚糖对小鼠肠道菌群的影响

目的 应用聚合酶链式反应-变性梯度凝胶电泳（PCR-DGGE）技术研究水溶性壳聚糖对正常小鼠肠道菌群的影响。方法 使用SPF级昆明小鼠18只,随机分为3组,每组6只,依次为正常对照组（NC）、水溶性壳聚糖高（WSC-H）和低浓度组（WSC-L）,灌服对应药物30 d后收取鼠便,细菌基因组DNA提取,PCR-DGGE电泳得到肠道菌群图谱,计算菌群结构多样性指数,聚类分析相似性并鉴定优势条带序列。结果 水溶性壳聚糖处理后小鼠肠道菌群结构发生改变,多样性指数、丰富度和均匀度较低,乳杆菌成为肠道中的优势菌群。结论 水溶性壳聚糖能够增加肠道中乳杆菌的种类和数量,起到益生元的作用来调节肠道微生态平衡。     

Developmental changes to gut microflora metabolism in mice

W.E. BRENNAN-CRADDOCK, A.K. MALLETT, I.R. ROWLAND AND S. NEALE. 1992. Developmental changes in the activities of bacterial nitrate reductase, nitroreductase and β-glucuronidase and their response to fermentable dietary fibre, were investigated in caecal contents from suckling mice (2-week-old) and in mice aged 4–24 weeks fed either a purified fibre-free diet or that diet supplemented with 5% (w/w) pectin. There was no apparent age-related trend common to the three enzymes studied. Nitrate reductase activity in the mice fed the fibre-free diet did not markedly alter with age. Pectin administration, however, was associated with a significant increase in nitrate reductase activity, particularly in 4-week-old mice. Nitroreductase activity exhibited an overall upward trend in mice from 2 to 12 weeks and thereafter decreased. Caecal β-glucuronidase activity in mice increased sharply between 2 weeks and 4 weeks of age, thereafter not changing significantly until the 24th week. Pectin feeding had no consistent effect on activities either of nitroreductase or β-glucuronidase. The changes in enzyme activities with age were not related to the concentration of bacteria in the caecum, which was highest in the 2-week-old mice.
We conclude that the weaning is a period in which marked changes in caecal bacterial enzyme activities can occur.     

Effect of the two-year milk-feeding on the gastrointestinal microflora of the cynomolgus monkey (Macaca fascicularis)

The effect of the two-year milk-feeding on the gastrointestinal (GI) microflora of a cynomolgus monkey was determined. Bifidobacterium spp. in the animal fed with cow's milk alone were distributed in higher number in the stomach, duodenum, cecum, and rectum. The increasingly higher numbers of Lactobacillus spp. and Candida spp. were counted in all regions of the GI tract of the animal fed with the formula diet. Bacteroidaceae, Enterobacteriaceae, and Streptococcus spp. were detected from the upper to lower intestines in the monkey given only milk, whereas in the monkey given the formula, those bacterial species were localized in only the lower intestines.     

SPF级KM小鼠与BALB/c小鼠肠道总菌多样性的比较

目的分析SPF级封闭群KM小鼠及近交系BALB/c小鼠的肠道菌群总菌多样性,比较两个不同遗传背景肠道总菌的丰富度、Shannon-Wiener指数和均匀度。方法收集SPF级KM小鼠和BALB/c小鼠新鲜粪便,提取粪便总菌DNA,用基于细菌16S rDNA序列的变性梯度凝胶电泳(PCR-DGGE)分析粪便总菌多样性。结果 SPF级KM小鼠及BALB/c小鼠粪便总菌多样性差异无统计学意义(P0.05),品系内不同性别之间粪便总菌多样性差异亦无统计学意义(P0.05)。结论选择SPF级小鼠进行微生态学相关研究时,封闭群KM小鼠及近交系BALB/c小鼠均可作为选择对象,同时可忽略菌群的性别差异。     

Lysine synthesized by the gastrointestinal microflora of pigs is absorbed,mostly in the small intestine

This study used a digesta transfer protocol to determine the site of absorption of lysine synthesized by the gastrointestinal microflora of pigs. Eight pigs were used, four with reentrant cannulas in the terminal ileum, two with simple T cannulas in the terminal ileum, and two intact. All pigs were given, for 5 days, the same low-protein diet that included fermentable carbohydrates. The diet of two pigs with reentrant cannulas (donor) and of the two intact (control) pigs was supplemented with (15)NH(4)Cl. The two other pigs with reentrant cannulas (acceptor pigs) and those with simple cannulas (used to supply unlabeled digesta) were given the same diet but unlabeled NH(4)Cl. Ileal digesta were collected continuously from all of the reentrant cannulas and kept on ice. All digesta from each donor pig were reheated and returned to the distal cannula of its companion acceptor, whose ileal digesta were discarded. Unlabeled ileal digesta from the pigs with simple cannulas were instilled into the distal cannulas of the donor pigs. At the end of the experiment, the average (15)N enrichment in the plasma free lysine of control pigs was 0.0407 atom % excess (APE); that of donor pigs was 0.0322 APE (79% of controls), whereas that of acceptor pigs was only 0.0096 APE (24% of controls). Due to nitrogen recycling, acceptor pigs had labeled lysine in the digesta of the stomach and small intestine, and donor pigs had labeled lysine in the digesta of the large intestine. If account is taken of the higher (15)N enrichment of microbial lysine in the large compared with the small intestine, it can be estimated that >90% of the absorption of microbial lysine took place in the small intestine.