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.     

Selective decontamination of the intestine and total gnotobiologic isolation in treatment of mice with acute radiation sickness]

Comparative study of ciprofloxacin, pefloxacin and amikacin showed that ciprofloxacin and pefloxacin had a selective action on the intestinal microflora of conventional mice. Amikacin induced inhibition not only of the opportunistic bacteria but also of the representatives of the indigenous microflora. The use of the drugs in combination with total gnotobiological isolation in treatment of experimental radiation sickness provided an increase in survival of the irradiated animals, the more so as ciprofloxacin was used.     

Sensitivity of the intestinal microflora of patients to antimicrobial preparations studied in order to conduct rational antibiotic treatment

The oral administration of amikacin, ampiox, nystatin to CBA mice and the external treatment of the animals with 1% chlorhexidine solution makes it possible to create the germ-free state in the animals which must be then kept in a sterile box. If such animals receive the decantate of the patient's feces, introduced in a single administration, the microflora, which is subsequently formed in the intestine of the recipient animals, is identical to the donor's microflora. This permits the rapid and accurate determination of the sensitivity of the patient's intestinal microflora to different antimicrobial preparations and their combinations. The antibacterial preparations, effectively suppressing the patient's intestinal anaerobic opportunistic microflora in the intestine of the recipient mice, produce, if subsequently prescribed for treatment, a pronounced corrective effect on such microflora in the patient's intestine.     

Microbial-host interactions specifically control the glycosylation pattern in intestinal mouse mucosa

The glycosylation of the intestinal cell layer is thought to control several key functions of the gut such as vectorial transports, defence against microbial agents or immunological processes. It has been assumed that the gut microflora may modulate the glycosylation pattern of the intestinal cell layer. However, there is no direct evidence for this regulatory process. The first goal of this work was to establish the germ-free mice intestinal glycosylation baseline using a histochemical approach and a panel of ten lectins with defined glycan specificities to tissue sections prepared from various cellular compartments of the small and large intestine. Using this baseline, we have studied the contribution of the gut microflora on the carbohydrate composition of glycoconjugates of intestinal cells by comparing the germ-free and conventional mice glycosylation patterns. Analysis of the germ-free mice intestinal glycosylation baseline revealed that the expression of glycans depends on the proximodistal gradient (small to large intestine) and on the cell lineage (absorptive, goblet, crypt, and Paneth cells), indicating that mice are able to create and maintain a strict topological and cell lineage-specific regulation of glycosyltransferase expression. By comparing germ-free and conventional mice, we find that the gut microflora specifically modulates the gut glycosylation pattern, quantitatively as well as qualitatively by changing the cellular and subcellular distribution of glycans. This is the first report in mice to directly demonstrate the critical contribution of microflora to intestinal glycosylation, a key characteristic of the gut.     

The effect of a preparation made from Solco lactobacteria on the survival rate and intestinal microflora of irradiated animals

Lactobacillus acidophilus strain Lat 11/83 Solco has been used for the normalization of intestinal microflora in experimental post-irradiation intestinal dysbacteriosis in mice. The results of these experiments indicate that live Solco lactobacteria, introduced intragastrically, facilitate the enhancement of the survival rate of irradiated animals and the normalization of microflora in their gastrointestinal tract. The strain can be used as bacterial preparation for the regulation of intestinal microbiocenosis.     

The effect of "Solco" lactobacteria (Lactobacillus acidophilus) on the survival and microflora of mice with a Salmonella infection

The Solco lactobacterial strain L. acidophilus Lat 11/83 has been used for the normalization of intestinal microflora in experimental post-infectious intestinal dysbacteriosis in mice. The results of experiments indicate that the intragastric administration of live Solco lactobacteria contributes to an increase in the survival rate of infected animals and the normalization of their gastrointestinal microflora. This strain may be used as a bacterial preparation for the regulation of intestinal microbiocenosis.     

白蚁肠道微生物研究方法概述

白蚁是木质纤维素的主要降解者,在森林生态系统碳氮循环过程中发挥着重要作用。白蚁肠道共生微生物主要包括原生生物、细菌、古菌和真菌。在白蚁对木质纤维素进行降解、发酵,从而产生乙酸、氢气和甲烷以及对氮的固定过程中,白蚁肠道共生微生物起着重要的作用。本文对白蚁肠道微生物的研究方法进行总结,概述了各种方法的优缺点,同时对肠道微生物的研究进展进行了总结,以期为白蚁肠道微生物的进一步研究和利用提供参考。     

虎斑颈槽蛇肠道微生物组成和分布特征

蛇类是一种研究能量平衡的模型动物,而肠道微生物则帮助宿主获取能量和营养。大多数肠道微生物的研究集中在圈养动物上,而对于野生蛇类的研究很少。本研究从3只野生虎斑颈槽蛇（Rhabdophis tigrinus）的大肠、小肠和泄殖腔内容物提取微生物总DNA,进行16S rRNA基因V4区域扩增子测序,分析虎斑颈槽蛇肠道核心微生物组成和分布特征。结果表明,阿尔法指数在不同肠道区域的多样性不存在显著性差异。大肠、小肠和泄殖腔3个肠道部位共享534个操作分类单元（OTUs）,大肠包含最多特有OTUs（388个）。门水平,梭杆菌门（Fusobacteria）在小肠（52.87% ± 14.49%）、大肠（41.12% ± 22.60%）和泄殖腔（65.70% ± 10.44%）均为优势菌。属水平,鲸杆菌属（Cetobacterium）在小肠（46.36% ± 13.86%）、大肠（21.95% ± 9.82%）和泄殖腔（58.18% ± 14.29%）为优势菌,柠檬酸杆菌属（Citrobacter）在小肠和泄殖腔中有显著性差异。此外,在其肠道检测到很多潜在的致病菌,例如,柠檬酸杆菌属、明串珠菌属（Trichococcus）和丹毒丝菌属（Erysipelothrix）,了解了潜在致病菌在虎斑颈槽蛇肠道中的分布情况。在聚类分析中发现泄殖腔的数据重复性较好,将本研究泄殖腔数据与前人研究过的食鱼蝮（Agkistrodon piscivorus）泄殖腔高通量测序数据进行联合分析,为更广泛开展不同蛇类肠道微生物组成的差异性分析提供理论借鉴依据。     

Lactobacilli and bile salt hydrolase in the murine intestinal tract.

Mice that have a complex intestinal microflora but that do not harbor lactobacilli were used to determine the contribution of lactobacilli to the total bile salt hydrolase activity in the murine intestinal tract. Bile salt hydrolase activity in the ileal contents of these mice was reduced 86% in the absence of lactobacilli and by greater than 98% in the absence of lactobacilli and enterococci compared with samples from conventional mice. Bile salt hydrolase activities were lower in ileal and cecal contents from lactobacillus-free mice colonized with enterococci than in samples from lactobacillus-free mice colonized with lactobacilli. Bile salt hydrolase activity in the duodena, jejuna, ilea, and ceca of reconstituted lactobacillus-free mice colonized by lactobacilli was similar to that in samples from the intestinal tracts of conventional mice. We conclude from these studies that lactobacilli are the main contributors to total bile salt hydrolase activity in the murine intestinal tract.     

Lactobacilli and bile salt hydrolase in the murine intestinal tract

Mice that have a complex intestinal microflora but that do not harbor lactobacilli were used to determine the contribution of lactobacilli to the total bile salt hydrolase activity in the murine intestinal tract. Bile salt hydrolase activity in the ileal contents of these mice was reduced 86% in the absence of lactobacilli and by greater than 98% in the absence of lactobacilli and enterococci compared with samples from conventional mice. Bile salt hydrolase activities were lower in ileal and cecal contents from lactobacillus-free mice colonized with enterococci than in samples from lactobacillus-free mice colonized with lactobacilli. Bile salt hydrolase activity in the duodena, jejuna, ilea, and ceca of reconstituted lactobacillus-free mice colonized by lactobacilli was similar to that in samples from the intestinal tracts of conventional mice. We conclude from these studies that lactobacilli are the main contributors to total bile salt hydrolase activity in the murine intestinal tract.     

西藏灵菇奶对抗生素相关性腹泻小鼠肠道菌群的调整作用

目的研究用西藏灵菇对抗生素引起的肠道菌群失调及病理变化的调整作用.方法由林可霉素造成小鼠腹泻模型,并证实肠道菌群紊乱后,将其分成灵菇奶治疗组和自然恢复组,7 d后对每个组小鼠进行肠道菌群检测,同时取回肠末段组织标本用光镜及电镜观察黏膜结构的变化.结果抗生素模型组大多数小鼠肠道黏膜出现不同程度的损害,小鼠肠道的正常菌群及病理组织改变基本恢复正常.结论灵菇奶不仅对肠道菌群有调整作用,而且对肠黏膜的修复有一定作用.     

Fortification of antimicrobial barrier of the small intestine in newborn mice after oral administration of ascorbigen]

Ascorbigen, a natural product, is an indole derivative of L-ascorbic acid. Its effect on postnatal development and antibacterial resistance of the small intestine was studied on newborn mice. Ascorbigen was administered to 3-5-day old mice in a dose of 100 mg/kg orally every day for 7-10 days. 30 minutes before the last administration of the drug clinical isolates of Staphylococcus aureus or Escherichia coli were administered intragastrically to the young mice. The animals were killed in 24 hours and the frequency of the isolation of the microbes from the blood, spleen, kidneys and liver was developed. The oral use of the drug normalized the intestinal microflora, provided a reliable decrease of the bacteria isolation from the blood, spleen, kidneys and liver and prevented the animal death. The morphological examination showed that ascorbigen significantly increased the number and activity of the Paneth cells in the gland crypts, the goblet cells in the villi and mononuclear cells in the selfplate of the intestine mucous membrane vs. the intact control.     

The use of a rat-derived microflora for providing colonization resistance in SPF rats

To obtain a suitable species-specific microflora for a new rat SPF-unit, germ-free WAG/Rij rats were associated with a flora derived originally from selectively decontaminated Cpb: WU (Wistar) rats. Caecal and ileal contents of these rats had been cultured anaerobically (37 degrees C) for 7 days and harvested. This cultured flora was given to germ-free Cpb: SE (Swiss) mice, which were kept in an isolator system and acted as a source of the flora to associate germ-free Wag/Rij rats. In these associated rats, several parameters indicative of the 'quality' of the intestinal microflora were investigated and compared to those in rats with a mouse derived anaerobic microflora. Parameters included relative caecal weight, colonization resistance and the concentration of faecal bile acids. The cultured rat-derived microflora normalized the observed intestinal parameters better than the mouse derived microflora, and provided better colonization resistance. We conclude that culturing of intestinal contents of selectively decontaminated animals can be a useful way to obtain a species-specific donor-microflora which can be used to start new SPF units.     

Indigenous microbes and their soluble factors differentially modulate intestinal glycosylation steps in vivo

It has been shown that Bacteroides thetaiotaomicron, a representative member of the gut microflora, signals intestinal epithelial cells both in vivo and in vitro and modulate specific glycosylation processes that may mediate intestinal functions. However it is not known whether these modulations depend on the presence of live bacteria or may be elicited by soluble factors produced in vitro by this bacterium. We used lectins and an histochemical approach to survey tissue sections prepared from various cellular compartments of the small and large intestine of NRMI/KI mice grown under gnotobiotic conditions. We compared the results obtained with bacterial culture supernatant and live B. thetaiotaomicron to those obtained from germ-free mice or mice having a conventional microflora. This approach allowed us to conclude that (1) a small but specific number of glycan patterns were restored after treatment with bacterial culture supernatant and (2) the B. thetaiotaomicron associated mice restored a larger number of patterns, however, the complete conventional mice pattern must be a function of the whole microflora in the gut. The possibility to modulate this complex glycosylation pattern by introducing exogenous bacteria and bacterial products should be considered as a promising approach towards understanding the molecular basis of microbial-host interactions.     

Bdellovibrio and the intestinal flora of vertebrates.

Bdellovibrio strain MS7 force-fed to fish and frogs via an intragastric tube did not become an integral component of the intestinal microflora. Strain MS7 fed to mice in drinking water was not recovered from the intestinal tract of mice. However, in vitro, the organism multiplied in intestinal contents of frogs and mice. Bdellovibrio inoculated into rabbit ileal loops was greatly reduced in number within 24 h. It was concluded that strains MS7 could be considered nonpathogenic to animals, at least when introduced into the digestive tract, and that it is not feasible at the present time to lyse pathogenic, gram-negative bacteria in the alimentary tract with Bdellovibrio.     

Bdellovibrio and the intestinal flora of vertebrates.

Bdellovibrio strain MS7 force-fed to fish and frogs via an intragastric tube did not become an integral component of the intestinal microflora. Strain MS7 fed to mice in drinking water was not recovered from the intestinal tract of mice. However, in vitro, the organism multiplied in intestinal contents of frogs and mice. Bdellovibrio inoculated into rabbit ileal loops was greatly reduced in number within 24 h. It was concluded that strains MS7 could be considered nonpathogenic to animals, at least when introduced into the digestive tract, and that it is not feasible at the present time to lyse pathogenic, gram-negative bacteria in the alimentary tract with Bdellovibrio.     

Does the intestinal microflora synthesize pyrroloquinoline quinone?

Pyrroloquinoline quinone (PQQ) functions as a cofactor for prokaryotic oxidoreductases, such as methanol dehydrogenase and glucose dehydrogenase. When chemically-defined diets without PQQ are fed to animals, lathyritic changes are observed. In previous studies, it was assumed that PQQ was produced by the intestinal microflora; consequently, antibiotics were routinely added to diets. In the present study this assumption is tested further in mice by: (i) examining the effects of dietary antibiotics on fecal PQQ excretion, (ii) isolating the intestinal flora to identify bacteria known to synthesize PQQ and (iii) determining in vitro if the intestinal microflora synthesizes PQQ from radio-chemically labeled precursors. The results of these experiments indicate that little if any PQQ is synthesized by the intestinal microflora. Rather, when PQQ is present in the intestine, the diet is a more obvious source.     

A method for harvesting non-cultivable filamentous segmented microbes inhabiting the ileum of mice

A method by which non-cultivable filamentous segmented microbes colonising the ileal epithelium of mice can be harvested was devised. Intact epithelial cells with attached filamentous microbes were obtained. An ethanol-treated preparation of epithelial material was used to restore the filamentous segmented microbes to the normal microflora of mice maintained by gnotobiotic methodology.     

Vaccination prevents Helicobacter pylori-induced alterations of the gastric flora in mice

Molecular analysis of the gastric microflora in mice revealed that Helicobacter pylori infection causes an increase in microbial diversity. The stomachs of H. pylori-infected animals were colonized by bacteria which are naturally restricted to the lower intestinal tract. Clostridia, Bacteroides/Prevotella spp., Eubacterium spp., Ruminococcus spp., streptococci and Escherichia coli were detected exclusively in the stomachs of infected animals, whereas lactobacilli dominated the gastric flora in noninfected mice. The H. pylori-induced shifts in the gastric microbiota were independent from histological pathology and from changes in the gastric pH but were prevented by immunization of mice with live Salmonella expressing H. pylori urease. Immunized mice displayed reduced H. pylori levels in the gastric epithelium and developed a normal gastric microflora, indicating that vaccination may be protective against H. pylori-induced changes in the gastric flora.