Interaction of Yersinia pseudotuberculosis with the epithelium of the small intestine in experimental infection

Some data showing specific ways of interaction of Yersinia pseudotuberculosis with the epithelium of the small intestinal mucosa have been received for the first time by using light microscopy of semithin sections. Comparative study of the lesion of the epithelium of different parts of rabbit small intestine by oral inoculation with Yersinia tuberculosis has expanded the ideas of the infection entry. It has been established for the first time that the most intensive penetration of the microorganisms into the epithelium of the mucous membrane takes place in the duodenum and jejunum. As the infected contents is evacuated via the intestinal tract, the Yersinia pathogenicity decreases, and in the ileum, the invasion of the microorganisms becomes less pronounced. It has been revealed that in pseudotuberculosis, there takes place a repeated dissemination of the infection in the intestinal tract because of decay of the involved enterocytes, which is of pathogenetic importance for the progress and outcome of the infection.     

Isolation and characterization of a spiral bacterium from the crypts of rodent gastrointestinal tracts

Spiral-shaped bacteria with a distinctive morphology were isolated from the intestinal mucosa of rats and mice on a campylobacter selective medium using microaerophilic incubation. These bacteria have been shown by other authors to be present in the intestinal tracts of several animal species but have not been cultured previously. The results of electron microscopic examinations and biochemical testing have shown that these organisms do not correspond to any known genus. Colonization experiments with pure cultures in gnotobiotic rodents have shown these bacteria to be mucosa associated, with a particular affinity for intestinal crypts. The pattern of colonization of the intestinal crypts in gnotobiotes known to be free of other mucosa-associated organisms differed from the colonization occurring in conventional animals that possess a normal mucosa-associated flora.     

Commensal bacteria make a difference

Nowhere is the relationship between microorganisms and eukaryotes as diverse, intimate and clinically relevant as in the gastrointestinal tract. An estimated 500-1000 mostly anaerobic species reside in the intestine, approaching enormous densities of 10(11)-10(12) organisms per gram colon content. The commensal interactions between intestinal microorganisms and animal hosts have been difficult to study in the past because of the diversity of microorganisms involved and because of the lack of culturability that accompanies many microbial consortia. However, recent work has provided new insights into these interactions.     

Isolation and characterization of a spiral bacterium from the crypts of rodent gastrointestinal tracts.

Spiral-shaped bacteria with a distinctive morphology were isolated from the intestinal mucosa of rats and mice on a campylobacter selective medium using microaerophilic incubation. These bacteria have been shown by other authors to be present in the intestinal tracts of several animal species but have not been cultured previously. The results of electron microscopic examinations and biochemical testing have shown that these organisms do not correspond to any known genus. Colonization experiments with pure cultures in gnotobiotic rodents have shown these bacteria to be mucosa associated, with a particular affinity for intestinal crypts. The pattern of colonization of the intestinal crypts in gnotobiotes known to be free of other mucosa-associated organisms differed from the colonization occurring in conventional animals that possess a normal mucosa-associated flora.     

昆虫肠道的宏基因组学:微生物大数据的新疆界

微生物作为自然界中普遍存在的生命体,通常以"微生物群落"的形式共存。这些物种相互协作适应环境变化的同时,也对环境产生了长期而深刻的影响。随着人类对于微生物了解的深入,微生物群落基础研究及其在健康和环境等领域的应用研究日益重要。昆虫肠道内存在种类繁多、数量庞大的微生物,一方面,这些肠道微生物种群结构的多样性与昆虫种类、龄期、消化道形式、食物的来源、环境等都息息相关。另一方面,这些菌群也对宿主的一些生理活动有着一定的影响。随着高通量测序技术、组学技术的发展,昆虫肠道宏基因组大数据挖掘和应用已经成为研究热点,极大地推动人类微生物资源利用的能力。本文概述了昆虫肠道微生物宏基因组学的发展现状和发展趋势,特别是肠道宏基因组学大数据的挖掘工具和应用,以及现阶段昆虫肠道宏基因组学的研究进展、应用、优势和瓶颈,并对今后昆虫肠道微生物组大数据研究方向进行展望。     

Beyond diversity: functional microbiomics of the human colon

Molecular tools have revealed wide microbial diversity in the human alimentary tract. Most intestinal microorganisms have not been cultured and the in situ functions of distinct groups of the intestinal microbiota are largely unknown but pivotal to understanding the role of these microorganisms in health and disease. Promising strategies to gain more insight into the functionality of the complex microbial communities in the human alimentary tract, including fermentation processes in the colon, are discussed. These research approaches could provide a basis for the definition of a healthy gut based on key properties of microbial functionality. This will also enable the development of direct nutritional strategies for intestinal disease prevention and health promotion.     

Role played by lactobacilli in controlling the population of vaginal pathogens

The role of Lactobacillus species in the female urogenital tract as a barrier to infection is of considerable interest. These organisms are believed to contribute to the control of vaginal microbiota by competing with other microorganisms for adherence to epithelial cells and by producing antimicrobial compounds. These bactericidal compounds include organic acid, which lowers the vaginal pH, hydrogen peroxide, bacteriocin-like substances and possibly biosurfactants.     

Structure of the intestinal flora responsible for development of the gut immune system in a rodent model

The intestinal flora comprising indigenous, autochthonous bacteria is constantly present in the alimentary tract of host animals, including humans. The indigenous bacteria greatly affect the structure and functions of the intestinal mucosa. Studies involving gnotobiotic mice or rats have shown that the presence of limited kinds of intestinal bacteria is responsible for the development of the gut immune system, such as secretory IgA, major histocompatibility complex molecules and intraepithelial lymphocytes. Understanding of the structure of the intestinal flora or the organization of the microbial population in the intestine, based on evaluation of the immunological responses, may clarify its functions in the host animal.     

苯丙氨酸在宿主和肠道微生物中的代谢研究进展

肠道微生物是宿主生理活动的重要参与者,与宿主的健康和疾病密切相关。研究表明,肠道微生物代谢产物是饮食诱导宿主－微生物相互作用的关键介质,这些代谢产物由微生物直接产生或由环境和宿主中相关分子的代谢转化产生。宿主和肠道微生物之间的化学对话是影响宿主生理的重要环节,对这些代谢途径和信号通路的研究可以进一步揭示微生物代谢与宿主的相互作用机制。芳香族氨基酸包括苯丙氨酸、酪氨酸和色氨酸,是宿主－微生物相互作用的重要信号分子,在胃肠道和远隔器官中发挥着重要的调节作用。本文就苯丙氨酸与肠道微生物的最新研究进展进行综述,重点阐述苯丙氨酸在宿主和肠道微生物中的代谢情况。

     

The role of biogeography in shaping diversity of the intestinal microbiota in house mice

The microbial communities inhabiting the mammalian intestinal tract play an important role in diverse aspects of host biology. However, little is known regarding the forces shaping variation in these communities and their influence on host fitness. To shed light on the contributions of host genetics, transmission and geography to diversity in microbial communities between individuals, we performed a survey of intestinal microbial communities in a panel of 121 house mice derived from eight locations across Western Europe using pyrosequencing of the bacterial 16S rRNA gene. The host factors studied included population structure estimated by microsatellite loci and mitochondrial DNA, genetic distance and geography. To determine whether host tissue (mucosa)‐associated communities display properties distinct from those of the lumen, both the caecal mucosa and contents were examined. We identified Bacteroides, Robinsoniella and Helicobacter as the most abundant genera in both the caecal content and mucosa‐associated communities of wild house mice. Overall, we found geography to be the most significant factor explaining patterns of diversity in the intestinal microbiota, with a comparatively weaker influence of host population structure and genetic distance. Furthermore, the influence of host genetic distance was limited to the mucosa communities, consistent with this environment being more intimately coupled to the host.     

基于高通量测序技术马肠道菌群研究进展

马肠道非常发达,其中定居着丰富又复杂的微生物菌群,这些微生物在宿主的生理、代谢、营养和免疫功能等方面有着重要作用.基于高通量测序的宏基因组学技术和分析手段的改进,对复杂环境中微生物的研究更加方便、透彻.本文就基于高通量测序的宏基因组技术在马肠道核心菌群、不同肠道段菌群结构、不同因素对肠道菌群结构的影响,以及马肠道微生物...     

Diversity of Nitrogen Fixation Genes in the Symbiotic Intestinal Microflora of the Termite Reticulitermes speratus

The diversity of nitrogen-fixing organisms in the symbiotic intestinal microflora of a lower termite, Reticulitermes speratus, was investigated without culturing the resident microorganisms. Fragments of the nifH gene, which encodes the dinitrogenase reductase, were directly amplified from the DNA of the mixed microbial population in the termite gut and were clonally isolated. The phylogenetic analysis of the nifH product amino acid sequences showed that there was a remarkable diversity of nitrogenase genes in the termite gut. A large number of the termite nifH sequences were most closely related to those of a firmicute, Clostridium pasteurianum, with a few being most closely related to either the (gamma) subclass of the proteobacteria or a sequence of Desulfovibrio gigas. Some of the others were distantly related to those of the bacteria and were seemingly derived from the domain Archaea. The phylogenetic positions of these nifH sequences corresponded to those of genera found during a previous determination of rRNA-based phylogeny of the termite intestinal microbial community, of which a majority consisted of new, yet-uncultivated species. The results revealed that we have little knowledge of the organisms responsible for nitrogen fixation in termites.     

Method of determining the microbial flora of the small intestinal cavity and mucosa in different gastrointestinal tract diseases]

Intestinal microflora in patients with chronic enterocolitis and duodenal ulcer was studied. Both the cavity of the small intestine and the structures of its mucosa were investigated. The method of aspiration biopsy was used, the samples of multiple washings of the intestinal mucosa and its homogenate were used for seeding. The results thus obtained in indicated that the structures of the mucosa contained microorganisms similar to those isolated from the intestinal cavity, but in lesser amounts and with different characteristics. The proposed method of detecting the microflora in the intestinal cavity and mucosa is simple and can be used in clinical practice.     

Gastrointestinal absorption and metabolism of apple polyphenols ex vivo by the pig intestinal mucosa in the Ussing chamber

Polyphenols contained in food have various positive effects on human health. The absorption and metabolism of polyphenols in the intestinal tract needs to be studied to estimate these effects. The Ussing chamber technique was used to investigate the transport behavior of apple polyphenols through pig small intestinal mucosa, which served as a model for human gastrointestinal mucosa. The identities and concentrations of polyphenols and their metabolites in the half-chambers (luminal and basolateral) within an incubation period of 4 h were determined by HPLC–MS/MS and HPLC–DAD (DAD = diode-array detection). Flux values were also measured. It was found that 5-caffeoylquinic acid and caffeic acid were absorbed and translocated to the basolateral side (1.9 and 3.7%, respectively), but other compounds, including glycosides of phloretin and quercetin, were observed without translocation. A Ussing chamber utilizing pig small intestinal mucosa is a suitable model for assessing the effect of apple polyphenols on mucosal integrity and nutrition absorption across porcine mucosa.     

多糖对肠道功能调节作用的研究进展

肠道是机体重要的消化器官,亦是共生微生物群的主要寄居场所,在维持机体正常生命活动如免疫和内分泌功能中发挥着重要作用。 肠道功能紊乱与疾病的发生以及发展过程密切相关。近年来,多项研究结果显示,多糖具有肠道功能调节作用,包括通过作用于肠道黏膜 参与机体免疫过程、保护肠道屏障结构和功能的完整性、调节肠道菌群组成以及刺激肠道内分泌。从伴随疾病过程中的肠道功能紊乱的角度, 对多糖调节肠道功能的作用机制进行综述。     

Foodborne Salmonella ecology in the avian gastrointestinal tract

Foodborne Salmonella continues to be a major cause of salmonellosis with Salmonella Enteritidis and S. Typhimurium considered to be responsible for most of the infections. Investigation of outbreaks and sporadic cases has indicated that food vehicles such as poultry and poultry by-products including raw and uncooked eggs are among the most common sources of Salmonella infections. The dissemination and infection of the avian intestinal tract remain somewhat unclear. In vitro incubation of Salmonella with mammalian tissue culture cells has shown that invasion into epithelial cells is complex and involves several genetic loci and host factors. Several genes are required for the intestinal phase of Salmonella invasion and are located on Salmonella pathogenicity island 1 (SPI 1). Salmonella pathogenesis in the gastrointestinal (GI) tract and the effects of environmental stimuli on gene expression influence bacterial colonization and invasion. Furthermore, significant parameters of Salmonella including growth physiology, nutrient availability, pH, and energy status are considered contributing factors in the GI tract ecology. Approaches for limiting Salmonella colonization have been primarily based on the microbial ecology of the intestinal tract. In vitro studies have shown that the toxic effects of short chain fatty acids (SCFA) to some Enterobacteriaceae, including Salmonella, have resulted in a reduction in population. In addition, it has been established that native intestinal microorganisms such as Lactobacilli provide protective mechanisms against Salmonella in the ceca. A clear understanding of the key factors involved in Salmonella colonization in the avian GI tract has the potential to lead to better approach for more effective control of this foodborne pathogen.     

儿童重症手足口病肠道菌群和肠道黏膜通透性的研究进展

手足口病是由肠道病毒引起的儿童常见的传染病,有研究显示肠道病毒进人消化道后在肠黏膜内复制繁殖并持续释放到血液而发病,肠道黏膜是病毒人侵和增殖的主要场所。肠道菌群能防御感染和增强肠道屏障功能,肠道屏障功能在防御外源性和内源性感染方面发挥重要作用,同时在维持肠道免疫稳定和平衡方面也有重要的作用。益生菌是指数量适当时对宿主健康有利的活微生物,有研究报道益生菌在辅助治疗手足口病上是有效的。开展这方面的研究,对于探索手足口病的发病机制和益生菌防治手足口病有十分重要的意义。     

Intestinal bacteria and ageing

Advancements in science and medicine, as well as improved living standards, have led to a steady increase in life expectancy, and subsequently a rise in the elderly population. The intestinal microbiota is important for maintenance of host health, providing energy, nutrients and protection against invading organisms. Although the colonic microbiota is relatively stable throughout adult life, age-related changes in the gastrointestinal (GI) tract, as well as changes in diet and host immune system reactivity, inevitably affect population composition. Recent studies indicate shifts in the composition of the intestinal microbiota, which may lead to detrimental effects for the elderly host. Increased numbers of facultative anaerobes, in conjunction with a decrease in beneficial organisms such as the anaerobic lactobacilli and bifidobacteria, amongst other anaerobes, have been reported. These changes, along with a general reduction in species diversity in most bacterial groups, and changes to diet and digestive physiology such as intestinal transit time, may result in increased putrefaction in the colon and a greater susceptibility to disease. Therapeutic strategies to counteract these changes have been suggested in ageing people. These include dietary supplements containing prebiotics, probiotics and a combination of both of these, synbiotics. Limited feeding trials show promising results with these supplements, although further longer-term investigations are required to substantiate their use in elderly healthcare fields.     

Isolation and cultivation of spirochetes and other spiral-shaped bacteria associated with the cecal mucosa of rats and mice.

A method for the culture of spiral-shaped bacteria associated with the intestinal mucosa of rodents is described. The appearance in culture of a spiral organism from rat ceca and a spirochete from mouse ceca is illustrated; these organisms are morphologically similar to the major inhabitants of the cecal mucosa in each animal species.     

Isolation and cultivation of spirochetes and other spiral-shaped bacteria associated with the cecal mucosa of rats and mice.

A method for the culture of spiral-shaped bacteria associated with the intestinal mucosa of rodents is described. The appearance in culture of a spiral organism from rat ceca and a spirochete from mouse ceca is illustrated; these organisms are morphologically similar to the major inhabitants of the cecal mucosa in each animal species.