Biological Sciences
Commensal Bacteria
Commensal bacteria are microorganisms that live in or on the body of a host organism without causing harm. They have a mutually beneficial relationship with the host, providing benefits such as aiding in digestion, producing essential nutrients, and helping to regulate the immune system. These bacteria are an important part of the body's microbiota and play a key role in maintaining overall health.
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11 Key excerpts on "Commensal Bacteria"
eBook - PDFProbiotics
Immunobiotics and Immunogenics
- Haruki Kitazawa, Julio Villena, Susana Alvarez(Authors)
- 2013(Publication Date)
- CRC Press(Publisher)
The intestinal microbiota can be divided into two main groups: the autochthonous or commensal biota, which proliferates in the intestine from the time of birth, becoming stable after weaning. The second group, called the allochthone or non-commensal microbiota, which are temporary and consist of different microorganisms introduced during ingestion of food. Probiotic bacteria are included in the last group. These bacteria are present in many of the fermented products that are consumed daily. The commensal intestinal microbiota plays an important role in maintaining the normal physiology and health of the host (Moreau and Gaboriou-Routhiau 2000). The composition and activity of commensal microorganisms are responsible for three basic functions: (i) metabolic: i.e., food breakdown, short chain fatty acids and vitamin synthesis (Backhed et al. 2004); (ii) barrier: i.e., protection against external and invading pathogens; (iii) interactions with the host and particularly influencing the development of the mucosal immune system (Sansonetti 2004). This last point shows once again the connection between the three main components of the intestinal ecosystem. A healthy intestinal tract is characterized by controlled homeostasis due to the balanced interaction between the Commensal Bacteria and the host mucosal immune system. Changes in this homeostasis, caused by abnormal microbiota, dysregulation of the immune responses or a combination of both, may influence the susceptibility of the host to chronic inflammatory conditions of the intestine such as inflammatory bowel diseases (Tlaskalova-Hogenova et al. 2004; Xavier and Podolsky 2007). In this scenario, the ability of the immune system to recognize between commensal and pathogenic microorganisms is essential to maintain homeostasis and prevent pathologies.
eBook - ePubThe Human Microbiota
How Microbial Communities Affect Health and Disease
- David N. Fredricks(Author)
- 2013(Publication Date)
- Wiley-Blackwell(Publisher)
10 From Fly to Human: Understanding How Commensal Microorganisms Influence Host Immunity and Health June L. Round Department of Pathology, Division of Microbiology and Immunology, University of Utah, Salt Lake City, Utah10.1. Introduction
A long-forgotten resident that persists on the bodies of most animals is the vast consortium of Commensal Bacteria that are collectively referred to as the microbiota. Most animals form intimate, unknown relationships with bacteria, and researchers are beginning to appreciate their profound impacts on host development [1]. These impacts range from inducing immune cells to governing intestinal architecture, nutrition, and even mating preference. Thus, the microbiota has become central to the health and wellbeing of multiple organisms. This chapter focuses on what can be learned about commensal–host relationships through multiple animal models including the fruit fly, zebrafish, and mouse. Analyses of these models will be based on comparisons of the models to ascertain commonalities and differences with respect to the influence of the commensal microbiota on host immunity and how information acquired from these models can be translated to treat human disease.10.2. Microbial Diversity in Humans and Animal Models
During development within the womb (or egg), animals are completely sterile; however, during birth, these once “clean” animals are rapidly colonized by the microbes within the environment. From that point forward, animals are in constant contact with bacteria, some commensal and some pathogenic; others are transient while some are stable. These resident Commensal Bacteria outnumber host cells by an order of magnitude and are present on almost all environmentally exposed surfaces of the body. The greatest diversity and density of bacteria are found within the gastrointestinal tract. The human microbiota collectively contains >100 times more genetic material than our own, and therefore mammals should be considered “super-organisms”, and studied in the context of both their own genome and their microbiome [2]. Of the known 70 bacterial divisions and the 13 divisions of Archaea that have been described to date, only two phyla predominate within the mammalian intestine: the Bacteroidetes (16.3%) and the Firmicutes (65.7%) [3,4]. Of the Firmicutes in the human intestine, most of the phylotypes identified belonged to the class Clostridia, including Clostridia cluster XIV and Feacalibacteria. Organisms belonging to this phylum that have been the topic of extensive research include the segmented filamentous bacteria (SFBs). A single Archaea was identified within the human intestine: Methanobrevibacter smithii
eBook - PDFManipulative Tenants
Bacteria Associated with Arthropods
- Einat Zchori-Fein, Kostas Bourtzis(Authors)
- 2011(Publication Date)
- CRC Press(Publisher)
The increas-ing attention that is currently paid to the bacterial flora in higher eukaryotes, and notably of plant rhizomes and the human gastrointestinal tract, shows that the scien-tific community is becoming aware of microbes not only being pathogenic, but also providing benefit to their hosts. Between pathogenic associations and their mutual-istic counterparts, all intermediates exist and fall all along a parasitism-mutualism continuum. Understanding the evolution of these associations, including host and microbial mechanisms that regulate interactions and transitions between different phenotypes, requires consideration of this entire spectrum of possibilities. There is no doubt that microbiology would benefit from a unified field of research, integrating the whole diversity of the microbial world and its interactions with other organisms (McFall-Ngai, 2008; Schwemmler, 1989). The use of the term symbiosis as it was originally defined by Albert Frank and Anton de Bary, i.e., the living together of organisms belonging to different species, is a first step in this effort of unification xviii Introduction (Committee on Taxonomy, 1937; de Bary, 1879; Frank, 1877; Sapp, 1994). We would like to take the opportunity here to dispel some confusion that has recently arisen regarding the origin of the term symbiosis . The Oxford English Dictionary traces the introduction of the word symbiosis into biology back to Alfred W. Bennett, who translated and edited a German textbook of botany into English in 1877 (OED, 2009; Thome, 1877). This view has meanwhile been adopted by several popular websites, including Wikipedia. Neither the original German edition nor the first English edi-tion mention symbiosis (Thome, 1869). Only the sixth English edition from 1885 (p. 267) makes use of the term symbiosis (Thome, 1885). One group of interest for studying host-symbiont relationships is the phylum Arthropoda, which has the following characteristics: 1.
- Alan L Buchman(Author)
- 2015(Publication Date)
- CRC Press(Publisher)
32 Commensal Bacteria also compete with pathogens and non-commensal bacte-ria for attachment sites and nutrients. The disappearance of commensals following antibiotic administration opens up an opportunity for the proliferation and coloniza-tion of gut surfaces with pathogenic bacteria. As mentioned previously, germ-free mice are more susceptible to colonization with H. pylori . 23 Another notable example is the colonization of the gut with Clostridium difficile following the administra-tion of broad-spectrum antibiotics with the subsequent development of diarrhea and colitis. In addition, some Commensal Bacteria secrete peptides (bacteriocins) that can impede the growth of other bacteria while others provoke the host’s epithelial cells to produce antimicrobial peptides. For example, Lactobacilli stimulate the pro-duction of defensins, whereas the pathogen Shigella flexneri downregulates their expression. 42 6.1.3.3 Regulation of Nutrient and Xenobiotic Metabolism The effect of the microbiota on human metabolism is considerable given that an esti-mated 10% of our caloric intake comes from intestinal microbial fermentation. 30,43 The microbiota of the human gut contains 150 times more genes that of the human host; thereby, substantially contributing to the host’s metabolic and digestive capacities. 44 One way that commensals contribute to increased energy production and assimila-tion is by making otherwise indigestible plant and animal products such as indi-gestible starches and plant cells available for intestinal absorption. For example, Firmicutes associate with insoluble substrates in the colon and lead to their degrada-tion. 45,46 Furthermore, bacterial species such as Ruminococcaceae and Bacteroides possess glycoside hydrolase enzymatic activity which generates metabolic products that can be further metabolized at the brush border.
eBook - PDFIntestinal Microbiota in Health and Disease
Modern Concepts
- Eduardo J. Schiffrin, Philippe Marteau, Dominique Brassart(Authors)
- 2014(Publication Date)
- CRC Press(Publisher)
1 Commensal Intestinal Microbiota and Mucosal Immune System Development and Function Katarina Radulovic 1 and Jan Hendrik Niess 1,2, * Introduction Instead of living as one individual organism, different species coexist in complex ecological niches constantly influencing each other. Humans are no exception from the symbiotic way of living since every healthy human individual coexists with an enormous number of microorganisms. The mutually dependent “life together” of two or more species is called symbiosis (Black 1996). Symbiotic relations of humans and microbial species always have positive outcomes for at least one member and this includes the relationships of mutualism and commensalism. Mutualism is a “win-win” situation in which both members benefit from the relationship (Black 1996). In commensalism the situation is “win-zero” since one member of the relationship benefits without helping or harming the other one (Black 1996). When considering the interactions between microbial communities, 1 Department of Internal Medicine I, University Hospital Ulm, Ulm, Germany. E-mail: [email protected] 2 Department of Visceral Surgery and Medicine, Inselspital, Bern, Switzerland. *Corresponding author: [email protected] 2 Intestinal Microbiota in Health and Disease: Modern Concepts some authors also include the relations with the negative outcome to one member into the symbiosis (Faust and Raes 2012). Such relations include parasitism (“win-lose” situation) amensalism (“zero-loose” situation) and competition (“loose-loose” situation) between the microbes (Faust et al. 2012; Faust and Raes 2012). Humans start their development in a sterile intrauterine environment, but from the very moment of birth all the epithelial surfaces in direct contact with the environment (skin, respiratory, gastrointestinal and urogenital tract) are colonized by microorganisms (Levy 2007). We are living with these microorganisms in mutualistic or commensal relationships.
eBook - PDF- Kathleen A. Ireland(Author)
- 2018(Publication Date)
- Wiley(Publisher)
3. Describe the role of the microbiome in homeostasis. With all the work that has been going on since 2008, there is a large body of evidence that humans and bacteria work together to maintain life. Scientists are in agreement that within the GI tract there are well over 500 bacterial species along with many as yet unidentified viruses. In a healthy adult, all of these microbes weigh almost 2.5 pounds, and function to help digestion, assist in nutrient absorption, and even shape our immune responses. We Each Have a Unique but Predictable Microbiome While the actual percentages may change with age and environment, there seems to be a common core of bacteria that we all carry on our bodies. The bacterial species we host vary slightly with area, but are common to all healthy humans. Table 11.1 lists the genus and species of this common core microbiome. Some bacterial species, like Staphlococcus epidermidis, are found in every area, while others such as Trepomena denticola, and Haemophilus influenzae are more localized. Note that there are two types of fungi and five protozoan species on this list. These microbes are part of our resident flora, and therefore are listed as part of the human microbiome, even though they are not bacteria. The bacteria that inhabit your skin will definitely include those species listed in Table 11.1. However, because you are unique in your biochemistry, your experiences, and your interactions with the envi- ronment, you will also carry your own unique assemblage of bacte- rial life. In fact, bacteria grow and divide so often and so quickly that even within species there are marked differences between bacterial strains. The E. coli bacteria in your intestine that are living and divid- ing once every 12 to 24 hours are carrying mutations in their DNA that are not found in colonies of E. coli from other individual’s intestine. Your strain of E.
eBook - PDF- Douglas S. Clark, Harvey W. Blanch(Authors)
- 1997(Publication Date)
- CRC Press(Publisher)
However, (1) See V. Nurmikko, Biochemical Factors affecting Symbiosis among Bacteria, Experientia 12, 245 (1956). 580 Microbial Interactions Table 7,2. Examples of Commensal Interactions. [FromJ.L. Meers "Growth of Bacteria in Mixed Cultures", p!56 in "Microbial Ecology", eds. A. Laskin and H. Lechevalier], A. Interactions where a compound is supplied by one organism and required by another. Compound Species producing compound Species requiring the compound nicotinic acid Hydrogen sulfide methane nitrate fructose Saccharomyces cerevisiae Desulfovibrio anaerobic methane bacteria Nitrobacter Acetobacter suboxydans Proteus vulgaris Sulphur bacteria methane oxidizing bacteria denitrifying bacteria Saccharomyces carlsbergensis B. Interactions where a compound is removed by one organism. Compound Interrelationship oxygen hydrogen sulfide food preservatives mercuric germi- cides aerobic organisms may reduce the oxygen tension thus allowing anaerobes to grow toxic H2S is oxidized by photosynthetic sulfur bacteria and the growth of other species is then possible the growth inhibitors benzoate and sulfur dioxide are destroyed bio- logically Desulfovibrium form H2S from sulfate and the sulfide combines with Hg-containing germicides to permit bacterial growth they contain flagellated protozoa which host bacteria which, in turn, produce cellulases that provide their hosts with glucose by hydrolysis. Similar symbiotic relationships exist in the stomachs of the cow, where rumen microorganisms aid in digesting plant material. Other types of mutualism involve one species destroying a toxin for the other species, while the second species provides a nutrient for the first. Competition results from the struggle between organisms for a common essential resource, such as nutrients, water, light, or space, that is present in the environment in a limited amount. In microbial systems, competition is intense due to their high population densities and their short generation times.
- Lynnette R. Ferguson(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
169 © 2010 Taylor & Francis Group, LLC 8 Microbiome and Host Interactions in Inflammatory Bowel Diseases Relevance for Personalized Nutrition Wayne Young, Bianca Knoch, and Nicole C. Roy INTRODUCTION The human gastrointestinal tract is home to an estimated 100 trillion microor-ganisms. Collectively referred to as the intestinal microbiota, they are thought to outnumber the cells of their host 10 fold and represent by far the largest microbial community associated with the human body [1]. The intestinal bacteria in humans comprise 500–1000 bacterial species and complex metabolic relationships exist between bacterial communities and their host [2]. Figure 8.1 illustrates the different compartments of the human gastrointestinal tract, physiological processes and con-ditions, and the major bacteria genera found therein [3]. Very little is known about these interbacterial relationships and how they relate to host health, but it is known that increasing diversity of the large bowel bacteria promotes metabolic homeostasis and the ability to resist invading pathogens [4]. This complex ecosystem represents a huge reservoir of metabolic capability and plays a crucial role in a number of developmental and nutritional processes in the CONTENTS Introduction ............................................................................................................ 169 Qualitative and Quantitative Analyses of the Large Bowel Microbiota ................ 171 Large Bowel Microbial Ecosystem of Healthy Individuals ................................... 174 Mucosal and Bacterial Interactions in Individuals with IBD ................................. 176 Role of Microbiota in Assessing Nutrient and Gene Interactions in IBD .............. 180 Summary and Concluding Remarks ...................................................................... 181 References .............................................................................................................. 182
eBook - PDFMicrobial Host-Interaction: Tolerance versus Allergy
64th Nestlé Nutrition Institute Workshop, Pediatric Program, Sydney, November 2008
- P. Brandtzaeg, E. Isolauri, S. L. Prescott, Brandtzaeg, Isolauri, Prescott(Authors)
- 2010(Publication Date)
- S. Karger(Publisher)
The hygiene hypothesis [17] was put forth nearly two decades ago and argued that reduced exposure to infections in early childhood, as seen in developed countries, may increase the risk of allergic and autoimmune dis-ease. This hypothesis did not address the primary relationship of host and microbe – that of commensalism. Our studies show that symbiotic bacteria like B. fragilis that normally reside in the gastrointestinal tract produce molecules such as PSA that mediate healthy immune responses, balance the Th1/Th2 immune system, and protect the host from inflammatory disease. Th2 skew-ing of the immune system has been associated with allergic diseases such as asthma and eczema [18–20]. Mammals have lived with their commensal part-ners for eons, and each partner has co-evolved adaptively to depend on the other. The fact that intestinal bacteria directly stimulate the host immune system to have very beneficial responses demonstrates the essential nature of this host-bacterial interaction in promoting the host’s health. Disease may result from the absence of beneficial flora or of the molecules produced by members of this flora. Changes in flora may occur in response to environmen-tal cues. Diseases such as colitis could conceivably arise in the setting of an altered microbial flora in a genetically predisposed host. No pathogen has been found for diseases such as ulcerative colitis and Crohn’s disease. The inflam-matory T cells involved in these conditions seem to reflect responses to the molecules of commensal organisms. Perhaps the inflammation associated with these diseases takes place in the setting of a commensal flora with decreased numbers of or genetic changes in symbiotic bacteria such as B. fragilis . References 1 Hooper LV, Gordon JI: Commensal host-bacterial relationships in the gut. Science 2001;292:1115–1118. 2 Krinos CM, Coyne MJ, Weinacht KG, et al: Extensive surface diversity of a commensal micro-organism by multiple DNA inversions.
eBook - PDFAnimal Welfare in Animal Agriculture
Husbandry, Stewardship, and Sustainability in Animal Production
- Wilson G. Pond, Fuller W. Bazer, Bernard E. Rollin, Wilson G. Pond, Fuller W. Bazer, Bernard E. Rollin(Authors)
- 2011(Publication Date)
- CRC Press(Publisher)
193 Fungal Endophytes and Plants ............................................................................................. 193 Modern Agriculture and Symbiosis with Plants ................................................................... 193 Microbes and Mutualism/Commensalism with Animals .......................................................... 194 Gastrointestinal Tracts of Production Animals ..................................................................... 194 Pregastric Fermentation and the Ruminant .......................................................................... 198 Symbiosis and Evolution in Animals ........................................................................................ 200 Summary and Conclusions ............................................................................................................ 201 References ...................................................................................................................................... 202 186 AnimalWelfareinAnimalAgriculture by herbivores is accomplished by specialized bacteria in gastrointestinal compartments that are optimally maintained by each host animal for bacterial growth. Within the mammalian digestive tract, commensal microorganisms can provide energy, amino acids, and vitamins for the host, and provide protection against parasitic microorganisms. This chapter focuses on environmental sus-tainability of the many symbiotic relationships among plants, animals, and microbes that enhance our global food production. LIFE ON EARTH Life on Earth is complex and interactive, with organisms forming populations, which in turn form communities, or ecosystems, both locally and globally. The ecology is defined by the interactions between species and their composition within that system that drives natural selection, evolution, and genetic composition.
eBook - PDF- Enrica Pessione(Author)
- 2014(Publication Date)
- CRC Press(Publisher)
Furthermore, interspecies nutritional interactions are crucial to maintain the stability of host-associated communities in the gut. It is now well established that humans can be classified as belonging to three main distinct “enterotypes” selected on the basis of both genetic and epigenetic factors (for exhaustive reading see Arumugam et al. 2011). External perturbations (antibiotics, probiotics, prebiotics, and diet) and internal perturbations (age, stress, immunodepression, and endocrine disorders) can alter the community composition of the intestinal ecosystem. Nevertheless, individual microbiota shifting to a new enterotype is not so common, since the system tends to return to its original state (Wu et al. 2011). The optimization of metabolite exchanges and feed-back responses could be the reason why bacteria have established a successful and permanent ecological niche colonization and symbiosis with humans. The complex interplay between microbial species is mainly based on carbon and nitrogen acquisition, ATP generation and pH/redox balance control (Fischbach and Sonnenburg 2011). A paradigmatic example of this is the reciprocal relationship that exists between Bacteroides (hydrolytic-saccharolytic) and Clostridia (peptidolytic) in the human gut. Although the complexity of this ecosystem (which also includes the active presence of the human host, that produces metabolites and multiple chemical signals) does not allow any simplification, a general rule is that Bacteroides consume sugars and Clostridia utilize peptides. Bacteroides can metabolize 12 Interactive Probiotics protein-encapsulated plant carbohydrates through proteolytic activity, thus releasing useful peptides for Clostridia. The latter can deaminate peptide-derived amino acids, thus supplying free NH 4 + to Bacteroides. NH 4 + is then used by the Bacteroides together with CO 2 and SCFA (short-chain fatty acids) to biosythesize amino acids.
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