Symbiotic bacteria

Last updated

Symbiotic bacteria are bacteria living in symbiosis with another organism or each other. For example, rhizobia living in root nodules of legumes provide nitrogen fixing activity for these plants. [1]

Contents

Types of symbiosis

Types of symbiotic relationships are mutualism, commensalism, parasitism, and amensalism. [2]

Endosymbiosis

Endosymbionts live inside other organisms whether that be in their bodies or cells. [3] The theory of endosymbiosis, as known as symbiogenesis, provides an explanation for the evolution of eukaryotic organisms. According to the theory of endosymbiosis for the origin of eukaryotic cells, scientists believe that eukaryotes originated from the relationship between two or more prokaryotic cells approximately 2.7 billion years ago. It is suggested that specifically ancestors of mitochondria and chloroplasts entered into an endosymbiotic relationship with another prokaryotic cell, eventually evolving into the eukaryotic cells that people are familiar with today. [4]

Ectosymbiosis

Ectosymbiosis is defined as a symbiotic relationship in which one organism lives on the outside surface of a different organism. [3] For instance, barnacles on whales is an example of an ectosymbiotic relationship where the whale provides the barnacle with a home, a ride, and access to food. The whale is not harmed, but it also does not receive any benefits so this is also an example of commensalism. An example of ectosymbiotic bacteria is cutibacterium acnes. These bacteria are involved in a symbiotic relationship with humans on whose skin they live. Cutibacterium acnes can cause acne when the skin becomes too oily, but they also reduce the skin's susceptibility to skin diseases caused by oxidative stress. [5]

Symbiotic relationships

Certain plants establish a symbiotic relationship with bacteria, enabling them to produce nodules that facilitate the conversion of atmospheric nitrogen to ammonia. In this connection, cytokinins have been found to play a role in the development of root fixing nodules. [6] It appears that not only must the plant have a need for nitrogen fixing bacteria, but they must also be able to synthesize cytokinins which promote the production of root nodules, required for nitrogen fixation.

Symbiotic bacteria are able to live in or on plant or animal tissue. In digestive systems, symbiotic bacteria help break down foods that contain fiber. They also help produce vitamins. Symbiotic bacteria can live near hydrothermal vents. They usually have a mutual relationship with other bacteria. Some live in tube worms.

Transmission

There are two major modes of transmission for symbiotic bacteria. The first is horizontal transmission in which microbes are acquired from the environment and either the environment or the host population serves as the inoculum for the symbiosis. [7] An example of horizontal transmission is the deep sea tube worm and its symbiont. [7] The second type of transmission is vertical transmission in which the symbiont is passed down from the parent to the offspring and there is no aposymbiotic phase. [7] An example of vertical transmission is seen in Drosophila melanogaster and its Wolbachia spp. symbionts. [7]

Examples of Symbiotic Relationships

Corals

Corals have been found to form characteristic associations with symbiotic nitrogen-fixing bacteria. [8] Corals have evolved in oligotrophic waters which are typically poor in nitrogen. Corals must therefore form a mutualistic relationship with nitrogen fixing organism, in this case the subject of this study, namely Symbiodinium. In addition to this dinoflagellate, coral also form relationships with bacteria, archae and fungi. [9] The problem is that these dinoflagellates are also nitrogen limited and must form a symbiotic relationship with another organism; here it is suggested to be diazotrophs. In addition, cyanobacteria have been found to possess genes that enable them to undergo nitrogen fixation. [8] This particular study goes further to investigate the possibility that in addition to the named dinoflagellate and certain cyanobacteria, endosymbiotic algae and the coral contain enzymes enabling them to both undergo ammonium assimilation.

Due to the small size of the genome of most endosymbionts, they are unable to exist for any length of time outside of the host cell, thereby preventing a long-term symbiotic relationship. However, in the case of the endonuclear symbiotic bacterium Holospora, it has been discovered [10] that Holospora species can maintain their infectivity for a limited time and form a symbiotic relationship with Paramecium species.

Plants and rhizobial bacteria

There is a mutualistic relationship between legumes and rhizobial bacteria enabling the plants to survive in an otherwise nitrogen-poor soil environment. Co-evolution is described as a situation where two organisms evolve in response to one another. In a study reported in Functional Ecology, [11] these scientists investigated whether such a mutualistic relationship conferred an evolutionary advantage to either plant or symbiont. They did not find that the rhizobial bacteria studied had any evolutionary advantage with their host but did find great genetic variation among the populations of rhizobial bacteria studied.

Chemosynthetic Bacteria and Mussels

Symbiotic, chemosynthetic bacteria that have been discovered associated with mussels (Bathymodiolus) located near hydrothermal vents have a gene that enables them to utilize hydrogen as a source of energy, in preference to sulphur or methane as their energy source for production of energy. [2]

Termites and Cellulase-Producing Bacteria

Termites are known by many as pests that feed on wood. However, termites cannot digest the wood alone. Instead, they rely on a non-bacterial protozoan called Trichonympha to help in the digestion process. [12] Trichonympha is an endosymbiont that lives inside termites and also acts as a host to bacterial symbionts. The bacteria inside Trichonympha in termites produces cellulase. Cellulase enzymes are used to break down cellulose which is found in plants' cell walls. The termites, the gut protist Trichonympha, and the cellulase-producing bacteria are all involved in a 3-way obligate symbiotic mutualism. The termites benefit from the other two species because they transform the wood into nutrients that the termites can digest. Additionally, the Trichonympha benefit from the termites because the termites provide a place to live and access to food. The Trichonympha also benefit from the bacteria because they help break down the cellulose in wood that the protist consumes. Finally, the bacteria benefits because it gains a place to live and the nutrients it needs to survive.

Symbiotic Bacteria in Humans

Gut Bacteria

The human gut contains approximately thirty-eight trillion microbes. [13] The gut is a dynamic ecosystem as it is composed of both constant and transient components, meaning some bacteria establishes itself and remains throughout the human’s lifetime and other bacteria is ingested and later leaves in feces. [14] When babies are born, they are born without any bacteria in their intestines. However, as soon as they enter the world, they begin accumulating gut bacteria through food and other means. [15] Most bacteria in the human body are actually good for us and help with carrying out necessary life processes. Gut bacteria in humans often aid in the breakdown of foods and synthesize important vitamins that could not be processed by humans alone. [16] Therefore, humans must be careful when taking antibiotics when they are sick. Antibiotics do not differentiate between the good and bad bacteria in our bodies and therefore, kill both. If not treated carefully, this can lead to issues with the gastrointestinal tract because of an imbalance of bacteria in this microbiome. [17] Therefore, some doctors recommend taking a probiotic when taking antibiotics to restore the good bacteria.

Benefits of Bacterial Symbiosis

Organisms typically establish a symbiotic relationship due to their limited availability of resources in their habitat or due to a limitation of their food source. Triatomine vectors have only one host and therefore must establish a relationship with bacteria to enable them to obtain the nutrients required to maintain themselves. [18]

A use for symbiotic bacteria is in paratransgenesis for controlling important vectors for disease, such as the transmission of Chagas disease by Triatome kissing bugs. Symbiotic bacteria in legume roots provide the plants with ammonia in exchange for the plants' carbon and a protected home.

Related Research Articles

<span class="mw-page-title-main">Endosymbiont</span> Organism that lives within the body or cells of another organism

An endosymbiont or endobiont is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. This phenomenon is known as endosymbiosis. Examples are nitrogen-fixing bacteria, which live in the root nodules of legumes, single-cell algae inside reef-building corals and bacterial endosymbionts that provide essential nutrients to insects.

<span class="mw-page-title-main">Symbiosis</span> Close, long-term biological interaction between distinct organisms (usually species)

Symbiosis is any type of a close and long-term biological interaction between two biological organisms of different species, termed symbionts, be it mutualistic, commensalistic, or parasitic. In 1879, Heinrich Anton de Bary defined it as "the living together of unlike organisms". The term is sometimes used in the more restricted sense of a mutually beneficial interaction in which both symbionts contribute to each other's support.

<span class="mw-page-title-main">Host (biology)</span> Organism that harbours another organism

In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist guest (symbiont). The guest is typically provided with nourishment and shelter. Examples include animals playing host to parasitic worms, cells harbouring pathogenic (disease-causing) viruses, or a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources to micropredators, which have an evolutionarily stable relationship with their hosts similar to ectoparasitism. The host range is the collection of hosts that an organism can use as a partner.

<span class="mw-page-title-main">Rhizobia</span> Nitrogen fixing soil bacteria

Rhizobia are diazotrophic bacteria that fix nitrogen after becoming established inside the root nodules of legumes (Fabaceae). To express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently fix nitrogen. In general, they are gram negative, motile, non-sporulating rods.

Diazotrophs are bacteria and archaea that fix atmospheric nitrogen(N2) in the atmosphere into bioavailable forms such as ammonia.

<span class="mw-page-title-main">Root nodule</span> Plant part

Root nodules are found on the roots of plants, primarily legumes, that form a symbiosis with nitrogen-fixing bacteria. Under nitrogen-limiting conditions, capable plants form a symbiotic relationship with a host-specific strain of bacteria known as rhizobia. This process has evolved multiple times within the legumes, as well as in other species found within the Rosid clade. Legume crops include beans, peas, and soybeans.

<span class="mw-page-title-main">Nod factor</span> Signaling molecule

Nod factors, are signaling molecules produced by soil bacteria known as rhizobia in response to flavonoid exudation from plants under nitrogen limited conditions. Nod factors initiate the establishment of a symbiotic relationship between legumes and rhizobia by inducing nodulation. Nod factors produce the differentiation of plant tissue in root hairs into nodules where the bacteria reside and are able to fix nitrogen from the atmosphere for the plant in exchange for photosynthates and the appropriate environment for nitrogen fixation. One of the most important features provided by the plant in this symbiosis is the production of leghemoglobin, which maintains the oxygen concentration low and prevents the inhibition of nitrogenase activity.

<i>Buchnera aphidicola</i> Species of bacterium

Buchnera aphidicola, a member of the Pseudomonadota and the only species in the genus Buchnera, is the primary endosymbiont of aphids, and has been studied in the pea aphid, Acyrthosiphon pisum. Buchnera is believed to have had a free-living, Gram-negative ancestor similar to a modern Enterobacterales, such as Escherichia coli. Buchnera is 3 µm in diameter and has some of the key characteristics of its Enterobacterales relatives, such as a Gram-negative cell wall. However, unlike most other Gram-negative bacteria, Buchnera lacks the genes to produce lipopolysaccharides for its outer membrane. The long association with aphids and the limitation of crossover events due to strictly vertical transmission has seen the deletion of genes required for anaerobic respiration, the synthesis of amino sugars, fatty acids, phospholipids, and complex carbohydrates. This has resulted not only in one of the smallest known genomes of any living organism, but also one of the most genetically stable.

<span class="mw-page-title-main">Aposymbiosis</span>

Aposymbiosis occurs when symbiotic organisms live apart from one another. Studies have shown that the lifecycles of both the host and the symbiont are affected in some way, usually negative, and that for obligate symbiosis the effects can be drastic. Aposymbiosis is distinct from exsymbiosis, which occurs when organisms are recently separated from a symbiotic association. Because symbionts can be vertically transmitted from parent to offspring or horizontally transmitted from the environment, the presence of an aposymbiotic state suggests that transmission of the symbiont is horizontal. A classical example of a symbiotic relationship with an aposymbiotic state is the Hawaiian bobtail squid Euprymna scolopes and the bioluminescent bacteria Vibrio fischeri. While the nocturnal squid hunts, the bacteria emit light of similar intensity of the moon which camouflages the squid from predators. Juveniles are colonized within hours of hatching and Vibrio must outcompete other bacteria in the seawater through a system of recognition and infection.

<span class="mw-page-title-main">Bacteriocyte</span> Specialized cell containing endosymbionts

A bacteriocyte, also known as a mycetocyte, is a specialized adipocyte found primarily in certain insect groups such as aphids, tsetse flies, German cockroaches, weevils. These cells contain endosymbiotic organisms such as bacteria and fungi, which provide essential amino acids and other chemicals to their host. Bacteriocytes may aggregate into a specialized organ called the bacteriome.

<i>Mixotricha paradoxa</i> Species of protozoan

Mixotricha paradoxa is a species of protozoan that lives inside the gut of the Australian termite species Mastotermes darwiniensis.

Horizontal transmission is the transmission of organisms between biotic and/or abiotic members of an ecosystem that are not in a parent-progeny relationship. This concept has been generalized to include transmissions of infectious agents, symbionts, and cultural traits between humans.

<i>Trichonympha</i> Genus of flagellated protists

Trichonympha is a genus of single-celled, anaerobic parabasalids of the order Hypermastigia that is found exclusively in the hindgut of lower termites and wood roaches. Trichonympha’s bell shape and thousands of flagella make it an easily recognizable cell. The symbiosis between lower termites/wood roaches and Trichonympha is highly beneficial to both parties: Trichonympha helps its host digest cellulose and in return receives a constant supply of food and shelter. Trichonympha also has a variety of bacterial symbionts that are involved in sugar metabolism and nitrogen fixation.

Actinorhizal plants are a group of angiosperms characterized by their ability to form a symbiosis with the nitrogen fixing actinomycetota Frankia. This association leads to the formation of nitrogen-fixing root nodules.

Cyanobionts are cyanobacteria that live in symbiosis with a wide range of organisms such as terrestrial or aquatic plants; as well as, algal and fungal species. They can reside within extracellular or intracellular structures of the host. In order for a cyanobacterium to successfully form a symbiotic relationship, it must be able to exchange signals with the host, overcome defense mounted by the host, be capable of hormogonia formation, chemotaxis, heterocyst formation, as well as possess adequate resilience to reside in host tissue which may present extreme conditions, such as low oxygen levels, and/or acidic mucilage. The most well-known plant-associated cyanobionts belong to the genus Nostoc. With the ability to differentiate into several cell types that have various functions, members of the genus Nostoc have the morphological plasticity, flexibility and adaptability to adjust to a wide range of environmental conditions, contributing to its high capacity to form symbiotic relationships with other organisms. Several cyanobionts involved with fungi and marine organisms also belong to the genera Richelia, Calothrix, Synechocystis, Aphanocapsa and Anabaena, as well as the species Oscillatoria spongeliae. Although there are many documented symbioses between cyanobacteria and marine organisms, little is known about the nature of many of these symbioses. The possibility of discovering more novel symbiotic relationships is apparent from preliminary microscopic observations.

The hologenome theory of evolution recasts the individual animal or plant as a community or a "holobiont" – the host plus all of its symbiotic microbes. Consequently, the collective genomes of the holobiont form a "hologenome". Holobionts and hologenomes are structural entities that replace misnomers in the context of host-microbiota symbioses such as superorganism, organ, and metagenome. Variation in the hologenome may encode phenotypic plasticity of the holobiont and can be subject to evolutionary changes caused by selection and drift, if portions of the hologenome are transmitted between generations with reasonable fidelity. One of the important outcomes of recasting the individual as a holobiont subject to evolutionary forces is that genetic variation in the hologenome can be brought about by changes in the host genome and also by changes in the microbiome, including new acquisitions of microbes, horizontal gene transfers, and changes in microbial abundance within hosts. Although there is a rich literature on binary host–microbe symbioses, the hologenome concept distinguishes itself by including the vast symbiotic complexity inherent in many multicellular hosts. For recent literature on holobionts and hologenomes published in an open access platform, see the following reference.

<span class="mw-page-title-main">Marine microbial symbiosis</span>

Microbial symbiosis in marine animals was not discovered until 1981. In the time following, symbiotic relationships between marine invertebrates and chemoautotrophic bacteria have been found in a variety of ecosystems, ranging from shallow coastal waters to deep-sea hydrothermal vents. Symbiosis is a way for marine organisms to find creative ways to survive in a very dynamic environment. They are different in relation to how dependent the organisms are on each other or how they are associated. It is also considered a selective force behind evolution in some scientific aspects. The symbiotic relationships of organisms has the ability to change behavior, morphology and metabolic pathways. With increased recognition and research, new terminology also arises, such as holobiont, which the relationship between a host and its symbionts as one grouping. Many scientists will look at the hologenome, which is the combined genetic information of the host and its symbionts. These terms are more commonly used to describe microbial symbionts.

<span class="mw-page-title-main">Holobiont</span> Host and associated species living as a discrete ecological unit

A holobiont is an assemblage of a host and the many other species living in or around it, which together form a discrete ecological unit through symbiosis, though there is controversy over this discreteness. The components of a holobiont are individual species or bionts, while the combined genome of all bionts is the hologenome. The holobiont concept was initially introduced by the German theoretical biologist Adolf Meyer-Abich in 1943, and then apparently independently by Dr. Lynn Margulis in her 1991 book Symbiosis as a Source of Evolutionary Innovation. The concept has evolved since the original formulations. Holobionts include the host, virome, microbiome, and any other organisms which contribute in some way to the functioning of the whole. Well-studied holobionts include reef-building corals and humans.

<span class="mw-page-title-main">Symbiosome</span>

A symbiosome is a specialised compartment in a host cell that houses an endosymbiont in a symbiotic relationship.

<span class="mw-page-title-main">Marine microbiome</span>

All animals on Earth form associations with microorganisms, including protists, bacteria, archaea, fungi, and viruses. In the ocean, animal–microbial relationships were historically explored in single host–symbiont systems. However, new explorations into the diversity of marine microorganisms associating with diverse marine animal hosts is moving the field into studies that address interactions between the animal host and a more multi-member microbiome. The potential for microbiomes to influence the health, physiology, behavior, and ecology of marine animals could alter current understandings of how marine animals adapt to change, and especially the growing climate-related and anthropogenic-induced changes already impacting the ocean environment.

References

  1. ↑ Andrews M, Andrews ME (March 2017). "Specificity in Legume-Rhizobia Symbioses". Int J Mol Sci. 18 (4): 705. doi: 10.3390/ijms18040705 . PMC   5412291 . PMID   28346361.
  2. 1 2 Petersen JM, Zielinski FU, Pape T, Seifert R, Moraru C, Amann R, et al. (August 2011). "Hydrogen is an energy source for hydrothermal vent symbioses". Nature. 476 (7359): 176–80. Bibcode:2011Natur.476..176P. doi:10.1038/nature10325. PMID   21833083. S2CID   25578. Closed Access logo transparent.svg
  3. 1 2 "Microbial Symbioses | Boundless Microbiology". courses.lumenlearning.com. Retrieved 2021-11-12.
  4. ↑ Cooper, Geoffrey M. (2000). "The Origin and Evolution of Cells". The Cell: A Molecular Approach (2nd ed.). Sinauer Associates. ISBN   978-0-87893-106-4.
  5. ↑ Andersson, Tilde; Ertürk Bergdahl, Gizem; Saleh, Karim; Magnúsdóttir, Helga; Stødkilde, Kristian; Andersen, Christian Brix Folsted; Lundqvist, Katarina; Jensen, Anders; Brüggemann, Holger; Lood, Rolf (5 March 2019). "Common skin bacteria protect their host from oxidative stress through secreted antioxidant RoxP". Scientific Reports. 9 (1). doi:10.1038/s41598-019-40471-3.
  6. ↑ Frugier F, Kosuta S, Murray JD, Crespi M, Szczyglowski K (March 2008). "Cytokinin: secret agent of symbiosis". Trends in Plant Science. 13 (3): 115–20. doi:10.1016/j.tplants.2008.01.003. PMID   18296104.
  7. 1 2 3 4 Bright, Monika; Bulgheresi, Silvia (March 2010). "A complex journey: transmission of microbial symbionts". Nature Reviews Microbiology. 8 (3): 218–230. doi:10.1038/nrmicro2262. PMC   2967712 . PMID   20157340.
  8. 1 2 Lema KA, Willis BL, Bourne DG (2012). "Corals form specific associations with diazotrophic bacteria". Applied and Environmental Microbiology. 78 (9): 3136–44. doi: 10.1128/AEM.07800-11 . PMC   3346485 . PMID   22344646.
  9. ↑ Knowlton N, Rohwer F (October 2003). "Multispecies microbial mutualisms on coral reefs: the host as a habitat" (PDF). The American Naturalist. 162 (4 Suppl): S51–62. doi:10.1086/378684. PMID   14583857. S2CID   24127308.
  10. ↑ Fujishima M, Kodama Y (May 2012). "Endosymbionts in paramecium". European Journal of Protistology. 48 (2): 124–37. doi:10.1016/j.ejop.2011.10.002. PMID   22153895.
  11. ↑ Barrett LG, Broadhurst LM, Thrall PH (April 2012). "Geographic adaptation in plant–soil mutualisms: tests using Acacia spp. and rhizobial bacteria". Functional Ecology. 26 (2): 457–68. doi: 10.1111/j.1365-2435.2011.01940.x .
  12. ↑ Upadhyaya, Subodh (March 2012). "Isolation and Characterization of Cellulolytic Bacteria from Gut of Termite". Academia.edu . 1: 14–18.
  13. ↑ Sender, Ron; Fuchs, Shai; Milo, Ron (19 August 2016). "Revised Estimates for the Number of Human and Bacteria Cells in the Body". PLOS Biology. 14 (8): e1002533. doi: 10.1371/journal.pbio.1002533 . PMID   27541692.
  14. ↑ Chow, Janet; Lee, S. Melanie; Shen, Yue; Khosravi, Arya; Mazmanian, Sarkis K. (2010). "Host–Bacterial Symbiosis in Health and Disease". Mucosal Immunity. Advances in Immunology. Vol. 107. pp. 243–274. doi:10.1016/B978-0-12-381300-8.00008-3. ISBN   978-0-12-381300-8. PMC   3152488 . PMID   21034976.
  15. ↑ Quigley, Eamonn M. M. (September 2013). "Gut bacteria in health and disease". Gastroenterology & Hepatology. 9 (9): 560–569. PMC   3983973 . PMID   24729765.
  16. ↑ "What is a Symbiotic Microbial Community?". News-Medical.net. 2021-05-21. Retrieved 2021-11-12.
  17. ↑ Chandel, Navdeep S.; Budinger, G. R. Scott (3 July 2013). "The Good and the Bad of Antibiotics". Science Translational Medicine. 5 (192). doi:10.1126/scitranslmed.3006567. PMC   3997060 . PMID   23825300.
  18. ↑ Beard CB, Dotson EM, Pennington PM, Eichler S, Cordon-Rosales C, Durvasula RV (May 2001). "Bacterial symbiosis and paratransgenic control of vector-borne Chagas disease". International Journal for Parasitology. 31 (5–6): 621–7. doi:10.1016/s0020-7519(01)00165-5. PMID   11334952.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.