# Pasteuria ramosa

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Species of bacterium

Pasteuria ramosa Daphnia magna infected with Pasteuria ramosa Scientific classification Domain: Bacteria Kingdom: Bacillati Phylum: Bacillota Class: Bacilli Order: Bacillales Family: Pasteuriaceae Genus: Pasteuria Species: P. ramosa Binomial name Pasteuria ramosa Metchnikoff, 1888

***Pasteuria ramosa*** is a gram-positive, endospore-forming bacterium in the [Bacillus](/source/Bacillus)/[Clostridia](/source/Clostridia) clade within [Bacillota](/source/Bacillota). It is an obligate pathogen of [cladoceran](/source/Cladocera) [crustaceans](/source/Crustacean) from the genus *[Daphnia](/source/Daphnia)*.[1] *Daphnia* is a genus of small planktonic crustaceans including *[D. magna](/source/Daphnia_magna)*, *P. ramosa*'s most popular host target*.* Other hosts include *[D. pulex](/source/Daphnia_pulex)*, *[D. longispina](/source/Daphnia_longispina)*, *[D. dentifera](https://en.wikipedia.org/w/index.php?title=D._dentifera&action=edit&redlink=1)*, and *[Moina rectirostris](https://en.wikipedia.org/w/index.php?title=Moina_rectirostris&action=edit&redlink=1)*. An established and widely used [coevolutionary](/source/Coevolution) model of [host-pathogen interactions](/source/Host-pathogen_interactions) exists with *P. ramosa* and *[D. magna](/source/Daphnia_magna)*.[2][3]

## Growth and sporulation

Endospores of *P. ramosa*

*P. ramosa* is an [obligate](/source/Obligate) pathogen and it can only grow inside its host. Transmission between hosts takes place through the [endospore](/source/Endospores) stage, and is strictly [horizontal](/source/Horizontal_transmission).[1] These endospores are highly resistant to different environmental stresses, including freezing temperatures, and can remain in the environment for decades without any deleterious effects. The infection can be explained in 5 steps: (1.) Encounter (2.) Activation (3.) Attachment (4.) Proliferation and (5.) Termination.[4] The process starts when a *Daphnia* has ingested a spore of *P. ramosa* during filter feeding. The spore receives a signal to begin germination, and attaches to the host esophagus. The pathogen then enters the body cavity of the host by penetrating the esophagus wall. Once inside the body cavity, the bacterium begins to propagate in cauliflower like colonies. Propagation of spores is usually observed in the haemocoel and musculature.[4] After the infection has spread throughout the host, the bacterium begins to sporulate. The spores are shed into the environment from the dead host and can remain in the sediment for decades while maintaining their infectivity.[4] Additionally, these spores may be ingested by their immune hosts and pass through the gut of the *Daphnia* unharmed by any immune cells. This makes the spores very difficult to kill.[5]

## Pathogenicity

The infection success of *P. ramosa* depends on its ability to attach to the host esophagus and to spread into its body cavity where the propagation of the pathogen takes place. Propagation of the spores take place over a period of 10-20 days and ultimately leads to death of the infected host and the release of millions of created spores into the surrounding area.[6] The attachment step of the infection depends on the genotypes of the host and the bacterium, meaning that only certain host genotypes can be infected by certain strains of the bacterium.[4][7] Although the process through which the genotypic interactions occur is unclear, environmental factors, such as temperature, play a large role in the castration of *Daphnia*. Studies have shown that female *Daphnia* are sterilized at warmer temperatures (20–25 °C (68–77 °F)), but still have the ability to reproduce at lower temperatures (10–15 °C (50–59 °F)).[8] This difference in temperatures can be observed in different seasons and can lead to a high amount of variability between *Daphnia*, a crucial part of its ability to coevolve with *P. ramosa.* During *P. ramosa* infection, the size of the *Daphnia* increases significantly. This phenomenon is known as pathogen-induced [gigantism](/source/Gigantism). In addition, the lifespan of the host is significantly reduced.[1] *P. ramosa* are killed by the [ultraviolet radiation](/source/Ultraviolet) in sunlight with local adaptation occurring such that those in clearer lakes produce fewer spores but ones that are more infective.[9]

## Coevolutionary model with *Daphnia magna*

*P. ramosa* has coevolved with its host *Daphnia magna*. The mode of [coevolution](/source/Coevolution) in this system fits the model with [negative frequency-dependent selection](/source/Negative_frequency-dependent_selection) where the rare genotype is favored since the more common host genotype is more likely to become the target of a specialized pathogen.[2][3][10]

## Taxonomy

A culture established by James T. Staley, [ATCC](/source/ATCC_(company)) 27377T, was previously considered to be the [neotype](/source/Neotype) for this species, but has been reassigned to *[Pirellula staleyi](https://en.wikipedia.org/w/index.php?title=Pirellula_staleyi&action=edit&redlink=1)* Schlesner and Hirsch, 1987[11] because it did not conform to Metchnikoff's original description of *Pasteuria ramosa*.[12]

## References

1. ^ [***a***](#cite_ref-Development_1-0) [***b***](#cite_ref-Development_1-1) [***c***](#cite_ref-Development_1-2) Ebert, D.; Rainey, P.; Embley, T. M.; Scholz, D. (1996). "Development, life cycle, ultrastructure and phylogenetic position of *Pasteuria ramosa* Metchnikoff 1888: rediscovery of an obligate endoparasite of *Daphnia magna* Straus". *Philosophical Transactions of the Royal Society of London B*. **351** (1348): 1689–1701. [doi](/source/Doi_(identifier)):[10.1098/rstb.1996.0151](https://doi.org/10.1098%2Frstb.1996.0151).

1. ^ [***a***](#cite_ref-Genetic_2-0) [***b***](#cite_ref-Genetic_2-1) Carius, H. J.; Little; Ebert, D. (2001). "Genetic variation in a host-parasite association: Potential for coevolution and frequency-dependent selection". *Evolution*. **55** (6): 1136–1145. [doi](/source/Doi_(identifier)):[10.1111/j.0014-3820.2001.tb00633.x](https://doi.org/10.1111%2Fj.0014-3820.2001.tb00633.x). [PMID](/source/PMID_(identifier)) [11475049](https://pubmed.ncbi.nlm.nih.gov/11475049). [S2CID](/source/S2CID_(identifier)) [35183797](https://api.semanticscholar.org/CorpusID:35183797).

1. ^ [***a***](#cite_ref-Host-parasite_3-0) [***b***](#cite_ref-Host-parasite_3-1) Ebert, D. (2008). "Host-parasite coevolution: Insights from the *Daphnia*-parasite model system". *Current Opinion in Microbiology*. **11** (3): 290–301. [doi](/source/Doi_(identifier)):[10.1016/j.mib.2008.05.012](https://doi.org/10.1016%2Fj.mib.2008.05.012). [PMID](/source/PMID_(identifier)) [18556238](https://pubmed.ncbi.nlm.nih.gov/18556238).

1. ^ [***a***](#cite_ref-Resolving_4-0) [***b***](#cite_ref-Resolving_4-1) [***c***](#cite_ref-Resolving_4-2) [***d***](#cite_ref-Resolving_4-3) Duneau, D.; Luijckx, P.; Ben-Ami, F.; Laforsch, C.; Ebert, D. (2011). ["Resolving the infection process reveals striking differences in the contribution of environment, genetics and phylogeny to host-parasite interactions"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3052238). *BMC Biology*. **9**: 11. [doi](/source/Doi_(identifier)):[10.1186/1741-7007-9-11](https://doi.org/10.1186%2F1741-7007-9-11). [PMC](/source/PMC_(identifier)) [3052238](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3052238). [PMID](/source/PMID_(identifier)) [21342515](https://pubmed.ncbi.nlm.nih.gov/21342515).

1. **[^](#cite_ref-5)** King, K. C., Stuart, K. J. R. A., Wilson, P. J., James, J., & Little, T. J. (2013). "The bacterial parasite *Pasteuria ramosa* is not killed if it fails to infect: Implications for coevolution." *Ecology and Evolution*, **3**(2), 197–203. [doi](/source/Doi_(identifier)):[10.1002/ece3.438](https://doi.org/10.1002%2Fece3.438).

1. **[^](#cite_ref-6)** Auld, S. K. J. R., Graham, A. L., Wilson, P. J., & Little, T. J. (2012). "Elevated haemocyte number is associated with infection and low fitness potential in wild *Daphnia magna*." *Functional Ecology*. **26**(2):434–440. [doi](/source/Doi_(identifier)):[10.1111/j.1365-2435.2011.01959.x](https://doi.org/10.1111%2Fj.1365-2435.2011.01959.x).

1. **[^](#cite_ref-7)** Luijckx, P.; Ben-Ami, F.; Mouton, L.; Du Pasquier, L.; Ebert, D. (2011). "Cloning of the unculturable parasite Pasteuria ramosa and its Daphnia host reveals extreme genotype-genotype interactions". *Ecology Letters*. **14** (2): 125–131. [doi](/source/Doi_(identifier)):[10.1111/j.1461-0248.2010.01561.x](https://doi.org/10.1111%2Fj.1461-0248.2010.01561.x). [PMID](/source/PMID_(identifier)) [21091597](https://pubmed.ncbi.nlm.nih.gov/21091597).

1. **[^](#cite_ref-8)** Mitchell, S.E.; Rogers, E.S.; Little, T.J.; Read, A.F. (2005). ["Host-parasite and genotype-by-environment interactions: Temperature modifies potential for selection by a sterilizing pathogen"](https://doi.org/10.1111%2Fj.0014-3820.2005.tb00895.x). *Evolution*. **59** (1): 70–80. [doi](/source/Doi_(identifier)):[10.1111/j.0014-3820.2005.tb00895.x](https://doi.org/10.1111%2Fj.0014-3820.2005.tb00895.x). [PMID](/source/PMID_(identifier)) [15792228](https://pubmed.ncbi.nlm.nih.gov/15792228).

1. **[^](#cite_ref-9)** Rogalski, Mary Alta; Duffy, Meghan A. (2020). ["Local adaptation of a parasite to solar radiation impacts disease transmission potential, spore yield, and host fecundity*"](https://academic.oup.com/evolut/article/74/8/1856/6850798). *Evolution*. **74** (8): 1856–1864. [doi](/source/Doi_(identifier)):[10.1111/evo.13940](https://doi.org/10.1111%2Fevo.13940). [hdl](/source/Hdl_(identifier)):[2027.42/156433](https://hdl.handle.net/2027.42%2F156433). [ISSN](/source/ISSN_(identifier)) [0014-3820](https://search.worldcat.org/issn/0014-3820).

1. **[^](#cite_ref-10)** Decaestecker, Ellen; Vergote, Adelien; Ebert, Dieter; De Meester, Luc (2003-04-01). ["Evidence for strong host clone-parasite species interactions in the Daphnia microparasite system"](https://doi.org/10.1111%2Fj.0014-3820.2003.tb00290.x). *Evolution; International Journal of Organic Evolution*. **57** (4): 784–792. [doi](/source/Doi_(identifier)):[10.1111/j.0014-3820.2003.tb00290.x](https://doi.org/10.1111%2Fj.0014-3820.2003.tb00290.x). [ISSN](/source/ISSN_(identifier)) [0014-3820](https://search.worldcat.org/issn/0014-3820). [PMID](/source/PMID_(identifier)) [12778548](https://pubmed.ncbi.nlm.nih.gov/12778548). [S2CID](/source/S2CID_(identifier)) [1626602](https://api.semanticscholar.org/CorpusID:1626602).

1. **[^](#cite_ref-11)** Clum A, Tindall BJ, Sikorski J, Ivanova N, Mavrommatis K, Lucas S, et al. (2009). ["Complete genome sequence of *Pirellula staleyi* type strain (ATCC 27377T)"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035237). *Standards in Genomic Sciences*. **1** (3): 308–316. [doi](/source/Doi_(identifier)):[10.4056/sigs.51657](https://doi.org/10.4056%2Fsigs.51657). [PMC](/source/PMC_(identifier)) [3035237](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035237). [PMID](/source/PMID_(identifier)) [21304671](https://pubmed.ncbi.nlm.nih.gov/21304671).

1. **[^](#cite_ref-12)** Judicial Commission of the International Committee on Systematic Bacteriology (1986). ["Opinion 61: Rejection of the Type Strain of *Pasteuria ramosa* (ATCC 27377) and Conservation of the Species *Pasteuria ramosa* Metchnikoff 1888 on the Basis of the Type Descriptive Material"](https://doi.org/10.1099%2F00207713-36-1-119). *International Journal of Systematic and Evolutionary Microbiology*. **36** (1): 119. [doi](/source/Doi_(identifier)):[10.1099/00207713-36-1-119](https://doi.org/10.1099%2F00207713-36-1-119).

[Portal](https://en.wikipedia.org/wiki/Wikipedia:Contents/Portals):
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Taxon identifiers Pasteuria ramosa Wikidata: Q23817021 GBIF: 3228070 IRMNG: 11354213 ITIS: 968782 LPSN: pasteuria-ramosa NCBI: 225322 Open Tree of Life: 591104 SeqCode Registry: 29013

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Adapted from the Wikipedia article [Pasteuria ramosa](https://en.wikipedia.org/wiki/Pasteuria_ramosa) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Pasteuria_ramosa?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.