Pasteuria Penetrans
   HOME

TheInfoList



OR:

''Pasteuria'' is a genus of mycelial and endospore-forming, nonmotile gram-positive bacteria that are obligate parasites of some
nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...
s and
crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
s. The genus of ''Pasteuria'' was previously classified within the family Alicyclobacillaceae, but has since been moved to the family Pasteuriaceae.


Steps of infection

Animals that are susceptible to ''Pasteuria'' become infected when they are exposed to endospores in soil or water. Therefore, ''Pasteuria'' are transmitted horizontally between hosts and when an infected host dies, it releases spores to the soil or sediment. The likelihood of infections is related to the endospore density in the environment and can be affected by temperature. However, the ability of an endospore to attach to and infect a host is highly specific and following contact with a compatible host, ''the Pasteuria'' endospores are activated, penetrate the host's cuticle, proliferate within the host thereby restricting it from reproducing and ultimately the host dies. In water fleas, the ability of the endospore to successfully attach during the infection process is related to the genotype of the host and the parasite. However, in phytonematodes there was no direct relationship between cuticle heterogeneity as exhibited by endospore attachment and the phylogeny of the nematode. Furthermore, in phytonematodes the cues which initiate germination differ between different endospore isolates. For example, in ''Pasteuria penetrans'' that infects root-knot nematodes (''Meloidogyne'' spp.) endospore germination usually occurs sometime between the nematode entering the root, setting up the feeding site and the first molt as currently there are no reports of second-stage juveniles (J2) of ''Meloidogyne'' spp. containing either developmental stages or endospores of ''P. penetrans.'' However, developmental stages and endospores of a field population of ''Pasteuria'' have been observed in J2s of ''Heterodera avenae''''.'' An infected root-knot female can contain up to two million endpsores, while an infected J2 of ''H. avenae'' will contain less than a thousand endospores''''. Interestingly, endopores that do not infect water fleas and pass through a resistant host can still remain viable and infectious. This suggests that different species or strains of the bacterium have evolved different life-cycle strategies''.''


Effects of parasite

The life-cycles of the bacteria that infect cladoceran parasites and phytonematodes have been shown to be similar in that during infection they both exhibit morphological stages that are in common with the original description by Metchinkoff. Following infection with ''Pasteuria'', the parasite interferes with the reproduction of their female hosts. Hosts can live with the parasite for a prolonged period of time after infection. In ''
Daphnia ''Daphnia'' is a genus of small planktonic crustaceans, in length. ''Daphnia'' are members of the Order (biology), order Anomopoda, and are one of the several small aquatic crustaceans commonly called water fleas because their Saltation (gait), ...
'', ''P. ramosa'' induces gigantism. ''P. penetrans'' parasitized females of the nematode ''
Meloidogyne javanica ''Meloidogyne javanica'' is a species of plant-pathogenic nematodes. It is one of the tropical root-knot nematodes and a major agricultural pest in many countries. It has many hosts. ''Meloidogyne javanica'' reproduces by obligatory mitotic part ...
,'' on the other hand, were smaller than healthy individuals, although there is a direct relationship between the numbers of endospores produced by an individual female and its volume.


Potential as biocontrol

Due to the effect of ''Pasteuria'' on reproduction, especially on nematode pests of important crops, there is an interest to develop ''Pasteuria'' as a biological control agent. In 2012,
Syngenta Syngenta Global AG is a global agricultural technology company headquartered in Basel, Switzerland. It primarily covers crop protection and seeds for farmers. Syngenta is part of the Syngenta Group, entirely owned by Sinochem, a Chinese state ...
acquired a company named Pasteuria Bioscience to commercialize ''Pasteuria'' as a biological control. In 2013, Syngenta launched CLARIVAâ„¢ pn, which has the active ingredient of ''Pasteuria nishizawae'' to combat the soybean cyst nematode. The effectiveness of ''Pasteuria'' as a biocontrol may depend on the biotypes of the nematode host that are present since they can vary in their susceptibility to ''Pasteuria''.


Species of ''Pasteuria'' and their hosts

Currently, four species of ''Pasteuria'' and two candidate species are described, all of which are obligate parasites with specific hosts. The described species and their hosts include: * '' P. nishizawae'' Sayre et al. 1992: parasite of cyst-forming nematodes in the genera '' Heterodera'' and '' Globodera.'' * ''P. penetrans'' Thorne 1940 ex Sayre & Starr 1986: parasite of root knot nematodes in the genus ''
Meloidogyne Root-knot nematodes are plant-parasitic nematodes from the genus ''Meloidogyne''. They exist in soil in areas with hot climates or short winters. About 2000 species of plants worldwide are susceptible to infection by root-knot nematodes and they ...
'' spp. * '' P. ramosa'' Metchnikoff 1888: parasite of
Cladocera The Diplostraca or Cladocera, commonly known as water fleas, is a superorder (biology), superorder of small, mostly freshwater crustaceans, most of which feed on microscopic chunks of organic matter, though some forms are predatory. Over 1000 sp ...
ns, including ''
Daphnia ''Daphnia'' is a genus of small planktonic crustaceans, in length. ''Daphnia'' are members of the Order (biology), order Anomopoda, and are one of the several small aquatic crustaceans commonly called water fleas because their Saltation (gait), ...
.'' * ''P. thornei'' Starr & Sayre 1988: parasite of root-lesion nematodes in the genus ''
Pratylenchus ''Pratylenchus'' is a genus of nematodes known commonly as lesion nematodes.Crow, W. TAmaryllis lesion nematode, ''Pratylenchus hippeastri''.EENY-546. University of Florida IFAS. 2012. They are parasitism, parasitic on plants and are responsible ...
.'' Candidate species and their hosts include: * ''P. aldrichii'' Giblin-Davis et al. 2011: parasite of bacterivorous nematodes in the genus ''Bursilla'' spp. * ''P. usage'' Giblin-Davis et al. 2003: parasite of the sting nematode'',
Belonolaimus longicaudatus ''Belonolaimus longicaudatus'' (Sting nematode) is a common parasite of grasses and other plant crops and products. It is the most destructive nematode pest of turf grass, and it also attacks a wide range of fruit, vegetable, and fiber crops suc ...
'' Additional species of ''Pasteuria'' have been named but are yet to be formally described, including: * "''P. hartismeri''" Atibalentja et al. 2002b * "''P. goettingianae''" Bishop et al. 2007.


See also

*
List of bacterial orders This article lists the orders of the Bacteria. The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI) and the phylogeny is based on 16 ...
*
List of bacteria genera This article lists the genera of the bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, ...


References

{{Taxonbar, from=Q16987565 Gram-positive bacteria Bacteria genera