Beijerinckia

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Beijerinckia
Systematics
Domain : Bacteria (bacteria)
Department : Proteobacteria
Class : Alphaproteobacteria
Order : Rhizobiales
Family : Beijerinckiaceae
Genre : Beijerinckia
Scientific name
Beijerinckia
Derx 1950

Beijerinckia is a genus of proteobacteria . It is a soil bacterium. By fixing nitrogen , it makes an important ecological contribution. Furthermore, Beijerinckia is one of the plant growth promoting rhizobacteria , i.e. it promotes the growth of plants.

Appearance

The cells of Beijerinckia are straight or slightly curved rods. They are flagellated peritrich. Beijerinckia forms terminal inclusions of poly-β-hydroxybutyrate (PHB). Occasionally permanent forms in the form of cysts are formed.

Growth and metabolism

Beijerinckia depends on oxygen, it is aerobic . It also tolerates low oxygen concentrations ( microaerophilic ). The metabolic pathway is breathing .

Nitrate cannot be used or only very slowly. Beijerinckia seems to need only small amounts of calcium and has a fairly high need for iron .

ecology

Species of Beijerinckia are soil bacteria and are common in soils of the tropics, especially in acidic oxi and ultisols . They are among the plant growth promoting rhizobacteria ( PGPR ). These bacteria are found in the rhizosphere of plants and can promote the growth of these plants. In most cases, PGPRs are not typical for all strains of a bacterial species; only individual strains have this ability. In addition to strains of Beijerinckia , these also include strains of Bacillus spp., Arthrobacter spp., Azospirillum spp., Pseudomonas cepacia (according to current nomenclature Burkholderia cepacia ), Pseudomonas chlororaphis , Erwinia ssp., Aeromonas spp. and some other bacteria. The promotion of growth concerns, among other things, higher germination rates, increased absorption of nutrients and increased growth of the roots. The PGPR also strengthen the protection of the plant against harmful pathogens such as nematodes, bacteria, insects or fungi. This happens u. a. by releasing antimicrobial metabolic products. An example of this is 2,4-diacetylphloroglucinol (DAPG), which is produced in particular by Pseudomonas species. Bacterial enzymes can also dissolve the chitin in the cell walls of harmful fungi and thus prevent them from penetrating the roots of the plant. PGPR can occur in many plant species, and possibly all species. Beijerinckia occurs freely mainly in acidic tropical soils and is also widespread worldwide in the rhizosphere of grasses such as Poaceae (sweet grasses). Beijerinckia is two to three times more common in rhizospheres than free in the ground.

Beijerinckia is one of the free-living, aerobic nitrogen fixers. Under good conditions, it fixes 30 kg of nitrogen per hectare and year. Like other nitrogen fixators, Beijerinckia needs molybdenum for nitrogen fixation and optimal growth. The quantities required are between 4.0 and 35.0 mg / l.

Systematics

The genus Beijerinckia is the type genus of the family Beijerinckiaceae. The genus includes the following species and subspecies (as of June 2020):

  • Beijerinckia derxii subsp. derxii (Tchan 1957) Thompson & Skerman 1981
  • Beijerinckia derxii subsp. venezuelae corrig. Thompson & Skerman 1981
  • Beijerinckia indica subsp. indica (Starkey & De 1939) Thompson & Skerman 1981
  • Beijerinckia indica subsp. lacticogenes Thompson & Skerman 1981

The species Beijerinckia fluminensis , previously listed here, is a synonym of Agrobacterium radiobacter , which belongs to the Rhizobiaceae family .

literature

Individual evidence

  1. ↑ George M. Garrity: Bergey's manual of systematic bacteriology . 2nd Edition. Springer, New York, 2005, Vol. 2: The Proteobacteria Part C: The Alpha-, Beta-, Delta-, and Epsilonproteabacteria ISBN 0-387-24145-0
  2. ↑ Johannes CG Ottow : Microbiology of Soils: Biodiversity, Ecophysiology and Metagenomics , Springer Verlag, Heidelberg New York 2011, ISBN 3642008232 .
  3. ↑ a b Ulrich Gisi: Soil Ecology . Thieme, Stuttgart 1997, ISBN 978-3-13-747202-5 .
  4. ^ A b Jean Euzéby, Aidan C. Parte: Genus Beijerinckia. In: List of Prokaryotic names with Standing in Nomenclature ( LPSN ). Retrieved December 16, 2015 .