''Azospirillum brasilense'' is a very well studied,

nitrogen-fixing Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiological nitrogen fixation, abiologically in chemical industry, chemical industries. Biological nitrogen ...

(

diazotroph Diazotrophs are organisms capable of nitrogen fixation, i.e. converting the relatively inert diatomic nitrogen (N2) in Earth's atmosphere into bioavailable compound forms such as ammonia. Diazotrophs are typically microorganisms such as bacteria ...

), genetically tractable, Gram-negative, alpha-proteobacterium bacterium, first described in Brazil (in a publication in 1978) by the group of

Johanna Döbereiner Johanna Liesbeth Kubelka Döbereiner (28 November 1924 – 5 October 2000) was a Brazilian agronomist and pioneer in soil biology. Biography Döbereiner was born in Ústí nad Labem, in what was the Republic of Czechoslovakia, which is now the ...

and then receiving the name "brasilense". ''A. brasilense'' is able to fix nitrogen in the presence of low oxygen levels, making it a microaerobic diazotroph. An isolate from the genus '' Azospirillum'' was isolated from nitrogen poor soils in the Netherlands in 1925, however the species ''A. brasilense'' was first described in 1978 in Brazil, since this genus is widely found in the

rhizosphere The rhizosphere is the narrow region of soil or Substrate (biology), substrate that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome. Pore space in soil, Soil pores in the rhizosphere can ...

s of grasses around the world where it confers plant growth promotion. Whether growth promotion occurs through direct nitrogen flux from the bacteria to the plant or through hormone regulation is debated. The two most commonly studied strains are Sp7 (ATCC 29145) and Sp245, both are Brazilian isolates isolated from Tropical grasses from Seropedica, Brazil. The genome of ''A. brasilense'' Sp245 has been sequenced and is 7Mbp in size and spread across 7 chromosomes. The high GC content (70%) makes it challenging to engineer. Sp245 can be transformed with OriV origin of replication

plasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria and ...

s through

conjugation Conjugation or conjugate may refer to: Linguistics *Grammatical conjugation, the modification of a verb from its basic form *Emotive conjugation or Russell's conjugation, the use of loaded language Mathematics *Complex conjugation, the change o ...

and electroporation. The strain is natively resistant to both spectinomycin and

ampicillin Ampicillin is an antibiotic belonging to the aminopenicillin class of the penicillin family. The drug is used to prevent and treat several bacterial infections, such as respiratory tract infections, urinary tract infections, meningitis, s ...

antibiotics.

Kanamycin Kanamycin A, often referred to simply as kanamycin, is an antibiotic used to treat severe bacterial infections and tuberculosis. It is not a first line treatment. It is used by mouth, injection into a vein, or injection into a muscle. Kanamy ...

resistance is used as a selectable marker. ''A. brasilense'' has a high evolutionary adaptation rate driven by codon mutation and

transposon A transposable element (TE), also transposon, or jumping gene, is a type of mobile genetic element, a nucleic acid sequence in DNA that can change its position within a genome. The discovery of mobile genetic elements earned Barbara McClinto ...

hopping.

A strain originally classified as ''Roseomonas fauriae'' was reclassified as ''A. brasilense''. It was first isolated from a hand wound of a woman in Hawaii in 1971, and was named for Yvonne Faur "for her contributions to public health bacteriology and, specifically, for her contribution to the recognition of pink-pigmented bacteria."Rihs JD, Brenner DJ, Weaver RE, Steigerwalt AG, Hollis DG, Yu VL
Roseomonas, a new genus associated with bacteremia and other human infections.
Journal of clinical microbiology. 1993 Dec 1;31(12):3275-83.

References

External links

*
Type strain of ''Azospirillum brasilense'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{DEFAULTSORT:Azospirillum brasilense Rhodospirillales Bacteria described in 1978

References

Further reading

External links