Azospirillum brasilense

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{{Short description|Species of bacterium}}

{{Taxobox

| name = Azospirillum brasilense

| domain = Bacteria

| phylum = Pseudomonadota

| classis = Alphaproteobacteria

| ordo = Rhodospirillales

| familia = Azospirillaceae

| genus = Azospirillum

| species = A. brasilense

| species_authority = Tarrand, Krieg & Döbereiner, 1978

}}

File:SVAzB.jpg, a model plant for Zea mays (corn).|285x285px]]

Azospirillum brasilense is a very well studied, nitrogen-fixing (diazotroph), genetically tractable, Gram-negative, alpha-proteobacterium bacterium, first described in Brazil (in a publication in 1978) by the group of Johanna Döbereiner and then receiving the name "brasilense".{{cite journal|last1=Tarrand|first1=Jeffrey J.|last2=Krieg|first2=Noel R.|last3=Döbereiner|first3=Johanna|title=A taxonomic study of the Spirillum lipoferum group, with descriptions of a new genus, Azospirillum gen. nov. and two species, Azospirillum lipoferum(Beijerinck) comb. nov. and Azospirillum brasilense sp. nov.|journal=Canadian Journal of Microbiology|volume=24|issue=8|year=1978|pages=967–980|issn=0008-4166|doi=10.1139/m78-160|pmid=356945|hdl=10919/54873|hdl-access=free}} 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 rhizospheres of grasses around the world where it confers plant growth promotion.{{Cite journal|last1=Holguin|first1=G.|last2=Patten|first2=C. L.|last3=Glick|first3=B. R.|date=1999-04-07|title=Genetics and molecular biology of Azospirillum|journal=Biology and Fertility of Soils|language=en|volume=29|issue=1|pages=10–23|doi=10.1007/s003740050519|s2cid=14247674|issn=0178-2762}}{{cite journal |vauthors=Tien TM, Gaskins MH, Hubbell DH |title=Plant Growth Substances Produced by Azospirillum brasilense and Their Effect on the Growth of Pearl Millet (Pennisetum americanum L.) |journal=Applied and Environmental Microbiology |volume=37 |issue=5 |pages=1016–24 |date=May 1979 |doi=10.1128/AEM.37.5.1016-1024.1979 |pmid=16345372 |pmc=243341 |url=}} Whether growth promotion occurs through direct nitrogen flux from the bacteria to the plant or through hormone regulation is debated.{{Cite journal|last1=Boddey|first1=Robert M.|last2=Urquiaga|first2=Segundo|last3=Alves|first3=Bruno J.R.|last4=Reis|first4=Veronica|date=May 2003|title=Endophytic nitrogen fixation in sugarcane: present knowledge and future applications|journal=Plant and Soil|volume=252|issue=1|pages=139–149|doi=10.1023/a:1024152126541|s2cid=45876064|issn=0032-079X}} 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.{{Cite journal|last1=Mammedov|first1=TG.|last2=Pienaar|first2=E.|last3=Whitney|first3=SE.|last4=TerMaat|first4=JR.|last5=Carvill|first5=G.|last6=Goliath|first6=R.|last7=Subramanian|first7=A.|last8=Viljoen|first8=HJ.|date=December 2008|title=A Fundamental Study of the PCR Amplification of GC-Rich DNA Templates|journal=Computational Biology and Chemistry|volume=32|issue=6|pages=452–457|doi=10.1016/j.compbiolchem.2008.07.021|issn=1476-9271|pmc=2727727|pmid=18760969}} Sp245 can be transformed with OriV origin of replication plasmids through conjugation and electroporation. The strain is natively resistant to both spectinomycin and ampicillin antibiotics. Kanamycin resistance is used as a selectable marker.PhD qualifying exam talk, Department of Bioengineering at Stanford University, Tim Schnabel, 12/12/2017 A. brasilense has a high evolutionary adaptation rate driven by codon mutation and transposon hopping.File:Nitrogen fixation operon of A. brasilense Sp245.jpg, 8 putative functions, 11 completely unknown and no homologs.|760x760px|alt=]]

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."{{Cite journal |doi = 10.1099/ijs.0.64549-0|pmid = 17158972|title = Reclassification of Roseomonas fauriae Rihs et al. 1998 as a later heterotypic synonym of Azospirillum brasilense Tarrand et al. 1979|journal = International Journal of Systematic and Evolutionary Microbiology|volume = 56|issue = 12|pages = 2753–2755|year = 2006|last1 = Helsel|first1 = L. O.|last2 = Hollis|first2 = D. G.|last3 = Steigerwalt|first3 = A. G.|last4 = Levett|first4 = P. N.|doi-access = free}}Rihs JD, Brenner DJ, Weaver RE, Steigerwalt AG, Hollis DG, Yu VL. [http://jcm.asm.org/content/31/12/3275.short Roseomonas, a new genus associated with bacteremia and other human infections.] Journal of clinical microbiology. 1993 Dec 1;31(12):3275-83.