Aquaspirillum

Aquaspirillum (ak'wă-spī-ril'ŭm) is a genus of helical aerobic bacteria in the family Neisseriaceae that lives in freshwater.

Aquaspirillum
Scientific classification
Domain: Bacteria
Phylum: Pseudomonadota
Class: Betaproteobacteria
Order: Neisseriales
Family: Neisseriaceae
Genus: Aquaspirillum
Hylemon, 1973
Species

see text

Synonyms

Microvirgula Paturaeu, 1998

Taxonomy

In 1832, the genus Spirillum was created and encompassed an array of helical bacteria. In 1957, the large genus was reviewed and narrowed to include 19 species based on morphology and a few other physiological characteristics. The genus Aquaspirillum was not created until 1973, when another review of Spirillum led to the division of the genus into Aquaspirillum, Oceanospirillum, and Spirillum.[1]

Etymology

The genus' name is a combination of several words. Aqua comes from Latin, meaning water; speîra comes from Greek, meaning a spiral; spirillum come from Neo-Latin, meaning a small spiral. Put together, the genus' name means "small water spiral."[2]

Species

The new genus comprised the following 13 species when it was created:

The following five species were added to Aquaspirillum in the years after its creation:[3]

Phylogenetic Analysis

A phylogenetic analysis of the genus showed data that suggested all but three species of Aquaspirillum should be moved into their own respective genera as Aquaspirillum is phylogenetically heterogeneous.[4] However, no new genera for the misclassified species have been proposed, so they technically remain in Aquaspirillum.[5]

Description

All Aquaspirillum species are rigid helical cells with the exception of A. delicatum and A. fasciculus. The cells measure 0.2–1.5 mcm in diameter. They all have a polar membrane underneath their cytoplasmic membrane, and generally have two tufts of flagella, on each pole. However, they may instead have one single flagellum at each pole instead of either of these tufts.[1][6]

Growth Requirements

Most species of Aquaspirillum are aerobic, but some exist in areas with microaerophilic activity, performing certain amounts of nitrogen fixation. The aerobic species respire using oxygen as a terminal electron acceptor, but the some species, including the microaerophilic ones, can also grow anaerobically using nitrate.[1] Most species experience optimal growth in a medium which is 30–32° Celsius.[7]

References
  1. Pot, Bruno; Gillis, Monique; De Ley, Jozef (2006). "The Genus Aquaspirillum". The Prokaryotes: 710–722 – via Springer Link.
  2. "Genus: Aquaspirillum". LPSN - List of Prokaryotic names with Standing in Nomenclature. Retrieved 2021-05-07.{{cite web}}: CS1 maint: url-status (link)
  3. Terasaki, Yasuke (1 April 1979). "Transfer of Five Species and Two Subspecies of Spirillum to Other Genera (Aquaspirillum and Oceanospirillum), with Emended Descriptions of the Species and Subspecies". Microbiology Society. 29.
  4. Ding, L; Yokota, A (2002). "Phylogenetic analysis of the genus Aquaspirillum based on 16S rRNA gene sequences". FEMS Microbiol Lett. 212 (2): 165–9. doi:10.1016/s0378-1097(02)00747-4. PMID 12113929.
  5. Pot, B. and Gillis, M. 2015. Aquaspirillum. Bergey's Manual of Systematics of Archaea and Bacteria. 1–39.
  6. "Aquaspirillum". web2.uwindsor.ca. Archived from the original on 26 February 2020. Retrieved 7 May 2021.
  7. Hylelmon,P.B., J.S. Wells, N.R.Krieg and H.W. Jannasch (1973) The genus Spirillum: a taxonomic study
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