Aquaspirillum Autotrophicum

''Aquaspirillum'' /ˌakwəspəˈrɪləm/ is a genus of helical aerobic bacteria in the family ''Neisseriaceae'' that lives in freshwater.

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''.

Etymology

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

Species

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

*''Aquaspirillum anulus''
*''Aquaspirillum aquaticum''
*Aquaspirillum arcticum, ''Aquaspirillum'' ''arcticum''
*''Aquaspirillum delicatum''
*''Aquaspirillum dispar''
*''Aquaspirillum giesbergeri''
*''Aquaspirillum gracile''
*Aquaspirillum itersonii, ''Aquaspirillum'' ''itersonii''
*''Aquaspirillum metamorphum''
*'':fr: Aquaspirillum polymorphum''
*''Aquaspirillum putridiconchylium''
*''Aquaspirillum serpens'' (type species)
*''Aquaspirillum sinuosum''

The following five species were added to ''Aquaspirillum'' in the years after its creation:

* ''Aquaspirillum autotrophicum''
* ''Aquaspirillum bengal''
* ''Aquaspirillum fasciculus''
* ''Aquaspirillum magnetotacticum''
* ''Aquaspirillum psychrophilum''

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. However, no new genera for the misclassified species have been proposed, so they technically remain in ''Aquaspirillum''.

Description

All ''Aquaspirillum'' species are rigid helical cells with the exception of ''Aquaspirillum delicatum, A. delicatum'' and ''Aquaspirillum fasciculus, 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 Flagellum, flagella, on each pole. However, they may instead have one single flagellum at each pole instead of either of these tufts.

Growth Requirements

Most species of ''Aquaspirillum'' are aerobic, but some exist in areas with Microaerophile, microaerophilic activity, performing certain amounts of nitrogen fixation. The aerobic species Cellular respiration, respire using oxygen as a terminal electron acceptor, but the some species, including the microaerophilic ones, can also grow Anaerobic respiration, anaerobically using nitrate. Most species experience optimal growth in a medium which is 30–32 °C.Hylelmon, P.B., J.S. Wells, N.R.Krieg and H.W. Jannasch (1973) The genus Spirillum: a taxonomic study

References

{{Taxonbar, from=Q24041534

Bacteria genera