''Spirillum'' is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...
of
Gram-negative
Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...
bacteria in the family ''
Spirillaceae
Spirillaceae is a family in the order ''Nitrosomonadales
The NitrosomonadalesBoden, R; Hutt, LP, Rae AW (2017) Reclassification of ''Thiobacillus aquaesulis'' (Wood & Kelly, 1995) as ''Annwoodia aquaesulis'' gen. nov., comb. nov., transfer of ...
'' of the ''
Nitrosomonadales
The NitrosomonadalesBoden, R; Hutt, LP, Rae AW (2017) Reclassification of ''Thiobacillus aquaesulis'' (Wood & Kelly, 1995) as ''Annwoodia aquaesulis'' gen. nov., comb. nov., transfer of ''Thiobacillus'' (Beijerinck, 1904) from the ''Hydrogenophil ...
'' of the ''
Betaproteobacteria
Betaproteobacteria are a class of Gram-negative bacteria, and one of the eight classes of the phylum Pseudomonadota (synonym Proteobacteria).
The ''Betaproteobacteria'' are a class comprising over 75 genera and 400 species of bacteria. Together, ...
''.
[Garrity, George M.; Brenner, Don J.; Krieg, Noel R.; Staley, James T. (eds.) (2005). Bergey's Manual of Systematic Bacteriology, Volume Two: The Proteobacteria, Part C: The Alpha-, Beta-, Delta-, and Epsilonproteobacteria. New York, New York: Springer. pp. 354–361. .][Podkopaeva (D.), Grabovich (M.), Kuever (J.), Lysenko (A.M.), Tourova (T.P.), Kolganova (T.V.) and Dubinia (G.): Proposal of Spirillum winogradskyi sp. nov., a novel microaerophilic species, an amended description of the genus Spirillum and Request for an Opinion regarding the status of the species Spirillum volutans Ehrenberg 1832. Int. J. Syst. Evol. Microbiol., 2009, 59, 2916-2920.] There are two species of ''Spirillum'' with validly or effectively published names - ''
Spirillum winogradskyi
''Spirillum winogradskyi'' is a gram-negative, bacterium from the genus of Spirillum which was isolated from the sulfidic sludge
Sulfidation (British spelling also sulphidation) is a process of installing sulfide ions in a material or molecul ...
'' and ''
Spirillum volutans
''Spirillum volutans'' is a gram-negative, bacterium from the genus of Spirillum which occurs in freshwater. It has an amphitrichous flagellar arrangement. ''Spirillum volutans'' is one of the largest bacte