Formal styling
Cyanobacterium Rippka, Cohen-Bazire, 1983 emend. Oren et al., 2022
Effective publication
Rippka, Cohen-Bazire, 1983
Emended in
Oren et al., 2022
SeqCode status
Valid (ICN)
Cannonical URL


Inferred stem
Gr. masc. n. kyanos, a blue dye; Gr. neut. n. bakterion, a small rod; N.L. neut. n. Cyanobacterium, a small blue-green rod
Nomenclatural type
Cyanobacterium stanieriT


Oren et al., 2022:
Unicellular cyanobacteria that reproduce by transverse binary fission in a single plane. Cells are widely oval to rod-like curved. Cell width is 1.7–4.5 µm and cell length is 2.5–7 (rarely up to 12 µm). Morphologically similar to Synechococcus and Cyanobium but differing by larger mean cell dimensions and in the arrangement of the thylakoids which align in more or less parallel planes and pass throughout the entire cell. They also differ in mean DNA base composition.

The range of DNA G+C content 37.5–38.7 mol%. The type species is Cyanobacterium stanieri Rippka and Cohen-Bazire.

The genes encoding proteins involved in carotenoid biosynthesis identified in the four genome sequences available for Cyanobacterium are in support of a pathway permitting the synthesis of β-carotene, zeaxanthin and myxoxanthophylls, as well as for the absence of echinenone as reported for strain PCC 7202. In contrast, the lack of a crtL(e) ortholog is in conflict with the presence of α-carotene as the major carotenoid. The genome of C. stanieri strain PCC 7202, like those of the other three strains of this genus, also encodes two proteins (CruE and CruH) involved in the biosynthesis of synechoxanthin. Therefore, althoufh not previously reported, these representatives of Cyanobacterium may under appropriate growth conditions synthesize this aromatic carotenoid.

In agreement with physiological and biochemical analyses, genes (nifD, nifK and nifH) encoding nitrogenase subunits, and cpeA and cpeB encoding the α- and β-subunits of C-phycoerythrin are lacking in the four genomes analysed. The lack of gvpA and gvpC coding for the gas vesicle structural proteins is in agreement with the absence of these structures that have so far never been observed in members of the genus Cyanobacterium as emended here.
Oren et al., 2022: The descriptions of Cyanobacterium gen. nov. and C. stanieri sp. nov. are hereby ascribed to the authors R. Rippka and G. Cohen-Bazire who first provided a detailed description of this taxon (Rippka, Cohen-Bazire, 1983). An emended description taking into account later studies is provided in this article, approved by one of the original authors (R. Rippka, co-author of this study). According to previously published phylogenetic inference based on sequence analyses of the 16S rRNA genes, the genus Cyanobacterium can be assigned to the family Geminocystaceae Tuji et al. 2021, validly published under the ICN, and not to the Cyanobacteriaceae Komárek et al. 2014, which at the time was based on the invalid genus name Cyanobacterium, and thus has no nomenclatural standing under the ICN.
Bacteria » Cyanobacteriota » Cyanophyceae » Chroococcales » Geminocystaceae » Cyanobacterium
Geminocystaceae ncbi assigned in Oren et al., 2022
Alternative placements
Children (2)


Outside links and data sources
Search sequences
Local history
Registered by
Rodriguez-R, Luis M 5 months ago
Reported valid by
Rodriguez-R, Luis M 5 months ago


Citation Title
Oren et al., 2022, International Journal of Systematic and Evolutionary Microbiology Validation of the names Cyanobacterium and Cyanobacterium stanieri, and proposal of Cyanobacteriota phyl. nov
Emended this name
Assigned this taxon
Rippka, Cohen-Bazire, 1983, Annales de l'Institut Pasteur / Microbiologie The cyanobacteriales: A legitimate order based on the type strain Cyanobacterium stanieri?
Effective publication

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