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A Microbial Biorealm page on the genus Chroococcus

Chroococcus turgidus. Image courtesy of Wim van Edmond. Copyright 2000-2005.


Higher order taxa:

Bacteria; Cyanobacteria; Chroococcales


Chroococcus dispersus, C. submarinus, C. submarinus kopara-BM, C. turgidus

NCBI: Taxonomy Genome

Description and Significance

Chroococcus, a unicellular organism that is a genus of cyanobacteria, is blue-green in color and macroscopic colony mounded. Within the outside sheath, microscopic colonies are found with indistinct trichomes. Chroococcus are usually found in colonies of two, four, or eight cells with a transparent protective covering sheath containing photosynthetic pigments. Like all cyanobacteria, Chroococcus is a prokaryote and therefore lacks any of the membranous organelles of eukaryotes. Known for its underwater habitat, Chroococcus prefers the sludge of lake and river bottoms to call home.

Chroococcus, like other cyanobacteria, has signifanct ecological implications as a productive microbe. Chroococcus uses an extensive quantity of atmospheric carbon for photosynthetic processes, creating free oxygen in the atmosphere. In addition, Chroococcus is part of the first genus to use water to access electrons and hydrogen for photosynthesis, which also produces more free oxygen to be used by other organisms.

Genome Structure

Relatively few studies have been performed on the background genetics of Chroococcus as of yet. Although there are currently no known genome sequencing projects, there is hope of one beginning soon because of Chroococcus's significant implications as an oxygen production source.

Cell Structure and Metabolism

Chroococcus sp. Image courtesy of Dr. Morgan Vis of Ohio University.

Chroococcuscells are ovoid or rod-shaped unicells with a diametere ranging between 0.4 to 40µm (Ditty). Formerly thought of and named as a blue-green strain of algae, cyanobacteria shares a close resemblance with green eukaryotic algae. In addition to physical similarities, cynaobacteria and algae also share similar habitats, often growing together.

Chroococcusis an autotrophic organism able to survive almost without any freshwater or oxygen source (Carboni). Chroococcusproduces oxygen and adenosine triphosphate through phtosynthetic methods using sunlight as the catalyst.


Chroococcus is known to traditionally inhabit freshwater areas, but has also been identified in water sources of higher salinity. Chroococcus has also been found in plankton inhabiting water reserves (Komárek). Chroococcus is often incorrectly identified, therefore outlining a true habitat pattern is difficult.


Carboni, G. Microworlds. Nov 2004.

Davidson, M.W. Molecular Expressions: Featured Microscopist: Wim van Egmond. 01 Dec 2003.

Ditty, J.L., S.B. Williams, and S.S. Golden. "A Cyanobacterial Circadian Timing Mechanism.Annu. Rev. Genet. 2003. 37: 513-43.

Hong J, Ma H, Otaki M."Controlling algal growth in photo-dependent decolorant sludge by photocatalysis." J Biosci Bioeng. 2005 Jun;99(6):592-7.

Kirkwood AE, Nalewajko C, Fulthorpe RR."The occurrence of cyanobacteria in pulp and paper waste-treatment systems." Can J Microbiol. 2001 Aug;47(8):761-6.

Komárek, Jiří and Tomáš Hauer.1992. CyanoDB: The online database of cyanobacterial genera. Database of cyanoprokaryotes: Databse of Genera.

Rezanka T, Dor I, Prell A, Dembitsky VM."Fatty acid composition of six freshwater wild cyanobacterial species." Folia Microbiol (Praha). 2003;48(1):71-5.