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Name derivation:

Early green sphere

 

Classification:

Prochlorococcus  S.W.Chisholm, S.L.Frankel, R.Goericke, R.J.Olson, B.Palenik, J.B.Waterbury, L.West-Johnsrud and E.R.Zettler  1992;  only one species has been described to date, and it is accepted taxonomically (Guiry and Guiry 2013).

 

Order Synechococcales; Family Synechococcaceae

 

Morphology:

Subspherical unicells ~ 0.6 um diameter.

 

Similar genera:

 

Habitat:

Free living marine phototrophs with at least two ecotypes adapted to different light intensities (HL = high intensity strains, LL = low intensity strains). Phylogenetic studies of strains indicate closeness of genomes is mainly related to their habitat depth, i.e. vertical spatial separation along the light intensity gradient, rather than geographic horizontal distribution; concentration of Prochlorococcus in the Arabian Sea was 1 3.5 x 105 cells ml-1 in September 2001 (Fuller at al. 2006).

Considered to be the most abundant and smallest oxygenic photosynthesizers, also with the smallest genome (1.7 Mb and ~ 2,000 predicted protein-coding genes). Collectively the genus may produce the predominant amount of oxygen in the ocean plankton (Rocap et al. 2003.

 

References:

Chisholm, S. W., S. L. Frankel, R. Goericke, R.J. Olson, B. Palenik, J.B. Waterbury, L. West-Johnsrud, and E.R. Zettler 1992. Prochlorococcus marinus nov. gen. nov. sp.: an oxyphototrophic marine prokaryote containing divinyl chlorophyll a and b. Archives of Microbiology 157: 297-300.

Fuller, N.J., G.A. Tarran, M. Yallop, K.M. Orcutt and D.J. Scanlan 2006. Molecular analysis of picocyanobacterial community structure along an Arabian Sea transect reveals distinct spatial separation of lineages. Limnology and Oceanography 51(6):2515-2526.

Guiry, M.D. and G.M. Guiry 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 10 September 2013.

Rocamp, G., F.W. Larimer, J. Lamerdin, S. Malfatti, P. Chain, N.A. Ahlgren, A. Arellano, M. Coleman, L. Hauser, W.R. Hess, A.I. Johnson, M. Land, D. Lindell, A.F. Post, W. Regala, M. Shah, S.L. Shaw, C. Steglich, M.B. Sullivan, C.S. Ting, A. Tolonen, E.A. Webb, E.R. Zinser, and S.W. Chisholm 2003. Genome divergence in two Prochlorococcus ecotypes reflects oceanic niche differentiation. Nature 424:1042-1046.