Prochlorococcus marinus

Class: Cyanophyceae Prochlorococcus is one of the most abundant and well studied marine phytoplankton. There are many subgroups of this cyanobacterium that exhibit fine-scale diversity and several distinct isolates now have full genome sequences available1. Found in tropical and temperate seas all over the world, these tiny photosynthetic bacteria fill a relatively specific, but highly successful niche. Cyanobacteria are key components of marine phytoplankton, especially in oligotrophic regions where they are often found to be the main primary producers. Cells are ca. 0.6um in diameter. 1Rocap, G., F. W. Larimer, J. Lamerdin, S. Malfatti, P. Chain, N. A. Ahlgren, A. Arellano, M. Coleman, L. Hauser, W. R. Hess, Z. 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: 1042-1047. (Preceding Page Photo Credit: Claire Ting, Chisholm Lab, MIT, 2003. EM of MIT9313. Copyright Chisholm Lab, MIT.)