Photoautotrophic prokaryotes

Prokaryotes Autotrophs Chemoautotrophs Photoautotrophs Aerobes Energy from energised minerals Energy from oxidised sources, Fe3+, S()42, NO s Energy from light, Mg, Mn Tolerate and use 02 from moderate to high atmospheric levels Use of Mg2+, Fe2+, Mo(W)... 

Within this diverse group of organisms, three basic evolutionary lineages are discernable (Delwiche, 2000). The first contains all prokaryotic oxygenic phytoplankton, which belong to one class of bacteria, namely, the cyanobacteria. Cyanobacteria are the only known oxygenic photoautotrophs that existed prior to —2.5 Gyr BP (Ga) (Lipps, 1993 Summons et al., 1999). These prokaryotes numerically dominate the photoautotrophic community in contemporary marine ecosystems and their continued success bespeaks an extraordinary adaptive capacity. At any moment in time, there are —10 cyanobacterial cells in the contemporary oceans. To put that into perspective, the number of cyanobacterial cells in the oceans is two orders of magnitude more than all the stars in the sky. 

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