Prochlorococcus and Other Photosynthetic Picoplankton


The smallest yet most abundant photosynthetic organism on earth is the marine cyanobacterium, Prochlorococcus, which represent a key component in marine ecology and global biogeochemical cycles. This tiny cell is extremely successful, dominating throughout the surface photic zone of the subtropical and tropical low nutrient, oligotrophic regions of the world's oceans from ∼45 °N to 40 °S. It has evolved to be an oligotrophic specialist, through a reduction in cell size, a streamlined genome and a reduced cellular requirement for the limited resources available in this environment. The ability to examine the abundance and distribution of Prochlorococcus in the wild, and measure its genomic and metabolic properties in the lab and field, has made Prochlorococcus a model system for advancing our understanding of the ecology of marine microbes.

Key Concepts:

  • The smallest photosynthetic cells in the oceans (picophytoplankton) dominate numerically and contribute significantly to primary production on a global scale.

  • Prochlorococcus is a cyanobacterium with a reduced cell size and streamlined genome providing it with advantages over other phytoplankton in oligotrophic oceans around the world.

  • The ability to measure genomic and metabolic properties in natural populations and isolates, and the ability to follow population dynamics, makes Prochlorococcus an excellent model system for studying microbial ecology on all scales.

Keywords: marine cyanobacteria; phytoplankton; biological oceanography; ecophysiology; microbial genomics

Figure 1.

(a) Epifluorescence micrograph of cultured Prochlorococcus and Synechococcus cells. The red is the chlorophyll fluorescence that occurs when the cells are exposed to blue light (excitation wavelength is 488 nm, and emission wavelength is 670 nm long pass). Contrast was adjusted after photo was taken to better visualise cells. Figure courtesy of Abraham Lorrain, University of Southern Maine. (b) Transmission electron micrograph of Prochlorococcus MED4. Figure courtesy of SW Chisholm Lab, Massachusetts Institute of Technology.

Figure 2.

Flow cytometric dot plots (‘signatures’) of scatter and fluorescence obtained for a marine sample collected in the Pacific Ocean at a depth of 65 m (OLIPAC cruise, Cast 94, 5°S to 150°W). (a) Red (chlorophyll) fluorescence versus forward scattered light; (b) Red fluorescence versus side scatter; (c) Red versus orange (phycoerythrin) fluorescence; (d) Orange fluorescence versus side scatter. Prochlorococcus (Proc), Synechoccccus (Syn) and picoeukaryotes (Euk) are discriminated on the basis of the autofluorescence of their natural pigments, chlorophyll or phycoerythrin. 0.95‐μm fluorescent beads were added as internal reference. Reproduced with permission from Marie et al. .

Figure 3.

Neighbour‐joining phylogenetic tree of ITS sequences (not including sequences from the tRNAs). Numbers at nodes are support values (bootstrap values) of MegaNJ and MegaME respectively. Black dots indicate culture isolates that have their complete genome sequenced, black triangles indicate novel cultured isolates and undesignated sequences are from environmental DNA samples. Novel culture isolates have their isolation location preceding their isolate name (HOT‐Hawaii Ocean Time‐series, BATS‐Bermuda Atlantic Time‐Series, UH‐University of Hawaii and SA‐South Atlantic). Clade designations have been determined from Lavin et al. . Environmental DNA samples are from Lavin et al. (LLI‐VI), Martiny et al. (NC1) and Rocap et al. (HL). Grey box indicates novel isolates that have been isolated and maintained in nitrate containing media. Statistical evaluation of tree topologies was performed by bootstrap analysis with 100 resamplings. Environmental DNA samples and culture isolate names are denoted by their GenBank accession numbers. Figure courtesy of Kathryn H. Roache‐Johnson, University of Southern Maine.



Ahlgren NA and Rocap G (2006) Culture isolation and culture‐independent clone libraries reveal new marine Synechococcus ecotypes with distinctive light and N physiologies. Applied and Environmental Microbiology 72: 7193–7204.

Ahlgren NA, Rocap G and Chisholm SW (2005) Measurement of Prochlorococcus ecotypes using real‐time polymerase chain reaction reveals different abundances of genotypes with similar light physiologies. Environmental Microbiology 8: 441–454.

Bertilsson S, Bergland O, Karl DM and Chisholm SW (2003) Elemental composition of marine Prochlorococcus and Synechococcus: implications for the ecological stoichiometry of the sea. Limnology Oceanography 48: 1721–1731.

Bertilsson S, Berglund O, Pullin MJ and Chisholm SW (2005) Release of dissolved organic matter by Prochlorococcus. Vie Milieu 55: 225–231.

Bibby TS, Mary I, Nield J, Partensky F and Barber J (2003) Low‐light‐adapted Prochlorococcus species possess specific antennae for each photosystem. Nature 424: 1051–1054.

Bouman HA, Ulloa O, Scanlan DJ et al. (2006) Oceanographic basis of the global surface distribution of Prochlorococcus ecotypes. Science 312: 918–921.

Campbell L, Liu HB, Nolla HA and Vaulot D (1997) Annual variability of phytoplankton and bacteria in the subtropical north pacific ocean at station ALOHA during the 1991–1994 ENSO event. Deep‐Sea Research 44: 167–192.

Casey JR, Lomas MW, Mandecki J and Walker DE (2007) Prochlorococcus contributes to new production in the Sargasso Sea deep chlorophyll maximum. Geophysical Research Letters 34: 1–5.

Chisholm SW, Frankel SL, Goericke R et al. (1992) Prochlorococcus marinus nov. gen. nov. sp.: an oxyphototrophic marine prokaryote containing divinyl chlorophyll a and b. Archives for Microbiology 157: 297–300.

Chisholm SW, Olson RJ, Zettler ER et al. (1988) A novel free‐living prochlorophyte abundant in the oceanic euphotic zone. Nature 334: 340–343.

Christaki U, Jacquet S, Dolan JR, Vaulot D and Rassoulzadegan F (1999) Growth and grazing on Prochlorococcus and Synechococcus by two marine ciliates. Limnology Oceanography 44: 52–61.

Coleman ML and Chisholm SW (2007) Code and context: Prochlorococcus as a model for cross‐scale biology. Trends in Microbiology 15: 398–407.

Coleman ML, Sullivan MB, Martiny AC et al. (2006) Genomic islands and the ecology and evolution of Prochlorococcus. Science 311: 1768–1770.

Dufresne A, Ostrowski M, Scanlan DJ et al. (2008) Unraveling the genomic mosaic of a ubiquitous genus of marine cyanobacteria. Genome Biology 9: R90.

Dufresne A, Salanoubat M, Partensky F et al. (2003) Genome sequence of the Cyanobacterium Prochlorococcus marinus SS120, a nearly minimal oxyphototrophic genome. Proceedings of the National Academy of Sciences of the USA 100: 10020–10025.

Durand MDR, Olson RJ and Chisholm SW (2001) Phytoplankton population dynamics at the Bermuda Atlantic time series station in the Sargasso Sea. Deep‐Sea Research II 48: 1983–2003.

Field CB, Behrenfeld MJ, Randerson JT and Falkowski P (1998) Primary production of the biosphere: integrating terrestrial and oceanic components. Science 281: 237–240.

Gieskes WW and Kraay GW (1983) Unknown chlorophyll a derivatives in the North Sea and the tropical Atlantic revealed by HPLC analysis. Limnology Oceanography 28: 757–766.

Goericke R and Repeta DJ (1992) The pigments of Prochlorococcus marinus: the presence of divinyl chlorophyll a and b in a marine prochlorophyte. Limnology Oceanography 37: 425–433.

Hess WR, Rocap G, Ting CS et al. (2001) The photosynthetic apparatus of Prochlorococcus: insights through comparative genomics. Photosynthesis Research 70: 53–71.

Johnson PW and Sieburth JM (1979) Chroococcoid cyanobacteria in the sea: a ubiquitous and diverse phototrophic biomass. Limnology Oceanography 24: 928–935.

Johnson ZI, Zinser ER, Coe A et al. (2006) Niche partitioning among Prochlorococcus ecotypes along ocean‐scale environmental gradients. Science 311: 1737–1740.

Kettler GC, Martiny AC, Huang K et al. (2007) Patterns and implications of gene gain and loss in the evolution of Prochlorococcus. PLoS Genetics 3: 2515–2528.

Lavin P, Gonzalez B, Santlbanez JF, Scanlan DJ and Ulloa O (2010) Novel lineages of Prochlorococcus thrive within the oxygen minimum zone of the eastern tropical South Pacific. Environmental Microbiology Reports. doi: 10.1111/j.1758‐2229.2010.00167.x.

Malmstrom RR, Coe A, Kettler GC et al. (2010) Temporal dynamics of Prochlorococcus ecotypes in the Atlantic and Pacific oceans. ISME Journal. doi: 10.1038/ismej.2010.60.

Marie D, Brussaard C, Partensky F and Vaulot D (1999) Flow cytometric analysis of phytoplankton, bacteria and viruses. In: Paul Robinson MEJ (ed.) Current Protocols in Cytometry, pp. 1–15. New York, NY: Wiley.

Martiny AC, Coleman ML and Chisholm SW (2006) Phosphate acquisition genes in Prochlorococcus ecotypes: evidence for genome‐wide adaptation. Proceedings of the National Academy of Sciences of the USA 103: 12552–12557.

Martiny AC, Kathuria S and Berube PM (2009) Widespread metabolic potential for nitrite and nitrate assimilation among Prochlorococcus ecotypes. Proceedings of the National Academy of Sciences of the USA 106: 10787–10792.

Martiny AC, Tai AP, Veneziano D, Primeau F and Chisholm SW (2008) Taxonomic resolution, ecotypes and the biogeography of Prochlorococcus. Environmental Microbiology 11: 823–832.

Moore LR and Chisholm SW (1999) Photophysiology of the marine cyanobacterium Prochlorococcus: ecotypic differences among cultured isolates. Limnology Oceanography 44: 428–438.

Moore LR, Goericke R and Chisholm SW (1995) Comparative physiology of Synechococcus and Prochlorococcus: influence of light and temperature on growth, pigments, fluorescence and absorptive properties. Marine Ecology Progress Series 39: 257–269.

Moore LR, Ostrowski M, Scanlan DJ, Feren K and Sweetsir T (2005) Ecotypic variation in phosphorus acquisition mechanisms within marine picocyanobacteria. Aquatic Microbial Ecology 39: 257–269.

Moore LR, Post AF, Rocap G and Chisholm SW (2002) Utilization of different nitrogen sources by the marine cyanobacteria Prochlorococcus and Synechococcus. Limnology Oceanography 47: 989–996.

Partensky F and Garczarek L (2010) Prochlorococcus: advantages and limits of minimalism. Annual Review Marine Science 2: 305–331.

Partensky F, Hess W and Vaulot D (1999) Prochlorococcus, a marine photosynthetic prokaryote of global significance. Microbiology and Molecular Biology Reviews 63: 106–127.

Partensky F, Hoepffner N, Li WGW, Ulloa O and Vaulot D (1993) Photoacclimation of Prochlorococcus sp. (Prochlorophyta) strains isolated from the North Atlantic and the Mediterranean Sea. Plant Physiology 101: 285–296.

Rocap G, Distel D, Waterbury JB and Chisholm SW (2002) Resolution of Prochlorococcus and Synechococcus ecotypes by using 16S‐23S ribosomal DNA internal transcribed spacer sequences. Applied and Environmental Microbiology 68: 1180–1191.

Rocap G, Larimer FW, Lamerdin J et al. (2003) Genome divergence in two Prochlorococcus ecotypes reflects oceanic niche differentiation. Nature 424: 1042–1047.

Savage DC (1977) Microbial ecology of the gastrointestinal tract. Annual Review of Microbiology 31: 107–133.

Scanlan DJ, Ostrowski M, Mazard S et al. (2009) Ecological genomics of marine picocyanobacteria. Microbiology and Molecular Biology Reviews 73: 249–299.

Scanlan DJ and West NJ (2002) Molecular ecology of the marine cyanobacterial genera Prochlorococcus and Synechococcus. FEMS Microbiology Ecology 40: 1–12.

Seymour JR, Ahmed T, Durham WM and Stocker R (2010) Chemotactic response of marine bacteria to the extracellular products of Synechococcus and Prochlorococcus. Aquatic Microbial Ecology 59: 161–168.

Steglich C, Futschik M, Rector T, Steen R and Chisholm SW (2006) Genome‐wide analysis of light sensing in Prochlorococcus. Journal of Bacteriology 188: 7796–7806.

Steglich C, Mullineaux CW, Teuchner K, Hess WR and Lokstein H (2003) Photophysical properties of Prochlorococcus marinus SS120 divinyl chlorophylls and phycoerythrin in vitro and in vivo. FEBS Letters 553: 79–84.

Sutherland KR, Madin LP and Stocker R (2010) Filtration of submicrometer particles by pelagic tunicates. Proceedings of the National Academy of Sciences of the USA 107: 15129–15134.

Urbach E, Scanlan DJ, Distel DD, Waterbury JB and Chisholm SW (1998) Rapid diversification of marine phytoplankton with dissimilar light harvesting structures inferred from sequences of Prochlorococcus and Synechococcus (Cyanobacteria). Journal of Molecular Evolution 46: 188–201.

Van Mooy BAS, Rocap G, Fredricks HF, Evans CT and Devol AH (2006) Sulfolipids dramatically decrease phosphorus demand by picocyanobacteria in oligotrophic marine environments. Proceedings of the National Academy of Sciences of the USA 103: 8607–8612.

West NJ, Schonhuber WA, Fuller NJ et al. (2001) Closely related Prochlorococcus genotypes show remarkably different depth distributions in two oceanic regions as revealed by in situ hybridization using 16S rRNA‐targeted oligonucleotides. Microbiology 147: 1731–1744.

Zinser ER, Coe A, Johnson ZI et al. (2006) Prochlorococcus ecotype abundances in the North Atlantic Ocean as revealed by an improved quantitative PCR method. Applied and Environmental Microbiology 72: 723–732.

Zinser ER, Lindell D, Johnson ZI et al. (2009) Choreography of the transcriptome, photophysiology, and cell cylcle of a minimal photoautotroph, Prochlorococcus. PLoS ONE 4: 1–18.

Zwirglmaier K, Jardillier L, Ostrowski M et al. (2008) Global phylogeography of marine Synechococcus and Prochlorococcus reveals a distinct partitioning of lineages among oceanic biomes. Environmental Microbiology 10: 147–161.

Further Reading

Bang M and Chisholm P (2009) Living Sunlight: How Plants Bring Life to the Earth. New York: Blue Sky Press/Scholastic. 43pp. (a children's book on Photosynthesis).

Chen M and Bibby TS (2005) Photosynthetic apparatus of antenna‐reaction centres supercomplexes in oxyphotobacteria: Insight through significance of Pcb/IsiA proteins. Photosynthesis Research 86: 165–173.

Herrero A and Flores E (eds) (2008) The Cyanobacteria: Molecular Biology, Genomics and Evolution, 484pp. Norwich, UK: Caister Academic Press.

Kirchman DL and Mitchell R (eds) (2008) Microbial Ecology of the Oceans, 2nd ed., 620pp. New York: Wiley.

Lindell D and Post AF (1995) Ultraphytoplankton succession is triggered by deep winter mixing in the Gulf of Aqaba (Eilat), Red Sea. Limnology & Oceanography 40: 1130–1141.

Morel A, Ahn Y‐H, Partensky F, Vaulot D and Claustre H (1993) Prochlorococcus and Synechococcus: a comparative study of their optical properties in relation to their size and pigmentation. Journal of Marine Research 51: 617–649.

Nadis S (2003) The Cells that Rule the Seas. Scientific American, 52f. December.‐0078‐1FA8‐807883414B7F0000.

Palca J (2008) The Most Important Microbe You've Never Heard Of, National Public Radio Morning Edition. Available at on June 13, 2008.

Paul JH and Sullivan MB (2005) Marine phage genomics: what have we learned? Current Opinion in Biotechnology 16: 299–307.

Van Mooy BAS, Fredricks HF, Pedler BE et al. (2009) Phytoplankton in the ocean use non‐phosphorus lipids in response to phosphorus scarcity. Nature 458: 69–72.

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How to Cite close
Moore, Lisa R(Dec 2010) Prochlorococcus and Other Photosynthetic Picoplankton. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0022840]