A term in aquatic microbiology: picocyanobacteria

Picocyanobacteria (plural of picocyanobacterium) are tiny cyanobacteria—less than two micrometers in size [1].  The prefix pico is derived from the Italian word piccolo for small. The size of picocyanobacteria cells is smaller than that of typical cyanobacteria cells, which ranges from one to forty micrometers [2].

Picocyanobacteria occur in freshwater and marine environments. They are photosynthetic organisms. Their diversity and distribution in dependence on light penetration through water layers and also on other factors is of great interest in ecology. For example, the abundance and composition of picocyanobacterial assemblages has been studied in many lakes of varying trophic state in relation to biomass and dissolved matter [3,4]. A two-year flow-cytometry investigation and in situ experiments in Lake Tahoe revealed seasonal patterns and clear temporal and spatial partitioning between picophytoplankton communities (picocyanobacteria and picoeukaryotes) [4].

Picocyanobacteria are the dominant microbes in the sunlit epipelagic zone of open oceans [5,6]. According to Tim Friend, “these little guys are of tremendous ecological importance” [5].  He informs that various institutions and research centers began sequencing the genomes of marine picocyanobacteria in 2003. Insight in picocyanobacterial metabolisms is critical for our understanding of global environmental and climate changes. Picocyanobacteria species—for example, those in the Synechococcaceae family—have an important role in carbon fixation and nutrient cycling in diverse marine ecosystems [7].

Keywords: marine microbiology, nanobiology, limnology, oceanography, microbial ecology, terminology.

References and more to explore
[1] Wiktionary: picocyanobacterium [en.wiktionary.org/wiki/picocyanobacterium].
[2] Cyanobacteria: huey.colorado.edu/cyanobacteria/about/cyanobacteria.php.
[3] F. R. Pick: The abundance and composition of freshwater picocyanobacteria in relation to light penetration. Limnol. Oceanogr. 1991, 36 (7), 1457-1462 [www.jstor.org/stable/2837651].
[4] Monika Winder:  Photosynthetic picoplankton dynamics in Lake Tahoe: temporal and spatial niche partitioning among prokaryotic and eukaryotic cells. J. Plankton Res. 2009, 31 (11), pp. 1307-1320 [plankton.ucdavis.edu/pdf/Winder_JPR09.pdf].
[5] Tim Friend: The Third Domain. The Untold Story of Archaea and the Future of Biotechnology. Joseph Henry Press, Washington, D.C., 2007; page 143.
[6] The Darwin Project: Selective pressures on picocyanobacterial nitrogen use [darwinproject.mit.edu/?page_id=16].
[7] S. Huang, S. W. Wilhelm, H. R. Harvey, K. Taylor, N. Jiao and F. Chen: Novel lineages of Prochlorococcus and Synechococcus in the global oceans. The ISME Journal 2012, 6, pp. 285-297. DOI: 10.1038/ismej.2011.106.