SAR11 clade dominates ocean surface bacterioplankton communities
Robert M Morris1, Michael S Rappé, Stephanie A Connon
1Department of Microbiology, Oregon State University, Corvallis, Oregon 97331, USA.
Nature
|December 20, 2002
Summary
The SAR11 clade, a group of bacteria, are the most abundant microbes in the ocean, making up over a third of cells in surface waters. These ubiquitous marine bacteria are among the most successful organisms on Earth.
Area of Science:
- Marine microbiology
- Oceanography
- Genomics
Background:
- The SAR11 clade is the most abundant bacterial ribosomal RNA gene detected in seawater.
- Little is known about the cellular abundance and ecological role of SAR11 organisms.
Purpose of the Study:
- To quantitatively measure the cellular abundance of the SAR11 clade in marine environments.
- To estimate the global population size of SAR11 cells in the oceans.
Main Methods:
- Gene cloning to detect ribosomal RNA genes.
- Quantitative measurements of cellular abundance in seawater samples.
- Extrapolation to estimate global cell numbers.
Main Results:
- SAR11 clade constitutes, on average, one-third of cells in surface waters and nearly one-fifth in the mesopelagic zone.
- In some areas, SAR11 comprises up to 50% of the surface microbial community.
- Estimated global population of SAR11 cells in the oceans is 2.4 x 10^28.
Conclusions:
- The SAR11 clade is a dominant and highly successful microbial group in the global oceans.
- SAR11 bacteria are a significant component of marine microbial communities across various oceanic zones.
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