DIP a bucket into the ocean and you are catching a sample of the 鈥減rimordial sea鈥� from which all complex life on Earth evolved. It turns out that there are hundreds of times more species of microbes in the oceans than we thought.
Mitchell Sogin of the Marine Biological Laboratory at Woods Hole in Massachusetts collected water samples from sites in the Atlantic Ocean and hydrothermal vents around a Pacific volcano, and used a new technique known as 454-tag sequencing to identify organisms from small snippets of DNA.
Most microbes were from a small number of known species, but in the background Sogin discovered 鈥渁nother world鈥�: millions of previously unknown species present only in tiny numbers (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0605127103). 鈥淲e expected to find a few more species, but we have found orders of magnitude more,鈥� he says.
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Sogin speculates that the bacteria are a vast source of genetic diversity: species with diverse attributes that can take over key planetary functions such as recycling carbon and nitrogen after some massive global change, whether 鈥渟nowball Earth鈥� or global warming. 鈥淏acteria are the best hope we have for keeping life on Earth,鈥� says Victor Gallardo of the University of Concepcion in Chile, a member of the international Census for Marine Life project.
