Sorcerer II: the search for microbial diversity roils the waters.

raig Venter is not short of ambition.With the human genome fresh off the sequencing machines, he set his sights on a project of even grander scale: to describe the immense wealth of genetic information living in the world's oceans.This voyage into biologically uncharted waters was, according to the Web site of the expedition vessel Sorcerer II, inspired in part by the voyage of H. M. S. Beagle [1].Venter, it seems, would like to be remembered as the Charles Darwin of the 21st century (Figure 1).This is the largest effort to describe the genetic diversity in the world's oceans.The voyage around national and international waters, collecting from around 150 sites and interrogating samples at the level of the gene rather than at the level of the organism, has already turned up between 5 and 6 million genes.Most of these genes have never been seen before, says Venter.Analysing this immense collection of data, the researchers discovered that many of the genes encode proteins that fall outside standard classifi cation schemes.Proteins grouped within their own unique kingdoms are turning up in other kingdoms as well-forcing the team to reconsider the evolutionary relationships of established kingdoms."This project is revealing some of the biggest discoveries about the environment," says Venter.(For more on these discoveries see the synopsis of the research articles [2].) Untapped DiversityThe Sorcerer II probably captured only a tiny fraction of the genetic diversity out there, says Mitchell Sogin, Director of the Josephine Bay Paul Center in Comparative Molecular Biology and Evolution at the Marine Biological Laboratory in Woods Hole, Massachusetts.In August 2006, Sogin and his colleagues published a detailed analysis of variable stretches of ribosomal RNA collected from the marine microbial world (Figure 2) [3]."We estimate there are at least 25,000 different kinds of microbes per litre of seawater," says Sogin. "But I wouldn't be surprised if it turns out there are 100,000 or more."A few of these microbes are common, and Venter will probably use them to recover complete gene sequences, he says."The vast majority of low-abundance organisms are going undetected."Venter is more than aware that there's a lot more to be discovered, but for the moment the goal is to sequence as many genes, in their entirety, as possible from these ecologically rich environments.These data raise a host of intriguing questions: in particular, what is the structure and function of the novel proteins these genes encode, and what role do they play in the metabolism of these undescribed microbes?Just as Darwin's work drove a change in the way we see the world, so Venter is hoping these marine data will do the same in years to come. Legal FrameworkBut times have changed.In the 21st century, there are plenty of hurdles to clear before the collecting and describing of biodiversity-even microscopic biodiversity-can go ahead.

Abstract licence: CC BY

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   CAMERA: A Community Resource for Metagenomics · 2007

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