Researchers have sequenced for the first time, genomes of bacteria that live in the sea. The microbes belong to cyanobacteria group, says Donald Bryant of Pennsylvania State of University. They account for roughly half of the photosynthesis in the oceans. They remove about 10 billion tons of carbon from the air.

Sallie Chisholm of the Massachusetts Institute of Technology and his team sequenced Prochlorococcus marinus, the most abundant photosynthetic. Its strongholds are the tropical and temperate oceans; it is less common in polar waters and close to land. Prochlorococcus is short on genes that would help it respond to environmental changes. The other species sequenced,

Synechococcus, has a larger genome and is less abundant at 10,000 cells per ml of seawater but is more widely distributed.
The genome of Synechococcus shows that it can process a wider range of chemicals than Prochlorococcus. Some of its enzymes are adapted to breakdown nickel and cobalt, probably as a way of conserving iron, which is in short supply in the sea, and it can use several different sources of nitrogen.