Invisible War Rages in World's Oceans: Bacteria Battle for Survival

A war is being waged constantly in our oceans--and we had no idea it was happening until now. Researchers have found that two bacteria are constantly battling one another, and may determine the outcome of how much carbon dioxide enters Earth's atmosphere.

The study, which was published in the journal Nature, discovered new viruses that constantly battle against the bacteria that make their homes in our oceans. The bacteria, known collectively as SAR11, are the most abundant organisms known to inhabit seawater.

The researchers first identified these viruses from water collected from the Sargasso Sea and coastal Oregon waters. Finding four viruses in total, the scientists then sequenced the genomes of these newly named "pelagiphages" and compared them with the DNA from other viruses. They found that these new viruses had many similarities with other viruses that attack other ocean-dwelling bacteria. In fact, the researhers eventually discovered that these pelagiphages routinely hunt and kill millions of cells from SAR11 every second. Previously, scientists thought that since SAR11 was so abundant, there was no way that it was attacked by viruses.

SAR11 is known for being competitive and good at scavenging organic carbon. In addition, it's effective at changing in order to avoid infection. While viruses attack it, in other words, it is still able to thrive and persist in abundance.

Yet this competition is being played for greater stakes--at least when it comes to our atmosphere. SAR11 is known for being one of the smallest known genetic structures of any independent cell, and also for its massive role in consuming organic carbon. With this carbon, SAR11 generates energy while producing carbon dioxide and water in the process. In addition, SAR11 recycles organic matter which provides the nutrients needed by algae to produce about half of the oxygen that enters Earth's atmosphere every day. It has a huge influence on the carbon cycle.

These findings give scientists a new understanding of the carbon cycle and how exactly carbon dioxide enters our atmosphere. These viruses, in essence, can drastically affect how much gas is released and could help pave the way to learning more about how to limit greenhouse gases.