Viruses are not such villains after all. They may, in fact, be the reason we are alive.
 
A new study contends the fact that half the planet's oxygen is a by-product of bacteria suffering from viral infections.

"Instead of being viewed solely as evolutionary bad guys, causing diseases, viruses appear to be of central importance in the planetary process. In fact, they may be essential to our survival," said Nicholas Mann of University of Warwick and author of the study.

"The micro-organisms responsible for providing oxygen and locking away carbon dioxide are actually single celled bacteria called cyanobacteria," he added.

These organisms, which are instrumental in making our planet habitable, are infected by a range of different types of viruses, which causes them to produce oxygen.

These findings were presented on Wednesday at the Society for General Microbiology's 162nd meeting in Edinburgh.

These bacteria are responsible for removing carbon dioxide and locking it away in their bodies, which sink to the bottom of the ocean when they die, removing it forever and limiting global warming.

The researchers, using molecular techniques, have identified the genetic codes of these viruses and how some of them are responsible for providing the genetic material that codes for key components of photosynthesis machinery.

Viruses may also help to spread useful genes for photosynthesis from one strain of bacteria to another.