New research more than a mile beneath the ocean's surface has revealed a dynamic struggle between viruses and bacteria that scientists can trace to beginnings of life on Earth.

Amid the clouds of mineral-rich water billow from hydrothermal vents on the light-deprived ocean floor, viruses infect bacterial cells to access miniscule globules of sulfur stored inside the organisms.

In reaction to the viral infection, the bacteria end up burning more their sulfur reserves, which the viruses in turn use to replicate -- often so much so that individual bacteria cells fill to the point of blowing up.

"Our findings suggest that viruses in the dark oceans indirectly access vast energy sources in the form of elemental sulfur," University of Michigan marine microbiologist and oceanographer Gregory J. Dick said in a news release.

His research team collected DNA from deep-sea microbes found in seawater from hydrothermal vent sites in the western Pacific Ocean and Gulf of California and identified viruses as key players in the thriving ecosystems -- which include creatures like 6-foot tube worms, giant clams, mussels and shrimp -- clustered around deep-sea vents.

A paper summarizing the findings was published online May 1 in the journal Science.

Dick's research also suggests that viruses serve as evolutionary agents in chemosynthetic systems by swapping genes with the bacteria.

"We suggest that the viruses serve as a reservoir of genetic diversity that helps shape bacterial evolution," he said.

Similar microbial exchanges have been observed in shallow ocean waters between photosynthetic bacteria and viruses that prey on them, however the UM research marks the first time such an interplay has been seen in a chemosynthetic system where microbes rely solely on inorganic compounds for nutrients.

The new discovery will help researchers understand how marine biogeochemical cycles, including the sulfur cycle, will respond to global environmental changes like the ongoing expansion of dead zones. Certain bacteria, believed to generate the greenhouse gas nitrous oxide, will likely expand their range as oxygen-starved zones continue to grow in the oceans.

"Viruses play a cardinal role in biogeochemical processes in the ocean's shallow and mid-to-deeper waters," said David Garrison, program director in the National Science Foundation's Division of Ocean Sciences, which funded the research. "This study suggests that viruses may have a similar importance in deep-sea thermal vent environments."