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Viruses make zombies of deep sea vent bacteria

Two "black smokers" vent super-heated, mineral-rich water in the Lau Basin in the western Pacific Oc

Water samples collected by an remote submarine revealed how viruses hijack deep-sea bacteria at hydrothermal vents (Source: MARUM, University of Bremen and NOAA-Pacific Marine Environmental Laboratory)

Zombie bugs Viruses hijack bacteria that feed on sulphur-spewing vents on the ocean's floor and then reprogram the bacteria's DNA, a new study finds, essentially brainwashing the bacteria to devour more of the chemicals erupting from the vents.

The bacteria then burn up their stored sulphur reserves faster. These overeating zombie bacteria create excess energy that the viruses use to reproduce, until the bacteria burst and release a fresh wave of virus particles.

Microbiologists knew that surface-dwelling viruses could take over bacteria that draw their energy from sunlight.

However, this new study, published in the journal Science, marks the first observation of that process in ecosystems thriving on the nutrient-rich, scalding hot water of deep ocean vents.

"Viruses play a cardinal role in biogeochemical processes in the ocean's shallow and mid-to-deeper waters," says 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."

Ironically for the bacteria, known as SUP05, the viruses seem to use a version of the bacteria's own genetic code to hijack the microorganisms. At some time in the evolutionary history of SUP05 and its viral attacker, there may have been an exchange of genes between the two, sugges the study's authors.

"We suggest that the viruses serve as a reservoir of genetic diversity that helps shape bacterial evolution," says study co-author University of Michigan marine microbiologist Gregory J Dick.

"There seems to have been an exchange of genes, which implicates the viruses as an agent of evolution. That's interesting from an evolutionary biology standpoint."

Tags: biology, microbiology, weird-and-wonderful