Australian researchers answer the microbe mystery in world first research

It is believed that sunlight is the source of life for the tiniest organisms in the ocean, but a discovery from Australian researchers has uncovered how deep sea microbes survive in the dark

In the depths of the ocean, microbes have mysteriously thrived without the help of light. Now the secret to their survival has been uncovered by Australian scientists in a world-first discovery.

Unlike their counterparts that float in shallow waters, basking in sunlight and getting energy through photosynthesis, deep sea microbes have had to leverage power in a more creative way, through a process called chemosynthesis.

Collecting samples for the deep sea microbe study.

Lead researchers at Monash University Rachael Lappan and Chris Greening say trillions of microbes in the deepest part of the sea have used two common gases - hydrogen and carbon monoxide - in lieu of light to survive.

The deepest samples the study looked at were 1000m deep, obtained from Tara Oceans Data, a global public dataset.

Microbes from tropics to the poles exist thanks to this alternative energy source, with the five-year expedition also collecting samples from temperate, tropical and sub-Antarctic waters.

“In the ocean, we measured how much hydrogen and carbon monoxide was in the water to confirm that it is there and available as an energy source. When we brought the seawater back to the lab, one of the things we did was we would measure the concentration of hydrogen and carbon monoxide overtime in the seawater,” Dr Lappan said.

“We could then watch how quickly the live microbial communities in all the life microbes in the seawater would consume those gases over time,”

While the five-year expedition into the lives of deep sea microbes has delivered long-awaited answers about marine life, Dr Lappan said there is still more to learn.

“It all comes together slowly but when we started writing the paper, you’re kind of surprised and impressed by your own work… You think this is something really cool which you’re not thinking about when you’re in the depths of analysis the data at the time,”

“There’s still a lot yet to learn about the deep ocean and life out there and how it survives without sunlight.”