Photo/IllutrationThis thermophilic, hydrogen-oxidizing and sulfur-reducing bacterium was found in the deep seas of Okinawa. (Provided by the Japan Agency for Marine-Earth Science and Technology)

A bacterium species that uses multiple methods to survive in the deep seas of Okinawa Prefecture could provide clues on how life was formed on Earth, Japanese researchers said.

The scientists from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and other institutions discovered the new and fairly primitive species of thermophilic, hydrogen-oxidizing and sulfur-reducing bacteria, in 2003.

The bacteria was found in seabed mud near a hydrothermal vent about 1,370 meters deep off Yonagunijima island, Okinawa Prefecture. The bacteria measure about 1-2 micrometers in length.

The team’s study found that the bacteria use hydrogen as an energy source to produce amino acids, which are essential for life activity, and other nutrients from available organic matter.

When no organic substances are available, the bacteria can still synthesize organic matter and other products from carbon dioxide, albeit at a lower efficiency, the study showed.

A number of theories have been put forward on the origins of life on Earth.

One hypothesis says life originated where organic matter, a source of nutrition, was abundantly available. But that does not explain how early organisms could secure enough organic substances to survive when they had used up all the organic matter around them.

Another theory argues that early life forms synthesized nutrition on their own by using energy obtained from their surroundings. But this theory cannot account for how they could continue producing the necessary amounts of nutrition.

“Organisms from the early stages of life on Earth were perhaps using both mechanisms flexibly, like the bacterium species we have found is doing,” said Takuro Nunoura of JAMSTEC, a member of the research team.

The research results were published online Feb. 2 in Science, a U.S. magazine.