NASA image of vapor plumes on Enceladus

Weird deep-sea Earth bacteria could actually survive on Enceladus

Contributed by
Mar 11, 2018

We might not know if things are swimming in the unexplored seas of Enceladus yet, but it’s now seen as more likely than ever since an experiment just proved some bizarre Earth bacteria they could survive on Saturn’s frozen moon.

We already know there is hydrothermal activity bubbling under the ice of Enceladus. Cassini observed the plumes of water vapor shooting into space, and which were later found to contain molecular hydrogen and methane, which may mean life is thriving somewhere in those strange waters. Silica-rich dust particles indicated that those plumes are issuing from hot-water vents similar to those on the bottom of the ocean floor on Earth. Enter the terrestrial bacteria that may behave like (hypothetical) alien microbes.

“Methanogenic archaea are among the organisms that could potentially thrive under the predicted conditions on Enceladus,” said scientist Ruth-Sophie Taubner and colleagues in a study recently published in the journal Nature Communications. “Some of the methane detected in the plume of Enceladus might, in principle, be produced by methanogens.”

Methanogens are anaerobic bacteria that make their own energy by producing methane and release the gas as a by-product of cellular metabolism, which is why scientists think the methane in those vapor plumes may come from a living source. They are often found crawling around hydrothermal vents along with thick bacterial mats and tube worms that look like huge lipsticks. While we have no idea what kind of life-forms may be hiding in the depths of Enceladus, we may have an idea of what comes out of their innards.

This is the type of bacteria Taubner’s team chose to work with. They used three strains of methanothermococcus okinawensis, a high-pressure-tolerant methanogen that gorges on the molecules known to exist on Enceladus. M. okinawensis is known to thrive at temperatures similar to what you’d find around hydrothermal vents on Earth (about 212 degrees Fahrenheit) and what scientists think they would find on the Saturnian moon.

After conditions on Enceladus were simulated with the appropriate temperature, pressure and chemistry, one strain of the bacteria survived. This strain somehow stayed alive even after it was exposed to harsh chemicals found on Enceladus that can be growth inhibitors. The scientists believe that if these bacteria can survive on the closest thing to Enceladus possible on Earth, then the methane on Enceladus is probably given off by a similar alien microbe.

“Here we show that methanogens can produce methane under Enceladus-like conditions, said Taubner and her team, “and that the estimated molecular hydrogen production rates on this icy moon can potentially be high enough to support autotrophic, hydrogenotrophic methanogenic life.”

NASA is already considering a mission to explore ocean worlds such as Enceladus and Jovian moon Europa. Other space agencies also want to investigate. Even with Cassini gone, a new orbiter could continue what it started by analyzing samples from those plumes.

It could mean aliens—maybe not intelligent ones with starships and ray guns—but life-forms that spawned anywhere but Earth still count as aliens.

(via Universe Today)