Scientists to Model Life on Saturn’s Moon in the Lab

(Illustration: Kelvinsong, from Wikimedia Commons)

“Life on Titan most likely would have inhabited the ocean, where organisms would have given off metabolic waste products and potentially even left fragments,” said D’Arcy Meyer-Dombard, associate professor of earth and environmental sciences at UIC and co-principal investigator on the grant. “Some of these biosignatures would eventually be transported to the ice sheet above, and possibly through the ice sheet back to the surface and possibly the atmosphere by geological processes, but we need to know what signatures to look for.”

The biosignatures would be detected using instruments that could be sent to orbit or land on the surface of Titan in the future.

Meyer-Dombard and Kenig will re-create conditions found in Titan’s ocean in the laboratory, grow microorganisms under these conditions (high pressure, extreme cold), and look for characteristic chemical and biological signatures that could help other researchers detect and identify life, or traces of extinct life forms on Titan and beyond.

To mimic the deep underwater zone where life is believed to have most likely existed if it did, Meyer-Dombard and Kenig will re-create the conditions of Titan’s ocean in the laboratory. To do so they must construct and maintain a growth chamber at approximately -15 C at extremely high pressure. Pressures on Titan are two to eight times higher than previously explored life-supporting environments on Earth. They will use different kinds of microorganisms such as strains of the bacteria Moritella or Archaea, Pyrococcus as model Titan life forms to grow in the chamber, but these organisms will have to be trained to grow at very high pressure. They will also use organisms found in environments on Earth that are “analog” environments to those on Titan.

Because of the intense high pressure and extremely low temperatures, the microorganisms will grow and divide very slowly. The researchers anticipate leaving the microorganisms in the chamber for several years, occasionally — and very carefully — siphoning off a small sample of cells to examine.

“Because of the high pressure, we need to be very careful with this chamber, especially when we are going in to collect samples,” Kenig said.

Kenig and Meyer-Dombard have a few ideas for the design of the growth chamber, which they estimate will be about the size of a ping-pong ball. These kinds of experiments have never been attempted before.

Kenig and Meyer-Dombard believe that the microorganisms they grow in their chamber will exhibit alterations in gene expression as well as membrane morphology and composition.

“The high pressure could cause changes in the cell membrane that enable it to remain fluid and flexible under such high pressure — specifically, the lipids in the membrane could become shortened. If we know what these high-pressure induced changes look like, we can look for them in samples that may be collected one day on Titan or on other similar moons or planets,” Kenig said.

Contacts and sources:
Sharon ParmetUniversity of Illinois at Chicago