Bacterial Structures May Help Search for Life On Other Planets

A bacterial structure could provide clues on life in another planet, a study found.

Existing studies about stromatolites, which are heaps of calcium-carbonate rocks that are formed through lime-producing cyanobacteria, are said to offer some fossil evidence of life on other planets, Mars in particular.

Erica Suosaari, a science fellow for Bush Heritage Australia, which is a non-profit conservation and land management organization, have studied the "life-giving" potential of stromatolites.

"Looking for evidence of life in the rocks is like finding a needle in the haystack," Suosaari told AstroBiology.

"If stromatolites have definitive bio-signatures - such as self-organized morphologies that are indicative of life processes - then it may be possible to look for that 'signature' in rocks on the surface of other planets and significantly reduce the size of that haystack."

Suossari is based at the 500,000-acre Hamelin Station Reserve in Western Australia, which houses the Hamelin Pool Marine Nature Reserve - one of the world's most diverse and abundant examples of marine stromatolites.

Modern and ancient stromatolites

Bacterial communities that created stromatolites are responsible for making Earth life-friendly. These cyanobacteria were among the first living organisms to generate energy from the Sun through photosynthesis and creating oxygen as a byproduct. As the planet evolves, cyanobacteria have changed the Earth's atmosphere from 1 percent oxygen to over 20 percent, AstroBiology reports.

Suosaari and her colleagues conducted a research on stromatolites or "living fossils" in Hamelin Pool, and a paper based on this research was published in the journal Scientific Reports.

In the study, Suosaari and her colleagues found that modern stromatolites have more similarities with ancient stromatolites than previously thought.

The researchers discovered that the microbial communities in Hamelin Pool produce a fine-grained limestone known as micrite (microcrystalline calcite), which is responsible for creating stromatolite structures that are similar to the ancient ones seen in the fossil record.

Hamelin Pool stromatolites are also dominated by a coccoid cyanobacterium that traces back 2 billion years to an ancient version of the microbe called Eoentophysalis.

The study suggests that stromatolites provide a "window" to ancient Earth, with microbes of the same ancient lineage living and creating oxygen for billions of years.

Microbial communities in Mars

While Suosaari's research focuses on stromatolites in a small region in Australia, she said that it is possible to export similar microbial communities to other places - other planets in particular.

Because stromatolite-building microbial communities produce oxygen, Suosaari said that they could also be exported to Mars - as well as to other planets in the solar system - to make it habitable for humans.