A new study published in the Journal of the International Society for Microbial Ecology sheds more light on unusual ‘curtains’ of biological material known as Nullarbor cave slimes.

This strange, slimy microbial community lives in water-filled underground caves beneath the Nullarbor Plain, a desert region in Australia. “Earlier studies on the community suggested that there was an unusual chemistry going on in the caves, but we didn’t know how the microbes were making a living in the cave environment,” said senior author Prof Ian Paulsen of Macquarie University.

In order to find this ‘missing link,’ Prof Paulsen and colleagues made use of a range of new technologies, such next-generation sequencing of environmental DNA and scanning electron microscopy to take an in-depth look at the composition of slime community in a cave called Weebubbie. This approach detected a dominant group of organisms in the cave slimes, known as the Thaumarchaeota. This community of microbes thrives in the total dark, independent of photosynthesis.

It is thought that the periodic inundations of the Nullarbor caves by the sea occurred a number of times in the geological past and so researchers suggest that the Weebubbie Thaumarchaeota may have a marine origin.

“We know that the Nullarbor Plain’s karst system arose from the sea in the Middle Miocene period and so this may be a clue as to where the Weebubbie Thaumarchaeota came from,” Prof Paulsen said.

“This analysis shows that the organisms make up the Weebubbie cave slime community make their living in a very unusual way – by oxidizing ammonia in the salty cave water – and are completely independent of sunlight and ecosystems on the surface.”

“It just goes to show that life in the dark recesses of the planet comes in many strange forms, many of which are still unknown,” Prof Paulsen concluded.

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Bibliographic information: Sasha G Tetu et al. Life in the dark: metagenomic evidence that a microbial slime community is driven by inorganic nitrogen metabolism. The ISME Journal, published online February 21, 2013; doi: 10.1038/ismej.2013.14