Microbe colony yields insight into how life survives

AN ancient colony of microbes thriving without oxygen, warmth or light beneath a rusty glacier has led scientists to re-evaluate what it takes for life to survive.

The bugs, believed to be descended from ocean-dwelling organisms, have evolved a unique ecosystem in a briny pool under 400 metres of ice. They have flourished there for at least 1.5 million years, transforming sulphur and iron compounds to fuel growth. Scientists believe they can shed light on survival of early life on Earth, or how it might exist on other planets.

Professor Ann Pearson, from Harvard University in Boston, US, said: “It’s a bit like finding a forest that nobody has seen for 1.5 million years. Intriguingly, the species living there are similar to contemporary organisms, and yet quite different, a result, no doubt, of having lived in such an inhospitable environment for so long.”

The microbes’ home is below the Taylor Glacier, a giant slab of ice in the McMurdo Dry Valleys of Antarctica. Scientists discovered the bugs in water samples taken from Blood Falls, where bright red minerals spill out of the glacier. It used to be thought red algae were responsible for the feature, but scientists learned the colour was due to rust.

The source of the “Falls” was found to be an iron-rich pool under the glacier.

Water samples revealed a complete lack of oxygen but high levels of sulphur, a geochemical signature of marine environments.

A report appears in the journal, Science.

Co-author Dr Jill Mikucki, Dartmouth College in Hanover, New Hampshire, US, said: “This briny pond is a unique sort of time capsule from a period in Earth’s history. I don’t know of any other environment quite like this on Earth.”