All living organisms use a chain of chemical reactions to transform nutrients into a form that can be used by their cells to generate energy. In the process, electrons spurring from the dissection of complex molecules into simpler ones must be transferred to some final oxidizing agent, which is usually oxygen. Exotic microorganisms can use other substances as electron acceptors, including sulphate or metal ions.

This was true for the bacteria living under the Taylor Glacier. Mikucki and her team believe iron was the final destination of their electron transport chain, and they use sulphate as catalyst. Not only has this mechanism never encountered before, but also scientists doubted it was even possible, because iron and sulphate would just react together to make the inert mineral iron pyrite. The study published in Science magazine suggests the subglacial microbes found a way around this.

"I think this is a fantastic study," said Alan Kaufman, a biogeochemist at the University of Maryland, College Park. It presents "a spectacular new environment that we can explore to understand life on the edge."

The discovery may explain how life on the planet survived during the so-called ‘Snowball Earth’ period, a hypothetical age some 600 to 800 million years ago when glaciers covered most of its surface. It may also suggest that life can be encountered in extra-terrestrial environments like under the surface of Mars or on Jupiter's icy moon Europa.