Extreme Life as a Geological Force

The search for traces of ancient life in Martian meteorites is getting a major boost from Canadian geologists studying hot springs.

“I could show you many, many pictures of bacteria from modern hot springs that look identical to the object from a Martian meteorite that some think is a microbe,” says University of Alberta professor Dr. Brian Jones, referring to the famous ALH84001 meteorite. In 1996, a team of NASA-sponsored scientists announced they’d found what looked like a 4.5 billion-year-old fossilized Martian microbe in the meteorite.

“But is it?” says Dr. Jones, who during the past decade has studied hot springs in Canada, Kenya, Chile, and New Zealand. “We know from looking at the modern hot spring minerals that not everything that looks like a microbe is one.”

Once thought to be lifeless steaming cauldrons, during the past several decades hot springs have received a biological make-over. Researchers have discovered a menagerie of life forms – dubbed extremophiles – thriving in scalding-hot water as acidic as cola and laced with foul-smelling hydrogen sulphide gas.

Dr. Jones’ work focuses on how these organisms contribute to the formation of intricate, solid crystals from the hot mineral-rich solutions. It’s an understanding that may tell us whether the features in meteorites are microbes, or microbe-formed.

In a just-published study of Jasper National Park’s Miette hot springs – a favourite with tourists – Dr. Jones, and graduate student Sandy Bonny, reveal that several of the dozen or more single-celled creatures in the hot spring act as foundations for the development of mineral crystals.

“These microbes are playing a key role in the precipitation of minerals such as silica and calcite, and are evidently important in geologic processes in hot springs,” says Dr. Jones. The research also suggests that minerals formed by photosynthesizing microbes have a distinctive chemical signature. If this result is validated, scientists may be able to tell whether a mineral was formed with the help of a microbe or solely by geologic processes.

In a similar study of the Waikite Geyser on New Zealand’s North Island, Dr. Jones and University of Saskatchewan research partner Dr. Robin Renaut linked microbes to the formation of elaborate, millimetre-sized, shrub-like silica deposits.

Both NSERC-funded studies are reported in a special issue of the Canadian Journal of Earth Sciences devoted to hot spring processes, including the role of microbes.

While Dr. Jones avoids emphasizing the extra-terrestrial links to his work for fear of sensationalizing it, his research has helped create a mini-boom in the new discipline of geomicrobiology.

And, his hot springs research is pointing out that when it comes to looking for extra-terrestrial life, and the earliest life on Earth, it’s necessary to look even closer than we’ve done in the past. Using advances in electron scanning microscope techniques, Dr. Jones and others have found the remains of nanobacteria, infinitesimally small creatures measured in billionths of a metre.

“In many hot springs, the size of these organisms is smaller than we ever imagined it could be,” says Dr. Jones.

Contact:

Dr. Brian Jones
Tel.: (780) 492-5249
E-mail: brian.jones@ualberta.ca

The current special hot springs issue of the Canadian Journal of Earth Sciences is freely available online at
http://pubs.nrc-cnrc.gc.ca/cgi-bin/rp/rp2_vols_e?cjes.