New life form may be a
BY TOM GOSLING, EDITOR, ASCENT TECHNOLOGY MAGAZINE
THE JURY is still out until the DNA evidence is presented, but the case for nanobes being living things is getting stronger by the month.
About ten times smaller than any free-living thing is supposed to be, these "nanoscopic" creatures are setting the scientific world abuzz. Their discovery may totally change our thinking about the origins of life, and has given new strength to the theory that the widely-publicised "micro-fossils" found by NASA in a Martian meteorite were evidence of primitive life forms.
Up till now, critics have argued they couldn't have been bacteria, on the grounds that there were no living examples of nano-sized cells on earth - but now, almost certainly, there are. Other theories - that nano-bacteria may be responsible for kidney stones and be involved in processes such as rusting and the greening of copper - are now also being taken more seriously, and the door is opening onto a whole new area of knowledge.
At the centre of the excitement is a team of scientists at the University of Queensland. The team's leader, Dr Philippa Uwins, is a geologist who discovered the nano-organisms in 1996 while using a scanning electron microscope to examine sandstone cores from an oil exploration drilling program. In what was supposed to be a routine consultancy job, she broke open a sandstone sample from 3-5km beneath the ocean floor off the north of Western Australia. She was looking for a filamentous clay mineral called illite, the presence of which can affect oil extraction, when she started seeing some other filaments.
"I thought 'these aren't minerals, this is not illite', and a colleague saw some of my photos and thought I had fungi contaminating the samples," she said. "I knew they couldn't be fungi because they were way too small, so I started finding out more about it and that's how I got into this whole area."
A further impetus came when she noticed that containers and equipment in the laboratory were being "colonised", and realised that whatever she had found was growing, becoming visible to the naked eye within two to three weeks.
"I started to notice furry patches on the copper mounts," Dr Ewins said. "In one case they formed the replica of a fingerprint on the surface of a Petri dish."
In unfunded research, mainly out of curiosity, Dr Uwins and her colleagues, Richard Webb and Anthony Taylor, performed numerous tests using state-of-the-art ultra high resolution scanning electron microscopy, transmission electron microscopy, X-ray spectroscopy and DNA staining. The tests showed the nanobes fulfilled the following criteria to qualify as life: -
Further, they tested a variety of plausible non-biological explanations for the nanobes, gradually discounting materials such as crystalline materials, carbonates, fullerenes, carbon nano-tubes and non-living polymers.
Since the publication of their paper "Novel nano-organisms from Australian sandstones" in November last year in the US journal American Mineralogy, Dr Uwins has given numerous presentations world-wide, and has had what she calls a "very positive reaction".
"I often end my talks with an invitation to all present to challenge our thesis if they can, but no-one has come up with a challenge," she said. "Even people working on 'biomorphs' - non- living things that look like they're of biological origin - have said they can't argue against our findings."
Dr Uwins and her team have now submitted another paper for publication, which provides further evidence for nanoscopic life. She says nanobes show a striking morphological similarity to fungi, only on a much reduced scale. As part of their current research the team is attempting to quantify the rate of growth of nanobe colonies. This research on molecular and structural analysis was funded by a small grant of $19,400 from the Australian Research Council (ARC). However a delay in further funding is holding back the vital DNA sequencing, which will show where the nanobes fit on the "tree of life", and could open the way for studying their metabolism and reproductive cycle.
"The ARC money for salaries ran out half way through the year and we are just waiting on some other funding proposals to come through so we can get going on that," Dr Uwins said.
Even though she believes there is no longer any question that they are living organisms, Dr Uwins will not - at least, not until DNA tests have been completed - use the word "nanobacteria". "We chose the word 'nanobes' because it parallels the word 'microbes' and is deliberately vague on whether these things can be classified as bacteria," she said. "It does denote that they are probably alive, and also that they are smaller than microscopic - nanoscopic, if you like."
Conventional wisdom has held that nothing smaller than 150 nanometres - 150 millionths of a metre - can survive independently as an autonomous life form, because that is the minimum size needed to contain the necessary genetic and other life support material. The nanobes discovered by Dr Uwins, however, were only 20-150nm in diameter - remarkable considering that the size of a single ribosome (site of protein synthesis) is roughly the same as the smallest nanobes. Equally as amazing, the nanobes most likely came from a sandstone rock sample retrieved from 3-5km below the ocean bed, where the pressure is around 2,000 atmospheres and the temperature ranges from 115-170°C.
"They are very tough structures," said Dr Uwins. "Usually, if you're going to process a biological specimen for a scanning electron microscope, you put it through fixation and dehydration to maintain its structure, but the nanobes will go in and out of microscopes and withstand the vacuum and the electron beam and the X-rays. "This is where the debate comes in over the Martian mineralised bacteria, because it suggests they can withstand space travel."
critic of the research has pointed out that nanobes could
be the degraded remains of organic matter
from oil. "That is a fair comment and
we will have to do a follow-up project," commented Dr
Uwins. "The samples were just
routine consulting samples, and we weren't looking
to find rocks with nano-organisms.
"The anecdotal evidence is that they probably did come from the sandstone, but the question as to where else they could come from is a good one - maybe they're more common than we think."
First Published in ASCENT TECHNOLOGY
MAGAZINE (Nov 99).