What first interested you in this kind of research, and did you think it would ever lead you to "worms from hell"?
When our team first discovered "Bacillus infernus" in a deep drill hole in Virginia in 1998 I immediately became enthralled because it meant that life could exist beneath the surface of Mars. But I always thought of life in terms of single-cell organisms, bacteria. But I never ever would have dreamt that we would land a big one like H. mephisto.
How big are they?
not that big to you - only 1/2 mm, but you can them worms squirming with you naked eye. for me that is enormous.
How many people worked on this research/dig? How long did it take you?
it was not so much a dig as an underground safari. We went into the deep Au mines of South Africa, the mines that were the inspiraton for Tolkien's mines of Moria. down in the tunnels you can access high pressure fissures of water by opening a valve. that water contains microbes and the occasional worm issuing from the fractures behind the tunnel walls. the water is hot and steamy, stinks of rotten eggs, and full of methane gas. quite enjoyable.
Given that nematodes have never been seen this deep before, and that many were skeptical that they could even exist, these worms must have special adaptations that allow them to live in this environment. What special adaptations do these worms have and how is this reflected at a genetic level?
That is an excellent question. in fact one of the most important mysteries that remains to be solved about deep life, or dark life as we sometimes call it. In the case of H. mephisto, it has a fairly high temperature tolerance, up to 43 degrees C. it also reproduces asexually, without the need of a male. this make sense I imagine as it is less likely to find a suitable male 1 mile underground in tiny fissures unless they are capable of emitting some potent pheromones. eating bacteria is an essential since that would be the most abundant organism down there. But at the genetic level is the real question. Which of its genes are critical to life in the subsurface and from whence did it obtain them? those are questions remaining to be solved by a good molecular biologist.
It is my understanding that this Nematode was found a mile deep in a South African mine. Is there any chance a miner could have accidentally brought one of these worms down to that level from the surface/near surface on say his/her shoe?
That is correct. When hunting for subsurface life you have to take care that you are not detecting your own foot prints. Or from the air that is used to ventilate the mines to keep the temperature down to survivable levels and remove the noxious gas. So what we did was collect soil samples from the tunnel close to the borehole where H. mephisto was found. We use the same procedures on the soil that was used on the borehole water. No H. mephisto. In fact no nematode whatsoever. In fact in all the samples from the mine where H. mephisto was found, no nematodes. We even filtered 40,000 liters of mining water that is used in the mines to cool the air and drill the boreholes. No nematodes. This is a good thing, because H. mephisto's surface brethren are not very nice at all. The mining water, because it is refrigerated, is often used as drinking water by the miners, so the mine treats is with bleach and hydrogen peroxide to make sure that the miners do not get sick. Nematodes cannot handle that kind of treatment. even the bacteria are shattered by it. The mine does an excellent job in terms of mine safety and the good thing for us is that this keeps the contamination down.
Now when we collect the water from the borehole, that water goes straight from the pipe through our sterile filters without every seeing the air.
And that how you hunt for subsurface life.
What's the next step in your research on this?
We hope to complete the genome sequence on H. mephisto and compare it so some closely related specimens that we can find from the surface near the mines. This is challenging but might give us a better picture of both the origin of H. mephisto and whether its genome has adapted or it has evolved in the subsurface.
We are also interested in what H. mephisto or other nematodes likes to eat. Does it have any preferences?
We also need to better understand where nematodes appear in the subsurface and how prevalent they are.
Finally, we need to look for nematodes beneath the sea floor near deep sea vents. They exist on the seafloor, so they should exist beneath the sea floor.
so many more underground safaris ahead.
Are organisms such as nematodes used in the pharamceutical R&D industry?
Fascinating question. A quick search on the internet reveals that they are. A source of an anticoagulant in one case. Attempts to find interesting drugs from subsurface microorganisms is not a new thing and has not led to many significant discoveries, but perhaps nematodes will be a different story.
Have you been able to determine the number of species in the ecosystem which you have found? Is there only one bacteria and only one nematode?
Yes we have. In the fissures where you find H. mephisto, many more species of bacteria are present, but only one species of nematode. In the deeper fissure where we found only one species of bacteria, D. audaxviator (bold traveller), the temperature was probably to hot for nematodes.