Livin' Life to the Extremophile: Chemosynthesis (Part 3)

Greetings from Romania friend! Last time we talked about the distant planet Jupiter and her tantalizing moons that may or may not contain life. For now though, let’s put Europa, Io, Titan, and Enceledus on the back burner. Let’s talk about the creatures we recently discovered right here on Earth that live in places we originally never even thought to look for life.

In the first part we discussed Vostok Station and the skeptical past surrounding the historical outpost. Now we’re going to actually talk about the kind of creatures we can expect to find down there, and why avoiding surface contamination is absolutely essential in uncovering this fascinating alien world beneath our feet. We begin our journey in Romania with the discovery of an ancient cave by biologist Cristian Lascu.

From there we will be heading in the complete opposite direction. Instead of the bizarre albino insects of Molive cave we’ll be visiting the bizarre denizens of the deep around the vents of the Mariana Trench. Geothermal activity in this region plays a huge role in the evolution of sustainable life.

But it doesn’t just stop there. From pools of sulfuric acid in Yellowstone National Park, to strange non-pigmented air breathing detoxifying fish in Mexico, there is one thing that is incredibly evident in this peculiar little world of ours.

Life will always find a way.

Movile Cave – Romania

Movile Cave, Romania. A veritable hellscape to human beings. The air is thick with hydrogen sulfide and very little oxygen. In fact, the deeper you travel into its depths, the higher the likelihood you’ll need a respirator to keep breathing normally. That isn’t a problem for intrepid spelunker and biologist Cristian Lascu, who braved the harsh unforgiving environment to explore the world this cave system has kept hidden from us for hundreds of millions of years.

And what a find indeed! In what we would have ruled before as an uninhabitable climate he found life, and what’s more, the farther in he went, the more life he discovered, and the more diverse it would become. Centipedes, spiders, and other insects were present. What’s more is unlike other typical cave dwellers that tended to remain dormant and lethargic so as to conserve energy, these creatures were fast and highly active, as if there was no shortage of energy. But that was impossible, the cave was completely sealed off for a long, long time from outside intervention. What were these strange creatures using for energy in place of sunlight?

The answer lay in the water. Lascu dove into the underwater passageways and found that in a passageway that opened up to an air bubble there was a scum accumulated across the surface of the water. This scum, or biofilm as its more commonly referred to as, seemed to be the centerpiece for this self-contained ecosystem.

By a process called chemosynthesis these single-celled organisms were consuming the toxic chemicals in the water and converting them into energy. Their food chain made up the food chain for the insects food chain. Huh, funny how that whole circle of life thing works ain’t it? J. Chemosynthesis works a lot like photosynthesis does, except in place of sunlight as the catalyst a chemical component is used, in this case, hydrogen sulfate.

Marianas Trench – Pacific Ocean

That beautiful and expensive deep sea submarine is ALVIN and he’s more than just your average DSV. If it wasn’t for ALVIN the door to astrobiology wouldn’t have opened as quickly as it did. In 1977, scientists operating this little fellow around the Mariana Islands in between Japan and Australia found something that took their breath away.

Life.

Yes, the Mariana Trench, one of the coldest, highest pressured, darkest, and deepest places on our planet contains life. How incredible of a find indeed, and it wasn’t just of the microbial kind. Fish had adapted to the pressures, huge tube worms darted out at prey from the ocean floor, mussels lay scattered beneath ALVINs body. But what made this possible? Clearly these fish weren’t surviving by Chemosynthesis? That seemed highly unlikely.

Then it dawned on them. The geothermal vents along the ocean floor. The other incredible discovery that ALVIN had made. It had long been theorized that these openings from the Earth’s core existed, spewing super heated gases into the water as the tectonic plates shifted underneath. Microbes grew in mass along these vents, absorbing the super dense methane escaping the core. Methane, under normal circumstances is a gas, but as we learned on Titan, this isn’t always the case.

Even though the heat escaping these vents is enormously high, the water around them doesn’t boil. At these depths, the pressure is so high it raises the boiling point to unachievable levels. This phenomena is what keeps these microbes, the bottom of our seabed food chain, from burning up, and allows them the ability to reproduce and thrive in this hostile environment of the deep.

Yellowstone National Park – United States

            Astrobiology wasn’t the only new field brought about by these tiny single-celled marvels of life. In a whole other part of the world just ten years before, Dr. Thomas Brock was about to make a discovery that would turn the world of biology on its head. In The Great Fountain Region of Yellowstone National Park, was a whole new ecosystem just begging to be explored. One of the first to come out of this was Thermus aquaticus. A chemotroph (obtains its energy from chemical reactions rather than photosynthetic ones) that is also capable of sharing the photosynthesis of its cyanobacterial neighbors.

Not only had Dr. Brock just discover Hyperthermophiles, pioneered the future study of Extremophiles in general, but his discovery of T. aquaticus would later lead to breakthroughs in DNA fingerprinting analysis and the exciting new field of biotechnology!

But it wasn’t just this little Chemotroph that was new to the party. It turns out the bio mats found on the surfaces of such alkaline and sulfur rich water-sources was very similar to the mucous-like biofilm found on the water surface in Movile Cave. It was comprised of hundreds of microorganisms that had not only learned to adapt to their hostile environment, but actually had evolved to embrace it.

Cyanobacteria, Chemoorganotrophs, Green-sulfur bacteria, methanogens, gram-postive fermentative bacteria, these are some of the amazing new organisms they discovered that make up the complex ecological structure found here in Yellowstone. If life can take hold in a place like this, then perhaps life could thrive on Titan after all.

Cueva De Villa Luz – Mexico

The Villa Luz Cave. Found in Mexico this marvel has been featured on the BBC special “Planet Earth” in the past because it’s strange and diverse ecology. The air, much like Movile Cave’s, is rich is hydrogen sulfide, poisonous amounts actually. The difference is where Romania’s cave was sealed off, this one is open, by a main entrance and skylights throughout. However stalactites that hang from the ceiling are what help make the air unbearable, even with all the ventilation.

These unique stalactites, donned “snotties” by researchers give off a byproduct of the chemosynthesis. What is it you ask? Why sulfuric acid of course! This caustic substance hits the ground and as it melts through whatever it touches produces the noxious gases that fill the air, but this is just the start of the incredible and surprisingly well rounded ecosystem.

There is fish located here that has evolved within the dark depths. That’s not surprising since we discovered life living at the bottom of the Marianas Trench that we find a fish living in the dark. It also shouldn’t shock us that the “snotties” are constantly dropping acid bombs into the water effectively contaminating it with the stuff. But what should surprise us is how these fish are able to tolerate it.

Over time the Atlantic Mollies have developed a toxin screening system that allows them to breath and filter the water in the caves. This is a pretty remarkable development, but what’s even more incredible, they aren’t even the top of the food-chain in here! It turns out there’s an insect that preys on the mutated fish! Quite a turn of events if you ask me.

Another theory about their incredible immuno-system development comes from more recent scientists doing studies in the cave. The locals have long since incorporated the cave and the fish into their religious beliefs, using a poisonous mix of the Barbasco plant to kill them and bring them to the surface for easy harvest. Over time an immunity has begun to develop that these fish now seem to be passing on genetically to their offspring. Now that’s impressive.

Lake Vostok – Antarctica

I bet you  were wondering when I was going to get back to Lake Vostok. Well fret no more because here we are! Full circle! As of the time of this writing 3000+ species of organisms have been discovered living in the icy waters below. No new life has been found (contaminants only,sorry micro-geeks L) but the fact that life is down there at all is enough to make scientists everywhere go “hmm.”

It is truly incredible when you think about it. The water itself is assumed to be only 27 degrees F. This means that it’s below freezing. The only reason it stays in its liquid state they believe is because of geothermal heating underneath and the enormous pressures of the ice built up on top. The lake is essentially the creamy center of a geological Oreo.

Further analysis of the bacteria found in Lake Vostok will need to be undergone, but for now, it’s enough just to know that it’s down there. If bacteria can survive the inclimate conditions at the bottom of the ice shelf then it’s quite possible that it can survive the glacial temperatures likely to be found on Enceladus and Europa. Only time will tell.

In Conclusion

From “Nearing Zero” by the delightfully funny “Nick Kim”

         As I said earlier and as so hilariously somewhat discussed in the above comic, life will find a way to overcome and adapt every obstacle we or the world throws at it. The true test will be of whether or not we discover something new on Europa or on Titan. We’ve already seen some of the incredible ways they adapt, now let’s talk a second about how these things apply.

Europa is incredibly cold, but it has possible geothermic activity, the Marianas Trench is incredibly deep, dark, and cold. The pressures there would be unbearable for us but yet life has found a way to live harmoniously and in sync with the habitat. If we find similar features on Europa, it’s extremely possible that we find the signs of life that accompany those.

As for Titan, with its sulfurous and toxic surface it seems absurd for us to think of life being there, but then again they thought it was absurd for life to exist in places like Movile Cave and Ceuva De Villa Luz. We have methanogenic creatures right here on Earth and Titan is practically brimming over with liquid methane. It now seems even more improbably that life wouldn’t exist there considering.

Enceladus and Io may be dead ends, but we have found creatures thriving in the depths of volcanoes, and who knows. Perhaps there is a whole new kind of hyperthermophile out there that can survive even more severe conditions than the ones discussed in this article. Guess we won’t know till we get there, and I couldn’t be more excited to find out. J

-Ryan Sanders

For further reading on the places mentioned in this article and more on microbiology, you can follow any of the links below. Happy learning!

-       “Life In Hell” A great documentary on Hyperthermophiles and the main source for this article.

-       Various Collected Articles on Yellowstone and the Thermophiles that reside there.

-       Dr.Thomas Brock’s “Life at Extreme Temperatures” (I rank this up there with Dr. Gold’s “The Deep Hot Biosphere” Both excellent studies with lots of overlapping information)

-       “A Natural View of Microbial Biodiversity within Hot Spring Cyanobacterial Mat Communities” A Scientific journal discussing in part life in Yellowstone.

-       Scientific Journal on the ecology of Cueva de Villa Luz

-       News article about the locals and their religious ritual slowly evolving indigenous populace.

In the fourth and final installment of our spotlight on Extremophiles we’re going to talk about the processes of some of the creatures (and the creatures themselves) that live in the hostile environments described above. Some are strange, some are cute, some are terrifying, but every single one of them, from single-cellular to conscious and complex, is a unique window into the tenacity of life.