Welcome back. Now we're going to look at a few more types of extremophiles, and we'll see that life thrives in incredible reign of environments. It can thrive, without oxygen. You know, with anaerobes. We really talked about live thriving under extreme high temperatures, but it can also thrive under extreme low temperatures. In low pH, or high pH. In very salty environments in environments under very high pressure, potentially under low pressure. Very dry environments, where there's no rain. In other environments with scarce nutrients. Actually, deep within rocks, you'll find endoliths. And finally we'll turn to life forms that not only could survive radiation, but actually thrive in a radiation rich environment. So lets start by talking about some of the things that survive in extreme cold. These Psychrophiles. And these think lifeforms are capable of growing and reproducing in water, very salty water, down to minus 15 degrees centigrade. Now, water freezes, fresh water freezes at 0 degrees centigrade, but if you add salt to water. That water can stay liquid, at lower temperatures. And very salty water will stay in the liquid form, down to these very low temperatures. Now, life cannot survive or at least grow, frozen. For life to survive it actually has to be in liquid water. But liquid water can get quite cold. And there's lots of different lifeforms that actually survive under these very cold conditions, and one example is fungi, that grow under alpine snowfields. We see this. On a purplish colored snow, and here's a surface all covered with the snow. And this is snow algae and these snow algae has special forms of their cell membrane. Most cell membranes would basically freeze and crack, under these very low temperatures. But snow algae have a special membrane, a surface, who's chemistry is designed to survive these extreme cold. One of the interesting things to think about fungi, is we think of them as primitive. But if you go back to that tree of life. And look at how different lifeforms are related to each other, in terms of the genetic makeup or their ribosomes. We are actually much more closely related to fungi, than fungi are to say, bacteria or archaea. So this stuff in some ways, is a close relative. Here's another one of my favorite life forms, Snotties. These delightfully named creatures, live on the ceilings and walls of caves, where there's a lot of hydrogen sulfide, what they do is they get energy by converting that hydrogen sulfide to sulfuric acid, that sulfuric acid then eats away at the cave walls. So they then expose more sulphur that they can use. So there's this nice process they have, that by eating into the cave walls they expose more food. And the caves grow and grow. What you see here, are phlegm balls. These are gooey mats and we've talked about mats before. Made up of these secretions of cave slime from the snotties. And, I've never been in a cave filled with snotties, but I must admit I'm not that excited about the idea of crawling through lots and lots of this goop. Let's go to a completely different environment, the Atacama desert, and here's a picture of me several years ago; walking across the Atacama desert. A place that's famous for many things, among them these giant, drawings done by pre-Columbian people, who lived there, used them to to mark out their trading routes, and mark their trails through this desert. And the Atacama is an amazing place I've been there because it's a very good place to do astronomy. We operate many large telescopes there. The largest international collaboration on the ground for telescopes. It's called ALMA, the Atacama Large Millimeter Array up in San Pedro de Atacama. We have many large optical telescopes operated both by large consortium's of European. And North and South American nations, because Chile is such a good place to observe. Because it is so dry and the sky is so clear. is an incredible place. I've been to restaurants there, that don't have rules. And you ask the waitress, in your best Spanish. Does it ever rain here? And she tells you no. You asked them have you ever seen rain? And then she told me yes, once she went to her cousin's wedding in Santiago, and it rained when she was there. There are places in the Atacama that have not had rain in recorded history. And on average you're looking at places that have about a millimeter of rain per year. Yet, is a place in some ways, filled with life. There are salt lakes. And in which lifeforms thrive off of the minerals in the salt lakes or survive and thrive off of volcanic gases. A lot of those lifeforms are halophilic, they love salt, here is Owens Lake in California. This lake is mostly evaporated, you took the lake and like a place like the Dead Sea, there's a lot of evaporation, the lake, becomes more and more concentrated, the salinity level in this lake is ten times that of the ocean. Yet, you can see it's covered. With life, there are these halophilic bacterial mats, that thrive there. Here's another very different environment, where we see life thriving. Undersea vents, these undersea vents and many of them lie you know, at the boundaries where the continents are coming apart. The sea floor is splitting, there is up-welling of volcanic magma. The magma interacts, geothermally heats the water, and you have these vents where hot high pressure steam comes up. Rich in, lots of chemicals. Sulphur, methane, and so on. And they're life forms, that thrive in this. Their energy source is not the sun. It's not photos, it's a life cycle, or an ecosystem, that is not based on photosynthesis. But rather on chemosynthesis. On taking things like the methane, and the hydrogen sulfide, and converting them, into energy. And there are very rich ecosystems, that thrive there. It's not just tiny, single cell bacteria or archaea. You'll find things like these giant tube worms, and here's a huge colony of tube worms. And these tube worms can grow to over seven feet long. Thriving off the environment, around these undersea vents. These undersea vents are very interesting places to think about. Both for the origin of life, and for astrobiology, right? These, to have an undersea vent, what do you need? You need water, you need volcanic activity, we know the early Earth was very active volcanically, it's also deep under water. It's a place that's relatively protected, from the heavy bombardment that's taking place in the early history of the Earth. It's not like being on the Earth's, parts of the Earth's surface, we're you're exposed to that bombardment. So this looks like a place where if life originated, it could thrive in the early Earth. It's also a kind of environment, that we believe exists, on many of the, moons of the Jovian planets. Right, we think that, we know, we observe there's volcanic activity there. We believe there's water on places like Europa. So it's intriguing to think. Of life, originating. Perhaps, with a separate bio-genesis, in a place like Europa. So Pyrococcus Furiosus, is one of the denizens of these undersea vents. It's a small archaea. It's about a micron or so, across. Has a number of interesting features. It can thrive in temperatures up to 100 degrees centigrade. It can reproduce in just 37 minutes, is a very rapid life cycle. It makes use of tungsten a pretty rare element. As a basic part of it's biochemistry uses a Tungsten base enzyme. And it has this very interesting process of PFU polymer rays that can proofread and repair it's DNA damage. DNA researchers have made use of a number of the special byproducts of these extremophiles things like tag pop pomarays which has a billion dollar industry in molecular biology was originally extracted from an extremeophyle in Yellowstone Park. And this PFU polymer race. Is another very useful bi-product of studying these archaea. Another fascinating and extreme environment very evocative of some of the moons around other planets, is Lake Vostok. So Lake Vostok is a sub-glacial lake. In Antarctica, so here's Antarctica the South Pole, one of the coldest places in the planet, it's right near Lake Vostok. This lake is covered with four kilometers of ice, there's a Russian experiment that has been drilling down. Into the ice. Extracting water from the ice, and this lake here, the largest of all the sub glacial lakes. It's about 400 known in Antarctica. This sub glacial lake has been isolated from the rest of the planet. For about 20 million years. It's been covered with ice and there's been no way for life to get in or out. So people are very eager to find out, is anything alive down there? We suspect that there may be some geothermal activity below the lake. That could provide a source of energy and nutrients. So it's possible that life could survive there. So far the biological evidence has been intriguing. There are samples that show previously unidentified bacteria, it seems to host life, but at the moment this is still an area of scientific controversy. Because there's some issues about whether or not the the samples that have come from this lake, had been contaminated by the core itself and by the process of coring bringing material down. And this is something, an area where there's data coming in just now. And we're learning about the properties of Lake Vostok, learning about this extreme environment with a very interesting analog for extra terrestrial systems. Another fascinating extremophyle, class of extremophiles are Endoliths. These are things like lichen, that live inside rocks, so there often grow very slowly, they extract their energy from the chemistry of the rock. There's lichen surviving inside antarctic sandstone. Sandstone's are porous, so things like water can get in. And in fact we find these endoliths not just in surface rocks, but deep down in the deep biosphere. Several kilometers below the Earth's surface. Life seems to thrive. At the end of this lecture, we'll talk with one of my colleagues Telesonstad, who goes deep down in to mines in South Africa. Deep down into gold mines, gold mines are one of the places people are willing to go very deep to get stuff. They don't really dig that deeply for studying extremophiles. Bacillus takes advantage of that environment and those minds and has been studying some really fascinating endoliths. And we'll hear more about them, in a few minutes. Another in my list of fascinating extremophiles. Is Bacillus Infernus. This is a, a thermophilic bacteria. Another form that's, strictly anaerobic. Does not use any oxygen. Does not use any energy forces from the sun. It could survive very deep underground, depths of a couple miles, about three kilometers. And when you see life form and it and, survive and thrive in environments like this, it's very easy to imagine, taking this Bacillus Infernus, and launching it inside a rock into space. And having it thrive there. It doesn't really make use of any of the properties of the Earth's surface. So, we've talked about a bunch of different properties of the extremophiles, and before we go on I would like you to answer a pair of questions about these extremophiles. And then we'll come back and talk some more.
