Astronomy 101: Looking To The Stars For Extremophile Examples!

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Sup everybody, welcome to astronomy. I’m Timmy, the tardigrade but you can call me Tim, Timbo, or whatever floats your boat. I know this is supposed to be a morning class, but I'm more of an afternoon kinda dude, so we'll have it later in the day.

We were waiting the whole time.

Woops, sorry dude but there was a piece of moss that had the perfect spot for my head. I’ve been teaching here and there for several years before coming to the Society of Symbionts. Some might know that I am also the swim coach and I’m like the champion of tarti paddle.

So, what are we talking about today?

Uh you don’t know your own material? The syllabus says something about space and extremophiles?

Right, right. Well, we're linked to everything on Earth and our ancestors gave rise to multicellular organisms, I’m sure you’ve already learned about all that stuff in Professor Xi’s class. However, we may not be limited to this planet, we may be catching the cosmic waves.

What?

Space man talking about living in that big void. Giants are starting to catch this vibe and started a relatively new field called astrobiology. This field aims to answer the biggest question out there: is Earth the only planet with life? There have been those that have been listening for years for signals coming from intelligent life with no success; there are even 4000 planets in our galaxy and still they have not found any existence of life as we know it out there. But the giants are looking too big; they need to focus on the little things in life, like us. See, outer space can be very gnarly; the temp can go from extremely cold to extremely hot, it can be very dry, and there is a lot of radiation out there.

So could extremophiles be able to survive these places?

Right on; that is what astrobiologists believe. Now, there are like two main types of extremophiles: generalist and specialist. This refers to the microbe ability to chill in either one extreme condition (a specialist) or multiple (a generalist). I am a generalist and have partied, relaxed, and slept in extreme environments. Extremophiles give astrobiologists great insight into how anything can survive in these harsh environments both on our planet and beyond.

One particular dudette that is used as an important model in astrobiology is Haloarchaea. These microbes produce blooms of vibrant colors including red, orange, and purple. These colorful blooms have often been seen from airplanes and on occasion, they can be seen from space!

Haloarchaea can hang their head in a variety of extreme conditions including:

Salinity (salt)

Temperature (both hot and cold)

No oxygen

Radiation (UV & ionizing)

Low pressure

Ph (both acidic and alkaline)

Man, there are a lot of extreme environments out there.

Correctomundo little one, many of you may not have traveled to any of these locations, but don't worry we will bum our way to them eventually. They do exist on earth such as the deep sea or Antarctica. Although not exact, these inhospitable conditions mimic those of other planets out there, making extremophiles in these areas excellent models for potential life outside of earth.

Two friends of mine, Halobacterium sp. NRC-1 (from the solar salterns of San Francisco Bay) and H. lacusprofundi (from a hypersaline Deep Lake, Antarctica), were compared by the giants. How did scientists compare them you ask? They were put on an extreme ride, being shot 35 km (~22 miles) high in the atmosphere to see if they would survive. My bro from Antarctica dealt with the cold better and was able to survive and grow after its journey to the stratosphere.

By looking deep within ourselves, deep within the genome and proteome (fancy word for all the proteins of an organism), scientists can reveal what allows microbes to live in such places. Many organisms have neutral proteins, meaning they are neither acidic nor basic. However, proteins from extremophiles are very acidic.

Why are proteins acidic?

Good question, let’s take salt for an example, too much salt and you lose osmotic equilibrium, causing water to leave you and go into the mineral, making you a shriveled raisin. This can cause the proteins in you to shut-down and denature. If you live in extremely salty conditions like Halobacterium and H. lacusprofundi, you need to avoid this. The acidic proteins allow these microbes to stay hydrated and maintain function in environments most would not survive.

These microbes may be good models for both potential life forms on other planets as well as the study of the evolution of life, but how can astrobiologists detect life so far away? Most Haloarchaea produce pigments that may protect them from light and help them grow and repair. Pigments such as these may also provide a great starting point for astronomic detection of life on other planets. As technology improves, telescopes like LUVOIR and HabEx can see farther and better identify atmospheres from far away planets by detecting different wavelengths such as light.

It might be possible for them to detect pigments such as the ones seen from Haloarchaea. However, the pigments we have on earth need to be studied more to make sure they are accurate. Even then, there is a high possibility for false positives.

Many other of our friends also make good models. Take the rad Deinococcus radiodurans. The giants have a book of world records that state this microbe can survive more radiation exposure than any other living organisms. They even found Deinococcus by mistake when they tried to sterilize meat in a can using radiation. Deinococcus kept on living, chowed down on the meat and spoiled it. Ha, Ha, Ha it’s cute when the humans think they can get rid of us!

The giants even got them really high.

Uh, like drugs?

Nah man, space.

Oh right.

Deinococcus has been up there a couple of times. Recently, they were held up outside the international space station for a year. There, they were exposed to the elements including the radiation that is thrown off by the sun. After that time these microbes were able to still grow and thrive.

Coach, does that mean they are resistant to radiation?

Actually no, their DNA is damaged a lot by the radiation. But they are the best handyman when it comes to DNA, they may be the best at repairing their DNA, preventing harmful mutations. So these microbes might be suited for space travel.

Not to brag, but I might be able to accomplish this as well.

(Sarcastic) really?

Chaaa man, in fact one of my uncles was sent up to space to be tested on, though he was always on to work with the G man.

We tardigrades can also withstand radiation, a lot higher than the giants. We can be dried out and survive very hot and cold temperatures, staying in this state for years only to be brought back to life with just a drop of water. We even have proteins that protect the inside of our cells when this occurs.

Wow super cool.

It is not the most fun thing to happen to us, but it is useful. The fact we can do this leads to the theory of panspermia or that life can be seeded on other planets by microbes hitching a ride on asteroids and comets. These microbes then seed that planet and start growing.

Right on. Well, that is it for today, I will see everyone tomorrow when we go to the hot springs to chillax and talk to some local extremophiles. Homework is to take a nice nap under the sun. Latter dudes!