Name: 微生物学者だけど「細胞や細菌」について質問ある？ | Tech Support | WIRED Japan
Uploaded: 2025-02-25T09:05:26.000Z
Duration: 28 min 17 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Let's answer your questions from the internet.

So at culture pulp asks, wait, are there actual brain eating amoebas?

The good news is that only a few people every year in North America end up running into one of these organisms.

And if they do, there's not a lot of hope for you.

For example, there can be infections in Texas or sometimes in Mexico.

The way that this happens might be if you jump off a rock face into really warm water and the water just goes right up your nose.

If it has one of these amoeba, an amoeba called Naegleria fowleri, might be able to get access to your brain.

It's not designed to eat your brain, but if it finds itself up there, it's gonna start eating and growing and dividing and dividing and dividing until you have millions and millions and millions of brain eating amoebas up there.

atbeehive01 asks, does the smell of farts tell you a lot about the microbiome of the gut?

I assume a lot of it is driven by what we eat.

The microbes in your gut are helping you to digest your food.

And when they break that down, they break it down into nutrients.

So volatile fatty acids are small molecules like propionate, acetate, and butyrate.

So when you smell poop, what you're really probably smelling is butyrate.

Normally, if your gut is functioning properly, these volatile fatty acids are being absorbed by your cells because they're a source of energy.

That's where you get a lot of the energy from these microbes in your gut.

But if you've got an imbalance in that system, because you ate something bad, then some of these volatile fatty acids are gonna come out with those farts.

And that's when things are gonna start to stink.

So if you ever smell garbage that's been sitting out on the street for a few days, you'll start to get these volatile fatty acid smells.

You can also get methane out of your gut.

So about a third of human beings have methanogens.

Methanogens use hydrogen and CO2, and they turn it into methane.

These people, as well as people who make a lot of hydrogen, or maybe the people who are able to light their farts on fire if you've ever seen that.

If you eat a lot of protein, that protein is gonna have some sulfur in it.

And the bacteria in your gut, when they break down that, they can make a gas called hydrogen sulfide.

And hydrogen sulfide smells like rotten eggs.

So yeah, the smells you're getting are controlled by what you eat, but very much it's the microbes that make 100% of those smells.

If so, how many could dance on the head of a pin?

The head of a pin is pretty pointy, maybe two microns, give or take.

But a bacterium is typically about the size of two microns.

So if we were to zoom way in, we would see that it would have just about enough room for maybe one microbe, maybe two microbes.

At Ed Wilson asks, if the number of microbial cells in a body is of the same order as that of human cells, how much of my weight is microbes?

So if we add up all the cells in your body, and then add up all of the microbial cells in your body, we find that they're actually about the same.

Microbial cells, bacteria in particular, are about a thousand times smaller than human cells.

So if we add up all of the mass of the bacterial cells, you're gonna find that that's two to six pounds.

And that'll change throughout the day, right?

Because when you go to the bathroom, when you poop, that poop is basically solid microbes, except for maybe the stray corn kernel or a little bit of lettuce.

You've just lost a couple of pounds of microbes, but don't worry, they're gonna grow back.

At Rover Suede, what is the fastest bacteria?

Like if I were to stage a little race under a microscope, who would win?

The fastest bacteria is Delavibrio bacteriovorans.

Literally, that translates into the wiggly leech that eats bacteria.

Its real speed is about maybe 150 microns per second, which is blazingly fast for a microbe.

If we were to shrink ourselves down to the size of this microbe, it would be about 600 miles an hour, right?

So you find them in freshwater habitats, typically.

It's a predator of bacteria, so they need to be really fast because they're chasing down those bacteria to try and attach to them and kill them.

You almost can't see them because you're looking under the microscope and they sort of go, fwoom, fwoom, because they're just that fast.

If you want to look at them under the microscope, you have to add something really viscous that's gonna try to slow them down.

At JeSwissCECE asks, predatory bacteria, that shit is real AF.

You are right, there are tons of predatory bacteria.

So these are bacteria that eat other bacteria.

They come in a lot of different varieties.

They talk to each other using molecules so they can zero in on prey, and then they surround the prey and secrete enzymes that cause them to dissolve.

There can be epibiotic parasites and predators like Vampirovibrio that latch onto the outside of a cell and suck its cytoplasm.

And one of the most terrifying is Delavibrio.

So Delavibrio lives in aquatic habitats, usually freshwater, where it tracks down its prey.

It will actually attach to the prey, and then it will penetrate the cell wall and push itself inside of that cell where it will grow.

It will replicate several times to make maybe eight or 10 or as many as 12 cells inside of the guts of the prey cell that it's attacking.

And then when it's done, they explode out and they swarm out.

At MitchBrown43, my biology test was like, how do most bacteria move?

I didn't even need to read the rest of the answers.

Bacteria move through a process called chemotaxis.

Bacteria don't have eyes or ears like you or I, so they don't know where they're going.

And so they do what we call a biased random walk.

They definitely move towards food, so they can sense if the food concentration is high.

And if it's bad or if it's getting worse, they just like shake themselves up, swim off randomly in a new direction.

And through this random series of runs and tumbles, they actually are really effective at finding the right way to go.

Well, there's lots of different ways that microbes move.

So many microbes have a flagella, usually stiff and helical shaped.

It spins and propels them and helps them wiggle.

But then when they want to run, they turn those flagella in the right direction and they all sort of coil up with each other.

And that allows the bacteria to shoot forward.

Some bacteria also move by what we call gliding.

They sort of drive themselves along the surface with these suction cups.

They're just one little cell out in the world.

And so they need to find conditions that are right for them.

They sense all of these things and then try to use this biased random walk to get where they need to go.

At Newstart 2024, the last of us, zombie infection is real.

Fungi can devour insects from the inside out.

And experts say it's not too far-fetched that a similar parasite could evolve to infect humans.

The clickers that you saw where the fungus infects people coming out of the person's head,

I wouldn't worry too much about that unless you're an insect.

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微生物学者だけど「細胞や細菌」について質問ある？ | Tech Support | WIRED Japan

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