For those that aren’t aware, yeast are a type of fungi.
Just as we are a part of the animal kingdom, yeast are in the same group as mushrooms, moulds, and… well, I think that’s about it. Unless you’re going for a Fun-guy kind of vibe (HUR HUR HUR 😂).
Fungi have two typical morphologies, a fancy word that means, ‘shapes’.
You’ve got your yeasts (spherical and bud like), and then you have your moulds (or hyphael forms). One species of fungi can switch between the two shapes, depending on the situation.
Take Candida albicans, for example.
Candida is a very common fungal species that grows on our bodies. You will literally have a population of them on you right now if you’re a normal, healthy individual.
These guys can typically be found in yeast form, until they get engulfed by our own white blood cells- usually when they’re somewhere where they’re not supposed to be. Engulfing potential pathogens is a very common way for some white blood cells to ‘nuke’ or destroy foreign material.
But for Candida, sensing the danger that they’re in, literally morph from a yeast to a hyphael form, in order to burst open the white blood cell and escape destruction.
I guess kind of like that infamous scene in Alien.
If you haven’t seen it, I won’t spoil it for you.
But for those that have, you can now picture the horror I felt when I first learnt this at Uni.
And this is why I’m not a Mycologist, a person who studies fungi.
Because I find the whole thing terrifying, for some reason.
But that doesn’t mean I don’t like yeasts (or fungi)… per se.
Fungi are essential for a lot of things we… well, I dunno about need… but want.
Bread, cheese, beer, mead, prosciutto…
All of these things require a lot of help from some fungi.
I just thought I’d add that disclaimer before launching into the main topic of this post, which is on ‘fun little experiments to do at home’, or, ‘Fun with Bugs’, if you will.
If you’re looking for a relatively straight forward demonstration of how microbes grow, there’s an extremely simple experiment that you can set up at home.
No need for fancy lab equipment- just some stuff you can find at your local supermarket.
You will need:
- Party balloons
- A 500 ml hard plastic bottle (or few) with the lids (and plastic ring) removed
- 250 ml warm water (~35 degrees Celsius)
- 1 teaspoon of white sugar (the finer the better)
- 10 g dry instant yeast
All you have to do is get your plastic bottle, fill it with the warm water, and dissolve the sugar in it by gently swirling the bottle.
Once dissolved, carefully pour in the dry yeast, give it another good, gentle swirl, and quickly seal the bottle with a balloon. Please be very careful that you don’t shake the bottle (like a cocktail), because we don’t want to introduce extra bubbles.
And slowly but surely… the balloon will inflate!
This is because the yeast in the water are producing gas (carbon dioxide), while eating and breaking down the sugar.
You know when your yeast are actively growing, because you’ll see lots of foam and bubbles, which you can see in the image with the yellow balloon.
Now, that in itself is pretty standard, but how about adding some more stuff to the mix?
What might happen if I added some salt 🧂 to my yeast mix?
Salt is usually used to preserve foods, which is to say, stop microbes from growing on it.
So if I added salt to the yeast mixture, how might that impact the inflating balloon? Would it inflate the same, or faster, or slower?
By playing around with things that might speed up or slow down the fermentation in the yeast, you can make a panel of yeast balloons like above.
I mentioned salt as an example above, but what else might have an impact on yeast growth? Have you heard of any other household items that are used to prevent things from growing? What about soap? Does that kill germs, or just simply wash them off down the sink?
As Melbourne begins its planned seven day lockdown, this might be a fun little activity at home. See if you can come up with things to play around with. 🎈
A Ph. D graduate in Microbiology, residing in Victoria, Australia. Currently working in multiple locations but still in the STEM field. 👀 🦠 🧫 🧬