Hello, this is Dr. Chobsey and welcome back to another video. Today I'm going to show you how you can make one of the most important tools that a microbiologist uses in their day-to-day life in the lab, which is one of these, an agar plate. Only I'm going to show you how you can make one using ingredients you may find in your own kitchen.
But before I do, I'd really appreciate it if you could hit the subscribe button and like button to help the channel grow. So, what is so important about these little slices of jelly? Well, this is the most important tool that microbiologists use because this is where they grow all the bacteria that they do their research on and not just researchers. If you have an infection and the doctor sends a sample away to a lab first thing they'll do is they'll grow up the sample on one of these so they can identify what kind of bacteria or fungi you have been infected with in the laboratory. Plates like this can be used to grow organisms ranging from common laboratory strains of E.
coli and yeast up to highly infectious organisms that require special containment procedures. Now you may think that to create one of these tools for research purposes you may need exotic ingredients, high-tech equipment. But what if I told you that these stacks of plates here I made in my very own kitchen using common household appliances and ingredients. You don't need anything high-tech or expensive at all.
I'm going to show you now what you need and how to make them. Okay, so have in front of me here almost all of the things that you'll require for making these plates. The main recipe will involve salt, yeast extract and either gelatin or vegetarian gelatin depending on your preference. You need to dissolve all this in boiling water. So we've got a kettle and a bottle of water.
We'll be mixing them all together in a jug using a spoon. And for the actual ingredients you can be weighing them out in scales and using some little bowls to weigh them out in. If you have small little dessert bowls like this you can use this to actually make the plates if you don't have any but if you want to go for the full experience you can get some cheap plastic petri dishes off of Amazon, eBay or anywhere you feel like you want to go.
I will leave a link to these in in the description in case you want to buy them from there. No commission, in fact all of the products here are not sponsored by any of the companies involved, they're just random pieces, random ingredients bought from local supermarkets. So first off, I need to weigh out the amount of powder you're going to be using.
Okay so the ingredients I'm going to be using for making these plates involve about two grams of One sachet of this vegetarian gelatin which is roughly six and a half grams and one gram of this reduced salt yeast extract and that will be dissolved in about 300 milliliters of boiling water. Okay so now I've got all these ready all I need to do is boil the water and start mixing them all together. First I add the salt to the jug as it's the easiest ingredient to start with followed by the correct volume of boiling water. Once the salt has dissolved, I add the yeast extract using a mixing spoon and mix it well until everything is dissolved.
Finally, I add the gelatin powder in small amounts, mixing constantly until it's dissolved. Adding the gelatin too quickly will cause it to forge large lumps that will be difficult to remove. If the gelatin does not fully dissolve, you can gently heat the mixture in a microwave to help it dissolve fully. Just remember to top up the volume with boiling water as it will evaporate in the microwave.
Okay, so now I'm back and I've got my molten mix of agar here, well, gelatine here. You can see it's all still liquid. I'm just about to top it up, back up to 300 millilitres with boiling water.
Now one of the bits that I didn't show in the B-roll footage there was that I needed to heat up the mixture in the microwave for... a good couple of minutes to allow all of the gelatin to dissolve because it doesn't always dissolve straight away as the water cools down. But now it is all dissolved and ready to pour into plates.
Now each of these plates will hold about 20 millilitres of liquid so with 300 millilitres in total here we have enough for about 15 plates give or take, depends on how generous we are with the with the mixture. Hopefully I'll get this done in one take as I don't want it to solidify before I'm finished. Although if it does solidify before you finish doing yours, you can always reheat it in the microwave. Just keep an eye on it and make sure it doesn't overboil and top up with water back to where you should be. Just to make sure that your concentrations of everything are the same.
So, for making one of these plates, all you need to do is take off the lid, gently pour a little bit of the liquid into it. Try and get as little bubbles as possible, just so that it's completely covered the bottom of the plate. Simple as that. And repeat for all of the other plates. Simple as this.
After you've mixed all of these together, what you'll end up wanting to do is put them in the fridge for about an hour to cool down and solidify. And then they'll be ready for you to start using. And to make sure they work, what I'm going to be using today is a bit of baker's yeast.
So, the sort of thing you'll normally find in one of your supermarkets. Okay, so our hour in the fridge is up and our plates have solidified nicely So that's them done now you notice you may notice now that I am Keeping upside down with the jelly side on top the lid on the bottom There's a lid there and the reason for this is as you can see there is a little bit of condensation Well, obviously the I'm never not on that one But on some of these there is a bit of condensation. Let's see if I can find a good example of one.
This one here. All that water on the bottom there. Now obviously, we don't want that dripping down onto the plate when we're putting stuff on it. So, what we always tend to do is have the jelly layer on the top.
and the lid on the bottom so the plate is upside down to prevent any condensation or anything settling onto the gelatin layer of the plate and potentially contaminating any results that we have any adding any extra bacteria or fungi that we don't want okay so the next thing will be to test that these plates are actually working now for that we may have seen at an earlier point in the I've got some yeast, some dried baker's yeast. All I'm going to do with this, or have done with this previously, is I've just added it to a little bit of water. There's a nice cloudy tube there. So all I'm going to do is take one of these plates, this one here, move the others over to the side, and I'm going to take a cotton bud and... Put it in a zigzag pattern across the plate.
Now, to make it so you can see how much you're doing the pattern, I'm just going to dry that off because it has been in the fridge. And the air outside is now condensing on the plate, on the outside of it. So, I'm going to start off at one end, start off at the top, and just do a little zigzag pattern, not overlapping, just going across.
in that kind of a pattern. Okay, just to allow the cells to spread out. So I'm just going to take one cotton bud, open up my little yeast solution, just going to dip it in just so I get some cells on the tip, and gently, very gently trace over the line. We'll be incubating these plates at room temperature here and it'll take quite a long time for them for it to grow. Ideal conditions for bacteria such as E.coli and fungi such as yeast which I've got here it's normally 37 degrees overnight.
Now just let you know how much this will grow in one day at room temperature here. I do have one extra plate that I made up last night and that is how much growth you get in one day. day. Now you can't see too much about the individual cells here so what I'm going to do is I'll get some b-roll shot of this and put it up on the screen now so you can see how big the colonies are now and in two days time I'll show you how this plate looks and how this one looks. Okay so it's been about 48 hours since I made the agar plates or the homemade agar plates so let's see how they fared after we put the yeast on them.
So I'll start off showing you the plate that I prepared the day before. As you can see there's a lot of growth on there, a lot of individual colonies. So at the top there you can even see it's more of a streak than individual colonies.
So each little dot on there, I don't know how well the camera is able to... pick them up you can see a few little dots around the edges each one of those is from a single cell of yeast and if you smell it you can tell it's definitely baker's yeast because it smells like bread dough okay on to the one that i showed on camera as you can see it's not really got as much growth as the other one but it is 24 hours behind but you can definitely see there are a few individual colonies on there that are much larger than the others So overall the plates have worked very well and that's about it. So thank you for watching, hopefully you found this video interesting.
And don't forget to subscribe, like the videos, leave comments down below and I'll see you next time.