Hey everybody, Dr. Rowe. This video, the terminology is going to be the key. I'm going to talk about all the different types of growth media that we might use in the lab or are used in labs. I just share a lot of images because they look cool, so I'm going to give some examples of each one so you can kind of see them.
Alright, so the first two terms have nothing to do with this first image. This is actually called chocolate auger. But the first two terms to know when you're dealing with different growth medium is complex media versus chemically defined media.
So complex media is what we primarily use, which is the only thing I use in the lab, which is you basically don't know exactly what's in each batch. So we have basically we use things like nutrient broth and triptych soy broth that is a combination of like pre-digested beef and yeast and these kind of things. You mix in all the other ingredients. So you're just making food, right?
You don't like if you're making a big stew at home or something, you wouldn't know exactly what was in each bite, but you know went into the batch, right? So that's complex media. and that's the type that we use.
If you have to know exactly what is in a plate or a batch, you would use what's called chemically defined media. So complex media is what we use, chemically defined media, like if you're doing research and you have to know exactly what is in each sample, that's what it's called, chemically defined media. Now what you're looking at here is an example of an enriched media or an enrichment media.
So when you have organisms, so another term, when you have organisms that are fastidious, fastidious These are organisms that need essential nutrients added or they won't grow. They won't survive. So an enrichment media is designed to add exactly what something would need to survive. So this is an example of a fastidious organism. This would be Haemophilus influenza.
It only grows, and lots of organisms actually won't grow in media, but this one only grows in a special media, which is called chocolate agar. No, no chocolate. Sorry, I definitely don't want to eat this.
This is like partially digested partially broken down blood because so in this chocolate agar the blood the blood's been treated and it's and it's released what what hemophilus influenzae needs which is actually some of your factors right your blood clotting factors factor 10 and 5 which is an ad kind of cool so so this is a special enrichment media this organism will not grow just on any nutrient broth this is going to be for a special type of media to grow a certain type of organism so That's what this would be an example of an enriched or an enrichment media. This one's an example, my favorite example of a selective media. So I actually took this picture in the laboratory. This is when we did when we complete the PGLO lab. So a selective media is going to inhibit the growth of the organisms you don't want to grow and then support the growth of the ones that you do.
So what makes this kind of cool? So my students made these. These are genetically modified E. coli bacteria.
that have been given genes that allow them to glow under the presence of UV light. I won't go into all the details of that now. But the cool thing is these bacteria are growing on plates full of ampicillin. So this makes these plates selective media because if the E. coli that we use, the K12 strain, if it wasn't genetically modified, the ampicillin will kill it.
So here we don't have to worry about spreading these or streaking these or anything because the media, the growth surface, is actually what determined what could grow here. It killed off all the competition, so only our genetically modified organisms survived. So that would be an example of a selective media.
It got rid of all the organisms we didn't want to see so we could see the ones that we did. And hopefully you understand there's going to definitely be some overlap between these different types of media. This is another one that would be, to me, it'd be both an enrichment, enriched and a selective media. But this is called McConkie's Auger.
And it has actually like bile salts and crystal violet. which keeps almost all gram-positives from growing. So this is a selective media plate because it keeps gram-positives from growing, but then also it helps gram-negatives grow that like to live in your gut, the enteric bacteria. So a lot of the organisms that grow inside of our guts are going to love this McConkie's auger.
So it's going to be a selective media by getting rid of the gram-positives, and it's going to be an enrichment media by... helping the organisms grow that like to be around things like bile salts. So this would be a good way to look for a lot of the anterior bacteria seeds, so like your pseudomonas and E.
coli and that group there. So the other thing that's on here, though, this is also a, so we've already said it's a selective media and enrichment media, this is also a differential media. And what that means is you can actually diagnose or see something visually that tells you something about what's growing.
So this has a pH indicator in it as well. So if you look at the top, we're looking at serratia marquescens. Maybe you can see that kind of faint red look, especially on the left-hand side. We're looking at serratia marquescens, which does not ferment lactose, so it's not turning hot pink. On the bottom, this would be E.
coli, which is fermenting lactose. And as it does so, it causes a pH change, and that causes the color change. So not only did this, this is a special plate, right? This plate, it kept the gram-positive bacteria out, helped the gram-negatives grow. and just by looking at it we can tell if they are lactose fermenters, like on the bottom, or not on the top.
So that's a pretty special plate there, and that's the McConkie's Auger. All right, the last one I have here would be a Blood Auger. So we use blood auger plates a lot when we're looking for the beta hemolytic strep. So as you can see here, beta hemolysis, so that would be hemolysis, that would be the rupture and digestion of the blood that's in there. There's actually sheep blood mixed in here.
So this would be another example of an enrichment media, selective media, and differential media. Because by looking, if you see these clear zones, that tells you whatever microbe is here is lysing, is destroying those blood cells. So that's going to be what makes it differential. We can just take a look at it. but also it is an enrichment media because a lot of the organisms need the blood to feed off of and it would be a selective media because other ones wouldn't want to grow there so okay so those are some different examples of the different types of growth media that you'll be exposed to in microbiology have a wonderful day be blessed