Subtitles section Play video Print subtitles - This episode is sponsored by Skillshare. I saw these images circulating around the internet that showed bacterial cultures growing in Petri dishes and claiming to represent the effectiveness of masks in stopping or minimizing the spread of germs. It was in relation to COVID-19 and whether or not we should all be wearing masks. So today we're gonna recreate this experiment and document it to see how accurate it was and whether or not our mask results come out the same. - Now we trace the images back to the Twitter user, Dr. Rich Davis, love that very expensive name, he is a director of a microbiology lab, so yes, his results seem VV legit, but we want to reproduce his demonstration on our own for a few reasons. One, because it's an excuse to do some fun at home science, and maybe we'll have some new friends in quarantine, aka these bacterial cultures. Two we wanna see if our results will be consistent. - Three, we really wanna test homemade masks because the ones in the pictures look like surgical mask, but I feel like a lot of people just made their own at home, like these ones, my mom made that are super cool. She just basically put two layers of cotton fabric together and some elastics on them. Mom, you did an amazing job, I feel like a science superhero walking down the street. So yeah, there's a whole bunch of them, should she start a line? Now, just before we start, I know some of you might be screaming at your screen saying, but Mitch Coronavirus is a virus, not a bacteria. And that's totally true, so let us explain why this experiment is still relevant. - Right now scientists believe that the main mechanism of transmission for SARS CoV-2 virus is through respiratory droplets. The virus doesn't just float around, it relies on moisture from an infected person to trap. And given that bacteria from the mouth, nose and throat travel in the same way, while these dishes aren't gonna show us how much SARS CoV-2 virus is on them, it will show us the relative amount of droplets. And these droplets by proxy are telling us how our germs spread, whether we're wearing a mask or not wearing a mask. - As an added bonus, I actually got some friends who work in a lab at the University of Toronto, who are also going to recreate this experiment with us at the same time, but under even more ideal conditions for the bacteria to grow, which we'll get to in a bit. Ultimately, all this is to test and figure out how well masks work. Okay, so we are here with our agar plates, I've got gloves on, these have been sterilized, we actually got them from our friend, Amanda who works in a lab who was able to prep these in a proper autoclave, and we've sterilized this countertop and we're trying to be super careful because we only wanna see what's actually coming out of my mouth. - [Narrator] Hot. - Hot. These are called LB plates. Basically it means that the agar that's in them is going to help the bacteria thrive. There's other kinds that help fungus thrive, but in this case, we wanna see the bacteria come up cause that's mostly what's gonna come out of my mouth. - [Narrator] Once we had all the plates ready to go, we began the experiment. We held each plate around 1.5 feet away from the face and coughed twice on one, (coughs) sneezed twice on one, (sneezes) a fake sneeze had to suffice, talked for one minute to one. - There's hydrogen and helium then lithium, beryllium. - And sung for one minute to one. ♪ There's hydrogen and helium then lithium, beryllium. ♪ - Finally, we then repeated all of these activities with a mask on. (coughs then sneezes) - This is the periodic table ♪ The noble gas is stable ♪ Now that we have all our samples done, we're gonna keep them in this room which is the warmest room in our house, I'm literally like sweating right now. All the bacteria, eats up all that agar goodness and grows, and then we'll just come back and check on them soon. - [Narrator] One week later. - Now because we don't have an incubator in our home, obviously, our samples will grow pretty slowly, so I enlisted the help of some friends who work at the Molecular Genetics Department at the University of Toronto who are going to duplicate this experiment under even more ideal conditions. Of course, because of COVID-19, we weren't allowed to go in the lab, so they're gonna walk me through the important differences right now. - At the lab, we've used Brucella Blood Agar plates. Brucella is a type of media and it's supplemented with sheep's blood, heme and vitamin K, and these are additional nutrients that a lot of organisms in the microbiota need to grow. - That won't necessarily change the result, it will just help to amplify any of the bacteria that are actually coming out of me, right? - Absolutely, we would expect to see the exact same results at home as in the lab, except we might be seeing different species of bacteria growing on our home plates than we are in lab, and in the lab we're giving them a lot more nutrients and a lot more conditions to help them grow even better. - Also in the lab I know that or using an incubator, why is an incubator useful and what does it actually do? - So we typically grow bacteria in a 37-degree incubator, and this is because our bodies hover around 37 degrees, assuming you have no fever. And so any microbe that grows inside the body grow the best at 37 degrees. - What do we actually expect to grow on these plates and is any of it dangerous? - In general what you're going to see is just the commensal, normal everyday bacteria and fungi that you have within us. And we need them, they provide us our nutrients, they help us digest our food, they help protect us against other bacteria and fungi that are trying to cause us harm. Most of them are really helpful and also friendly. - Yeah, they're our friends. That's really cute, it's nice to know that. - One other big thing to remember is that we actually can't see viruses growing on plates in a lab or even at home, and that's just because viruses are so small. So while this experiment is a great experiment at giving a snapshot of what could be in your droplets, this will not include any kinds of viruses and it's not gonna include any types of bacteria or fungi that can't grow in the conditions we provided them in. So it's always gonna be an underestimation. - This is the most important question, what will you be singing to your Petri dishes? - I thought long and hard about this, and I've decided to go with the classic karaoke song, Uptown Girls. - Yes. - [Narrator] Three days later. - As if we ever would say it like that. (both laughing) - Alright, so we are ready to look at our results, we have.. - Say hello to our new little friends, to our roommates. - Our plates have been growing for over a week, maybe almost two now. - I think it's two weeks now. - Whereas the laboratory plates are only gonna have been two days. All right, shall we start with coughing? The Petri dish for coughing, there's no colonies on the mask Petri dish and there's one big chunker chunker on the no-mask Petri dish. - And maybe another little one over there but yeah. - Yeah, with the lab results, we see no bacterial cultures when coughing with a mask, and coughing without a mask, we see one sort of smacked up in the middle, really good aim. Coughing, we weren't sick, we had a dry cough. I remember while doing it being like, is on anything coming out? - So the sneezing Petri dishes are where we saw the most difference. So again, the masked sneeze showed nothing on Petri dish, but the unmasked sneeze is out absolutely covered. There's probably, I don't know, 50 little colonies growing? - Hmm. - Wow, I mean, obviously this is why, even when there's not a global pandemic, you sneeze into your arm. Why when people sneeze on the subway you have a good reason to be like, what? - Cover your mouth. And it's just so much. I'm so surprised as that nothing seemingly made it through on the masked one and yet so much made it through without a mask. The lab results were also interesting, no cultures when you had a mask on with sneezing, but then without the mask tons all over the plate. - The plates from talking, we see without a mask, there are about eight, there's quite a few colonies growing, with the mask, there are none. So I think this is really striking because talking is something that we are all doing. Lab results show talking with the mask, no bacterial cultures and talking without a mask, a lot. - Yeah, I know it's actually surprising, maybe almost as much as the sneezing in this case. - This is why it's so important that you have a mask on. - It probably depends how much enunciating we were doing. - I was reading a study where they actually analyzed using computers and like lasers, how many droplets were coming out of people's mouths as they spoke, and they got them to say stay healthy because the T-H noise is known to create a lot of droplets. I think the T-H noise yeah. - So singing we're seeing nothing on the masked version, and we're actually seeing quite a few drops on the no mask. Do not sing without a mask right now people. It's pretty, it's kind of staggering, there's probably six to eight colonies starting, some of them big. And this makes sense when you hear about how choirs were spreading COVID and how they've shut down Broadway for good reason. - Finally, in the lab with singing nothing with the mask and a lot without a mask. So I'd be curious to see what would happen if this had a full week like ours, it could probably cover the whole plate. So these plates are helping us to understand how much is coming out of us and the effectiveness of masks in stopping those droplets and not necessarily how effective the mask is in protecting you. So that's just something to take in mind. - Yeah, wearing a mask is altruistic, it's about you protecting other people around you, which I think is kind of a beautiful thing. I'm wearing this mask for other people. - For other people. And I also just wanna say that masks are potentially part of the solution, but they're not the whole solution. - Yeah. - So, we should be very masks, we should be washing our hands, - Physically distancing. - Yeah. Isolating completely if you've ever been exposed. And then obviously we're all hoping that vaccines and treatments come together. And that is kind of like a holistic look at how we can all be working together to stop the spread of this virus. Now, if you love learning and trying new things then you absolutely have to check out today's sponsor, Skillshare, who's giving the first thousand of our subscribers a two-month free trial of premium membership where you can test out and push your creativity. - Skillshare is an online learning community with thousands of classes about music, film, creative writing, but they even have courses about sustainable living and environmentalism.