WEBVTT - Biofilms (featuring Dr. Katrine Whiteson) 0:00:07.800 --> 0:00:11.560 Great News Extraordinaries. Doctor Katrina Whites in his back. This 0:00:11.720 --> 0:00:14.880 time she's here to talk to us about biofilms. We're 0:00:14.920 --> 0:00:17.880 going to talk about biofilms that are delicious, which she 0:00:17.960 --> 0:00:20.119 shares with the rest of her neighborhood. We're going to 0:00:20.160 --> 0:00:23.120 talk about biofilms that are adorable and you can find 0:00:23.160 --> 0:00:25.720 in the ocean. And we're going to talk about biofilms 0:00:25.720 --> 0:00:28.240 that are incredibly dangerous. And we're going to talk about 0:00:28.280 --> 0:00:31.600 how Katrina is using phages to do battle with these 0:00:31.680 --> 0:00:35.680 dangerous biofilms. And if you're dealing with an incredibly dangerous biofilm, 0:00:36.040 --> 0:00:38.440 obviously Katrina is someone that you want to have in 0:00:38.479 --> 0:00:42.760 your corner. Welcome to Daniel and Kelly's Microbial Universe. 0:00:55.880 --> 0:00:56.040 Hi. 0:00:56.200 --> 0:00:59.120 I'm Daniel. I study particles and aliens. 0:01:01.200 --> 0:01:04.840 Hello, I'm Kelly Reader Smith. I study parasites and space 0:01:04.880 --> 0:01:06.600 and I love kombucha. 0:01:08.920 --> 0:01:11.520 You are just pandering, pandering, pandering, aren't you. 0:01:11.880 --> 0:01:14.720 I will pander to Katrina. I'm a big Katrina fangirl. 0:01:14.800 --> 0:01:17.800 I also like keefer And if you had something growing 0:01:17.920 --> 0:01:21.039 on your countertop, would you like lean over and give 0:01:21.080 --> 0:01:21.520 it a lick? 0:01:21.840 --> 0:01:23.960 I have a child who licks just about everything that 0:01:23.959 --> 0:01:27.720 it hasn't killed that child yet, so probably i'd be fine. 0:01:27.920 --> 0:01:31.000 I'd rather not, but I've got pretty good evidence that 0:01:31.000 --> 0:01:32.640 that it's not often lethal. 0:01:38.120 --> 0:01:40.080 Well, on today's episode, we're going to be taking an 0:01:40.160 --> 0:01:43.759 intellectual nibble of all sorts of gooey growths. 0:01:44.080 --> 0:01:48.480 And today's intellectual nibble is inspired by a wonderful question 0:01:48.600 --> 0:01:51.680 by listener Jen. Let's go ahead and listen to Jen's question. 0:01:51.800 --> 0:01:55.320 Now, Hi, Daniel and Kelly. I recently saw an Instagram 0:01:55.320 --> 0:01:58.160 post about someone who got lee Jionella from their water floster. 0:01:58.640 --> 0:02:01.320 This cod me thinking about bio films and I love 0:02:01.360 --> 0:02:03.880 a whole episode on a topic. What do you think? 0:02:04.400 --> 0:02:06.720 I don't know if there'll be any aliens, but certainly 0:02:06.720 --> 0:02:07.720 poop will be involved. 0:02:08.160 --> 0:02:11.480 And it turns out we have the perfect person that 0:02:11.520 --> 0:02:13.600 we know to talk about biofilms. 0:02:13.639 --> 0:02:17.040 Who is it, Daniel, It's Katrina. 0:02:17.120 --> 0:02:20.440 Of course, anytime we have an excuse to bring Katrina 0:02:20.520 --> 0:02:24.560 back on the show is a good day, because you. 0:02:24.480 --> 0:02:26.120 Think she's gonna side with you on all of our 0:02:26.120 --> 0:02:27.760 disagreements so you can out vote me. 0:02:27.880 --> 0:02:30.440 Just wait and see in the episode how that turns 0:02:30.440 --> 0:02:32.799 out for me. Oh, and we've got this like long 0:02:32.880 --> 0:02:35.320 running debate about who what guest has been the most 0:02:35.480 --> 0:02:37.280 common guest on the show. And I just like to 0:02:37.280 --> 0:02:39.440 clarify that I don't really think of Katrina as a guest. 0:02:39.480 --> 0:02:43.080 I think of her as somewhere between guest and co host. 0:02:43.480 --> 0:02:45.160 You know, she's not on the show all the time, 0:02:45.360 --> 0:02:47.520 but she's like, I don't closer to co host than 0:02:47.560 --> 0:02:52.160 anything else anyway. So we wanted to ask the extraordinaries 0:02:52.600 --> 0:02:55.040 what is a biofilm to get a handle on how 0:02:55.120 --> 0:02:59.040 much folks know about biofilms, and so let's go ahead 0:02:59.040 --> 0:02:59.920 and hear what they had to say. 0:03:00.000 --> 0:03:03.280 Hey, my first thoughts were like some thin layer of 0:03:03.360 --> 0:03:05.640 organic matter on top of like a body of water. 0:03:05.960 --> 0:03:08.480 Then I thought what would the weirder thing be, and 0:03:08.800 --> 0:03:12.320 then I thought like, maybe it's some way of capturing 0:03:12.480 --> 0:03:14.880 video using biotechnology. 0:03:15.280 --> 0:03:18.680 I think that a biofilm is some sort of colony 0:03:18.760 --> 0:03:23.000 of microbes or bacteria or something that creates a film, 0:03:23.840 --> 0:03:28.440 much like a plastic film that embraces and protects some 0:03:28.680 --> 0:03:29.639 organic thing. 0:03:30.200 --> 0:03:35.040 A complete guess may be a biological film that goes 0:03:35.120 --> 0:03:40.040 round or protects bacteria, microbes, something like. 0:03:39.960 --> 0:03:43.520 That biofilm is that thin, slimy membranous gluey like film 0:03:43.560 --> 0:03:45.560 material that all my free d orders were covered with 0:03:45.600 --> 0:03:46.640 when they were born. 0:03:46.600 --> 0:03:50.280 Thanks by It is a biological film that grows in 0:03:50.640 --> 0:03:53.360 water systems, so it's actually well named. 0:03:53.720 --> 0:03:57.800 It is a thin layer of organic material, usually bacteria, 0:03:57.880 --> 0:04:00.960 I believe, maybe cyanobacteria and some of the things as well, 0:04:01.320 --> 0:04:05.360 that forms over rocks, forms over sentiment surfaces, and acts 0:04:05.400 --> 0:04:07.760 often as a preservative in the fossil record. 0:04:08.080 --> 0:04:10.560 An example of a biofilm might be the gunk on 0:04:10.600 --> 0:04:13.240 your teeth if you don't brush often, or maybe a 0:04:13.280 --> 0:04:15.760 movie about Abraham Lincoln or some such. 0:04:16.000 --> 0:04:19.839 I believe that biofilm is a natural sort of layer 0:04:20.040 --> 0:04:24.440 that some organisms have that protect them from outside invasions. 0:04:24.520 --> 0:04:27.400 I guess, almost like humans have skin, like. 0:04:27.360 --> 0:04:31.280 A thin layer of biological material. 0:04:32.400 --> 0:04:34.120 Such as bacteria. 0:04:34.040 --> 0:04:38.920 Or blue green algae that forms a film on top 0:04:38.960 --> 0:04:43.000 of water. Eventually, if they become thick enough, they become 0:04:43.400 --> 0:04:44.760 what's called a matt. 0:04:45.120 --> 0:04:48.920 Biofilm That sounds kind of like something that be on 0:04:49.000 --> 0:04:49.880 the surface. 0:04:49.480 --> 0:04:53.080 Of a leak, like a algae or something. 0:04:53.360 --> 0:04:53.800 I don't know. 0:04:53.839 --> 0:04:58.120 It might be like a shall of a cellar or something. 0:04:58.680 --> 0:05:03.360 A biofilm is not a nineteen seventies documentary about childbirth 0:05:03.800 --> 0:05:08.800 at biofilm is a layer of biological material e g. 0:05:09.120 --> 0:05:12.640 Bacteria that surfaces like you have in a fish tank. 0:05:13.080 --> 0:05:14.839 Wow, these are some great answers. 0:05:15.120 --> 0:05:18.800 So our audience actually knows quite a bit about biofilms. 0:05:18.880 --> 0:05:21.000 Can I share a fun fact that one of our 0:05:21.040 --> 0:05:24.640 audience members shared with us? Yeah? Okay, so Robin wrote 0:05:24.720 --> 0:05:29.320 and said, interestingly, biofilms can be important in paleontology as 0:05:29.320 --> 0:05:33.039 they can help stabilize sediment surfaces to make trace fossils 0:05:33.040 --> 0:05:36.400 more likely to preserve. Oh wow, anyway, long story short, 0:05:36.480 --> 0:05:41.120 biofilms are important for making fossils stick around longer. Robin, 0:05:41.440 --> 0:05:42.440 that's amazing. 0:05:42.760 --> 0:05:45.239 Thank you so much for showing very cool. Yes, wow, 0:05:45.279 --> 0:05:49.159 ancient bacteria are helping preserve the fossil record. 0:05:49.320 --> 0:05:49.599 I know. 0:05:49.760 --> 0:05:52.480 So cool And so anyway, I love when when listeners 0:05:52.480 --> 0:05:55.159 are like, oh, actually I could have been a guest 0:05:55.160 --> 0:05:56.880 on your show because I know a ton of stuff. 0:05:56.880 --> 0:06:02.520 Another listener works on microscopes for visualize biofilms, and I 0:06:02.560 --> 0:06:04.440 was like, oh my gosh, you all are amazing. So anyway, 0:06:04.480 --> 0:06:06.880 people made me laugh, people taught me stuff. What a 0:06:06.880 --> 0:06:08.240 great setup for this episode. 0:06:08.320 --> 0:06:10.120 Well, these are my favorite kind of episodes. We need 0:06:10.120 --> 0:06:12.120 to discovered. There's a whole topic with like a deep 0:06:12.120 --> 0:06:14.800 well of science that you never heard anything about, and 0:06:14.839 --> 0:06:16.800 so there's a lot to learn here and it can 0:06:16.839 --> 0:06:19.840 really change your perspective on like disease and how we 0:06:19.880 --> 0:06:22.159 study it and how things work inside the body. 0:06:22.440 --> 0:06:26.200 Yes, and unsurprisingly with a topic like that, you and 0:06:26.279 --> 0:06:28.880 I had a ton of fun talking to Katrina. I 0:06:28.960 --> 0:06:32.560 maybe had even more fun because she did sign with 0:06:32.600 --> 0:06:35.440 me a lot, and so maybe we should go ahead 0:06:35.480 --> 0:06:37.159 and just jump into the episode. 0:06:37.240 --> 0:06:40.680 It's my great pleasure to once again introduce Professor Katrina Whitson. 0:06:41.040 --> 0:06:44.600 She's the most frequently requested guest on the pod. She's 0:06:44.720 --> 0:06:48.000 co director of the Whites and Research Institute and recently 0:06:48.120 --> 0:06:52.600 self appointed chair of in House Fermentation, colloquially known as 0:06:52.680 --> 0:06:57.640 Queen of Kombucha, potential poisoner of neighborhood children. Katrina, welcome 0:06:57.680 --> 0:06:58.760 back to the podcast. 0:07:00.000 --> 0:07:04.920 Wow, that is not the benign feeling that I have 0:07:05.040 --> 0:07:09.400 towards most microbes and our kombucha. 0:07:09.520 --> 0:07:12.480 It was a really mixed bag, butN intro there, Daniel. 0:07:12.240 --> 0:07:14.600 Well, you know we tell like it is on this podcast. 0:07:14.840 --> 0:07:18.160 You know, if we don't sugarcoat anything, including the fact 0:07:18.160 --> 0:07:19.840 that we may be poisoning neighborhood children. 0:07:20.200 --> 0:07:24.080 Wait, have the parents of neighborhood children been contacting y'all 0:07:24.120 --> 0:07:26.400 to get a bit of additional information about what they're 0:07:26.400 --> 0:07:27.600 in bibing at your household? 0:07:28.600 --> 0:07:30.960 I think Daniel's the only one who's worried about the 0:07:30.960 --> 0:07:32.160 safety of this kombucha. 0:07:32.240 --> 0:07:34.280 But he did ask me to make a waiver. 0:07:34.240 --> 0:07:37.440 And why is that? And why is that? 0:07:38.640 --> 0:07:38.760 So? 0:07:38.960 --> 0:07:42.400 We do now have a waiver if you drink the 0:07:42.480 --> 0:07:44.520 kombucha at our house, or like if we bring it 0:07:44.560 --> 0:07:46.800 to someone's house, because our the neighborhood kids were just 0:07:47.600 --> 0:07:50.120 enjoying it and saying it tasted like apple cider, and 0:07:50.200 --> 0:07:53.080 Daniel viewed this beautiful activity. 0:07:52.680 --> 0:07:53.840 As with suspicion. 0:07:54.800 --> 0:07:57.320 Why do they sign a waiver Because we have. 0:07:57.320 --> 0:07:59.960 This thing bubbling away in the corner of our kitchen. 0:08:00.120 --> 0:08:03.480 Who knows what's growing in there. Nobody's testing it, nobody's 0:08:03.520 --> 0:08:06.120 doing any safety protocols. Now we're just feeding it to 0:08:06.120 --> 0:08:09.080 any child who wanders into the house, sending them home. 0:08:09.240 --> 0:08:11.400 You know, who knows what happens. I don't want to 0:08:11.400 --> 0:08:12.320 be responsible. 0:08:12.720 --> 0:08:15.680 The kombucha waiver is mostly a sarcastic document. 0:08:15.960 --> 0:08:19.960 Just to be clear, I feel like I have so 0:08:20.040 --> 0:08:24.240 many questions, like how many children are wandering into your house? 0:08:24.360 --> 0:08:26.520 And do you just like leave the door open? How 0:08:26.560 --> 0:08:27.440 did this start? 0:08:28.400 --> 0:08:28.600 Oh? 0:08:28.640 --> 0:08:30.920 Man, it's one of these old fables. You know, there's 0:08:30.920 --> 0:08:34.160 a house in the forest, the children wander in. And 0:08:34.200 --> 0:08:36.480 then you know the old lady who mixed kombucha in 0:08:36.520 --> 0:08:37.080 the forest. 0:08:37.800 --> 0:08:39.640 Oh, gome back. 0:08:39.360 --> 0:08:42.280 On you, let me try that one again. 0:08:43.679 --> 0:08:44.720 Oh my gosh. 0:08:44.760 --> 0:08:47.040 And then you know the beautiful young scientist who mix 0:08:47.080 --> 0:08:50.560 kombucha in the forest, you know, draws them in with 0:08:50.600 --> 0:08:51.200 her poison. 0:08:51.600 --> 0:08:54.920 I need Daniel to survive so that we can't continue 0:08:54.960 --> 0:08:58.720 recording together. So I am cutting off this guest introduction 0:08:58.880 --> 0:09:01.800 right here. We are moving on to the meat of 0:09:01.840 --> 0:09:06.080 the interview. Katrina. We are so excited to have you back, 0:09:06.640 --> 0:09:14.320 Daniel aside, and and today we're talking about biofilms, which 0:09:14.360 --> 0:09:17.280 is another one of the many amazing things that you 0:09:17.400 --> 0:09:21.439 work on. And so let's start with what is a biofilm? 0:09:21.440 --> 0:09:24.480 And I'd like to mention since you didn't hear the intro, 0:09:24.640 --> 0:09:27.760 because we're recording this before even Daniel gets to hear 0:09:27.800 --> 0:09:30.640 what our extraordinaries had to say about biofilms. We got 0:09:30.640 --> 0:09:35.280 a lot of great answers. Our audience is excited about biofilms. 0:09:35.559 --> 0:09:39.640 So let's start there, Katrina, what is a biofilm, Well. 0:09:39.440 --> 0:09:43.600 A biofilm is a structured community of microbes that are 0:09:43.600 --> 0:09:47.280 living together in a sticky matrix that they produce themselves 0:09:47.840 --> 0:09:51.360 so that they can face the world together as opposed 0:09:51.480 --> 0:09:55.560 to facing the world alone. And so they are unicellular organisms, 0:09:55.559 --> 0:09:57.800 but they choose to live in these communities. It can 0:09:57.840 --> 0:10:00.439 be just one kind of microbes, it can be different 0:10:00.480 --> 0:10:03.920 kinds of microbes, and they live in these structured communities 0:10:03.960 --> 0:10:07.480 surrounded by a goo of their own making, and as 0:10:07.520 --> 0:10:11.120 a result, they can stick to surfaces, they can float 0:10:11.120 --> 0:10:15.680 together in clumps, and they can be protected from all 0:10:15.760 --> 0:10:19.400 kinds of evils that might change the course of their 0:10:19.440 --> 0:10:20.240 lives in the world. 0:10:21.120 --> 0:10:23.439 What a joy to live in the goo secreted by 0:10:23.440 --> 0:10:24.160 those around you. 0:10:25.320 --> 0:10:26.319 It's not for everyone. 0:10:26.440 --> 0:10:30.360 It's like a little hoa, right exactly. You live in 0:10:30.360 --> 0:10:33.040 a gated community. So this is really fascinating because it 0:10:33.040 --> 0:10:36.400 sounds like it's sort of in between the usual way 0:10:36.440 --> 0:10:39.960 we think about organisms, like either you got individual cells 0:10:40.080 --> 0:10:42.000 on their own face in the world, and all the 0:10:42.080 --> 0:10:45.560 dangers of you know, people offering them kombucha versus like 0:10:45.800 --> 0:10:49.720 multicellular organisms, you know, like lions and tigers and whatever, 0:10:49.800 --> 0:10:52.800 where every cell has its own role and they're specialized 0:10:52.840 --> 0:10:55.160 and they all work together. So this is something sort 0:10:55.200 --> 0:10:57.640 of in between. Right, there's still as you say, unicellular, 0:10:57.679 --> 0:11:00.280 which I guess means they're all basically the same, but 0:11:00.360 --> 0:11:03.280 now they're forming like a macroscopic blob, so they can 0:11:03.320 --> 0:11:04.319 work together somehow. 0:11:04.800 --> 0:11:05.680 Yeah, exactly. 0:11:05.720 --> 0:11:07.280 So, I mean it doesn't have to be that they're 0:11:07.320 --> 0:11:09.360 all the same to be in a biofilm. It can 0:11:09.400 --> 0:11:12.000 be very different types of microbs that come together to 0:11:12.080 --> 0:11:16.040 form a biofilm. But yeah, they could also be identical 0:11:16.120 --> 0:11:20.080 sister cells and they are independent cells, the same type 0:11:20.120 --> 0:11:23.120 of cell, but they all live together and they do 0:11:23.280 --> 0:11:27.800 form structured communities where that's driven by the gradients of 0:11:27.880 --> 0:11:28.920 nutrients around them. 0:11:29.080 --> 0:11:31.320 What do you mean when you say structured communities, like 0:11:31.760 --> 0:11:33.520 some guys are on the outside and some are in 0:11:33.559 --> 0:11:35.199 the inside, or what do you mean by structure? 0:11:35.320 --> 0:11:35.760 Exactly? 0:11:36.240 --> 0:11:38.680 Yeah, I mean the way that when the biofilm gets started, 0:11:39.280 --> 0:11:42.600 somebody's got to produce something sticky and then that will 0:11:42.640 --> 0:11:44.120 help the first cell. 0:11:44.320 --> 0:11:49.599 That's the way a lot of fun projects start. Yes, Oh, who's. 0:11:49.360 --> 0:11:53.920 The sticky guy in the group? Gross? 0:11:54.280 --> 0:11:56.600 All right, somebody makes something sticky. All right, walk us 0:11:56.640 --> 0:11:57.280 through a Katrina. 0:11:57.880 --> 0:11:59.880 Yeah, somebody has to make something sticky. 0:12:00.640 --> 0:12:04.720 And then either that helps the first cell stick to 0:12:04.760 --> 0:12:07.800 a surface. Then either it can multiply you know, they're 0:12:07.880 --> 0:12:09.960 sitting and replicating in the middle of all this too, 0:12:10.679 --> 0:12:13.800 or other cells can come by and stick and become 0:12:13.880 --> 0:12:17.559 part of the community, and then they have really interesting 0:12:17.559 --> 0:12:22.079 molecular communication going on. And since most bacteria live in biofilms, 0:12:22.160 --> 0:12:26.160 probably eighty percent, there's a crazy diversity of how this happens. 0:12:26.679 --> 0:12:29.320 But you know, a classic example in a textbook would 0:12:29.360 --> 0:12:31.560 show a couple of microbes sitting on a surface and 0:12:31.600 --> 0:12:34.760 then as they get bigger and denser, they start to 0:12:34.880 --> 0:12:40.280 communicate with molecules to shout out about their density, and 0:12:40.320 --> 0:12:45.200 then that helps other processes happen. You know, they're used 0:12:45.200 --> 0:12:48.280 to living in these communities, so the molecules they're able 0:12:48.320 --> 0:12:50.960 to produce have all been selected for an evolution to 0:12:51.040 --> 0:12:53.679 be able to do things in biofilms. 0:12:54.679 --> 0:12:57.760 And that communication, I think I remember is it called 0:12:57.840 --> 0:13:01.120 quorum sensing? And if it is quorum sensing? Does that 0:13:01.160 --> 0:13:03.320 mean that we get to talk about the squid? Because 0:13:03.360 --> 0:13:05.480 every chance I get, I want to talk about the squid. 0:13:07.559 --> 0:13:10.600 That is a great example. And yes, that's a perfect 0:13:10.720 --> 0:13:12.360 example of quorum sensing. 0:13:12.559 --> 0:13:14.360 What's a quorum and why do we want to sense it? 0:13:16.280 --> 0:13:19.280 A quorum is just like a count, you know, like 0:13:19.320 --> 0:13:21.720 a number of people in the room, Like do we 0:13:21.840 --> 0:13:24.120 have a quorum? Like are there enough people here that 0:13:24.200 --> 0:13:27.040 we can call it a thing? And then sensing just 0:13:27.120 --> 0:13:29.880 means that they are sensing their own quorum. 0:13:30.280 --> 0:13:32.440 I see. And how does this work on the squid? 0:13:33.200 --> 0:13:35.679 Well, the squid is such a cool example. So there 0:13:35.679 --> 0:13:38.960 are these beautiful bobtail squid that the whole system was 0:13:39.000 --> 0:13:43.400 discovered in. And this was discovered by Margaret McFall nye 0:13:43.440 --> 0:13:46.600 who's now up at Caltech and her husband, Ned Ruby, 0:13:46.600 --> 0:13:49.880 who's a microbiologist. The two of them together have been 0:13:49.880 --> 0:13:52.800 working on this for decades and it's really it'll blow 0:13:52.840 --> 0:13:53.200 your mind. 0:13:53.400 --> 0:13:55.640 Are they like a little mini science biofilm? 0:13:56.920 --> 0:14:00.000 Well, you know what, they actually created a science biofilm 0:14:00.080 --> 0:14:03.240 because every person they trained fell in love with the 0:14:03.280 --> 0:14:05.080 squid and went off in the world to start their 0:14:05.080 --> 0:14:07.160 own lab to study the squid. And now there's these 0:14:07.160 --> 0:14:10.880 photographs of the sixty or one hundred labs that are 0:14:10.880 --> 0:14:14.320 all working on squid Vibrio the microbe that causes this 0:14:14.360 --> 0:14:16.160 phenomenon around the world. 0:14:16.200 --> 0:14:17.880 So that is actually a good way to look at it. 0:14:18.000 --> 0:14:20.080 But now I'm wondering who the sticky guy is out 0:14:20.080 --> 0:14:21.920 of that group. But let's move on. We don't need 0:14:21.960 --> 0:14:24.280 to know who the sticky guy is, all right, let's 0:14:24.280 --> 0:14:26.640 talk about the amazing squid and their amazing microbes. 0:14:26.960 --> 0:14:30.760 Yeah, well, these squid have evolved a relationship with a 0:14:30.800 --> 0:14:34.560 microbe called vibrio. Just as a big picture level, the 0:14:34.640 --> 0:14:38.720 Vibrio inhabit a light organ that the squid have, and 0:14:39.120 --> 0:14:42.080 when this vibrio, the bacteria and this light organ get 0:14:42.120 --> 0:14:46.320 dense enough, they quorum sense and actually produce light. Wow, 0:14:46.360 --> 0:14:49.680 and that light in the light organ will help the 0:14:49.680 --> 0:14:54.440 squid by canceling out their own shadows, and so then 0:14:54.480 --> 0:14:57.520 they're safer in the world because prendors can't detect them 0:14:57.560 --> 0:14:58.920 as easily because they don't have a shadow. 0:14:58.960 --> 0:15:01.560 Wait, so there's a squid floating around and it's casting 0:15:01.560 --> 0:15:03.720 a shadow because there's a source of light behind it. 0:15:03.960 --> 0:15:06.760 But then the bacteria in the squid produce the light 0:15:06.840 --> 0:15:09.240 to cancel out that squid shadow exactly. 0:15:09.320 --> 0:15:12.080 Wow, So that's the big picture thing going on. But 0:15:12.200 --> 0:15:14.000 there's a real biofilm story here. 0:15:14.240 --> 0:15:17.840 And so basically, when a squid is born, in the 0:15:17.880 --> 0:15:21.560 first six hours of its life, a single vibrio has 0:15:21.640 --> 0:15:25.400 to get into its light organ and this is this happens. 0:15:25.440 --> 0:15:28.600 I mean, there's tons of fibrio bacteria floating in the ocean, 0:15:28.640 --> 0:15:30.760 so the chances are very good that it'll work. 0:15:31.160 --> 0:15:33.920 But wherever squid live, this works. 0:15:33.640 --> 0:15:37.120 That a vibrio cell that gets into the light organ 0:15:37.320 --> 0:15:39.720 and starts multiplying, and this is. 0:15:39.680 --> 0:15:40.880 Critical for its survival. 0:15:40.920 --> 0:15:43.120 So it's like really interesting to think about the co 0:15:43.240 --> 0:15:45.560 evolution of the squid always needing to be in a 0:15:45.560 --> 0:15:47.640 place where there's a vibrio that can get in there 0:15:47.640 --> 0:15:48.760 in the first six hours. 0:15:49.440 --> 0:15:51.160 Why does it have to be in the first six hours. 0:15:51.920 --> 0:15:54.240 That's a really good question that Margaret McFall and I 0:15:54.320 --> 0:15:56.200 has answered in front of me multiple times. 0:15:56.240 --> 0:15:57.640 So let's see if I can come up with a 0:15:57.640 --> 0:15:58.320 good answer. 0:15:58.520 --> 0:16:00.840 But I mean, it's it's early enough in the squid's 0:16:00.880 --> 0:16:04.520 life that the vibrio gets in there, and I think 0:16:04.600 --> 0:16:07.960 that the light organ won't develop properly without the vibrio 0:16:08.080 --> 0:16:10.600 being in there. But I don't know, doctor McFaul, and 0:16:10.680 --> 0:16:13.800 I can answer that question for real, So, yeah, you 0:16:13.880 --> 0:16:17.120 need the vibrio in there, and it's it starts multiplying. 0:16:17.560 --> 0:16:20.440 And I don't know what age this daily cycle begins, 0:16:20.440 --> 0:16:23.800 but I think it's pretty early on that the vibrio 0:16:23.880 --> 0:16:27.040 will copy make copies of themselves inside the light organ, 0:16:27.680 --> 0:16:31.920 and once they hit a certain density a quorum, then 0:16:32.040 --> 0:16:36.200 the vibrio are capable of communicating within themselves to produce 0:16:36.480 --> 0:16:41.240 this smalllecule which causes light. And then every morning, the 0:16:41.320 --> 0:16:44.480 light organ ejects ninety five percent of the bacteria and 0:16:44.520 --> 0:16:46.080 the cycle starts all over again. 0:16:46.320 --> 0:16:49.480 So then they build up the density. 0:16:48.920 --> 0:16:52.120 Of microbes and it's actually at night that they are 0:16:52.480 --> 0:16:57.360 dense enough to do this light producing phenomenon with the 0:16:57.400 --> 0:17:00.360 quorum sensing. And that always confuses me because I think 0:17:00.400 --> 0:17:02.960 of the shadow as being more important during the day, 0:17:03.320 --> 0:17:06.560 but these squid are nocturnal and it's actually the shadow 0:17:06.600 --> 0:17:09.520 of the moon that's being canceled out by the light organ. 0:17:09.880 --> 0:17:11.200 It is such a cool system. 0:17:11.440 --> 0:17:12.879 It is. It's amazing. 0:17:12.960 --> 0:17:15.280 So the bacteria don't know if it's day or night. 0:17:15.320 --> 0:17:19.520 They're just producing light, but the squid's light organ ejects 0:17:19.520 --> 0:17:21.840 them when it doesn't want light, and then they grow 0:17:21.920 --> 0:17:24.000 back when it needs light again exactly. 0:17:24.119 --> 0:17:27.439 So it's timed so that they eject them in the morning, 0:17:27.800 --> 0:17:29.800 then the density is low again. Then they have all 0:17:29.880 --> 0:17:32.280 day to build that density back up, and at night 0:17:32.520 --> 0:17:35.119 there's enough of them to do the quorum sensing and 0:17:35.160 --> 0:17:35.760 produce light. 0:17:35.840 --> 0:17:37.119 And I think it's also. 0:17:36.920 --> 0:17:40.840 Because you need a fresh crop of healthy, young bacteria 0:17:40.920 --> 0:17:42.840 to be making light. I think if you left them 0:17:42.840 --> 0:17:46.280 in there for too long, they wouldn't really be in 0:17:46.359 --> 0:17:48.080 good shape for that job anymore. 0:17:48.200 --> 0:17:50.480 And presumably the bacteria need to get back out into 0:17:50.520 --> 0:17:53.480 the environment if they can hope to infect a new 0:17:53.560 --> 0:17:56.680 light organ and keep the cycle going. And so is 0:17:57.119 --> 0:17:59.560 getting out into the environment part of I don't know 0:17:59.600 --> 0:18:01.680 the psych Does it help the bacteria in that way 0:18:01.760 --> 0:18:03.720 or is it just they get booted? 0:18:03.960 --> 0:18:04.200 Yeah. 0:18:04.280 --> 0:18:07.199 Actually, Vibrio are kind of famous for being good at 0:18:07.240 --> 0:18:11.080 living independently in water and then also inside animals, and 0:18:11.119 --> 0:18:13.639 so the probably the most famous vibrio that people on 0:18:13.680 --> 0:18:17.439 this podcast have heard of is Vibrio cholera, and cholera 0:18:17.640 --> 0:18:20.960 also can live in water and it's perfectly happy living 0:18:21.000 --> 0:18:24.480 its life without a host. But if it does come 0:18:24.520 --> 0:18:27.400 into contact with a host in the case of the diarrhea, 0:18:27.400 --> 0:18:31.800 we've all heard about the cholera syndrome. That is, when 0:18:31.960 --> 0:18:34.920 the cholera gets into the gut and has a totally 0:18:34.960 --> 0:18:39.000 different lifestyle. Similarly, the vibrio and the squid can live 0:18:39.119 --> 0:18:41.800 independently in the ocean, or they can go into the 0:18:41.880 --> 0:18:42.399 light organ. 0:18:42.640 --> 0:18:45.440 Okay, cool. So it's got like this safe little home 0:18:45.480 --> 0:18:47.800 that it can reproduce inside of, and then every morning, 0:18:47.840 --> 0:18:50.480 after it's made a load of babies, it just releases 0:18:50.520 --> 0:18:52.639 the bacteria babies out into the world and then it 0:18:52.640 --> 0:18:53.760 gets to start the cycle again. 0:18:53.920 --> 0:18:54.720 Exactly cool. 0:18:54.760 --> 0:18:56.719 So it benefits from the squid not getting eaten too, 0:18:56.840 --> 0:18:58.800 because it gets to make babies every day. 0:18:58.880 --> 0:19:00.480 Yeah yeah, like a. 0:19:00.400 --> 0:19:04.000 Little protected zone to live in for a day. 0:19:04.320 --> 0:19:05.240 Exactly yeah. 0:19:05.280 --> 0:19:07.080 And why does it have to be a biofilm? Why 0:19:07.080 --> 0:19:09.960 can't it just be like a bunch of these guys 0:19:09.960 --> 0:19:11.840 floating around inside the light organ. 0:19:12.200 --> 0:19:14.840 I think we talk about that particular system as a 0:19:14.880 --> 0:19:18.320 biofilm because of the communication going on that they have 0:19:18.400 --> 0:19:21.280 to be at a certain density for that communication to work. 0:19:21.359 --> 0:19:24.000 So I guess that's kind of a circular definition. But 0:19:24.080 --> 0:19:26.120 I mean basically, you're not going to get light if 0:19:26.160 --> 0:19:29.480 they aren't at a density that allows them to communicate, like, hey, 0:19:29.600 --> 0:19:30.560 we're all here. 0:19:30.760 --> 0:19:32.720 And that's when they decide to produce the light. 0:19:33.680 --> 0:19:37.280 So that definition has to do with density, and they're 0:19:37.320 --> 0:19:41.600 all living inside that light organ, so they're corralled together. 0:19:42.280 --> 0:19:47.360 In other cases, the biofilm forms even without any kind 0:19:47.400 --> 0:19:51.399 of physical sac that they're living in, like this light organ. 0:19:52.000 --> 0:19:55.040 So biofilms can form in all different kinds of environments. 0:19:55.040 --> 0:19:57.720 They can be more out in the wild and just 0:19:57.800 --> 0:20:00.280 decide to clump together too, I see. 0:20:00.359 --> 0:20:03.200 So it's like the collective action here. That's crucial. Yeah, 0:20:03.240 --> 0:20:06.520 And I think the question in my mind was, you know, 0:20:06.720 --> 0:20:09.479