| 00:04 | Mhm. Yeah. Alright. So happy valentine's day. Okay. Um |
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| 00:30 | so we're gonna wrap up Chapter five . Okay. Uh so obviously that |
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| 00:40 | um today is the end of you . So we started to on thursday |
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| 00:51 | would be a viruses part one. as a flipped class. So recorded |
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| 00:58 | for that has been up since last . So um but nothing on Thursdays |
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| 01:04 | example, unit two is all exam stuff. Okay, so uh somebody |
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| 01:11 | smart work due tomorrow. Okay, not a long one, but I |
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| 01:19 | remember that that's due tomorrow. So of course exam on later this |
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| 01:25 | Uh You have any last minute you know, I'll email or office |
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| 01:31 | , you know whatever works and I think any, I don't think I |
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| 01:39 | anything else. Uh So let me let's just begin with kind of a |
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| 01:46 | Of last time. Okay, so finished up chapter four with bathroom information |
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| 02:00 | in the school information. So I uh both those things are can certainly |
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| 02:07 | awful information, nutrients driven, you , you have to have influx of |
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| 02:12 | to maintain that large fire film. In fact even initiated. Um remember |
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| 02:19 | were all about a surface and Right? Um The formation occurs under |
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| 02:30 | deprivation but of course other things as , uh any kind of distress situation |
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| 02:36 | potentially induce in those information. Um of course is a very uh resistant |
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| 02:44 | . Okay and um uh so then went into chapter I talk about zero |
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| 02:54 | . So in a nutshell basically Couple things. So one living in an |
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| 03:03 | world, auction being very reactive can with molecules creating these reactive types super |
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| 03:16 | , etcetera. And though they interact proteins and fake acids, other molecules |
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| 03:24 | them. And so any organisms living the presence of air, whether they |
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| 03:31 | 02 or not, okay. If going to survive in that environment, |
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| 03:35 | need to have protection. Right? have ourselves had the same thing, |
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| 03:40 | have protection against it. We have . O. D. We have |
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| 03:44 | a lace and proxies in ourselves to us with that. Okay. And |
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| 03:48 | similarly, other microbes that live in 02 have that protection. So that's |
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| 03:58 | is uh do they use oxygen? . And what's the requirement? |
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| 04:05 | So some some must have it at concentrations. Others can't handle that because |
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| 04:13 | don't have the full complement enzymes or have lesser amounts of them, |
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| 04:18 | Right? But they still need to they can only handle it at lower |
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| 04:23 | . So you're Arabs clarifies um Faculty Arabs can live with or without |
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| 04:30 | They can they can do the full of respiration, aerobic anaerobic and |
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| 04:37 | Right. And so it all depends what situation they're just they're present. |
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| 04:42 | not What's the best thing? And they of course have the protection |
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| 04:47 | they can live you know in in in an auction environment. And then |
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| 04:51 | the middle is kind of the But in the middle of this diagram |
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| 04:57 | anna robes. Right? So and a rope can be does not use |
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| 05:04 | by definition as part of their They ferment or anaerobic respiration. Um |
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| 05:10 | the what differentiates the an arrow and arrow tolerant. Arab is the presence |
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| 05:17 | protective enzymes. The does not have . So it cannot live in 02 |
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| 05:25 | . Has to be away from Okay, um serotonin and Rokan. |
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| 05:31 | it doesn't use up too. But has the protection so it can live |
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| 05:35 | their environment. Yeah, it's basically distinction between these things. Right. |
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| 05:41 | so biofilm and of course any questions that. Okay, so then we |
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| 05:50 | right into the last half of five is basically focused on death if you |
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| 05:55 | . Okay. Death of microbes. . And so of course we're targeting |
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| 06:00 | you apply any kind of antimicrobial You're gonna reduce levels of all |
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| 06:05 | But of course the ones of interest those that are pathogens because they can |
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| 06:09 | disease. Right. So um and there were focused obviously on the right |
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| 06:16 | of that batch growth curve. Death right? Occurs exponentially. And |
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| 06:22 | it's about how can we uh add to kill microbes that will do so |
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| 06:32 | quickly and at a fast rate. , So logs of death is what |
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| 06:36 | into them. Okay. And so looked at these four terms. This |
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| 06:40 | where we ended last time. All , so sterilization and exceptions disinfection. |
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| 06:47 | , So we know um sterilization that you sterilized, there were no |
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| 06:54 | spores, viruses gone. Okay. not 99.9% killing it's 100%. |
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| 07:02 | And so of course disinfection interceptions, don't do that to reduce numbers. |
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| 07:09 | still remember the Subsys on tissues, tissues. Disinfection of is on inanimate |
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| 07:18 | . Right? Thus you can have two chemicals. Disinfectant can be much |
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| 07:24 | . Right, concentrated more harsh if will think bleach versus isopropyl alcohol. |
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| 07:31 | . Leeches are disinfected as a purple and accepted. So in sanitation relates |
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| 07:37 | to overall reduction of microbial numbers because represents kind of the level of |
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| 07:46 | Right? So I always use the of a restaurant kitchen where you try |
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| 07:52 | minimize the foodborne africa what illness and . And so using gloves, |
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| 08:00 | uh keeping the area clean, disinfecting , um uh food and proper |
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| 08:09 | So any of these things are things can potentially lead to a foodborne |
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| 08:14 | So that's kind of sanitary practices kind what defines or hygienic practices is what |
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| 08:21 | sanitation. Okay, so that kind nutshell is was last lecture. |
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| 08:28 | Any questions. Okay, so let's have some more terminology. So here |
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| 08:38 | so focused on the course production of numbers. So obviously we do that |
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| 08:45 | affecting their growth right now are either growth or just outright killing them. |
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| 08:53 | . And so we have these terms static bacterial silo bacterial politic okay to |
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| 08:58 | that. So anything that's a bacterial agent, like the name implies |
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| 09:02 | you're not actively killing cells but you're kind of inhibiting their growth. |
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| 09:08 | And the killing occur, effects occur bacteria seidel and bacterial agents. |
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| 09:15 | And so if you look at the here. Alright, so let's focus |
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| 09:21 | the solid line and all of My dad prefers the viable cell |
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| 09:27 | Okay, so the solid line, there's two measurements going on here. |
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| 09:33 | a bible cell count which is done briefly explain. You don't need to |
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| 09:39 | their exam or anything you do in lab. Later on basically you'll have |
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| 09:43 | sample if you know what the viable count is in there. Right? |
|
| 09:51 | cell count. What you do is have to get these on a |
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| 09:59 | Okay. In such a way that get isolated colonies, this is not |
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| 10:06 | a street plate, This is using nothing where you're basically putting a lot |
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| 10:13 | liquid on top of the plate, you're gonna spread it like a windshield |
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| 10:17 | right all across the plate. And you you have to dilute it requires |
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| 10:26 | because you know, a social spread the bacterial, you plop 1/10 of |
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| 10:32 | meal on a plate as is is gonna be some themselves. And it |
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| 10:36 | all rode together, there would be big long color. Right? And |
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| 10:42 | you can't get any distinguishing and then colonies. Right? So how do |
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| 10:46 | get that? But you have to , right? So you actually carry |
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| 10:49 | a series of solutions and you sample ones to see which gets you, |
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| 10:54 | know, lots of isolated colonies in form. Because the premise is that |
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| 11:01 | colony Equals one cell. Okay, makes sense. You put one little |
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| 11:10 | on a plate, it's gonna We're almost neighbors will come together to |
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| 11:13 | a colony visible, but it originates one cell. So that's the |
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| 11:18 | It's true for the most part, there are exceptions, but for most |
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| 11:21 | that's true. So what that means you can't call it on the |
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| 11:25 | You're counting cells that are running that tube, Okay, Because that's where |
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| 11:30 | came from. Right? So what have to do again, we're not |
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| 11:34 | into all the details. You there's calculation you do just back calculate based |
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| 11:38 | the delusion made and it gives you parameter called cells. For me. |
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| 11:45 | complicated. Right? It's also called a few per meal for colony forming |
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| 11:53 | . Again, your lab, you'll learn this stuff, but that's how |
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| 11:58 | get a viable capital because things are on your plate are viable cells, |
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| 12:04 | ? So what does that tell Well, if we look at this |
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| 12:10 | growth curves starting from this portion. ? Over here obviously as we measure |
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| 12:18 | bible cells were going up. it's growing. Okay. Uh here |
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| 12:25 | the arrows. You see the that's where we're adding our whatever it |
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| 12:31 | antimicrobial agent. Okay. Of course see at that point different responses. |
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| 12:41 | , what's going on beyond the Our agent. Okay. So the |
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| 12:48 | graph you see here plot is the line. Okay. The dash line |
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| 12:53 | totally count. And I suspect this done with a microscope. You look |
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| 12:59 | the microscope samples and just look at . There's ways you can count cells |
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| 13:04 | well. Um but it really doesn't between live and dead. Just all |
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| 13:09 | can't really tell which one's the dead for alive. Okay. But you |
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| 13:14 | if it's growing you're seeing an increase the number of cells. Okay. |
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| 13:20 | we add our agent. What's going on the left side now? Past |
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| 13:24 | arrow in that interval. So you back to your static agent inhibits |
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| 13:31 | So you're not gonna see any You don't kill him. If you |
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| 13:36 | killing going on, you see that count going. So basically you have |
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| 13:41 | flat no growth. Okay. No but no growth. Okay. No |
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| 13:47 | growth and the under the microscope, number of cells are basically staying the |
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| 13:52 | in that period. Okay, so go to both bacterial cyanobacteria, literally |
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| 13:58 | of those our drops and cell count the agent is actively killing the |
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| 14:04 | Right? So as you take samples here on this side. Okay are |
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| 14:12 | less and less colonies on your plate means viable counts going down. Something |
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| 14:17 | killing the thing. Okay so the then is so that's common to both |
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| 14:24 | that's what they do. That's your bacteriological agents killed. Right then. |
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| 14:28 | the difference here with this pattern? that pattern and see what pattern works |
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| 14:38 | nope. This pattern and that okay the dash line. Um So if |
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| 14:49 | are in both scenarios death is a and we know that because of the |
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| 14:54 | why are we seeing the dash Lyons come back to recital and going down |
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| 15:00 | bacterial lyric anybody. So visualize you're under the microscope. The bible counsels |
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| 15:10 | you that is going on right But bacteria side bacteria stat sir bacteria seidel |
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| 15:18 | . Those cells are under a microscope changing a number. They're kind of |
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| 15:22 | that okay. Are these dead cells yes or not? Absolutely that for |
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| 15:38 | because that's telling you that This this telling you that dang it. |
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| 15:48 | Stupid. This is telling you That is telling you that it's going |
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| 15:52 | . Okay so here two cells are right at the back spine is down |
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| 15:59 | . So what gives so it's here the metro societal agent but they're |
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| 16:07 | Right? But the operative word here lice you can kill cells without |
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| 16:15 | That's what's going on. The Sidelight right? Um They're just they're |
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| 16:21 | there's not being lice that communicated blows up. Okay detergents very commonly those |
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| 16:28 | of antimicrobials melt dissolve membranes. So certainly gonna lice itself. So it |
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| 16:37 | on the back paralytic agent. You really see anything on your microscope after |
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| 16:40 | period of time. Pretty much right the beginning. Right? And so |
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| 16:45 | keeps going down down down down they disappear right? Because they're being back |
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| 16:51 | the spinal agents do it differently. still kill the cells are just cells |
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| 16:55 | intact so that's what's going on. um Now um so there's so this |
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| 17:05 | illustrates the same point. Okay so um we just see to history says |
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| 17:16 | okay so in the bottom you see this would be likely what a looking |
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| 17:23 | a recital electrostatic bacteria, asylum might something like this. All right after |
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| 17:28 | added our chemical or biological agents. let's just say this is the point |
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| 17:34 | the arrow is okay and this is seidel static. Alright So what we're |
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| 17:41 | under the I'm sorry like bacterial igic here. Okay so the soldier is |
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| 17:49 | because they're being nothing complicated. Any about that. Yeah bacterial bacterial. |
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| 18:01 | yes. Typically yes because you can't if you're just doing a complete visual |
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| 18:10 | all the cells look the same. can't distinguish between live and dead. |
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| 18:14 | you can um there are fluorescent dyes can use nowadays that actually distinguish between |
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| 18:22 | and dead cells. So you could nowadays under a microscope you put on |
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| 18:27 | I think it's called accurate and orange . Live cells so you can actually |
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| 18:31 | distinguished by color but the cells are there but now you can visualize by |
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| 18:36 | different types of dyes nowadays. Yeah that that okay. Uh Okay |
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| 18:46 | um okay let's look at this question . Okay so this gets us in |
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| 18:52 | next couple of things here which is uh logs of death. And the |
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| 18:56 | values is kind of the parameter that's to evaluate how well an antimicrobial agents |
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| 19:04 | . So this is says uh the seniors of course is the definition. |
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| 19:10 | right here this okay so if this it is added to a culture containing |
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| 19:21 | of the six cf. You per . And the d value is two |
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| 19:26 | . How many bible cells are left eight minutes Uh predict 99% correctness, |
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| 19:44 | . Let me open it up. now you can answer. Okay let's |
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| 20:27 | down here from 10. Alright so it is going to be d okay |
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| 20:44 | let's just go through so we start that number of cells, one log |
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| 20:49 | death every 10 minutes. So we 2468 right down to 65432. Okay |
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| 20:58 | um and so this parameter of logs death Is used in different ways. |
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| 21:08 | sometimes it's just it's just one log kind of these kind of products have |
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| 21:16 | of modified to their particular product. it's not unusual to see 12 logs |
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| 21:20 | death for some things. So it's kind of depends and so a lot |
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| 21:25 | factors go into that, you know kind of disinfectant agent it is um |
|
| 21:33 | are they what it meant to Okay so there's different ways manufacturers to |
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| 21:38 | this but across the board is obviously killing cells and doing so in a |
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| 21:44 | fashion but they kind of each have own particular um tweak to it. |
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| 21:53 | Now Okay so the value. So just another way to come up with |
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| 21:59 | value. So very typically you have culture so this one happens to be |
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| 22:04 | 28. Right then they do the to it. And of course you |
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| 22:09 | a negative slope, right? Death then you go, Okay let's pick |
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| 22:14 | values that are a log apart. ? So 10 to the fifth then |
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| 22:19 | fourth just extrapolate. Okay and you a difference of about a minute. |
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| 22:24 | I forget what this was. But the value here will be considered one |
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| 22:28 | , one minute to get one log that. So lots of things affect |
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| 22:33 | efficacy. Right, so talk about load that refers to what's the self |
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| 22:40 | of what you're trying to treat. loaded with microbes, is it not |
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| 22:46 | will require you know it may require treatment in terms of concentration of |
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| 22:53 | longer time of exposure, these kinds things. Um the exposure time population |
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| 23:01 | . Is it is it full of uh in those four foreign bacteria? |
|
| 23:09 | . Well that may require something different it was just a cola or |
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| 23:13 | But to be honest and practical sense don't really get those kinds of analysis |
|
| 23:18 | something you're about to disinfect unless it something where your maybe your treatment is |
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| 23:25 | not working then you may need to may be required to do that kind |
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| 23:29 | analysis. But for most things you get to that level where you just |
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| 23:33 | to find out what exactly do you I'm cleaning and trying to get rid |
|
| 23:37 | ? You don't normally do that for practical standpoint but you know it could |
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| 23:41 | a difference in some cases. Organic I think is probably particularly important. |
|
| 23:48 | and um using any kind of pretty sure it probably says so on |
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| 23:55 | Lysol bottle or whatever your favorite is . It will say things surface first |
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| 24:01 | applying that's because dirt organically basically think dirt that's already on the surface. |
|
| 24:07 | ? So not really including the all this could be part of it |
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| 24:11 | it's very dirty which are trying to . It's best to clean it |
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| 24:16 | then disinfected otherwise disaffected may not be too the microbes efficiently. Alright, |
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| 24:23 | cleaner surface then disinfect uh crossing this the nature of the chemical? Uh |
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| 24:31 | it very harsh and can maybe harm surface you're trying to clean? Uh |
|
| 24:36 | it how stable is it? Is is it light sensitive? Some things |
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| 24:40 | light sensitive that don't work as well they're exposed to light? Or is |
|
| 24:45 | is it volatile? Is it like alcohol based disinfectant versus a maybe an |
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| 24:52 | based um have all basically they evaporate quickly. They may not have a |
|
| 24:59 | power or something like uh we called are more sticky if you're the last |
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| 25:06 | volatile Ized. But can you leave weird film on your surface? |
|
| 25:11 | you know, all these things have pluses and minuses point is there are |
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| 25:15 | of things that can affect the efficacy these things. Okay. Um Now |
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| 25:23 | now you might think there's some not an auto play, right? Will |
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| 25:28 | everything all at once. Right. you you don't really ever see I've |
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| 25:34 | seen anything that the treatment that gives that kind of response. Okay. |
|
| 25:38 | they all die it once. Because it can be very fast. |
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| 25:42 | can be a very fast rate. , But not all at once because |
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| 25:47 | it's all about any population that you're Okay, a lot of variables go |
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| 25:55 | it. So think of if it's particularly concentrated with cells, right, |
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| 26:01 | cells in the periphery likely going to killed more quickly than those that are |
|
| 26:06 | the interior. Right? So that there is going to give you a |
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| 26:09 | to kill it. But regardless, know, the members of each |
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| 26:15 | that population are gonna die when they enough damage. Right there, proteins |
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| 26:22 | proteins have been uh destroyed or the and or gas. And so we |
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| 26:29 | to a point where it's too I'm dead. That's not gonna be |
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| 26:33 | the same for every cell in the . That's why there's always a great |
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| 26:37 | uh granted it could be fast but still gonna be a rate. Um |
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| 26:45 | questions about that. So uh let's at so I just threw this one |
|
| 26:51 | . I'm not gonna expect you to again this and laugh, but this |
|
| 26:56 | what we call the disc disc diffusion . Okay, and uh this next |
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| 27:03 | um this diffusion method and I can't with my fingers. Let me take |
|
| 27:09 | off. Try this. Pen is finicky here this oh, there we |
|
| 27:15 | . This diffusion method, right? probably have seen this, I'm |
|
| 27:20 | And the little paper disks. Very contest antibiotics come come like this. |
|
| 27:26 | can test the efficacy of antibiotics but you can take by these paper disk |
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| 27:31 | soak it in anything you want as way to test how effective it is |
|
| 27:36 | the microbes. And so um so you would do here is you would |
|
| 27:42 | step one is make a long bacteria your plate. Right? So you |
|
| 27:47 | take a sample of liquid. Just it all over the place. All |
|
| 27:53 | together, right? But before you and let it grow you lay down |
|
| 27:58 | little discs on top right, they'll in pregnant with whatever you want, |
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| 28:04 | , your favorite disinfectants, whatever. ? Then you lay them down on |
|
| 28:09 | and then you incubate. Okay so can see obviously the areas that are |
|
| 28:14 | are um not clear right all through . This is bacteria that are |
|
| 28:21 | right? But of course you don't any bacteria or not visible at least |
|
| 28:27 | here. Right, clear areas around disk. So chemicals diffuse whatever chemical |
|
| 28:34 | diffuses out of the disc into the um surrounding uh area around it. |
|
| 28:44 | ? And so depending on the sensitivity the microbe it may or may not |
|
| 28:50 | in that area. Right? And how close it grows right to that |
|
| 28:57 | . Whether it's close, right close time. Close. All right, |
|
| 29:10 | more time. My pen is not . Sorry, try this, |
|
| 29:20 | Alright, so whether it's close or away thinking this guy right here that |
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| 29:29 | no that chemicals has no effect on bacteria grows right to the distance likely |
|
| 29:36 | the thing. Okay um Here's a bit is not much effect either. |
|
| 29:40 | is a big effect. So it's it's a quick and easy qualitative way |
|
| 29:48 | say oh yeah this is may be . That's maybe not. So well |
|
| 29:51 | one forget about it. Right So would obviously do more qualitative assessment after |
|
| 29:58 | on ones that are of interest but just the first pass. How's it |
|
| 30:03 | ? So so not at all what you then you can go into more |
|
| 30:06 | study but very easy way to check . And so uh so the with |
|
| 30:13 | that there's a million ways to test whether it's this method you can use |
|
| 30:19 | and test that in different ways. bottom line is obviously in the absence |
|
| 30:25 | the chemical the cells normally. Right you add chemical do you see a |
|
| 30:30 | ? And that's really the bottom Okay and how much you want to |
|
| 30:33 | into that part of it? You qualitative quantitative. That's that's kind of |
|
| 30:40 | to you. But this is a and easy way to start. So |
|
| 30:44 | a question that relates to that. so again so we have a growing |
|
| 30:51 | that gram positive bacteria we added So here would be so obviously we |
|
| 30:58 | grow this thing we would have prior that if we grow this that we |
|
| 31:05 | where mid log would be. Right the arrows indicating mid log and we |
|
| 31:11 | we add our and that's alright so got it. You would know that |
|
| 31:22 | have done this before and saw Okay grow something like that. So |
|
| 31:26 | would know before where mid lock would . Right? And so that's how |
|
| 31:30 | would add our at our chemical. let me get this eraser. And |
|
| 31:37 | so then um we banned the wait hours, right? So we add |
|
| 31:46 | and then it's four hour interval. we don't know what's gonna happen, |
|
| 31:52 | don't know what the pattern will right? We're gonna be exposed for |
|
| 31:55 | hours then will so will transfer it fresh culture, that's what's going on |
|
| 32:04 | here on the top. Right? we transferred to fresh broth without this |
|
| 32:10 | . Right? So we're gonna do right here, that's what's going on |
|
| 32:16 | there. Okay so for and add , let it go for four hours |
|
| 32:24 | transfer it okay to fresh medium without . Okay and so um so we |
|
| 32:32 | this four times we do that. common to do this at different delusions |
|
| 32:36 | the chemical. Okay. There's a of reasons for that. Probably the |
|
| 32:42 | one is you know why a money thing like you can use it as |
|
| 32:48 | lower concentration, you have to use much etcetera. Okay so here's what |
|
| 32:52 | get right? So in our right which is this one? See |
|
| 32:58 | ? So after four hours of exposure be disinfected measure in terms of growth |
|
| 33:06 | growth right then we look here at subculture. Okay which again we plopped |
|
| 33:17 | from transferred it from here and here see what happens. So this knowledge |
|
| 33:26 | , what is likely? How would classify this um disinfected? All |
|
| 33:34 | but let me open it again. , it's right again. Alright. |
|
| 33:40 | . All right, keep going, going. So how would you classify |
|
| 33:45 | ? Yeah, until again exposing four . Take it out fresh medium without |
|
| 33:52 | affecting what happens? Right, Oh okay, you get that. |
|
| 34:21 | . All right, counting down from . Okay. Let's see here. |
|
| 34:50 | . Alright. So uh it's obviously static because because um as we so |
|
| 35:05 | what we're doing here at this point this sample is asking we've exposed ourselves |
|
| 35:14 | disinfected. Okay. And we saw from most of the delusions we have |
|
| 35:23 | no sorry. We have growth no . Okay, so um right |
|
| 35:31 | Alright. No, gross. So we're asking okay what happened? What's |
|
| 35:37 | state of those sets? Are they they still alive? Are they are |
|
| 35:44 | dead? Okay. And that's what transfer to fresh broth was about, |
|
| 35:49 | ? So we put them in fresh without any disaffected to give them a |
|
| 35:53 | if they are where they grow. so we saw that of course that's |
|
| 35:58 | happened. Right? So that leads to believe it's got to be a |
|
| 36:03 | static agent because they weren't killed. were just kind of growth inhibited. |
|
| 36:11 | yeah this is just a quantitative Ok. Gives us a quick and |
|
| 36:17 | . Okay. Plus minus it did us to figure out that this solution |
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| 36:22 | really no good. Okay that was dilute to get an effect. Uh |
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| 36:27 | so we can explore this further of getting quantitative and getting viable counts and |
|
| 36:34 | not to see what's actually going But from this from what you see |
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| 36:36 | you can make the assumption that your . Okay? Um Now similarly we'll |
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| 36:45 | back look back at this one. if we were to um look here |
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| 36:54 | could we say in this clear area this a bacteria static or bacterial seidel |
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| 37:01 | ? Could you determine that? Just at the plate? No you can't |
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| 37:07 | the plate. Oh yeah that's a static asian respectable violated. Yeah it's |
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| 37:11 | a qualitative results. So you have do some further study. You do |
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| 37:15 | it affected the effect of the micro in order to get that information you |
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| 37:20 | to do some different type of Okay But again when you're doing this |
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| 37:24 | of stuff, particularly screening a bunch these at one time. So the |
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| 37:28 | pass is always kind of a qualitative to do it because it gives you |
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| 37:35 | quick answer to at least at least tell you what to explore further and |
|
| 37:38 | not to keep testing. Okay um questions about that. So um let's |
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| 37:50 | at so we'll get into some more on types of agents. Um So |
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| 37:57 | you might guess you know you expose added this incitement or antiseptic or a |
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| 38:05 | of some kind to microbe. What's going to affect? Potentially affect the |
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| 38:09 | you would think? Right, proteins and nucleic acids themselves and that's |
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| 38:14 | they do. Some are more specific certain targets than others but they'll have |
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| 38:20 | effect on all of these. Whether it's the membrane proteins of course |
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| 38:28 | are damaged when you mess with their structure. Right? Or co ordinary |
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| 38:35 | . So being a protein but you it to unfold the nature. |
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| 38:39 | Same with nucleic acids. Right. even go as far as breaking |
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| 38:45 | Okay. That can be done with radiation. So um so it's a |
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| 38:50 | of things these chemicals and treatments Okay so um so we'll look first |
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| 38:58 | physical agents and looking at temperature in ways. So both hot and cold |
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| 39:07 | not everything can be uh huh. every kind of component can undergo temperature |
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| 39:16 | things are affected by that. So have to use other methods. So |
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| 39:20 | like filtration radiation. What happened? so here we're focussed on temperature high |
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| 39:27 | . Right so the autoclave this is like standard conditions 15 P. |
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| 39:33 | I. 421 to B. Or 15 or 20 minutes you see |
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| 39:38 | . But it's the uh just the The operative part is the 15 and |
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| 39:45 | 21. And so right here. so steam under pressure gets you the |
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| 39:54 | that microbes don't ordinarily are never exposed even a hyper thermal file. Okay |
|
| 40:01 | when you're sterilizing something hypothermic file is gonna be of any concern because it's |
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| 40:06 | gonna be in whatever you're trying to , I'm pretty sure. Okay But |
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| 40:11 | so the uh it creates also a heat and that's what penetrates in those |
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| 40:18 | . And so that's why autoclaves are effective in killing and those spores. |
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| 40:22 | so of course you can boil. so there are equivalent treatments right? |
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| 40:28 | autoclave sterilized so boiling for 10 Uh hot air. So oven basically |
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| 40:34 | what that is convection oven of course a longer period of time. But |
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| 40:39 | can sterilize with this. Um Then gonna be other more milder, relatively |
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| 40:47 | free. So pasteurization. These were for foods and beverages uh as a |
|
| 40:54 | gentler way of reducing my criminal numbers at the same time keeping the flavor |
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| 41:03 | texture etcetera of of the product because the manufacturer wants to maintain that right |
|
| 41:11 | know we're out of milk. Trust that look and taste horrible. Okay |
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| 41:16 | you have to find other ways to that part of the food And and |
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| 41:20 | yet get the reduction of microbes. so that's what pasteurization is also. |
|
| 41:26 | and so uh so you need to short uh temp long time. I'm |
|
| 41:31 | high temp short time or low temp time. Okay. And these two |
|
| 41:37 | been around for quite some time. . It's the ultra high I think |
|
| 41:44 | much it's there all these are almost with each other. There's some really |
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| 41:50 | differences. But nonetheless it's a very time. Right in high tech. |
|
| 41:54 | this is a more relatively recent Okay. And it's proven to be |
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| 42:01 | for areas of the world because not has a fridge. Okay. So |
|
| 42:06 | are particularly useful in allowing a product be that undergoes alter pasteurization to have |
|
| 42:14 | long shelf life, right? Without . Well, once you open then |
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| 42:19 | ticking, but it can last on on a show for six months. |
|
| 42:24 | this is for you don't get regular . It's been quite useful. |
|
| 42:30 | And you know with all these methods well, there are indicator organisms. |
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| 42:38 | specific for what they are looking Okay. So for example, with |
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| 42:43 | , if you wanted to make sure is working fine. Okay. It's |
|
| 42:48 | reports that the so you just get a bacillus bacillus cultures are used for |
|
| 42:54 | standardization to see if it's working right milk pasteurization. It's very common to |
|
| 43:00 | this one. This has a cock . L. A. Has a |
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| 43:04 | think among the highest known resistances to but they don't form. And those |
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| 43:10 | . Right so they have a parameter measuring the pasteurization method on these organisms |
|
| 43:15 | make sure they can reduce their numbers . Um Now the cold temp |
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| 43:24 | cold temp does not kill typically slow down. Okay. And um you |
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| 43:32 | refrigerated foods right? To prevent spoils ? Provided you know as long as |
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| 43:39 | can because it uh it slows the down my coach. And some aren't |
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| 43:46 | are inhibited by um the preservation, ? So we in the lab we |
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| 43:54 | minus 80. I've used minus 20 minus 80. You can preserve |
|
| 44:00 | You have to kind of put him like a uh an antifreeze, so |
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| 44:03 | speak. Typically in glycerol to prevent one thing's freezes the ice crystals that |
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| 44:09 | to actually kill. So if you gently freeze and that's what use like |
|
| 44:15 | or something similar to kind of prevent . And we've had bacteria in minus |
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| 44:21 | for like 2017 6 years that I still revive. So quite um effective |
|
| 44:29 | that. But you know in terms food uh refrigerating food, there are |
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| 44:38 | is a type that actually grows refrigeration listeria, we'll talk about that at |
|
| 44:44 | end of the semester in the context diseases. But um it's found on |
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| 44:52 | of process like Delhi needs your your and ham alone and salami. Um |
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| 44:59 | the like and uh it's we've likely have all had hysteria. I'm notorious |
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| 45:07 | eating foods path through exploration date so to the annoyance of my wife. |
|
| 45:12 | uh I mean, I'll never really sick from I don't go to extremes |
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| 45:18 | it's very slimy or something. And . Um but it's why for most |
|
| 45:24 | us have healthy immune systems on an . But pregnant pregnant women do have |
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| 45:29 | be America. Right? And so it can affect the fetus, listeria |
|
| 45:34 | so um so it's practice for pregnant to not eat these kinds of foods |
|
| 45:42 | pregnancy. Okay, um now So again, not everything can hold |
|
| 45:48 | temperature. So we use filtration. call label liquids which are sensitive to |
|
| 45:55 | high heat. Uh so uh very . Really used to use 0.2 micron |
|
| 46:02 | . All the 0.45 will will remove bacterial types. Um 0.2 are generally |
|
| 46:11 | . Um but they don't really can't get rid of viruses. Oh, |
|
| 46:17 | those aren't really a concern. Typically your filter sterilizing. Uh the |
|
| 46:27 | And we have media in a lab can't be autoclaves. So we have |
|
| 46:30 | use filter sterilization for it. So certain things that use it for um |
|
| 46:36 | , radiation radiation um as I'm you know, as you look at |
|
| 46:44 | electromagnetic spectrum, we're interested in wavelengths are kind of on this on this |
|
| 46:54 | . Okay. To the right, , over here and beyond. |
|
| 47:03 | Less than that. So that's UV branch. 200 to 80. And |
|
| 47:08 | even lower. Right? So remember equates to wavelength shorter wavelength more |
|
| 47:13 | Okay. And so you be Non ionizing radiation and gamma rays. |
|
| 47:20 | rays ionizing radiation. Okay. So you'd be like uh can be effective |
|
| 47:28 | uh surface disinfection. We call We have a biosafety cabinet. We |
|
| 47:36 | culture work in as a as a light. And we turn it on |
|
| 47:39 | night to zap the surface, To kill anything that's on there. |
|
| 47:43 | it kills through mutating the cells based in D. N. A. |
|
| 47:50 | create enough of these. Of course can be lethal. Um But you |
|
| 47:55 | , many things stop UV light a plastic Petri dish that can stop |
|
| 48:00 | light. So uh to get more of penetration if you will uh gamma |
|
| 48:06 | X rays time. So you can the difference in wavelength to 300 nanometers |
|
| 48:13 | less than 3000.1. So, super energy and can generate these kind of |
|
| 48:18 | radicals you see here. Okay. fragmenting pay gas. So it's quite |
|
| 48:25 | . And it has it's gotten more more traction I guess as and and |
|
| 48:34 | um use on food frozen foods like chickens and things. Uh radiation is |
|
| 48:40 | common nowadays to obviously the danger there food borne pathogens using radiation to zap |
|
| 48:47 | uh very briefly obviously cause you don't to cook the frozen chicken cook the |
|
| 48:52 | . But they do use that industry that purpose. Um as well as |
|
| 48:56 | like uh plastics and other types of you wouldn't use radiation for liquids. |
|
| 49:08 | radiation could probably to a degree, it's uh it's also why you wear |
|
| 49:13 | lead apron. Right? Because it's powerful radiation. Um Okay, so |
|
| 49:21 | agents probably familiar with a lot of . So again, I'm not getting |
|
| 49:26 | in the weeds and super detail on kind of like, here's here's some |
|
| 49:31 | , there's kind of in general terms they do. Nothing more than |
|
| 49:35 | Okay, so they're phenolic six are compounds. So you see like over |
|
| 49:42 | , okay, these tend to be volatile. More, you know, |
|
| 49:46 | you apply them, can they hang for a bit? Okay. But |
|
| 49:50 | all they all three have in common proteins. DNA is lifted. So |
|
| 49:55 | of a range of targets here. , beta nine. Is that yellow |
|
| 50:00 | ? You probably seen your doctor's office wash hands with um I also is |
|
| 50:06 | The alcohol. So ethanol, we ethanol in the lab disinfect bench tops |
|
| 50:14 | it turns out that water does make difference. Right, so it's actually |
|
| 50:18 | ethanol Is more effective than 95%. , so, so alcohol is kind |
|
| 50:26 | help dissolve membranes, they get inside water helps to be more effective at |
|
| 50:31 | . Okay, so you got a bit more water to it. That |
|
| 50:34 | increases its its efficacy. Okay. so detergents. So this is a |
|
| 50:43 | these are called. Co ordinary means think they're called. But they have |
|
| 50:48 | common structure of being very long hydrophobic if you will. So that really |
|
| 50:55 | a fossil lipid that allows them to membranes which I um gasses. |
|
| 51:02 | So gasses aren't good for liquids. penetrate very brilliant liquids. But for |
|
| 51:09 | like plastics, your pipette tip boxes boxes, pipette tips, Petri |
|
| 51:15 | These things are often uh gasses are for that. Monoxide is the one |
|
| 51:20 | choice uh and it can be a agent for sure. Um as well |
|
| 51:27 | things like syringes, tubing etcetera. so what happens is it um in |
|
| 51:33 | presence of acid or base is what the kind to be really reactive forming |
|
| 51:40 | kinds of charged species. Okay. then those interact with proteins and gasses |
|
| 51:47 | cause damage. And so they can quite effective in in kind of what |
|
| 51:51 | used for which basically plastics of different and and these kinds of solid structures |
|
| 51:59 | you will. Right so um okay they're resistant. So because disinfectants attack |
|
| 52:12 | targets in itself, it's not common um bacteria to become resistant to. |
|
| 52:21 | they would have to accumulate enough mutations be able to counteract every target that |
|
| 52:27 | disinfectants or treatments are generating in the , it's not common. The only |
|
| 52:33 | it can be a problem is if then use that say for example |
|
| 52:39 | a very low concentration as you lower concentration of disinfectant below what you should |
|
| 52:47 | using. Okay. The manufacturer recommends the number of targets is less for |
|
| 52:54 | disinfecting. And then potentially mutations can that allowed to be resistant to |
|
| 53:00 | This chemical back here. This Right. This one is found in |
|
| 53:08 | found in a lot of hand Ok. It's and it's just been |
|
| 53:14 | because it was being put in very concentrations of bacteria became resistant to |
|
| 53:20 | So it can happen again if you you really minimize the concentrations of these |
|
| 53:26 | . Now, in contrast, antibiotics we have single parts. Right? |
|
| 53:35 | it's a um an enzyme that's part a process like several synthesis or Viber |
|
| 53:43 | subunit. Right? Protein synthesis. they typically all have single parts. |
|
| 53:50 | ? So it's not uncommon that, know, take a single mutation occurs |
|
| 53:56 | makes it resistant. Okay, of course that doesn't happen. What |
|
| 54:02 | is the situation is the constant exposure antibiotics because they're everywhere right there in |
|
| 54:09 | food we eat there in um they're the water. Right. Take |
|
| 54:15 | I think data where samples are taken different water samples um from sewage and |
|
| 54:22 | amount of antibiotics are like nuts. , so of course it's the presence |
|
| 54:28 | those that sets the stage for resistant . Right, Okay. Natural |
|
| 54:36 | Right. So we can minimize Okay. And minimize indiscriminate use about |
|
| 54:45 | other than that that can go a ways. But uh but of course |
|
| 54:51 | easier said than done I'm thinking but the we'll talk more about antibiotics veteran |
|
| 54:59 | but I'm only gonna I'm only showing just for illustrative purposes. Right? |
|
| 55:04 | the mechanisms of resistance. So it's . What you might think right if |
|
| 55:08 | have a bacterium and here's antibiotic, can it do to become resistant? |
|
| 55:15 | it can completely obliterate. Let's just at the diagram right? You can |
|
| 55:23 | this basically just destroy and activate the did too or whatever. Right? |
|
| 55:31 | just inactivated. Okay. Um It just say let's not let it come |
|
| 55:37 | to the cell. Okay. So things typically come in through various types |
|
| 55:42 | Torrance you know on the surface there's mutation occurs that. Now the specificity |
|
| 55:48 | commit to the cell. Alright, way is alter the target. |
|
| 55:56 | That was the right resistant. So to that. Halloween on the on |
|
| 56:05 | peptide cross bridge. Well it mutates now it's not alan there is something |
|
| 56:09 | you've altered the target. So now becomes resistant. Right? And then |
|
| 56:14 | then you can also pump it Alright that's another mechanism. So the |
|
| 56:20 | we talked about you know the cells cells kind of just stopped growing. |
|
| 56:25 | ? So so having um growth is not always for every antibiotic I'm finding |
|
| 56:33 | active growth, the antibiotic works But And so the bacteria is simply |
|
| 56:38 | not grow, right? And then antibiotic concentrations dissipate and it begins to |
|
| 56:44 | . So all different types of Okay. But it's why right? |
|
| 56:50 | we have to constantly having to find modify, modify what we have to |
|
| 56:56 | kind of tweak it somewhat. So definitely a war. And uh lastly |
|
| 57:04 | other other kind of ways besides chemicals. Right? What can we |
|
| 57:11 | ? Well, we could boost what already have. Alright, so probiotics |
|
| 57:19 | your own microbiome is really acquire your system. It does help your immune |
|
| 57:25 | . Okay. Uh So boosted with . If you are on antibiotics for |
|
| 57:33 | reason or system suppressed somewhat, then probiotics can help that. Okay. |
|
| 57:44 | And finally face Therapy. I think is becoming thing right? Is this |
|
| 57:51 | here? Um It's so we'll start about this on thursday. But fade |
|
| 57:59 | bacterial viruses. They're specific for bacteria there are species specific. Okay. |
|
| 58:07 | so there was a case and I it here or not. Um |
|
| 58:13 | An article here called Face Therapy. had no idea this has been going |
|
| 58:17 | for like 100 years. Okay. 100 years ago they didn't know as |
|
| 58:21 | about faith. The guy that discovered . This guy uh This is looking |
|
| 58:26 | 19 hundreds, 1910, 20 Of course Germ theory was well known |
|
| 58:32 | then we knew forward diseases he discovers that they infect bacteria. Put two |
|
| 58:38 | two together. Right, you fade kill these infectious bacteria makes sense. |
|
| 58:44 | they weren't really up to at this . You really had a very well |
|
| 58:50 | fage for mass production and I don't know all, there was no |
|
| 58:54 | So it kinda had mixed results but idea the idea kind of waned. |
|
| 59:00 | or they were actively working on it then it comes back really more |
|
| 59:05 | Okay, so this person here, were both on vacation in Egypt and |
|
| 59:13 | guy comes down with this disease. caused by a senator Baxter. |
|
| 59:20 | And there's no antibiotics to control So she scans the internet and saw |
|
| 59:26 | on page there. So they actually to the lengths of finding a page |
|
| 59:32 | would in fact this bacteria. And took like there were people that of |
|
| 59:38 | study page and they have like libraries cultures of page maybe end up having |
|
| 59:44 | to isolate from with the sisters different hunt which included coming through uh I |
|
| 59:53 | new faces from sewage barnyard waste, of navy ships. They finally found |
|
| 59:59 | and after taking the page improved almost . Right? So this has like |
|
| 60:08 | I think 13. So this is really spurred on again and it's logically |
|
| 60:13 | makes a lot of sense. Very specific in terms of the the |
|
| 60:18 | agent. Finding the agent. I believe that for every living thing out |
|
| 60:22 | there's a there's a virus that affects , Right? And so of course |
|
| 60:27 | lots of bacteria fades and so I this is the coming thing. Uh |
|
| 60:32 | think it's the right direction to But there's there's lots of lots of |
|
| 60:36 | here that have to be worked out because bacteria can become resistant. So |
|
| 60:41 | have to have that to to So but certainly I think a promising |
|
| 60:47 | to go in terms of fighting these infectious agent, especially with the level |
|
| 60:52 | antibiotic resistance we're seeing nowadays. So anyway I just want to throw |
|
| 60:56 | in uh the uh I think good . So alcohol early and uh again |
|
| 61:13 | have any questions you can email Come office hours. Uh |
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