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BIOL 2320_Microbiology for Non-Science Majors - 2320_9_28_23_CH7_edited
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00:00 OK. So chapter seven. So , this is applicable to those of
00:05 of you who are most of you are gonna be in health care,
00:08 ? Nurses, et cetera, um microbial growth, right? You're gonna
00:12 welcome from the clinic hospital. What you, you're gonna smell the sweet
00:17 of disinfectant, right? Um Because how you control growth, right?
00:23 , disinfectants, uh sterilizing agents, et cetera. So uh so we'll
00:30 at some of these methods, Basically kind of what's the basis for
00:35 you kill microbes? OK. Uh are the ways physical chemical methods?
00:41 . Um And so of course, gonna be a lot of terminology associated
00:45 this, but what we're looking at really the and so just uh real
00:50 , I kind of summarize kind of things to know once we finish this
00:55 is um terminology used to describe these uh uh the um types of
01:03 Why, how it, why is occurring in such a fashion?
01:06 How you kind of use some of measurements of this thing we call devalue
01:12 then uh the various methods. And what we're focusing on here having gone
01:17 uh the chapter on growth, So we had a growth curve like
01:22 to a number of cells in And you see we had lag phase
01:30 long phase and stationary. And then so basically in microbial controlling microbial
01:38 we're focused on this part, That's what we want to do is
01:43 some kind of chemical or physical condition the at the system and, and
01:50 kill, kill things, right? to do so uh in a rapid
01:55 , right? Make this, make as fast as you can.
02:01 Uh Let me anyway. So we're on the death part of the
02:04 right? How do we kill these and kill them quickly. OK.
02:08 let's look at this question. So you know, we had this
02:12 similar question in um chapter one, ? This is one of my pet
02:18 , the this term sterilization, how misused, right? Yeah. Sterilization
02:48 OK. So remember, but I you at the beginning, right?
02:52 taking it's OK to take none of above. OK? It's OK to
02:58 that one. All right, if . All right. Professor.
03:05 OK. Shout, what is What is it? Hello?
03:12 Don't worry about it. I'll redo . So yeah, new session
03:16 new session ID. OK. So it again. Just answer real
03:28 OK. All right. OK. this. All right. Then
03:49 So I think, uh, oops, 553690. There we
04:06 That's a good distribution. Right. , if, and none of the
04:09 sterilization, if you sterilize something by this two by two section here,
04:16 would not detect any cell virus No living thing. Ok. Or
04:26 or spor and no spor all Completely, completely devoid of any
04:31 Ok. Um, there's a few that can do that. Of
04:35 an auto, certain chemicals can do . Uh Certain gasses can do
04:40 OK? And so you can even things in an oven if you do
04:44 long enough. OK. The point no living thing, virus or endospore
04:49 present. OK. So when you're your lab bench with 70% ethanol,
04:55 are not sterilizing, you're disinfecting. ? If you're applying it to your
05:01 , skins, isopropyl alcohol, your . OK. Um Pasteurization is a
05:12 heating, so to speak, to microbial numbers, but they're not going
05:16 to zero. OK. Um That's more hygienic practices. Well,
05:23 gonna, we're gonna touch on all here in a second. Uh Degerm
05:26 more mechanical action like washing your hands then doing this kind of thing.
05:31 . So, but none, none A through e is bringing it down
05:35 zero. OK. Sterilization is bringing down to zero. OK. So
05:43 so, OK. So the um obviously we, when you do any
05:50 of these processes to reduce numbers, of course, are reducing the numbers
05:54 everything that's there, right? But we we try to target pathogens,
06:00 ? Because that's what is is the , right? That's what causes the
06:04 , right? Disease. So, , so when you're doing these
06:10 you know, take your favorite cleaning , right? Lysol, whatever,
06:16 ? Any of these people that many the manufacturers of these things are testing
06:20 pathogens, right? You can just on the label and see that you'll
06:24 an example of this here in a . So as we go through as
06:28 mentioned already, right, sterilization, ? Destruction of all living microbes,
06:32 , viruses right goes down to zero infection versus antisepsis, right? So
06:37 do you, what are you applying to? Right? If you applying
06:40 to living tissue antisepsis, this inanimate objects, walls, floors,
06:46 , bench top doorknob, what have ? Ok. Um For that reason
06:51 disinfectants are applied to these kinds of , you can, they can generally
06:57 always but generally be more stronger more more um caustic or you
07:05 more harsher if you will like think bleach, right? Uh washing your
07:11 with bleach versus with the hand right? Bleach is gonna be really
07:14 , right? But it's effective Bye. Um Degerm as mentioned is
07:20 of introduces the mechanical action part of just things physically off, right.
07:26 the action of the soap, plus hands helps to do that. Um
07:32 , this more relates to hygienic So think of if you've worked in
07:37 , in a restaurant, right? you go to the back kitchen,
07:41 ? Uh the kind of practices you there, right? Are the workers
07:45 like hair nets? Right? Are wearing gloves? Are they keeping the
07:49 clean or they work? Is there everywhere or is it, is
07:53 uh, is it dirty, is food everywhere on the floor and
07:56 Right. So, using clean practices , and, and, and by
08:00 this, you're uh, minimizing the for obviously in a restaurant, food
08:06 illnesses, right? Have, on the food and, and uh
08:10 it safer. Ok. So by this, you're basically reducing the overall
08:16 of everything, of course. And, um, you know,
08:20 safe levels and so, quote, , what's safe levels? Well,
08:24 what's determined by your local health right. So we've all seen maybe
08:30 the, the restaurant reports that come on, on Fridays on your local
08:35 stations, right? And they have list of, oh, so,
08:37 so restaurant 10 violations for, you , improper temperatures, right? Not
08:43 food at the right temperature instead of refrigerated, sitting out, um,
08:47 uh, uh, presence of rat , right? Things like this.
08:51 are all things that are not obviously practices, right? So,
08:55 so that's what you try to do terms of sanitation. So um so
09:02 mentioned before Lysol, an example, you can look on any, any
09:06 your favorite dis disinfectant you use in house, right? You can look
09:09 it and you'll see a label that have a very similar types of
09:14 So these are just what they're tested and there's a common set that all
09:19 will use to test. And so will include um both, for
09:25 gram negatives like an E coli. you go. 015787, right?
09:30 engine engine, right? Remember that staff of the gram positive. So
09:35 always gonna, there's always gonna be between these types in terms of
09:38 So you test both different types of . OK? So, um and
09:44 have a number on there, For marketing purposes, they'll throw a
09:48 . Uh of course they've tested it so this says kills 99.9%.
09:53 Um Kills cold and flu. This hundreds of services in your home.
09:58 . Nice. Uh Sanitizing soft et cetera, et cetera. All
10:02 . So they all have similar kinds language on here. So, um
10:08 , so just to get a, idea of what we're talking about numbers
10:13 and to prove, you know, you're killing 99.9% are you really getting
10:20 to zero? Well, kind of . So if you killed 99%.
10:25 ? You've killed, ok, we're in a million. Ok. If
10:29 killed 99% of them, you've killed cells. All right. So you're
10:33 to, you're down to, two, two, uh, 10
10:42 the fourth, right? So, both numbers here and on the,
10:47 . Ok. So 10 of the to 10,000 viable cells now, with
10:51 99% killing. So, logs of right around from 10 to 6 to
10:56 to the fourth. That's two OK? And that's what we're looking
11:00 when we're, when we're focusing you know, the parameters you use
11:04 measure how well something's working in terms killing is logs of death.
11:11 And so, um the uh So the uh um go another,
11:20 we go to what Lysol has 99.9 well, that's 999,000 cells
11:26 but we're not going to zero. still, we still have cells
11:29 right? 1000 much less, But the point is we're not
11:33 right? This is the action of disinfectant or it could be antiseptic is
11:37 the numbers down. OK. So we go to three logs of
11:41 OK. Oops. And so uh this log of death is the parameter
11:45 , we look at uh in a minutes, we'll look at the value
11:50 a, of an agent, whether a disinfectant or antiseptic, whatever the
11:54 relates to how long to get one of death, right? And so
12:01 only is the um the amount of important. OK. Uh But how
12:08 does it take you to get there another factor as well. Does it
12:11 you five minutes or it takes you hours or five days? Right?
12:15 , you wanna, you like to a combination of lots of death in
12:18 short amount of time. OK. um and various factors play into
12:24 OK. So uh OK. So uh obviously you're looking for a a
12:31 , you add the agent and it down. All right. That's obviously
12:34 you're looking for, but you can uh different effects, right? So
12:38 basic terms we use for this are , static bactero, bacterial li,
12:46 ? Um Bacterial static is inhibitory. you're not really killing cells but you
12:52 inhibiting their ability to, to So it's kind of static,
12:56 Ie but you're static. OK. two are both killing mechanisms, bacterial
13:02 bacterial li. OK. And so if we look at you,
13:08 you look at the graphs here, ? Let me put the third one
13:11 here. So all three graphs, ? So the dashed line, the
13:16 line represents total cell count. And could get this by looking under a
13:22 . OK? You take a known and you put it on your
13:26 There's a special slide you can use count cells, right? And so
13:31 basically are counting all the cells you . OK. And that's what the
13:35 line is. OK. So the is showing us. So in all
13:41 graphs, the arrow, it's showing where we're adding whatever the treatment
13:50 disinfectant, antiseptic, whatever. So that's the point at which we're
13:54 . So cells are growing initially and we add the agent. OK.
13:59 then um what's the effect after Right? So in, in both
14:04 , we are measuring, taking a at different times, looking under the
14:09 and counting the cells that are And then as well, we're doing
14:13 called, that's the, the, , the dark line, the non
14:19 line that's viable count. OK? that you're measuring the total number of
14:26 cells, OK? The total count the microscope is those cells can be
14:33 or alive, right? You can't the difference between a alive and dead
14:38 if they're both looking like this, it's a cox a cous, if
14:42 both look like that, you don't which one is dead, one's
14:46 right? You just know the total of them. OK? But you
14:49 do a special another technique that allows to measure live cells and you can
14:54 that count. OK? We call viable count. And so, um
15:00 so that's what you see here. viable viable count and total cell
15:05 So, bacteria static agent flattens out further growth, but it's still it
15:12 viable but not growing. OK. what bacterial static is. OK.
15:17 um the viable count flattens off. . The uh bactericidal and bacterially in
15:25 cases, the viable count this goes viable count. So, viable cells
15:33 going away, right? They're being by the agent. OK.
15:40 Um Here versus here looking at the cell count, OK? We're gonna
15:47 it right here, right? um the under the so different
15:54 So here is the total cell This is what you're seeing in the
15:58 , right? So they're staying the right after we've added the bacterial sidal
16:06 , OK? It's the same bacterially . We are seeing cells disappear,
16:12 ? So viable count, right? please call this one here and this
16:21 is here, OK? We know cells are being killed, right?
16:26 that's what this is telling us viable going down, viable count going
16:30 So, cells are being killed with treatments. Just when you're looking at
16:33 microscope, you might go OK, going on? Well, because you
16:37 , you can kill cells without blowing up, right? They're essentially being
16:41 up here, right? Because they're . So it's basically that's what we
16:46 a bacterial litigation license. The cells it, right, no longer present
16:50 that's what's happening as the agents working it, but you can still kill
16:56 without blowing them up, right? can inhibit protein synthesis and they just
17:00 but they still remain as a, cell look like a viable cell,
17:04 they're dead. OK. And so , this is the difference between bac
17:09 agent. OK. Are you obliterating cell? Are you just still
17:14 Ok. Um But the point is counts going down. And that's,
17:19 that's what's important. OK? Um just, you know, that's the
17:26 . They both, both in both , bacterial Matic, you're killing
17:31 It's just under the scope. They are, are dead but not lied
17:36 they're lied and obviously dead as OK. Um Any questions about
17:43 OK. And um and the agents different effects, some are bactericidal but
17:49 batic, some static. OK? And so we'll look at some of
17:55 in a, in a little So here. Um OK. That's
18:03 . OK. So you don't, you don't ever really, you don't
18:10 where when you apply the treatment, it is that everything instantaneously dies,
18:17 don't, you don't get that. ? You can be very close to
18:20 maybe, but it's always at some , it's a death rate of some
18:26 . OK? Uh Because it's all accumulation of damage, right? So
18:32 of a population uh will accumulate damage the chemical or whatever the treatment
18:39 is working on them. But cells slightly different. Maybe you have a
18:44 of cells that you're treating and maybe more on the outside are more susceptible
18:48 those underneath, right? If you a big glob of cells, and
18:53 that will introduce differences, but just you know, cells may vary
18:57 maybe, maybe their position or location affect it. Uh So the point
19:03 you don't, when you apply a , even like gamma radiation, which
19:08 super high energy, it can it still goes down at a,
19:13 a rate. OK? And um again, all about accumulating enough
19:19 to where again is enough to kill . OK. So um the um
19:29 uh efficacy of agents, OK. the devalue this is that again,
19:33 we're going to kind of logs of , right? How we the parameter
19:37 used in different manufacturers do kind of their own values. I mean,
19:44 all about, you know, negative , right? Getting death. Uh
19:48 , and doing that, you in a reasonable amount of time.
19:52 . So manufacturers use what's called the 12, you get 12 logs of
19:57 , right? Um But uh but all about, you know, obviously
20:03 cells. And so here's a basic that shows um a treatment being done
20:10 this particular organism. So here's where start, right? Of course,
20:14 have the downward slope cells being OK? Here's exposure time,
20:20 Then you just pick a couple of , right? That represent a one
20:25 difference, right? 10 to the 5, 10 of the fifth,
20:28 sorry, and 10 to the that's one log difference, right?
20:32 when you get one log of 90% killing. OK. And so
20:38 is the time frame for that? you just pick those two points and
20:41 just look down right here and the is about one minute or so,
20:47 ? So you can say the devalue this particular treatment is one minute,
20:53 ? It took one minute to get 90% death, ok? And so
20:57 just extract it from, from the . That's all you're doing.
21:02 And so like I said, manufacturers have different standards. Some have like
21:08 , you know, like I a deep uh may expand on just
21:12 just one log of death or maybe . Ok. So it all,
21:16 all depends on the the manufacturer, ? But the point is the constant
21:21 it's about getting death of cells, ? So there is um a lot
21:28 things that can influence how well a treatment works. Um Obviously, you
21:37 how much, how much of the is present, how much of the
21:39 are present, uh how dirty is surface has a big impact. So
21:44 why they say um even just for cleaning, right? If you're going
21:49 um uh disinfect um a toilet bowl a floor would have you,
21:56 That it's best to first clean Right. Sweep vacuum. What have
22:02 ? Right. Use just a general over the counter cleaner like pledge or
22:08 . You know, because that will what we call the organic load.
22:15 . Because that in itself, just dirt and stuff by itself can absorb
22:21 , uh, antiseptic or your And, um, and then,
22:26 if you didn't clean it first, , you know, the disinfect it
22:32 , not all of it would be very well. Right. Getting to
22:36 you want to disinfect. And so getting rid of the dirt and the
22:39 and the re and whatever first, a general cleaning is more effective,
22:43 ? Because you reduce that material that , that, that may not even
22:48 biological, right? So you, , then you can go and have
22:52 more effective disinfection that way. So, um, exposure time,
22:58 . Uh, how concentrated is the product? Um, how long
23:02 you leaving it on some, chemicals, uh, evaporate rather
23:09 So, something like ethanol doesn't last long. Ok. But something that's
23:13 , um, something like the chemicals call cannoli compounds, these kind of
23:19 around for a while, they don't so quickly. So that has a
23:23 kind of stain power. Ok. it can be kind of that feel
23:28 somewhat sticky feeling on the bench So, uh, there's a lot
23:33 , uh, what do you call kind of considerations? Maybe,
23:37 maybe you don't want that sticky right? But that might be a
23:41 , have a better staying power and power. So it's, uh,
23:45 know, it also, maybe what applying is so harsh and you're trying
23:49 clean a, uh, a metal of some sort and you corrode
23:52 you know, because the thing is harsh. So there's different considerations
23:55 you have in applying these different types chemicals. Ok. Um, ph
24:01 , some things are light sensitive, have to put it in a brown
24:05 so the light doesn't affect it. , it can damage the effectiveness of
24:08 agent. So lots of different things , can affect, right? If
24:12 have a disinfectant of some sort you in the garage, you kept it
24:16 , in the Houston heat for all long and now you want to use
24:19 . Oh, I don't know. may be ok. Maybe not.
24:22 it just depends. So a lot different factors play into this.
24:26 So, um, all right. let's look at an example of a
24:32 involving like this, this devalue. . And, uh, the,
24:41 once again, let me try again . Stupid connection. Yeah, I'm
24:50 , I don't get this, let try one more thing here.
24:58 So bear with me. Uh, know what, I'm not gonna risk
25:04 this whole thing shut down again. you'll get the points for it,
25:09 worry. About it. All So just, we'll just answer because
25:11 don't wanna have to go through another of this thing again. OK.
25:16 uh take a look, give you few seconds. It's not that
25:22 All right. So we got a culture that's at 10 to the
25:27 So CFU per M that's how you viable count. CFU per mil is
25:33 cells, colony forming unit, If you're in a lab, you'll
25:37 this uh deter uh measurement in lab later this semester. OK. So
25:45 have an agent that has a devalue 10 of two minutes. OK.
25:50 so how many viable cells were left eight minutes of exposure? Right?
25:55 there it tells you what a devalue right? Length of time to get
25:59 log of death. Ok. So think I have a, so that's
26:05 you're starting out with. OK. what do you ending up with after
26:11 minutes? And OK. Anybody you guess. Wow. Oops.
26:33 The see I told you it was hard, right? OK. So
26:40 , right? The value, right two minutes. So point point 0.8
26:46 . OK. Um All right. testing these chemicals, right?
26:53 very popular uh science fair, Junior high et cetera is doing these
27:00 of things, taking household products and how well they work. Um I've
27:06 everything from just basic household cleaners to spices, going to the spice rack
27:12 see how does Cayenne pepper work as as a disaffected? How does pepper
27:16 ? So very common? And so and they, they use not this
27:22 but they use the other method we'll about here in a second. So
27:26 you're doing lab is similar to this , this is what they call use
27:30 test. And there's a bazillion ways test antiseptics and disinfectants. The bottom
27:37 for all these is obviously you expose cells to a disinfectant or an
27:42 Are you seeing death occur basically in ? And you can, most of
27:47 are kind of like strictly qu qualitative a a look and see like getting
27:53 . Is it, I mean, it still growing? Is it viable
27:56 is it dead? Right? Uh you can get more specific,
28:01 If you uh later on, but , you're just trying to scream,
28:06 ? And so you kind of just want a yes or no answer more
28:08 less you can for those that give the yes answer, it's killing.
28:12 can go further into what's happening. typically you're kind of just let's see
28:16 happens. Let's get a yes or answer on this, right? And
28:19 with the metal rings uh in you use glass beads for this.
28:24 but the point is that you expose rings, uh take the rings and
28:28 them in a culture. OK? actively growing culture and then the cells
28:33 just stick, stick to the OK? Or the glass beads,
28:36 you're using that and then you have in there maybe for a minute or
28:41 and then you'll uh take them kind of dry off the excess
28:45 And so now they're the bacteria stuck, stuck to the surface of
28:50 ring. OK. Then you take ring and you plop it in disinfectant
28:55 . It's very common to use different of disinfectant. Um You wanna
29:02 OK. If I, if I a uh 1% solution of disinfectant,
29:07 I also use a 10% solution and the same effect? And if you
29:13 well, then you can save some because you use less disinfectant for the
29:17 dilute solution, right? So um you typically do different dilutions and then
29:22 you keep it in there for just 10 minutes. It's kind of a
29:26 condition you use and you use room because that's what you typically apply disinfectants
29:32 whatnot to you know, this regular temperature. And so let that go
29:37 then um move the rings and now going to put it into fresh broth
29:46 disinfectant. OK? So then you'll , OK? You'll incubate that.
29:52 there's no disinfectant here. OK? it, let it grow or see
29:57 it does grow. OK? So , you're, you're testing to see
30:02 , what's the state of the cells here? Were they killed by a
30:06 ? Somewhat killed, they survive. then you look to see,
30:11 Is there growth? OK. No or is there a little bit of
30:18 had somewhat effect or is there no ? Right? Is it disinfect it
30:23 , kill them no more viable Right. And that's a very
30:27 easy test to do. OK. And basically typically just go OK.
30:34 it plus plus or minus? Or is it plus plus lots of
30:41 ? Right? That's again, this is just a strictly qualitative
30:46 Yes or no. OK. Um common is this one here. So
30:54 filter disc method. OK. So you do is you, we'll have
31:01 plate and you'll swab the plate with , OK? Like, so now
31:10 just lay down a bunch of cells your plate and you ink and then
31:15 didn't have to, of course, them to have them grow. But
31:17 you do that, you put down disc like you see here in the
31:23 and that will be impregnated with the or, or or antibiotic, they
31:28 test antics this way. And so what you're gonna do is because the
31:34 in here will diffuse out away from disc OK? Into the surrounding
31:41 Yeah. And then, so remember laid down a bunch of cells.
31:45 , so now you're gonna incubate and gonna see are the cells that are
31:51 here around here. Are they gonna or not? Will they grow or
31:56 ? Right. So then you're gonna maybe a zone where there's no
32:02 right? The zone of inhibition is , right? So you can see
32:07 , couple of different results. So a E coli and here's a uh
32:14 , so gram positive, gram negative the same chemicals are on all four
32:18 exch et cetera. And so you , you know, quite a big
32:23 , smaller zone here. So more inhibitory chlorine, less cell,
32:30 thing called the OK. Uh exo no effect, right? The
32:37 grew up and around and under the itself, no effect on it right
32:44 , somewhat here, somewhat here, effect or chlorine. That's, that's
32:50 of an ugly, ugly result. like to have a more uniform circles
32:55 that. But nonetheless, you get point, right? So a big
32:59 , very inhibitory compared to no, effect by the chemical. OK.
33:05 so again, you see differences with same chemicals chlorine, right? Gram
33:12 and negative. So you have those . OK. Um Any questions about
33:18 , I think it was pretty I hope. OK. So
33:23 strictly qu uh qualitative, you're not this kind of yes or no
33:28 Um And so, um again, can the ones that test positive for
33:34 you can look into further to see more about it. OK. So
33:40 what what effects do these chemicals So we looked at, OK,
33:44 cause death. Uh they, they cell numbers. Um But what are
33:49 actually doing? Ok. Well, you might think, right, uh
33:54 the things in the cell that keep alive, right? So the
33:57 right? Uh some agents are very at breaking apart membranes and you do
34:03 stuff leaks out of the cell, the cell, um uh affecting proteins
34:08 the cell, whether through heat, your heat methods in an oven in
34:14 , um boiling it. OK. ph treatments uh uh affecting the uh
34:21 of the of the of the Uh metals can, can inhibit enzymes
34:26 things. OK. So, you , obviously, if you affect the
34:30 proteins in the cell, you obviously their function because function is all about
34:36 of living things are about the proteins have and those things working. And
34:41 you're affecting proteins, you obviously gonna an effect on the cells. And
34:45 also with um a nucleic acids, , they too will of course be
34:51 as well. So, um the physical agents, so we look at
34:58 temperature uh is a common way to . And so things like uh for
35:04 , obviously, we we autoclave all media used for lab to sterilize
35:09 Um you can uh do so through as well. But the steam under
35:16 , OK. That's what will kill those spores. Remember how resistant those
35:21 and so moist heat that gets, for penetration into the end those pores
35:28 the um he uh steam under you create temperatures so high 1 21
35:35 , that's things can't live with that , at those conditions, right?
35:39 so um that's what enables you to in those pores. Uh And that's
35:44 why you have to use an like to kill those things off,
35:48 ? Most everything else is killed within first minute or two in an
35:51 But you have the extended time to the end, those boys,
35:55 And you can do this on a scale or a small scale. You
35:58 see the auto auto claves and the office, they put the instruments in
36:03 to stay alive. So um it's, you can work at different
36:08 . Uh You can have equivalent uh to an auto is a, is
36:14 oven, OK? But of standard conditions for auto of this and
36:21 , 1, 21 C. sorry about that. Um The uh
36:28 . So the um uh in the , it would have to be of
36:33 , a longer, longer time, ? Compared to because you're not,
36:37 not under pressure and it's not it's just dry air basically in the
36:41 , but you can get there like hours at 1 70 C OK?
36:47 Now, in terms of pasteurization, ? This too is about knocking numbers
36:52 . But for pasteurization, this is for food, beverage and beverages.
36:57 ? Because um it involves lower OK? Because not only are you
37:03 to knock down microbial numbers in the , but you want to um preserve
37:09 flavor, the texture, the color the product, right? You wouldn't
37:15 to put milk in an auto right? Nobody would want to drink
37:19 . Must of look at it. . So it totally destroys obviously the
37:24 and the, and, and the of itself. Uh So pasteurization is
37:29 reserve for that reason for food and . OK. And uh for
37:34 of course, we're familiar with that terms of pasteurization and um it used
37:40 be uh like a low temp long . So 63 and 30 minutes used
37:46 be the standard many years ago, then came high temp short time.
37:52 Now more and more common is uh ultra high temperature. So just a
37:57 of seconds at 1 34. And especially proven, um uh useful in
38:05 in under, in developing countries where , you may for refrigeration may be
38:11 . And so if you have ultra temp that actually can keep milk
38:16 unopened on the shelf just at room for quite a while. OK.
38:20 months I think I've heard. And , uh again, for areas where
38:24 not be refrigeration might not be consistent that. And that's been very helpful
38:29 that in those situations. Um And , you know, with all these
38:33 , you do have targets. So your autoclave, if you use an
38:38 four form, you test it is auto working, right? If it's
38:42 my endos four form in, in autoclave uh for milk, this is
38:46 of those they use as Ella is , is the most um uh most
38:53 heat resistant type. That's not an four form type. And so they
39:00 these conditions of their milk with, this uh organism to make sure that
39:06 , they're killing these things. And so, um so again,
39:10 pasteurization, you're not sterilizing, you're going down to zero, but you're
39:13 down significantly. Uh the numbers, ? Um So, and again,
39:21 works by basically denaturing, destroying proteins the cell. OK? Um
39:30 cold temp will inhibit growth, It'll slow down, not necessarily
39:36 but it will slow down growth. ? Um It doesn't, it doesn't
39:41 , OK. But does slow down . Um It's used in different ways
39:46 . Uh obviously, you refrigerate right? Just to slow the process
39:50 spoilage of food. Um uh you freeze it as well, of
39:56 uh to preserve it longer. Um the lab, we use refrigeration to
40:01 cultures, right? Because it slows the growth and we can use them
40:05 a long period of time. Uh more. So, if we go
40:07 minus 80. Um the uh and what we call preservation, microbial preservation
40:16 , at, at these colder temperatures preserve them. And we can always
40:19 back and get more if we want . Uh you know, one problematic
40:24 is Listeria. These grow at um temperatures. So, the, the
40:31 Blue Bell Ice Cream Factory had a has had some trouble with this where
40:36 had outbreaks. people have eaten ice come down with Listeria and uh
40:42 for most of us, it's a that health immune system we get over
40:46 without much, without much damage if at all. Uh But of
40:51 more susceptive ones elderly. What have , they, there were fatalities associated
40:56 it but it's because you can, know, if you're ice cream
40:59 you're doing your thing in cold right? You don't clean the equipment
41:03 . Uh, that you're using Listeria potentially grow in these, in these
41:08 . Ok. Um, filtration. , not everything is amenable to auto
41:14 , right? Liquids can be susceptible it. Um It can destroy the
41:19 of the product. Uh I know lab there's a couple of media we
41:23 put in the autoclave because it doesn't , it doesn't work. So you
41:26 to use filtration. So, um so you can get filters that are
41:31 . So this refers to how tiny holes are in your filter, think
41:35 it. As a mesh, You get tiny holes. So 0.45
41:39 out bacteria, uh 0.2 obviously keeps bacteria and then, then some
41:46 you can get poor sizes below this . Um But um but you can
41:52 not just liquid, of course, you can also filter air HEPA
41:55 right? Can filter out the Uh And so the um and so
42:01 may have to be a, an depending on what you're trying to
42:06 Ok. Uh And I just threw in because your book mentions them.
42:11 there's other physical ways to reduce high pressure desiccation is drying out,
42:18 water, right? Osmotic stress. are other ways to reduce. And
42:23 this has been used for centuries, ? By packing meat and, and
42:30 in salt, right? Packing it salt that really creates osmotic differences,
42:36 ? So it draws the water out , of the, of the um
42:39 the, of the meat, of product and thereby preserves it in
42:44 Um So irradiation, this is becoming and more common. It's, it's
42:49 to um uh uh I know frozen , chickens irradiated to um to knock
42:58 the levels of things like salmonella and that are often associated with chicken
43:03 and uh foodborne outbreaks. And so use a radiation for that as well
43:07 other things. Um And so with radiation, it's all about wavelength,
43:14 ? So um light that is long um compared to short wavelength OK.
43:29 wavelength, a lot more energy, ? UV. Light gamma radiation,
43:34 ? Radio waves very long, Low energy, right? You're back
43:38 way. So it uh what we non radiation UV light. OK.
43:44 It can be useful, it's more we call um um surface disinfection.
43:51 shining a UV light on a surface can uh proved uh useful.
43:57 But lots of things stop you v pretty easily. So a shirt,
44:03 example, um piece of paper, AAA lid on a Petri dish or
44:08 can stop it. So uh you to take that into consideration. But
44:12 it can do is it can uh the bases in DNA, right?
44:18 mutations. OK. And uh so get a lot of UV light,
44:22 cells accumulate these mutations and eventually kills . OK? You do the same
44:28 when you get a sunburns, Because you're basically exposing UV light to
44:32 skin cells and creates kind of the effect and you get rid of your
44:36 from some being sunburn when your skin peeling, right? Uh And so
44:42 but the um it is does have applications uh but like more high energy
44:50 uh uh radiation, uh x-rays, rays. Uh these, these not
44:56 do more than just change the they actually break fragment the nucleic
45:03 So, obviously, that's gonna be . OK. When you begin to
45:07 up the uh DNA. OK. so, uh again, because of
45:11 very high energy you see the wavelength UV light, right, compared to
45:19 rays and X rays, much smaller wavelengths. And so, um
45:24 causes all kinds of damage, of . And so they use this for
45:28 like I said, some, some are irradiated as well as things like
45:33 uh pipette tips uh and other kind lab in the lab ware that's used
45:41 the plastics and things like that. So, uh but it can be
45:46 effective in the um all right, methods. So, vanilla compounds,
45:55 these have kind of this structure to . You don't need to memorize
45:59 But these vanilla compounds, they tend have a little bit more, they
46:05 evaporate so quickly. So they, you apply them, they kind of
46:08 to stay around and have a little extended killing time. The um the
46:14 but they do affect proteins again, kind of their thing and, and
46:17 of lipids and membranes, uh So you may have heard of uh
46:23 what's it called beta dyne? So is what's in beta, is
46:28 ok. Very common um uh disinfect you see in a doctor's office,
46:34 example, or uh in, in private surgery when they're uh disinfecting the
46:42 where they're gonna do the surgery, often have beta, it's like a
46:46 color, very noticeable, it's iodine there that uh is the agent that
46:51 does the killing damage, the uh pro affecting protein synthesis, et
46:56 Of course, bleach is very has a lot of killing power,
47:03 alcohols, right? So you use ethanol in the lab, OK.
47:08 disinfectant on the surface. So these work better with being of course dissolved
47:17 water. So 70% ethanol is actually effective than 95%. And so the
47:27 water helps to allow the alcohol to with the membrane. And so it
47:34 it more effective in dissolving it, actually works better than does 95% which
47:40 less water. So more water kind helps it uh dissolve into the membranes
47:44 , and cause it to disrupt the structure structure. Ok? Um The
47:52 metal, so these can be effective things like silver, maintaining silver or
47:58 or copper. Uh copper, I is used in a number of products
48:04 for um maintaining aquarium, aquarium I think because it works on uh
48:11 allergy, killing allergy in your Um But a little bit goes a
48:17 way, it can be very toxic , you know, at, at
48:20 levels, doesn't take a lot to toxic. So that's where you have
48:23 , you have to be careful with . Um the these agents,
48:32 Um Look like. So here's an of in that in that diagram or
48:37 image of that plate, one of chemicals used was abbreviated QUT OK.
48:44 what these are, are these things look like looks like a fossil
48:50 OK. And so that's actually the enhanced, it helps dissolve a membrane
48:56 that's what they do. OK. Similar with these detergent types. These
49:01 these detergent types have that similar fossil like structure and that enables them to
49:07 the membrane and li the cells. ? Um The preservatives like um
49:15 you see often in various foods, , bread, cereal, et cetera
49:21 things like citric acid, sorbic benzo and the action they have is
49:29 So the chemistry of it is being acid, right? They will
49:34 right? Creating the proton. This the this is this is what makes
49:38 an acid OK? And so the is is they only partially dissociate.
49:45 if you recall something like HCL, , when you dissolve that in
49:51 it all goes to hydrogen ions and ions, right? All to
49:58 None of this is left, no is left, all those completely dissociates
50:03 these two. But these things what call weak, weak acids. So
50:09 still have this this and this present solution. OK? Doesn't all
50:15 And so this is the key, is a thing that is relatively
50:19 OK? And can pass through a , right? So these things can
50:24 inside of the cell. Then when inside the cell, this happens inside
50:29 it. So you create acidity inside cell and these can be growth
50:35 And so you'll see these things in of different food foods as a preservative
50:40 , to uh retard spoilage. It's, it inhibits the growth
50:45 of bacteria and fungi as well. . So very common ingredient. You'll
50:50 that uh in various foods. And um gas, gas can be used
50:58 , it's often for um uh plastics , like things like uh sterilizing Petri
51:04 and then uh by pet tips and forth, uh the gas can penetrate
51:09 there very well. Obviously, you , you don't wanna use this to
51:14 liquids because gas doesn't penetrate liquids very . But for things that are
51:19 plastics, et cetera, this is used and it's basically a so ethane
51:24 is the one most commonly used in of the gas. Uh it can
51:29 quite effective. And so it has structure uh and under uh either acidic
51:35 basic ph it'll transform kind of like chain reaction. It kind of comes
51:41 and then interacts with proteins that play in the cell, uh ultimately killing
51:47 cell. Uh It it can be sterile, it means it can be
51:51 sterilizing agent under certain conditions and can certainly kill. So, uh but
51:58 know, the a lot of these of these things whether it's radiation or
52:03 or liquid kind of depends on what trying to, um, affect,
52:08 know. So what's the, what's structure of the thing you're trying to
52:12 ? Is it a solid floor or or is it something, um,
52:17 a liquid or what have you? these all influence, what, what
52:20 to make in terms of which, one to use? OK.
52:25 so any question, so I'm not get, you know, you
52:31 I'm not, I don't have a list of these things. Your book
52:33 a whole list of all these different . I don't expect you to memorize
52:37 tables. That's crazy. Just uh know, kind of examples of these
52:42 types here. OK? Is all looking for. Uh don't memorize an
52:47 list of these things um in terms resistance. OK. So we're well
52:53 of antibiotic resistance. OK. What resistance to these things? OK.
53:00 , fortunately, um the, so antibiotics, the target is very
53:08 OK. So antibiotic will target a component in protein synthesis or in cell
53:16 synthesis or some other bacterial activity. . And it's a single target.
53:23 so it's not uncommon for the bacterium develop a mutation, right? That
53:30 it to counteract that target. That is seeking. And so,
53:35 we know that because there's all kinds antibiotic resistant going around, OK?
53:39 for disinfectants, disinfectants have multiple right? They will affect a,
53:46 membrane to a degree, then they'll in and maybe affect proteins to a
53:50 and nucleic acid. So the multiple . So it, it would be
53:54 hard to uh for a, for particular type to accumulate every possible mutation
54:01 counteract every possible target that's happening. . That's not gonna happen. So
54:07 used at the prescribed concentration, then , that the, the uh becoming
54:17 is really not an issue. But it's when you want to,
54:22 you lower, if you dilute it , right? If you do
54:26 this in fact, then maybe to money, right? Make it stretch
54:30 , then you risk that because at lower con much lower concentration, the
54:36 of targets reduced becomes fewer and then potential to become resistant can occur because
54:42 it doesn't take, but maybe one two mutations for it to become
54:47 right? But if used at the you're supposed to, you're generally
54:52 That plus in a hospital, in hospital, they're on a, on
54:57 schedule schedule, they'll have two weeks , we'll use this type of
55:03 then we'll switch to another type in two weeks and then to this
55:07 So you're constantly changing the types of and that makes it even harder to
55:13 resistant to it. OK? So key is use at the prescribed
55:18 Don't, don't fiddle with it and it out. OK? And so
55:23 , the, the kind of resistance of types. So, viruses with
55:29 thick envelopes. We'll talk about these but they tend to be more resistant
55:33 at least resistant. I'm sorry, resistant at the top. So,
55:39 , that is, I think yeah, that's it for chapter
55:43 So, we'll pick it up next you left on the exam.
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