FSQA_6600DE_Lecture_2_Audio_audio (1)
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Hello, my name's Keith Warriner and from the earlier unit one you talk about the history of food science in general and Doctor Who really outlined how this was of interaction between chemistry, a bit of engineering and eventually microbiolo…
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1:55فصل 2: So what we're going to be doing. 151s · Speaker 2
So what we're going to be doing... is going through to outline the different modes of evolution. So a lot of you might be thinking, well, there's only one type of evolution. It's Darwinism, isn't it? But, you know, it's not quite as clear c…
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4:27فصل 3: you know, humans would appear. 136s · Speaker 3
you know, humans would appear. 30 seconds before midnight. But the first sort of microbes, they thought, kind of developed 20 minutes after the start of the Earth. But people disputed. Nobody was there. No fossil records, obviously, are kep…
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6:43فصل 4: it grew and grew. 120s · Speaker 5
it grew and grew. Now, neopanisperium is another interesting one. This means there wasn't a seeding event, a not single event. It was constant. They were constantly bombarded with microbes from outer space. You know, obviously, the conspira…
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8:43فصل 5: yes, it is. 241s · Speaker 3
yes, it is. And the other theory is the island volcano. So a bit like the hot springs, except on land. Basically, you get these eruptions with sulfur, ammonia, carbon, and all these kind of come together to produce the macromolecules that p…
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12:45فصل 6: oh, well, you know, why would it do that? 188s · Speaker 4
oh, well, you know, why would it do that? But there was an interesting set of experiments done with this responsive oil droplet. So, not to go too deep into it and digress, is that these oil droplets are made of free fatty acids, and when t…
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15:54
hot, cold, acid, alkali, different carbon sources and things like that. So this is a theory where lipid vesicles went from these sort of little vesicles into the wide world. Now, evidence to suggest that came from the archaebacteria. So the…
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20:31فصل 8: they're more. 118s · Speaker 5
they're more... resistant to thermal processing like lysteria compared to e .coli salmonella much more firmly resistant and they're very good at desiccation resistance now as i mentioned to you there's exceptions to rules for example corona…
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22:29فصل 9: gram negative. 97s · Speaker 4
gram negative. But as I mentioned to you, really, to get on in life and grow, they need a cell wall because this gives that physical barrier, the physical strength to tolerate osmotic pressures, the high salt, low salt, things like that. An…
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24:07فصل 10: gene line So in terms of evolution, then, really what we talk about evolution is this sort of passing on genes. 206s · Speaker 3
gene line So in terms of evolution, then, really what we talk about evolution is this sort of passing on genes. Like, we evolve, don't we? Maybe slowly. But we get inheritable characteristics from our parents. And sometimes they're benefits…
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27:33فصل 11: did survive. 103s · Speaker 7
did survive. A bit like what Aristotle was saying in a way, but Aristotle was just saying everything was just random, spontaneous. What Darwin was talking about is this inheritable feature. So if, for example, you have a giraffe and a giraf…
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29:17فصل 12: Now, that was all right, you know, and people accept that. 130s · Speaker 6
Now, that was all right, you know, and people accept that. But there's different kinds of evolution. So survival of the fittest, obviously, we can see it. You know, we can see it when we select the mutants. We can see it when microbes becom…
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31:27فصل 13: Keep riding with the theory. 93s · Speaker 7
Keep riding with the theory. You're more likely to give it to them. You're not getting benefit from it. You hope to get benefit maybe in the future, but you're not getting benefit now. So that genetic relatedness, that relatedness to you, y…
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33:01فصل 14: then you're good. 96s · Speaker 5
then you're good. People even say about microbes, it's just microbes, it's the genes themselves that pass on evolution. It's called a selfish gene. So all we're doing basically is swapping genes around. We're not really interested in microb…
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34:37فصل 15: Now, obviously, the non -cooperators ultimately fail because once their cooperators leave them behind. 89s · Speaker 7
Now, obviously, the non -cooperators ultimately fail because once their cooperators leave them behind... they're not adapted whereas the cooperators will always win out because they're cooperating and i think you get the idea but pathogens …
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36:07فصل 16: which basically saying, let's all produce amylase to degrade the starch and take the glucose up. 174s · Speaker 3
which basically saying, let's all produce amylase to degrade the starch and take the glucose up. You get the cross -feeding, and this happens a lot in the GI tract, where one, for example, will take in carbohydrates or a prebiotic like inul…
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39:01فصل 17: when we're more complex, we're more adaptable. 240s · Speaker 7
when we're more complex, we're more adaptable. And you can see that between eukaryotics and prokaryotics. So with eukaryotics, things like us, we can live on every part of the world to the coldest environment in the Arctic, to the warmest e…
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43:02فصل 18: they'll blow it up. 301s · Speaker 4
they'll blow it up. It'll nuke it, you know, nitric oxide and hydrogen peroxide and things like that. And obviously we have physical skin, which is a physical barrier, and other things like this. So they're there all the time. But then when…
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48:03فصل 19: This is where the Krebs cycle occurs, the energy production occurs, and it's the intricacy of this parasitic lifestyle. 119s · Speaker 1
This is where the Krebs cycle occurs, the energy production occurs, and it's the intricacy of this parasitic lifestyle. Although it's more symbiotic, this one, isn't it? For the simple reason, the mitochondria gives the cell energy, and obv…
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50:02فصل 20: saying, oh, every microbe must be destroyed. 301s · Speaker 4
saying, oh, every microbe must be destroyed. And there was this sort of phase where people were sanitizing everything. But the reality is, is that only a small percentage of microbes are actually pathogenic. The other ones actually do give …
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that and hitch a ride on a biofilm and things like this and reductive evolution is viruses it's parasites so these are a form of evolution where you're actually losing genes like shigella for example like shigella and e coli very closely re…
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56:24فصل 22: But yeah, genera, as you could imagine, they've got common features, but they're kind of different from that genera. 300s · Speaker 4
But yeah, genera, as you could imagine, they've got common features, but they're kind of different from that genera. So that's a species. And when we get to subspecies, it gets really confusing. And it even gets more confusing when you talk…
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1:01:24فصل 23: just lactic acid. 91s · Speaker 1
just lactic acid. And we can use that in yogurt, can't we, to preserve it? Now, heterofermentatives actually don't have an enzyme in the actual metabolic pathway to break down glucose. It does produce pyruvate, but it's got this enzyme phos…
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1:02:56فصل 24: well, who knows, it could be disproven. 93s · Speaker 2
well, who knows, it could be disproven. But I think the point is it was spontaneous to start with, whether it happened in the flats, whether it was introduced by meteors, who knows. But essentially what we have then is this common ancestor …
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and the psyllates, which are these sort of complex single -cells. Well, it's actually single -cells that go on the feeding of bacteria in wastewater, but that's no matter for another day. So genetically, we can look at the distance by the s…
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1:06:18فصل 26: some are spoilers, some are pathogenic. 142s · Speaker 7
some are spoilers, some are pathogenic. But we can group them into their adaption. So they adapt. to these micro -aerobic environments of the body, for example. We see compiler bacteria. We can see helicobacter, which causes ulceration. The…
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you know, you have to be a real expert to be able to identify it. And we don't need to go into all mould names and that, but we can see which ones are fairly relevant. And the ones that are relevant to the spoilers. So we've all had bread, …
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1:12:45فصل 28: as we've talked about, require a host to grow. 82s · Speaker 7
as we've talked about, require a host to grow. And we get ones like giardia, for example. We call this beaver fever. And the reason why it's called beaver fever is that it's usually associated with people who go camping and drink contaminat…
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1:14:08فصل 29: very rare in the developed world. 85s · Speaker 4
very rare in the developed world. You sometimes get it in developing countries because it's pigs. and natural carriers of it and they if you let them outside they kind of contract trichinella and it gets into the system and the viruses well…
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1:15:34فصل 30: acid, alkali, the water activity, which is a kind of salt or how dry the food is. 106s · Speaker 7
acid, alkali, the water activity, which is a kind of salt or how dry the food is. Is it low water activity, low moisture, high water activity, high moisture? Redox potential is a sense of... Oxygen availability. Is oxygen there or is it ana…
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1:17:21فصل 31: But, you know, who knows? 70s · Speaker 5
But, you know, who knows? The mystery is there. So. Typically, as I said to you, we don't think about... intrinsic factors extrinsic factors alone we kind of think them as a combination which is true because they collectively cooperate if y…
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1:18:31فصل 32: you know, passing the cold, it can grow in cold temperatures and room temperature. 114s · Speaker 6
you know, passing the cold, it can grow in cold temperatures and room temperature. But if we put math, high CO2... that inhibits it. So we've kind of said, oh, yes, we'll take care of the means of altitude temperature. We're taking care of …
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1:20:26فصل 33: which, again, it debates, everything like that. 300s · Speaker 4
which, again, it debates, everything like that. But we look at growth curves because we use those to predict what microbes would grow in a product so we can get those hurdles to stop it growing. Now, the classic growth curve is made up of d…
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1:25:27فصل 34: The spore formers like bacillus and clostridia, this is the decision they take to start producing endospores. 151s · Speaker 1
The spore formers like bacillus and clostridia, this is the decision they take to start producing endospores. And non -endospore formers start to downregulate, saying, right, the good times are finished. It's going to be a long time before …
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1:27:59فصل 35: isn't it? 268s · Speaker 4
isn't it? But then you start growing exponentially. You start getting much more cells, so much more signal. And... you get to a point where you trigger a threshold and produce what we call a phenotypic change. Now, cell -cell communication …
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are endospores, but what a Japanese group did, they were kind of going through sediments of AC, and don't ask me why, but they found these microbes and they just incubated them for over a year. And after a year, something started growing an…
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1:33:51فصل 37: isn't it? 220s · Speaker 3
isn't it? But what happens in the real world after the nutrients have been depleted, when we do get acids and that? in a stationary phase we get this transition into this sort of dormancy phase so obviously spore formers produce spores you …
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1:37:31فصل 38: Well, I ain't got much hair, but it's the same material as hair, very impermeable. 126s · Speaker 7
Well, I ain't got much hair, but it's the same material as hair, very impermeable. So these are going to be a physical barrier to all those antimicrobials, acids and things coming in. Now, it's always a mystery to me still. You know, I aske…
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1:39:37فصل 39: of juices. 111s · Speaker 3
of juices. So the story goes, back in the olden days, well, 2000, there was a lot of outbreaks to do with E. colo 157 in apple juice. And so someone said, I know, let's firmly pasteurize it or UV treat it. And either way, the thermal pasteu…
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1:41:29فصل 40: Basically, when we're looking at a food product and we're doing testing of it, we look for counts, don't we? 62s · Speaker 8
Basically, when we're looking at a food product and we're doing testing of it, we look for counts, don't we? Look for E. coli, salmonella, maybe total aerobic count. But if they're dormant, they don't grow an agar plate. And so what we get …
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1:42:32فصل 41: mold forms spores, not as resistant as bacterial endospores, but still tolerant. 109s · Speaker 7
mold forms spores, not as resistant as bacterial endospores, but still tolerant. And you would have thought, this is immortality. You know, the reality is that spores can survive millions of years. So why don't all cells do it? Well, it's a…
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1:44:21فصل 42: pH, water activity, extrinsic surrounding the food, you know, temperature, things like that. 301s · Speaker 5
pH, water activity, extrinsic surrounding the food, you know, temperature, things like that. So why did microbes definitely respect the ability to grow under extrinsic and intrinsic conditions and have a narrow range? And again, I think we'…
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1:49:23فصل 43: Well, microbes can be measured by optical density, where you get increasing turbidity and you measure at 600 nanometers. 79s · Speaker 1
Well, microbes can be measured by optical density, where you get increasing turbidity and you measure at 600 nanometers. It also can be measured by count plate or plate counting. So we can make dilutions, grow them and egg on, count the col…
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1:50:42فصل 44: which are out of place. 301s · Speaker 7
which are out of place. So the difference between them is that it's incomplete. Even they don't like using oxygen, which is sometimes the case. Like E. coli has a... electron transport chain but it doesn't like using oxygen if it doesn't ha…
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1:55:44فصل 45: doesn't it? 77s · Speaker 4
doesn't it? Physical separation, interventions like thermal processing, sanitation and things like that. So understanding transmission routes is key in order to avoid... the pathogens or spoilage microbes entering the chain and what is the …