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BIOL 2320_Microbiology for Non-Science Majors - 2320_9_26_23_CH27
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00:02 Hello folks. So this recording is cover uh the chapter 27 section on
00:08 microbiology. Uh I've included this uh to give me a little bit of
00:16 to the microbial world outside the We're mostly concentrated on, on uh
00:23 disease and how microbes uh affect the in terms of causing disease and how
00:29 fight disease and particularly in the second of the course. Um And even
00:34 then, so, uh I wanted give some uh at least a little
00:39 of, you know, microbial so to speak, that occurs in
00:44 . And so uh some of this very critical to our, to our
00:51 being and survival on this planet. Others, other microbial activities can contribute
00:55 problems sometimes in the environment. So gonna look at both of these um
01:00 examples of both of these and uh start with uh uh what we call
01:06 hydrologic cycle, which I'm sure you're with. Obviously, it's just basically
01:12 , the, the, the availability distribution of water that that occurs on
01:16 , which of course is through the of water from bodies of water.
01:23 , streams, rivers, lakes, cetera, that then um evaporate and
01:29 , you know, rain clouds and falls back to earth. And so
01:34 movement this way uh as it hits is through gravity, uh basically returning
01:40 back to water or whether a river stream, what have you. So
01:45 in the process of moving across uh , um obviously, the materials that
01:51 in the soil are picked up by water, both uh uh on top
01:55 underneath uh as it moves through, moves through it. And of
02:02 organic material is picked up and um can be used, you know,
02:08 , to move nutrients and things Um but it can contribute as well
02:13 issues and that's some of the things talk about here uh shortly.
02:17 as mentioned, um the uh runoff water into bodies of water of,
02:27 example, um the, the and both natural, of course,
02:33 but also that through man-made activities. , uh example is like an oil
02:38 that uh unleashes a tremendous amount of material, all those organic materials,
02:45 into the environment and, and that food for uh microbes that can then
02:51 utilize that in the form of aerobic that we talked about previously in chapter
02:57 . Uh Now, the effect is the oxygen being used uh consumed during
03:03 process comes from the water itself. thus, that limits that availability of
03:08 to other sea life, aquatic life that can have consequences and has had
03:15 . So, AAA term we look here that we use to represent the
03:23 content in water is called bod biochemical demand. OK. So it really
03:30 back to this same uh process we've before, right? So here's the
03:39 , right? So this is but you can insert here any kind
03:44 organic compound, you know, uh lipids, proteins, uh you know
03:50 organic types of compounds. And so the point is in aerobic respiration,
03:58 ? As we oxidize or break down organic component, we're consuming oxygen in
04:04 process. OK. So imagine if had one, just one molecule of
04:11 , we'll just go with glucose, molecule of glucose uh compared to a
04:15 molecules of glucose. Certainly the amount oxygen is going to increase as
04:20 You can see here the stom Mery the reaction, right? One mole
04:24 glucose, you consume six moles of in the process. So imagine if
04:29 was a million moles of a million , a million moles of glucose.
04:33 then you know, gonna be 6 moles of oxygen. So the point
04:38 the bod represents the represents the amount organic material through the consumption of
04:43 So if you have a lot of material that translates to a big big
04:49 , right? Because a lot of is gonna be needed to remove
04:53 Ok. So that's what bod It basically it's based on microbial aerobic
05:00 , right? Heros, right? heterotrophic aerobic metabolism. OK. Same
05:06 we've been talking about previously. And um so of course, the microbes
05:12 are feeding on this grow in numbers there. They are respiring, they're
05:17 energy they're growing. Uh but in process consuming the oxygen from the water
05:22 that's where you can have an impact wildlife. OK. So you see
05:26 up in the upper right corner is dissolved oxygen probe shown in the black
05:32 there. And you simply just let uh immerse in the water and you'll
05:38 a reading of, of milligrams per of oxygen. OK. So,
05:45 so when measuring samples, so it be and wastewater treatment plants do this
05:50 the time, but it can be kind of environmental aqueous environmental sample um
05:56 you can measure this in. And so from the diagram here,
06:00 can see, you know, the of oxygen consumption in a right relates
06:06 there being a lot of organic OK. So again, lots of
06:12 material equates to lots of oxygen consumption rapidly. And so that's why A
06:18 have the highest BOD D none, equal to zero. So it's,
06:32 span the spectrum here. AAA the , then B, then C,
06:36 D the least. Um So the terms of numbers and then, you
06:42 , you you don't memorize these But uh just to give you a
06:46 for, OK, if water is saturated with air, for example,
06:50 you can do simply by just taking AAA glass of water and just shaking
06:56 very vigorously to get air mixed in it. Uh or, or so
07:01 and stir very rapidly. Uh when saturated, it'll contain, the water
07:06 contain up 8 mg of oxygen per . Uh So you think?
07:13 well, what, what at what is life threatened that if, if
07:17 drops in the water? Well, not, not as far as you
07:20 think. So, going down to or five, I'm sorry. Excuse
07:23 , 5 mg per liter. Then you do begin to threaten uh
07:29 , right? Because some of these larger animals, right? So
07:32 they're gonna have a, a greater demand in a tiny microbe. So
07:36 won't take much oxygen reduction to begin impact fish and other aquatic animals.
07:43 So on the other end of the is what's a high bod or you
07:46 see that in sewage, right? high bod. Of course, it's
07:52 with organic materials. Ok. Um often, you know, companies that
07:58 companies can release material that's very high organic content. Uh because many manufacturing
08:04 have chemicals and things they use in processes that are waste products. And
08:10 they, of course, it's illegal do this if they do dump
08:13 then that represents adding a lot of to a, to a, to
08:17 system, usually a river or a or a pond or something. And
08:21 has consequences as we'll see and we see that. But so the point
08:26 is, don't forget, you it's all, it's all about what
08:28 learned before, you know, aerobic . And there's certainly other metabolisms that
08:36 occurring in addition to this. But has a significant impact because of
08:42 the 02 being consumed that can impact life in the area. Ok.
08:50 uh example here, so when we about dead zones or zones of
08:55 hypoxia just means reduction in oxygen that to the influx of organic material,
09:04 high bod discharge into a body of will trigger uh this bacterial aerobic respiration
09:14 thereby reducing the oxygen levels. And , and that can persist for some
09:18 as you see here off the coast Louisiana. And so, um and
09:26 had an impact. Uh I think since recovered but it can, it
09:29 impact for quite a while. So that oil spill contributed to a reduction
09:34 oxygen, says there are two, than 2 mg per liter that significantly
09:40 fish and other wildlife there. Um so, so if we look
09:49 you know, some other effects, of them is not always just um
09:54 an influx of um organic material. can also be due to the influx
10:02 other types of minerals that are necessary growth. And so I just put
10:06 simplified drawing. Uh here's a flower we all know, you know,
10:10 , flowers, plants, you they're, they're photo auto troves,
10:14 ? So all they need, they need much, they just need
10:17 right? They need water, Remember water is the electron donor and
10:22 , right? That's how they're gonna their carbon. They're gonna fix CO2
10:25 make their organic molecules. Uh But they can't manufacture is and so
10:33 you know, plants, algae and bacteria, this is what they
10:35 We're focusing on those photo tropes that, that uh use water
10:40 and produce oxygen in the process. . So what they can't manufacture is
10:48 , phosphorus, sulfur, these other uh nutrients uh that are needed for
10:55 as well. So, remember, is found in DNA and proteins,
10:59 is found in DNA, uh A . So sulfur and amino acids.
11:05 we need to, that needs to supplied. And so in nature,
11:08 things seem to be in balance. there's of course, lots of competition
11:12 nutrients. Um And because of you don't, you, if you
11:17 measurements in the environment for these kinds nutrients, you don't see an excess
11:22 if they're available, they're being Ok. So um so that kind
11:27 keeps everything in balance and when you an excess, well, those that
11:32 readily utilize it will then do so then can grow, have a huge
11:37 spurt. OK? And that can consequences. OK. And so particularly
11:44 things like plants, algae, bacteria. And so in aquatic
11:48 algae, santa bacteria, um you , if you, if they provide
11:54 excess of nitrogen phosphorus, they would use that and their numbers will exponentially
12:02 . OK? Remember that, remember J shaped curve, right cell number
12:09 time and their grows will do OK? And because they've got
12:16 they have sunlight, they have they're in water. And so you
12:19 an excess of nitrogen phosphorus and they rapidly grow. OK? And we
12:27 this effect in the process of OK? And so it's a stepwise
12:36 where one event leads to the next . OK? And so in this
12:42 , um uh A is not right? It ultimately, it ultimately
12:49 in a decrease in the oxygen not an increase. OK. Um
12:56 is also wrong because it initially doesn't decrease the content of photosynthetic
13:03 OK? But it does do It does result in high levels of
13:09 decomposition, respiration, right? Lots organic matter being broken down and depletion
13:17 oxygen as a result. So we that here in this example um or
13:23 could be a, a pond, river or what have you and the
13:27 land of course can be used for farming agricultural purposes. And then those
13:32 often uh certainly fertilizer is used. so uh typically an excess of fertilizer
13:39 , is utilized. And a lot that's a lot of that is that
13:42 up being um run off through run precipitation, irrigation, that excess
13:49 runs off to nearby bodies of right. So you see here,
13:53 land used for farming, we have runoff and then you have the influx
13:58 uh ammonia, nitrate phosphate combination of into uh the water stream.
14:05 And that's going to do the algae santa bacteria. Uh these are gonna
14:13 up this, these excess nutrients and take off and blow up and
14:18 That's why they call these things a , right? Algal bloom because of
14:22 extensive growth. Similar thing happens, in, in, in various bodies
14:28 water like off the coast of you'll see some, you probably have
14:32 about the red tide. That's exactly one of these things is. It's
14:36 reification process uh that the dumping of uh high organic content into,
14:43 the, into the gulf. And can lead to a an increase in
14:48 types of algae that produce toxins. so uh so it's, it's not
14:54 obscure phenomena. It's, it's a thing. And so the, so
14:58 thing is so with the aqua the um that level of growth can
15:03 only be sustained for, you until it runs out of those nu-
15:09 and phosphorus tris. And so, remember, you know, exponential growth
15:14 only is finite. There's not, doesn't go on forever. So there's
15:18 be a limit where it'll stop and , you know, nobody else.
15:21 more, no more nutrients coming in . Then the, then the mass
15:25 and this can look like a, green mat of growth spread out over
15:30 wide area. Uh But of you know, as I said,
15:34 they run out of nutrients, then dies and then, then it becomes
15:38 for the next level. And that's we see happening as the algae die
15:43 fall to the bottom. And then sediments are, you know, your
15:47 bacteria, aerobic respiration. Again, here we go, all right,
15:52 on that mat. So in the algae are in this spot where
15:59 glucose is at and so get use oxygen, oxygen, of
16:05 that the oxygen they use is coming of the surrounding water. And so
16:10 of the wildlife that's there can be affected by that lacking oxygen.
16:16 So, um so, uh so , you know, these,
16:24 these are effects that happen and you , especially in the context of combination
16:29 , of uh high, high bod content being spilled into water streams along
16:35 uh these other nutrients can create these of effects. Ok. Now,
16:41 what sort of treatment plant? So utilizes, of course microbial activity as
16:47 . Uh And, and the same respiration. So, uh as we
16:52 at this, as we look at question, uh we are not always
16:57 our treatment plants are about producing clean water. Many are but not,
17:02 not all. Uh almost many, , many manufacturing operations that use chemicals
17:09 their process, generate waste streams. so you can't discharge this material straight
17:16 the water. Uh And so, the, it's illegal to do so
17:21 some have done it. But regardless , you want to first reduce the
17:27 of organic content before you discharge And so for that reason, uh
17:33 , the goal for those plants is to produce drinking water, but just
17:37 produce water, that's a load, organic content that's safe to be uh
17:45 into, into bodies of water, safely discharged. Um So not,
17:52 not always on, on including clean drinking water. OK? The
17:59 increase the level of bod. you want to decrease the level of
18:02 . So that's not right. Uh a clear outgoing stream possessing that's exactly
18:08 you wanna do. OK. Uh the process is nonbiological. It's absolutely
18:14 . It's all mainly biological. So if you, if I had
18:20 describe wastewater treatment very briefly, it be uh promoting this aerobic peter trophic
18:28 . OK? That's when uh that's gonna consume the organic content for
18:33 OK? That's 12 is what you . What's coming into your system is
18:40 high bod level, high organic content of material and what you want exiting
18:46 a clear stream, low, very in bod, right? And so
18:53 get the aerobic respiration from the microbes that part of knocking down bod the
19:01 effluent. So, effluence what comes what comes out at the end
19:05 And so what you want there is it to be low bod, of
19:09 , but you want it to be clear stream. OK. So that
19:12 you need to have settling, settling . So the the bacteria and things
19:16 are knocking down your bod, you , you want them to do
19:21 but you don't want those cells to in your outs stream your effluent.
19:26 you, you, you want everything settle out. And so reduction of
19:31 and settling of material is what that's the goal of wastewater treatment in
19:36 nutshell. OK. And so we'll at how that happens. So a
19:41 municipal system, one that would likely in your subdivision that services maybe 100
19:48 60 homes or so is something like ? Uh What common is the,
19:53 the tanks, right? This is where this is where the activity occurs
20:00 breaks down the bod. OK. And so you see there's like
20:05 a little uh um structure that's that's this hub, so to speak.
20:15 that paddle, it, let's call . It also is, it
20:19 it enables someone to walk out and check the system, take samples
20:23 whatnot. But it also has a structure in the water that it
20:29 rotates in uh either clockwise or kind clockwise fashion, but it rotates and
20:35 creates turbulence in the water. It wa air into the water. That's
20:40 stimulates the aerobic respiration. Ok. So if we look at a a
20:46 and we're just gonna focus on, this here, not so much on
20:53 , this, you can have an digestion occurring as well at some
20:56 but we're just gonna focus on on, on the, on that
21:00 there. So, preliminary treatment. it's really AAA stepwise reduction in material
21:08 in. So you're gonna have a but you'd be surprised at the kind
21:11 material that comes into a treatment Uh in the beginning, it can
21:14 dead animal carcasses, it can be and so the kind of large debris
21:18 moved out first. That's what its treatment is. Then you go down
21:22 like things like um uh small sediments, things like this that are
21:26 soluble, that's, that's the primary . You have like mesh screens,
21:31 like a door screen kind of that to, to get that stuff
21:35 And now you're left with the soluble of organic material that then go into
21:40 secondary treatment and that's where the action occurring. That's your aerobic respiration.
21:45 ? The decomposition of this, of organic content, right? So there
21:50 where, where you wanna promote getting air mixed in into your
21:54 that's what's gonna promote this activity. . Now, if you are
21:59 a plant that's for producing drinking then you will do this tertiary treatment
22:04 is chlorinate. uh maybe UV light , to get rid of pathogens.
22:09 . So that's, that's uh something do as well. OK. So
22:14 another kind of another view. So we have uh a sec primary
22:20 here. OK. Uh Tertiary OK. So in the middle
22:27 this is where the actions occur in of microbial activity. OK. And
22:33 uh so in here, so you the aeration occurring. So you can
22:40 air forced in or you can just in, mix, mix it
22:44 like I mentioned previously. And here gonna have the um um activities.
22:54 then you're gonna promote the growth of organisms and then you're gonna uh have
22:59 uh activity occurring in here and as grow, they'll, they'll, they
23:05 in a, in a way such you, you promote the growth of
23:09 that are form filaments, filament this and they form this mesh network,
23:15 ? Let me just illustrate it. form this mesh of filaments and excreted
23:23 like starch like PHB material. If recall that from chapter uh four,
23:30 the kind of traps everything. And this is something that can settle
23:35 OK. And that's what the um of the clarification is, right?
23:42 you have the microbes growing, the promoted through aeration and, and mixing
23:47 in the system to get the respiration and then begin chomping down that
23:52 then the process grow and, and these filamentous types that then allow everything
23:58 settle out. And so that's why use the term clarification, a clear
24:04 of the stream, low bod and . And that what that's what passes
24:10 to the next phase. If it's drinking water plant um to produce clean
24:15 water, you chlorinate UV, knock out pants and so you may
24:22 to do nutri no, you don't to worry about this, but you
24:26 have things like nitrates in there that to be gotten out. It can
24:31 toxic in, in, in, the mouth. So in any
24:35 so really it's, it's, it's where, where the action with the
24:40 and microbes is occurring here. They their thing. Knock down beauty,
24:46 settle out and then that, that be reused. So that's what we
24:50 the activated sludge, the material that out that is still active, can
24:55 aerobically. We then uh as it out, we then bring it back
25:00 , and into the tank and then get it, get it going
25:03 All right. So these are, is where the action is happening is
25:06 these two tanks here. OK. we promote the growth in the aeration
25:12 . Then it, then it cuts in the clarification tank and it settles
25:16 and then it keeps recycling. So keep recycling that. Ok? So
25:20 not all, all about bacteria because protozoans do play a a big role
25:25 the process as well. So just to once again, reiterate the
25:31 the the process going on is this this and of course, you can
25:37 replace glucose with whatever the organic content , right? But it's the consumption
25:43 02 pro the energy and then grow in the process of knocking down bod
25:49 . So the sludge is typically So flock, flock and fluctuation.
25:55 the process of aggregating, you the these growth of these filamentous
26:02 right? As I drew in a ago, right? Forming these this
26:07 network of cells, right? And like starch, right? Phb other
26:14 material kind of holds it together and what kind of settles out,
26:18 But then we also have on there different types of protozoans as we see
26:24 . OK? I should mention this saper trophic. This relates to it
26:29 to decomposition. So Saros uh feed decayed organic material. OK. So
26:35 just an example of the types of , you see, uh, stalked
26:40 , which means they're kind of fixed place. But then they have these
26:44 up here that have rotating Celia, kind of scoop food into their
26:50 Uh, you may see some pre types, crawling types. You see
26:55 little legs here. Uh, they're crawling along on these, on
26:59 flock particles, the bacterial filamentous growth . Ok. Then you might see
27:04 , something like that, these micro that's a water bear. And so
27:08 healthy uh wastewater treatment system has a of these and bacteria all coexisting working
27:17 , so to speak to, to down this bod. So the um
27:25 , right? So the flock formation what allows is, is what settles
27:28 . It's what you want, you fluctuation because that's what will settle
27:33 producing a clear effluent. OK. so you see some types. So
27:37 is, here are the uh filamentous in this upper left quadrant here.
27:43 Here are other types you see branching . Uh But then you see protozoans
27:49 well. OK. So, um the thing about this process is you
27:56 get settling. So here's an So you always take all kinds of
28:00 during, you know, when when a plant's running to make sure
28:04 working, right? And here's a common test, uh very
28:08 All you do is take a water , take a sample out of the
28:10 , dump it into a graduate cylinder you start your stopwatch and you see
28:15 fast it takes for settling to And so these are two different samples
28:20 taking two different time points or Uh Then you, then you see
28:25 progress. Oh, excuse me, progress as we go as time goes
28:30 , you can see how clear um how you get really good settling and
28:36 have decent settling. Both are clear by the third picture down,
28:41 uh particularly on the right side, really clear and you see the material
28:45 has settled right here and that brownish , that's very typical. OK.
28:50 that's what you're looking, that's what looking for is to get a AAA
28:55 , uh material settling and you this that stream would then go on
29:00 uh to the next phase. Um , excuse me, the um thing
29:05 mention is the role of protozoans, ? So protozoans um will, so
29:13 have your, your bacteria. So flocks we call it, right?
29:22 forming these are filament, this bacteria like these guys and these guys
29:28 coming together and then you have uh that are on here as well.
29:35 ? But then you also have free types, right? Swimming bacteria.
29:47 ? We call these planktonic cells. worry about the term, but
29:53 let me see if I can write better. So plank tonic cells are
30:04 swimming cells. OK. Bacteria. swimming around, right? They're
30:10 they're not part of the filamentous And so these are entities that don't
30:15 out and the flocks do they And they fall out of solution.
30:21 , from assuming sellers represent bod as the flock. These, this all
30:26 bod as well. Yes, they've up organic content, but they themselves
30:32 bod as well. So the flocks settle out, takes care of
30:37 But what about their free swimming Right? You don't want to have
30:40 in your effluent. That's what protozoan . One of the major contributions is
30:44 types that eat these free swimming And so uh then they all kind
30:48 then, then, so these guys , right? Stocks, what
30:54 you will be sitting on the, the flocks and they can then eat
30:58 free swimming types. And so that's their contribution is to get rid
31:02 these types and then so that gets rid of them and then these
31:06 settle out. And so that results a and they knock down a bod
31:11 a clear effluent. OK. So really the importance of protozoans in
31:14 in the process. Um Now, . So that's what sort of
31:22 So, again, takeaways there are the goal there is promote growth of
31:29 aerobic respiring heterotrophic type microbes bacteria to , they're gonna knock down your organic
31:36 , lower your bod and then we to get, settle them out,
31:41 ? So we need to have a effluent as well. And so,
31:45 know, remember that they themselves also to bod. So you want them
31:50 settle out, right? Clear low bod, that's the goal.
31:54 , settling and aerobic respiration. So now we're going into a little
32:00 about uh so recall the importance of , right? We talked about,
32:05 know, plants, algae, others other photos auto tropes in general,
32:10 ? They, they just need sunlight, um co2 and they can
32:14 their thing but they can't make, know, nitrogen, phosphorus,
32:18 So uh these, these elements are to have. And so uh so
32:23 gonna kind of see the contributions of different nitrogen compounds in, in the
32:29 of what we call a nitrogen cycle nitrogen triangle. OK. So the
32:34 of these, the the conversion of to N two that is actually
32:41 OK. And de electrification leads to loss of nitrogen from the environment.
32:47 . As you see here here is . And so if it goes to
32:52 two, that's a gas, we're back into the atmosphere. OK?
32:59 Ammonia and ammonium ion. OK. there's actually two processes that produce that
33:10 and ammon application. OK. As see here, right? The fixation
33:14 a process that takes the atmospheric form nitrogen and brings it back into the
33:22 critical. Absolutely critical process. Nitrogen fixation because it's what balances the
33:29 of nitrogen from ecosystems by bringing it in. OK? And without that
33:35 , you're not bringing in nitrogen and needs it right? For, to
33:40 nucleic acids, to make uh you have to have nitrogen.
33:45 And so you see here at the breakdown of proteins produces ammonia.
33:50 so that's how us humans and other and other types get their nitrogen sources
33:57 distribute, it's through that right? of proteins. OK? Um So
34:04 as we look at uh so don't about the table here. And oxidation
34:09 , I just put that in there show the various forms of nitrogen.
34:13 a lot of oxidation states of OK? Nitrogen compounds. And each
34:20 those has like their role in the , right? So this middle diagram
34:26 , OK is kind of showing you continuum of these nitrogen components.
34:32 So we're looking at more what what call more reduced forms, more electron
34:39 forms. OK. So these serve as um as nutrients for, for
34:50 , you can use those compounds as electron source, right? Like glucose
34:55 one for us, we break it . Well, for lithic could be
35:00 . No two H two S, right. These are the classic lither
35:06 um than other forms of nitrogen, ? And it nitrate is kind of
35:11 the the the dividing line between the . that's and so, uh
35:19 A that that's simply just if a produces the product, it then holds
35:24 to it and it becomes part of cell structure. OK? That's
35:28 uptake, think of, think of as uptake. Um The gentrification by
35:35 is the end product of the process the cell, it doesn't hold on
35:40 it. OK? That's a dissimulator . So here, so different forms
35:47 nitrogen nitrate nitrite. These can serve terminal acceptor, right? So remember
35:55 little diagram I always draw in chapter the chapter five material, right,
36:00 transport chain, uh terminal acceptor and donor or a source actually,
36:09 So the little trophy, right? that's this part, right? This
36:19 serves that role, right? So represent using nitrate to nitrite nitrate to
36:25 , these are forms of anaerobic respiration these nitrogen compounds are taking the role
36:32 02 and being the terminal acceptor for anaerobic respiration. OK. So you
36:38 of have different roles and then we the loop here. Here's in two
36:42 to NH four. So that's right? So we can represent this
36:46 a triangle as you've, you've seen . OK. So, um so
36:52 we look at uh a a non process that's been around for a long
36:59 , the Haber Bosch process uh that one manmade process that produces ammonia.
37:09 , still used today to make Um But that occurs at um that
37:15 reaction occurs at very high pressures, temperatures requires a metal catalyst. Um
37:26 the biological process to produce ammonia not fixation occurs at moderate conditions,
37:32 ? Atmospheric pressure, et cetera. um so and, and N two
37:37 itself is abundant, right, 79% our atmosphere. So, um
37:44 you know, bringing it into the ecosystems is critical, right?
37:48 for all life us included. And so here we see just summarizing
37:55 the cycle, right? So each side has kind of its own
38:00 thing. All right. So fixation this kind of own unique process um
38:06 brings nitrogen into the environment in forms can be used, right? So
38:11 have both free living and symbiotic, types that can carry this out.
38:16 The bottom side of the triangle is , right? These utilize, they're
38:23 oxidizing these forms, right? And , and the form NH four
38:34 So NH three and in a solution uh converts to ammonium ion. And
38:41 that's typically what you utilize as a . So that becomes broken down by
38:46 , they get the energy from that it's broken down to nit trite,
38:51 then nitrate. And so the other of the triangle denitrification, that's an
38:57 respiration. So again, they're using as terminal acceptor, right?
39:04 it's substituting the role for 02 in hero, this AOB respiration. Uh
39:10 think, you know, and a right? So you can, you
39:14 provide nitro ammonium ammonia through breaking down proteins, things like that.
39:22 So we first focus on fixation. . So this is a unique
39:28 It's, it's a very, very consuming process, lots of a TPS
39:33 a DH. And um, and it uh is poisoned oxygen poisons
39:42 process. Ok. So, in of who does this right? It's
39:49 , it's widespread uh uh among bacterial . So it's strictly bacterial process um
39:57 everywhere. Um And there's free living symbiotic types. But by far,
40:02 symbiotic types account for the vast majority nitrogen fixed. OK. And
40:10 and so biologically, it accounts for of the nitrogen coming into ecosystems is
40:16 this process, mostly symbiotic, nitrogen . And so, and the symbiosis
40:23 between a ba a bacterium and a and it is species specific specific.
40:28 . So what kind of plants? , things like soybean as you see
40:32 , uh peanut plants, um alfalfa, uh what we call leguminous
40:40 . Ok. And so uh you see the the nitrogen fixing activity occurs
40:46 these little nodules that you see on plant up here, right? There's
40:49 of little nodules on the root and where the activity is occurring.
40:54 So um the sano bacteria, uh type that can also fix nitrogen
41:05 So, in specialized compartments, We call heteros as you see
41:10 And these occur about every occur every one there, every 10 cells.
41:16 the cells here, the green right? These are, you know
41:21 vegetative photosynth photosynthesizing cells. OK. they separate the nitrogen fixing process from
41:30 because remember um uh santa bacteria uh oxygen producing photosynthesis, right? And
41:39 since oxygen poisons the nitrogen fixation you have to separate those two.
41:45 nitrogen fixation won't work as oxygen will poison it. OK?
41:50 in any case, in terms of , the plant association with the,
41:54 the bacteria that do this activity looks like this. So we start here
42:00 our pea plant and crab and we're down to a root. So this
42:04 begins. So, so this process one where you have two, a
42:09 species and a plant species coming right? So this, this is
42:14 a random process. It's, it's all mediated through chemicals.
42:18 So chemical attractant signals are put out the two. That's what, that's
42:24 initiates the, the um infection we it infection threat to occur on these
42:31 hairs, right? As you see . And so a big part of
42:36 . Uh so you see the attraction to the attachment of the bacteria to
42:42 root hairs. And Rizo is a name for a very common type of
42:48 into fixing bacterium. Uh So what a phenomenon that occurs with these root
42:54 is the curling of it. So curling is necessary for initiating this infection
43:02 . And that's the portal through which bacteria then infect the plant cells.
43:07 so again, er all these steps mediated by different, different gene
43:10 different proteins and things mediated. So , it's a very orchestrated process.
43:15 . Uh And so as the cells , they, they then begin to
43:22 into what are called bacteroides. So you see, see uh see
43:28 forming in the plant, OK? they get, they get so numerous
43:34 big that they appear as these bulb nodules. Ok. So these are
43:42 nitrogen fixing factories if you will. . And so what happens is the
43:49 represent a differentiated form of the cell is basically a nitrogen fixing factory that
43:56 that keeps 02 out. Ok. it's occurring within the, within the
44:02 cell, OK? But it's OK? Into this bactero unit so
44:09 oxygen can get to it to poison process. Ok? And so the
44:13 certain benefits as well, it receives . And so it's very common to
44:17 these plants. Uh pea plants, plants, soy, soybean plants in
44:23 that are very nutrient poor, And so peanut plants grow in sandy
44:28 which aren't very nutrient rich, but are able to thrive in these areas
44:33 they have their own and end source you will. Ok. So
44:38 a very critical process. So going back to this basic ecology,
44:42 ? Even if you don't like to plants, right? You,
44:47 you ARIC carnivore, right? Just exaggerate here for a second.
44:51 you like to eat meat and that's you want to eat. Well,
44:54 meat you eat, that animal depends plants to eat. And so
44:59 if plants are provided these things like phosphorus that bac bacteria can provide,
45:05 that, that meat won't be available you. So um it's, it's
45:10 like I said, it's it's a process to, to all life on
45:15 planet. OK. So uh so we go to the bottom uh run
45:24 the triangle. So, nitrification. again, this is a little trophy
45:29 , using these ammonia to oxidizing breaking it down to nitrite,
45:34 broken down to nitrate, right. these are mediated by different species.
45:40 Simonis, nitro bacter, different different , excuse me, uh that do
45:45 step. Um And so what what can uh promote this excess excess
45:53 , of this activity can occur through you know, excess excess fertilizer usage
45:59 then stimulates the production of nitrate. if the nitrate is not available to
46:03 used by others, then it just on top of the soil and it
46:06 , you know, nitrate is nitric acid and that can alter uh
46:11 phs and affect plant growth. Um itself is also toxic. It can
46:16 with getting molecules producing carcinogens. nitrate alone is also uh just by
46:24 not good either. So it's, something you don't want accumulating um de
46:32 . So the other side of the , right? So remember these,
46:35 uh compon nitrogen components here can serve terminal acceptor, right? So the
46:40 means, you know, that's right? Taking the role of
46:46 So you have nitrogen compounds instead that so it's gonna respire with these.
46:53 so um but of course, you , in two, in, in
46:57 two onn two are gasses, all . So the these escape from uh
47:03 ecosystem then in that way, and loss of nitrogen from the environment,
47:10 the term denitrification. OK. And N 20 in particular is actually a
47:18 gas, very potent greenhouse gas. more so than CO2. So um
47:25 where you have a lot of denitrification N 20 release uh is an
47:31 right? Because we now know uh N 20 and other gasses like
47:38 contribute to the warming effect on this . OK. So here just gives
47:45 a kind of a practical example. so again, how, how these
47:50 intersect, right? So, so the high bod can come from um
47:55 runoff of organic materials, whether it's and things uh off the coast of
48:00 . Here, we're looking at it the water um along with uh
48:05 this is also a heavily agricultural area here. So you may have fertilizer
48:10 combined with uh runoff of organic And so the high bod leads to
48:19 again, that process, right of , consuming the organic material, aerobic
48:24 , oxygen gets sucked out of the . Now, we have a dead
48:28 zone of hypoxia. So now we aerobic conditions and if we have an
48:32 of, of ammonia nitrate, for , then then we can trigger
48:37 All right. So we see ration using nitrate nitrate excuse me
48:43 And so this is nitrate here, black line. So it goes down
48:47 it's consumed. Then the next step the process is the build up of
48:53 two ono two excuse me. So goes up, then that becomes consumed
48:58 others, right? So now there now no and then N 20
49:05 appears that's the red line. So in, so it's a cascade
49:10 The 11 is then used in the one and it build up, you
49:14 , into can occur and again, a very potent greenhouse gas and
49:18 in areas like this where this is , it can be uh in terms
49:22 quantities, very significant. So something be aware of. So yeah,
49:30 so, you know, in so this session, just to give you
49:32 little bit of a taste of the of the metabolic uh activities of microbes
49:39 how they can affect uh us in of uh in the environment. But
49:45 , remember, you know, the of the the um common theme here
49:51 when, when, when these activities triggered, what you know, the
49:55 respiration to reduce oxygen levels in you know, having an impact on
50:01 , uh these are often triggered by man is doing right. Release of
50:06 um for less a runoff, these due to manmade activity. So,
50:10 know, don't blame the bacteria, , blame us for providing the nutrients
50:14 trigger the whole process. So, but again, the nitrogen cycle,
50:20 nitrogen fixation and the importance of that to providing nitrogen components to, to
50:26 able to, to make the, know, the molecules of life.
50:30 so it's critical for everything on this . So um very important.
50:35 um anyway, so at least you a taste of kind of of of
50:39 microbial activities uh outside the context of human body and disease. So,
50:45 any case, uh that's wrapped up section. Thanks
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