 The second example come into this picture, it is not only the protease, sometimes some of the organic molecules can also directly bind to this bacterial cell wall or their vulnerable parts and break it down. So, they are also known as antibacterial reagents and from the time of Alexander Fleming we actually started producing a huge number of them and one of them which I am more interested to discuss here today is known as vancomycin. Those who are very much interested in the organic chemistry can go back and look into the structure of vancomycin, I am not going into there. So, the important thing was that this vancomycin was a very strong antibacterial reagent and most of the bacterias are actually failing to in the terms of bacteria pharmacology itself the tolerance level. The tolerance level was so important over there that even with a very small amount of this vancomycin the bacterias were dying and then they figured it out that the bacterias are not willing to let the fight go. They are trying to give a fight such a way that they can still survive in the presence of this strong antibacterial reagent. And during a study what some of the researchers found that they started changing some of the amino acids especially D aspartate or aspartic acid and D serine. These two amino acid they actually started changing. So, you can remember the aspartic acid it is actually having a CH2 C double of H or C double of minus group present over there and serine is CH2 OH group. So, you can easily see they are actually having some polar groups present over there which is obviously going to play a huge role getting the molecular recognition of this vancomycin to the particular position of the cell. And what bacterias are doing they are actually changing it to the L2 DMN acid and as they are changing to L2 DMN acid they are changing the overall three-dimensional orientation of the molecule with respect to the vancomycin. So, the vancomycin still comes and it knows like which of the distances or which of the bonds are interconnected they cannot find all the groups in the proper position. And once it cannot find all the groups in the proper position it cannot affect the antibacterial reactivity. And by that its antibacterial reactivity actually goes down and that is has been found that this tolerance level tolerance level means if your tolerance level is high that means you can survive even with a high concentration of antibacterial reactivity. And it is found that once the bacterias evolved with this DMN acids that tolerance level actually goes up. So, that is one of the very unique finding from this particular system that the tolerance level actually goes up over there. So, that is two different ways one is the protease one is organic molecule and both of them can wreak havoc on the bacterial cell walls and kill them but the bacterias are fighting back by L2 DMN acid orientation change. So, that is how it has been done and that is showing that one of the important part like how important it is to have the particular amino acids D or R state. Now, coming to the third example and this particular name you most of you probably heard vibrio cholera. So, this is actually the bacteria which actually triggers the cholera among us. So, this is the bacteria and this bacteria has two different phases in one phase it is actually the growth of these bacterias happens. So, they have two different phase growth phase. So, where the bacteria multiplies in numbers and just spread around but that is actually a very short span of their lifetime. Most of their lifetime if you try to take a look into we found they actually remain in a phase called stationary phase. So, these are the two phases of their life. What is the stationary phase? Stationary phase is that where the growth is stopped, growth is basically close to zero but the metabolism in the system is on. That means the system is live but it is not actually growing. So, in this phase it is very important because in this particular condition they are very vulnerable because they are not increasing a lot. So, that means if I give a drug and try to kill them if I kill it over here because they are not increasing I can kill it. And over there it is very interestingly found this vibrio cholera and it is probably a little bit scary that they started producing a lot of deamino acid in this stationary state. Generally they do not produce a huge amount of deamino acid in the growth phase but in the stationary phase they started producing a huge amount of deamino acid. Why it is important? Because this deamino acid again goes to this peptidoglycan which is again the forms that bacterial cell wall and over there it actually helps it to regulate the strength of that cell wall. So, if you put a deamino acid instead of L so there is a change in the overall arrangement and that actually strengthens the overall cell for this particular vibrio cholera system. So, that has been found and it has been found that when the vibrio cholera has having a good amount of deamino acid present over there they can survive demanding condition. So, what is the demanding conditions we are talking about or we are interested in? The demanding conditions we are more interested over here is called low osmolarity. So, what is osmolarity? Osmolarity doesn't generally means that when you have a particular ion or molecule present in a solution. So, it is kind of an idea or a parameter that actually gives you an idea how much concentration it is actually present. So, it is somehow connected to this molarity, molarity all those things. So, take a look into what is osmolarity? It is actually a biological term, but it is derived from a physical chemistry point of view. So, in very layman's term the low osmolarity means that you have very low amount of metal ions that means a very low amount of glucose and both the things are very important glucose, metal ions because they are the metabolite by which a living system can survive and what has been found that this bacterias when they actually goes to kind of you can say in a stationary phase where it is not growing just munching up whatever it is available around it. So, for that they actually change it to DM in acid so that they can even survive at a much lower availability of the metabolites. So, their survival instinct is actually kicks in and they can survive this particular kind of I would say the starvation period even at a very low food for them the metal ions and glucose at the food for them they can survive and one of the factor that is actually affecting it not the critical factor is the presence of this DM in acid because through this DM in acid one they actually controls the cell wall strength and will come in a little bit later how it can also controls the pickup of the different metal ions and glucose from the surrounding solution. So, that is how the bacteria try to exchange themselves and that is how it survives with the presence of DM in acid. Now, we go to the next example, example D fourth example. So, we are talking about bacteria. So, we will continue that don't worry that is the last time we are talking about bacteria. So, it is not a biology class we will come back to chemistry very soon. But some fun facts about bacteria. So, when we talk about bacteria as bacteria as not only can have two different phases that is the growth phase and stationary phase but it can also have two different lifestyle that it can survive. One of them you already probably learned this term called planktonic. You all heard about that like what is planktonic? So, you have all heard about plankton. They are like very small amount of bacteria especially the blue-green algae that is surviving on the surface of the water and produce the huge amount of oxygen through photosynthesis. So, most of the oxygen coming to the earth or most of the carbon dioxide that is getting bound in the glucose is actually done by this plankton. And mostly which is known as the phytoplankton if it is doing this kind of photosynthesis and zoo plankton if it is having more of a like animal kind of behavior. Anyways, so plankton behavior mostly is that they are surviving in very small families. So, like not more than a few number of bacterial cells are sticking together. So, that is called the plankton. So, what is the advantage of that? That means they can move around very easily. However, the problem is in this particular lifestyle that you are much vulnerable. Anything can come and kill you because there is no other thing present around you to save you. So, all of you probably heard this story that you stick together to fight together and that is what exactly also the case for biology and bacteria they follow up another system which is known as the biofilm. What is biofilm? No, nothing to connect it with the Bollywood movies. Biofilm is that they actually colonize. They colonize in such a way that it creates a layer of bacteria around them and that is comes like a film structure and that is known as the biofilm. And what is the major ingredient of this biofilm formation? Like the common ones that you can expect, protein, the polysaccharide that means the carbohydrates basically and even something called extracellular DNA. That means the DNA that can be surviving outside the cellular system. And all these three things and some other molecules also come together and create this film which actually gives an extra protective layer outside the cell wall for the survival of the bacterias. And this is very crucial, this bacterial biofilm because that actually very important for the survival of the bacterias against what it is called the environmental threats or antibiotic attack. So, that is what the biofilm is very important about. So, this biofilm is also very critical for our day-to-day life. Why? Because when we are talking about any bacterial infection, this is a season when we have some sore throat and all those things and we generally say, oh, you have a bacterial infection. So, if we look back and find out what is actually happening in our throat, we will find it is nothing but we created a biofilm over there and that biofilm is creating issues over there. So, most of the bacterial infection that we face, it is actually inflicted by these biofilms. So, that is why the biofilms are not a good thing, it is good thing for the survival of the bacterias but not good thing for the host like us. So, human healthcare is going to take a huge heat for that. These biofilms are also very bad for agriculture because the plants, when they are getting affected by this kind of biofilms, that is affecting their metabolism, that is affecting their growth and that has a direct effect on the products of the agriculture because we are giving so much of different substituents for a good growth of plants and this bacteria is actually heating them up through these biofilms. So, that is why it is not very good with respect to that. So, that is why it is not very good to have this kind of thing is happening there. So, again coming back to this biofilm, the bacterial infection is inflicted by that, the human health is getting affected, the agriculture where the plants are actually getting affected for this and our agriculture produce get a heat and not only that even in industrial scale, industrial corrosion can also happen through this biofilm. So, these bacterias can survive in water, gas or oil pipes. So, water gas is fine because that actually provides a very nice niche for it to survive and gas and oil generally their hydrocarbons on which they can chew upon because they reduce source of carbon for them instead of glucose. So, they can eat on those things and when they start eating on those things, they started to colonize and when they start colonize they form these biofilms which actually corrodes the pipes and that actually creates a lot of leakage around it. So, that is why biofilms are not very good. So, so far we are talking about that how the D amino acids are actually improvising and strengthening the overall cellular structure. Over here the example is that biofilm is bad and we can use D amino acid cocktail to degrade the biofilm and destabilize the biofilm and people have found that if you use particular cocktail that means D amino acid mixtures and depending on which particular bacteria you are talking about you need different amino acid mixtures they can actually prevent this kind of biofilm formation and there is a huge controversy actually how it actually happens because okay I give a D amino acid and magic it stops the biofilm formation but as it came is it comes to our mind like okay it works but how and that how it actually has two different answers. So, I will give you one by one. First answer was this D amino acids actually goes through the system and forms as an integral part of the biofilm whatever the biofilm is there. So, it tried to form that thing. So, it is going to sorry it shouldn't say biofilm I should say cell wall. So, it tried to form this cell wall on the outside and then the two different cell walls from two different bacterias is going to combine together and for that they need something called anchor protein which is going to bind two different cell walls from two sides. Now, what happens once you have an L amino acid over here that is binding fine. So, these are all L amino acids but at the same time if you able to inflict a few more D amino acid over there then what happens. So, again the same cell wall we have a lot of L amino acid and then say I have a few of the D amino acids and as it becomes a D amino acid this anchor protein this anchor protein cannot come and bind pretty well. Why? Because over here look into that this is another protein this is cell wall interacting with the glycoprotein structure. So, they need some molecular recognition over here and because you change some of the L to D amino acid now it cannot recognize it properly and that is why this anchoring part doesn't work very well and unless you put the anchoring this anchor protein is kind of like the adhesive which actually binds everything together it is not working properly and that actually shuts down the biofilm formation that is expansion number one. The second one is actually almost having the similar idea. So, that this D amino acid are actually playing a role over there but the D amino acid how they are coming into there that is actually debated. So, they say the D amino acids when they put there they actually even affect the machinery which actually creates protein and by that it actually affects the overall structure of the cell wall and then the same story follows that the anchoring protein doesn't work. Yes Rajdeep we have a question. Sir just for my question sir are you sharing the screen because I can't see anything theory. Okay is it true for everyone? No sir your screen is visible. Okay so Rajdeep I would suggest you if you can please log out and log in back again that probably works. Okay sir. Okay thank you. Yeah okay so this is how it is actually working over here that how the D amino acid getting incorporated. So, there are two different ways it get possible one is that D amino acid directly go and bind to the system and the other system is D amino acid affects the machinery. Machinery means the ribosomes they are affecting and affecting the how the different proteins are actually formed and that is how it is affecting. But anyways whatever the matter is what you found that if you have some D amino acid present over here the blue ones it is going to hamper the overall interaction and that is how the biofilm formation can be stopped. So D amino acid is not always bad it is not always harming us but if you can use it smartly you can even prevent the biofilms and attack back on the bacterias. So again our odc on this particular bacterial lifestyle will continue with this particular example. This is the last example we are discussing about it is about metals. So okay we come back to this inorganic slowly so metals scavenging. So as we all know every living entity requires metal for function. In the binary genetic chemistry we have probably learned that each and every metal have their own role to play and there are certain elements which are very critical for our survival which are known as the essential elements they are very critical. Now bacterias also survive on that. Now when a bacteria actually requires some essential elements to be cobbled up on how it actually does so it does in this following way. So I am just drawing a very simple cartoon. So say this is your bacteria inside and this is the cell wall and this cell wall is not totally intact they have some proteins present here and there which actually act as the gateway for controlling system going back and forth. Okay so those kind of systems are present. So through that protons, metal ions all those things go back and forth. Now what happens the bacteria say doesn't have a lot of metal ions to play with in the beginning so it has to get it somewhere. Now bacterias are not human beings that I can take an iron supplement and get my iron so biology has to fight for that. Where it fights so in a bacteria in a system when it is surviving outside there is water or environment and they are present a huge amount of say metal ions. So they have to grab that metal ion and bring it inside. Now it cannot directly always take the metal ion is it possible it is possible for like sodium, potassium this kind of ions because they are so huge in amount present outside that it can just get it through simple even osmosis system. However if you try to find a first transition element it is not that straightforward because of two reasons first the concentration is low. Second there may be different metal ions present for example iron is present, cobalt is present, nickel is present and say you require at that moment only iron but not nickel or cobalt. So you have to differentiate it. So how I can differentiate? So for that biology come out with a very unique idea known as cedarophores. So what is cedarophores? Cedarophores is nothing but multi-dentered ligands. So what biology does the bacterias does they kick out this kind of cedarophores outside and this cedarophores it is very similar you can say as an EDTA. Once it sees a metal ion it is just grabs it because it is a multi-dentered ligand so it is entropically favorable for it to bind these metal ions. So once it binds it it changes a little bit the overall property of the ligand obviously ligand without metal with the metal the properties will be different and this bacterias at that time cobbles that cedarophore with the metal inside it. So first it sends the cedarophore without any metal so I am putting it say in blue so cedarophore without metal and once it interacts and bind with that metal it creates cedarophore with metal this red one so this is with metal and this is without metal and then it cobbles it up and that is how the biology survives. Now the problem is that biology that in the biology bacteria is not the only player over there so there are some other bacterias are also present there who also try to get this cedarophores out it is kind of like a parasitic environment over there so they are just waiting someone giving their cedarophores outside and grabbing the metals and they are patiently waiting once it binds the metal they just grab the cedarophores bound with the metal so there is like a real dogfight going on over there for the metal ants so if a biology has to survive they have to work in such a way that they can actually not only get the metal but they can also take the metal without notifying the other living systems around it even the plants sometimes also use cedarophores to grade their nutrients so it has to fight with a lot of things so that is how the cedarophores are important and it is very much important for the life so over here DMU acid can have a huge role to play and for that I am going to give you an example how it is going to happen so over there I am going to show you an example of a particular cedarophore known as staphylopine what is a staphylopine? Staphylopine let me show you if I can have the picture so this is staphylopine this molecule present over here so you can see to it it is actually multidate ligate with a lot of carboxylic acid groups and all those things present and if I ask you what are those things actually you can see it is actually derived by amino acids for an example this portion over here this is derived from histidine this amino acid over here you can see it is derived from alanine so this kind of staphylopine which is actually nothing but a cedarophore which is made out of amino acid systems so what some of the bacteria does and over here I am showing you the kind of the lifestyle of it so it is actually created inside the system so it is inside and this is outside and it created it is created inside the cell and through this particular gateway which is known as CNTE don't worry about the name so through this it actually lives outside and over there you can see once it gets outside the metal ions comes and binds it can binds different metals zinc nickel cobalt and once it binds to it then it can get recognized by this binding pocket of CNTA and then it actually comes inside the cell and inside the cell when it comes the metal ions get released and this particular cedarophore can get recycled back back to the outside to grab metal now how the deamin acid is playing a role so over there you can see this system is made out of two amino acid alanine and histidine some of the bacterias what they do during the formation of this staphylofine inside their cell they use dehystidine instead of L and how it is going to help it because when it release the dehystidine band system it binds to the metal and up to that part is fine but then this recognition part recognition of this metal bound staphylofine it is very much dependent on this overall structure now if you change from L to D it is not recognized by the other bacterias or the other players present and this bacteria which is smart enough to change it only it has the molecular recognition system which can detects even the dehystidine bound metal ions and by that it swiftly smuggles the metal ions by putting the other bacterias or other competitors out of the race and that is how the bacteria are using this deamin acid L amino acid mixture very specifically to play out different orientations and that is how it controls the metal ions scavenging and surviving in very demanding conditions so these are the five examples we have gone through today so I hope that you probably recognize that how important the deamin acid is and that is mostly coming from the molecular recognition part of it it is not only helping it to to fight against the protease it helps it to fight against the antibacterial reagents sometime it also helps it to form a very strong cell wall to survive especially in the which is called the stationary phase of the of the bacterial life and we also found that it is not only the bacteria are using it it is also the human beings also learn and use it against the bacterias by disrupting the biofilms because biofilm formation is very much dependent on which amino acids are you are using and if you use particular cocktail of deamin acids that you can actually degrade the particular biofilms and also we learned how the metal scavenging can be also controlled by this important use of deamin acid so later today I will share a paper with you what you can look into and find out how the different roles of the deamin acids have been revealed by the scientists all over the year and how many different interesting roles it actually plays