L - 2 | Tamil Nadu Drug Inspector 2026 - Morphology, Classification & Identification of Bacteria

Added: 2026-05-31

[00:00:34]It's lights out and away we go.

[00:00:44]>> Hello everyone. Good evening. I hope my voice is audible to all of you.

[00:00:50]Good evening everyone.

[00:00:59]Hello everyone. Good evening all.

[00:01:01]Welcome. Welcome to the GDC classes English.

[00:01:07]So as you can see from our thumbnail, so it is a special class for the Tamil Nadu DI okay course. So in this class we are going to talk about in detail about bacteria, their classifications, their morphological classification, their staining technique, how the bacteria can be stained, how we can visualize the bacteria under a specific microscope.

[00:01:32]Then we will be talking about the bacterial reproduction, the different method of bacterial reproduction. Then we will be discussing about the some of the important MCQ which is important from your exam point of view. Just confirm whether my voice is audible or not so then I can start the things.

[00:01:56]Good evening all. Welcome back. Welcome back to the GDC classes English. So, we will be discussing this bacteria and its morphological classifications and the important MCQ from this point of view.

[00:02:09]So, just confirm in the chat box whether my voice is audible or not and whether the slide is still visible or not. Just confirm in the chat box.

[00:02:19]Okay. So, bacteria. So, bacteria is basically one of the major your prokaryotic organism. Okay. It comes under your major prokaryotic organism.

[00:02:32]So, which is basically Okay. So, these are the prokaryotic major prokaryotic organism. So, most what are the things that you want to focus here is So, these are basically microscopic. That means to visualize a bacteria, you need a specific instrument called microscope. Without it, you cannot visualize. Second is most important unicellular.

[00:02:59]They are having single cell. They are unicellular. They are prokaryotic organism. They possesses both DNA and RNA.

[00:03:08]Okay. So, first point is they are microscopic. That means to visualize this bacteria, you need a specific instrument called microscope. Second point is they are unicellular. They basically needed to be uh uh visualized. Uh they are unicellular.

[00:03:24]They are prokaryotic organism. So, they have both DNA and RNA as a genetic material. So, important component is its cell wall. Its cell wall is made from peptidoglycan.

[00:03:36]Okay. Its cell wall is made from peptidoglycan, which is a structural and functional component of the cell that is present around. So, if you will see the classification of the bacteria, so bacteria basically comes under your prokaryotic kingdom Monera. Okay. It comes under your prokaryotic kingdom Monera. So, these points what I'm trying to tell is these all are important points. Try to remember and write it down in your copy. Okay, try to keep one pen and paper and write down the things which will be basically important point I'm going to talk about. The first point which are unicellular, prokaryotic microscopic organism. So, their cellular contains the peptidoglycan layer. Third point is they are belonging to the prokaryotic kingdom Monera. If we talk about the size, so their size should be varied from 0.75 to 4 micron in diameter. Okay, they comes under your class The study of bacteria is called as bacteriology. Antonie van Leeuwenhoek which first time he observed bacteria using his own microscope. Okay, so this point is also Antonie van Leeuwenhoek. So, they basically first time they introduced to visualize this bacteria under a microscope. So, next point we are we are going to discuss.

[00:04:54]Okay, so the cell wall is a rigid structure. Okay, if we talk about the further point about cell wall, its cell wall having its rigid structure made up of peptidoglycan. Okay, and surround the plasma membrane as an external coat with 10 to 25 micrometer thickness. Okay, if the cell wall is a bacterial cell wall composed of macromolecular network of peptidoglycan called as murein.

[00:05:18]Okay, which protect the cell from the protect the cell. So, if we talk about the disaccharide portion so portion so they are consisting of N-acetyl this cell wall is consisting of N-acetyl glucosamine and N-acetyl muramic acid two major component Nag and Nam. Okay, Nag that is N-acetyl glucosamine and Nam N-acetyl muramic acid. This is composition of your cell wall. Okay, the term glycocalyx similarly imply the substance around the cell that is your glycocalyx. The bacteria glycocalyx is basically viscous, gelatinous polymer external to the cell wall and composed of polysaccharides, okay? Polypeptide or both, which helps in the attachment or adhesion, okay? Which helps the bacteria attachment or adhesion. If we talk about the bacterial cell wall, this is consisting bacterial cell wall is commonly founded in many bacteria and they are basically pathogenic in nature.

[00:06:15]Very, very important point to remember here. So, cell wall is basically pathogenic, okay? That means this cell wall basically induces disease, okay?

[00:06:26]This is important point to note. So, bacterial cell wall is important because it induces the disease. If we will talk about its classification or or its structure, let's talk about its structure in detail.

[00:06:42]Okay? So, this is the bacteria.

[00:06:47]Okay, let's name its all parts. So, this is your flagellum.

[00:06:57]Okay? It's inside the bacterial cell wall that is a uh small thin layer.

[00:07:15]Okay?

[00:07:17]So, this is your cell wall.

[00:07:26]This is your plasma membrane.

[00:07:35]So, inside over the bacteria surface, you will have small projections.

[00:07:56]The small projection on its surface.

[00:08:07]Okay, this is called as pili or fimbriae.

[00:08:16]Pili.

[00:08:17]Okay, inside the bacteria you will have the genomic content. Okay, like in case of human eukaryotic cell the genetic material is present inside the what we can call nucleus. But here there is no nucleus is there. It is present like this. Okay, so plasma membrane and all function we will be going to see one by one. Okay, so you just come to this way. So if we'll talk about the external structure of the bacteria, you are finding this pili.

[00:08:48]You are finding this capsules. Capsule is the external structure. You will find the flagella. Okay, you will find the bacterial sheath as well as cell wall.

[00:08:58]These are the external structure which is present outside the bacteria. Okay, so external structure and internal structure. Internal structure is those which is present inside the bacterial component. Okay, so please understand with it quickly key there is some internal structure. We have some external structure. Internal structure means where the bacteria is present outside like your flagella. This is your external structure. Your pili is your external structure. Then your bacterial sheath is your external structure. Okay, so these are the external structure. If you talk about internal structure you will find the cell membrane, cytoplasm, bacterial nucleus, and endospore. These are called as what? These are basically called as your bacterial internal structure. Okay? So, we'll be seeing one by one, flagella.

[00:09:50]So, very, very important point. So, flagella is a part of your bacteria.

[00:09:54]What is its function? It is responsible for the locomotion function. Okay? What is its function? It is function is locomotion. Okay? So, from moving one bacteria from one place to another, so bacteria will going bacteria will locomote with the help of this flagella.

[00:10:12]So, flagella is basically a hair-like filamentous structure about to 4 to 5 micrometer long, 0.01 to 0.03 micrometer in diameter. Okay?

[00:10:21]The filament is a thread-like part extending outside of the cell wall, which is made from flagellin protein.

[00:10:28]There is a specific protein present in flagella, which we call it as a flagellin protein. So, hook is a short hook is a short cover that joins the filament within the basal body. So, this filament to the basal body, to join this this hook is needed. Okay? So, the basal body is setting a ring embedded in the cell wall of the plasma membrane. It is consisting of two pair of ring that is gram-negative bacteria, one pair of that is it is a basal gram-positive bacteria.

[00:10:57]Synthesizing the polymer of the flagellum produces the energy revolution and regulate the movement of the flagella. Okay? Next part part of the bacteria is pili or fimbriae. So, it is basically responsible for the attachment. Okay? The major function is attachment. Okay? Adherence or attachment to the host cell. Attachment to the surface of absorption of nutrient. Sex pili helps in the bacterial DNA transfer by forming conjugation. Okay? So, they form this this is called as cytoplasmic bridge.

[00:11:29]Cytoplasmic bridge we called it. Okay? So, the pili are the short, hollow, non-helical filamentous structure about 0.5 micrometer length and 0.01 micrometer diameter. They are exclusively found in gram-negative bacteria. Very, very important point. This pili or fimbriae exclusively found in case of gram-negative bacteria. Okay? So, please understand this point. Okay? So, they are composed of a specific protein called pilin. Okay? They are short, numerous, and straight than straight than the flagella. Sex pili are special kind of pili that takes part in the bacterial conjugation. Very, very important process. What is conjugation?

[00:12:11]We'll be going to see in our our next slide. Okay? They are the larger than the usual pili. Okay? 0.3 to 0.1 micrometer in length. They are fewer in number, that is one to four in number.

[00:12:22]Okay? Function, they are adherence of the cell to the host cell, adherence to the absorption surface, also helps in bacterial conjugation.

[00:12:31]Next organelle. Next is capsule. So, capsule, what is the function of the capsule? So, capsule is basically the most outermost covering of this that is called as glycocalyx layer. This is the outermost layer surrounding to the cell wall. It is composed of either polysaccharide or polypeptide or both and water around 98% consisting of polysaccharide or polypeptide or both along with water. Around 90% of water it is present. Okay? The capsule is of two type. One is your macro capsule, another one is your micro capsule. Macro capsule thickness around 0.2 micrometer, micro capsule having thickness is less than 2 micrometer. What is the function of the capsule? It aids in the adherence, also I will help in adherence. Provides a physical strength to the cell.

[00:13:18]Confer the confer resistance against the phagocytosis. They protect the cell from proteolytic enzyme. These are the function of the capsule.

[00:13:28]Okay, next next layer is your sheet or and prosthetic. So the sheet is a hollow tube-like structure enclosing enclosing the chain forming bacteria. It provides a mechanical strength.

[00:13:44]What it do? It provides a mechanical strength.

[00:13:48]Next prosthetic is they basically increase the nutrient absorption. Next come to the picture is cell wall. So cell wall already discussed this is consisting of peptidoglycan.

[00:13:59]Peptidoglycan is further cross-linked polymer of NAM and NAG that is N-acetylmuramic acid and N-acetylglucosamine.

[00:14:07]Okay, types of cell wall. This is important. Gram-positive cell wall and Gram-negative cell wall. So Gram-positive cell wall is basically thick cell wall. Okay, and it contains large amount of peptidoglycan. Okay, because as it is thick the peptidoglycan quantity is also high. Okay, Gram-positive cells. So the upper Gram-positive cells say this is basically thick. This is be why it is thick due to presence of more amount of peptidoglycan. Okay, and about 40 to 90% of the cell wall, okay, arranged in the several layers.

[00:14:40]This type of cell wall is having acidic sugar. Okay, and important question always ask what is the things that present in the Gram-positive cell wall?

[00:14:49]Gram-positive cell wall contains teichoic acid, lipo teichoic acid, and glucuronic acid.

[00:15:11]glucuronic Okay, so these are the neutral sugar like mannose, arabinose, and rhamnose sugar. This type of cell wall wall wait cell wall basically takes up crystal violet dye and for and for give a purple color in gram positive staining. Okay? So, what is gram positive staining? Just quickly let me tell you just quickly.

[00:15:40]So, gram staining.

[00:15:42]So, just quickly discuss about gram staining.

[00:15:47]So, this gram staining was basically discovered by first time discovered or developed by Christian Grams, okay?

[00:15:58]Christian Gram.

[00:16:00]Okay? So, what is this function? So, this basically to differentiate differentiate between gram positive and gram negative.

[00:16:19]Gram positive and gram negative microorganism.

[00:16:25]Okay?

[00:16:27]So, now So, how we are going to differentiate?

[00:16:31]So, there is a four steps, okay? So, do you have to follow these four steps, okay? What is this? First one is primary dye mordant next is decolorizer and counterstain.

[00:17:07]Okay? So, primary dye is Yes.

[00:17:15]crystal violet Okay? next is mordant is your iodine.

[00:17:29]Third is decolorizer acetone or alcohol.

[00:17:39]Fourth one is counterstain is your safranin.

[00:17:43]Okay?

[00:17:47]You have to apply in this order only.

[00:17:50]Okay? Crystal violet, iodine solution, acetone or alcohol, and safranin. You have to apply in this order. So, what you have to do is you have to first apply crystal violet, then you apply with iodine, then you acetone or alcohol, then safranin. After this, there will be a color will develop.

[00:18:07]Okay?

[00:18:10]What will happen? So, after this, there will be a development of color. For detection of gram positive and gram negative. So, gram positive will gives What did he say?

[00:18:28]Gram positive will give violet color.

[00:18:36]It will give you red color, red or purple color.

[00:18:40]Red or purple color. So, this is the staining.

[00:18:46]So, for the detection of gram positive or gram negative. So, question One question asked from this part. So, why we use safranin? So, safranin What is the use of safranin? Safranin is basically used for gram negative microorganisms.

[00:19:06]On the basis of this, we will be differentiate gram positive and gram negative. By which technique? By gram staining, which is developed by Christian Gram for the differentiate between gram positive and gram negative microorganism. So, first we saw about gram positive. Now, we are going to talk about gram negative. So, gram negative cell wall is basically thin. It is not thick. It is basically thin.

[00:19:29]Okay? It is having very less amount of peptidoglycan. Okay? It is having less amount of peptidoglycan. It is comparatively more complex than the gram positive cell wall. Okay? It is comparatively more complex than the gram positive cell wall. It contains what it contains? It basically contains lipoprotein. Please note it down.

[00:19:51]Lipoprotein.

[00:19:54]Lipopolysaccharides.

[00:19:59]Okay? So, they basically project. So, these are basically more complex. Okay?

[00:20:04]The gram positive cell wall of the cell wall of gram positive is little bit simpler. But, if you compare with gram negative cell wall, it is little bit complex than the gram positive cell wall. It contains lipoprotein. It contains lipopolysaccharide. And the outer membrane addition to it contains peptidoglycan. Lipoprotein layer is composed of Brown's lipoprotein.

[00:20:27]Okay? It is composed of Brown's lipoprotein. The outer membrane is bilayer that is presence of two layer structure containing inner layer resemble to the plasma membrane and outer layer is made from lipopolysaccharide. It is rich on various protein called porin protein.

[00:20:44]Okay? It is composed of high amount of porin protein. Chalo, next thing. Now, we will see what is the difference between gram positive and gram negative cell wall. Because this difference is important from your exam point of view.

[00:20:58]If you understand the difference, then you can easily solve the question. So, first point.

[00:21:04]Gram positive As we As I told you, positive is thick, Gram negative is thin. So, Gram positive cell wall is thick.

[00:21:14]Okay, which is 20 to 80 nanometer. Gram positive is Gram negative is thin, it is just 10 1.5 to 10 nanometer.

[00:21:23]So, Gram positive Why is thick? Because it has high peptidoglycan content. Okay, why it is thin? Because it have low peptidoglycan.

[00:21:31]If you will talk about the protein lipid content, the Gram positive have low lipid content, but Gram negative have high lipid content.

[00:21:42]The main component of peptidoglycan is your teichoic acid and lipoteichoic teichuronic acid and lipo teichoic teichoic acid. Okay, if you will talk about the Gram negative, it is lipoprotein, lipopolysaccharide. Okay, so basically purple color. Okay, it basically so pink to red color.

[00:22:08]Okay?

[00:22:10]So So, Gram positive basically so purple color.

[00:22:20]Gram positive so purple color, Gram negative pink or red color.

[00:22:33]Okay?

[00:22:34]So, some some book also you will find it as a violet color also.

[00:22:39]Okay?

[00:22:40]So, now we are going to talk about the classification on the basis of the their morphology. Okay, so we can classify the bacteria based upon their shape, arrangement, based upon their staining technique, based upon the oxygen requirement, based upon the temperature, based upon the arrangement of flagella, and based upon the mode of nutrition. Okay? So, first classification is based on the arrangement, okay? Or morphology. So, bacteria are basically either they are round shape, okay? Or either they are spherical, okay?

[00:23:23]Either they are rod shape, either they are spiral shape, spiral shape, either they are comma shape.

[00:23:41]There are many things shape we are going to discuss today. So, first shape first type of shape that we are going to discuss about cocci or spherical shape.

[00:23:52]So, they are monococcic, okay? Single singular cocci, single cell that is your micrococcus luteus example. Is this monococcic? Diplo means two. If that is present in by by by two like this, okay? They are called as diplococcus pneumoniae, okay? Diplococcus pneumoniae is comes under this type of classification.

[00:24:14]Strepto, strepto mean chain. If bacterias are arranged like a chain like this, if it is arranged like this chain, we call it as a strepto.

[00:24:27]Okay? So, this streptococci are basically chain example example is your streptococcus pyogenes, okay? Next is tetracocci. Tetra means four.

[00:24:38]Tetra means four or not? So, if they are arranged like this, one, two, three, four. We call it as a tetracocci.

[00:24:47]That is your example is your pediococcus urinae, okay?

[00:24:51]Example is your pediococcus urinae. Next is staphylo. Staphylo means grapes, okay? You have seen the grapes now? So, how these grapes looks like? Like this, they arrange like this.

[00:25:04]Yes or no? So, this grapes arrangement So, this strepto This is example is staphylococci. Example is a staphylococcus aureus. Next is Sarcina.

[00:25:13]Sarcina is group of eight. If it is present as a group of eight, it is called as Sarcina.

[00:25:20]Up to this it is clear to everyone?

[00:25:23]Is this clear?

[00:25:33]Is this clear to everyone?

[00:25:36]Confirm me in the chat box.

[00:26:01]Confirm me in the chat box.

[00:26:08]Is this clear?

[00:26:22]Chalo.

[00:26:25]Next thing that we are going to discuss here is bacilli shaped bacteria. Okay?

[00:26:30]Bacilli shaped. So, bacilli means which are rod shaped bacteria.

[00:26:35]Like this.

[00:26:36]These are a rod shaped.

[00:26:41]Okay? So, they are either called monobacillus. Okay? That is single unattached rod shaped bacteria. That is your bacillus cereus. Okay? Next is diplobacillus. Diplo means two. Okay?

[00:26:55]Two rods of bacteria if present like in a in combination, that is your called as diplobacillus. Two rods of bacteria.

[00:27:03]Example is your Moraxella bovis. Next is streptobacillus. Strepto means chain.

[00:27:08]Okay? If these are present like this chain.

[00:27:20]These are called streptobacillus.

[00:27:22]Example is your streptobacillus moniliformis. Next is palisade. They are arranged like this this like arrangement. These are called palisades. That is Corynebacterium diphtheriae. Okay? Next is coccobacilli.

[00:27:36]Example is your oval-shaped Haemophilus influenzae. Next classification is spirochetes. Spirochetes means these are the spiral-shaped bacteria. They are axial filament which is contained under a external flexible sheet. Spirochetes bacteria includes spiral-shaped. They do not have rigid cell wall. Example is your Treponema pallidum. Next is spiral bacteria. You have bacteria with similar structure with spirochetes. That is your gram-negative, but they are more rigid. Example is your H. pylori. H. pylori is your spiral-shaped bacteria. Next is comma-shaped. Comma-shaped is your Vibrio cholerae. Okay? This is your under comes under your comma-shaped.

[00:28:15]Now, we completed the discussion of classification of the bacteria based on on its morphology which visualize under microscope. Next is based upon the flagella. So, we know this flagella is responsible for the locomotion. So, based upon the flagella, we can also classify. So, first is atrichous.

[00:28:34]Atrichous means without flagella. If bacteria has no flagella, we call it atrichous like your like your Bacillus anthracis. So, Bacillus anthracis is atrichous without any flagella. Next type is monotrichous. Mono means single.

[00:28:51]If single flagella at one end, we call it as a monotrichous. What is Next example is your Pseudomonas thiobacillus. Next is your lophotrichous. Lophotrichous means group of flagella, two or more flagella at single end.

[00:29:10]Okay, that is called lophotrichous.

[00:29:13]Example is your Pseudomonas fluorescens.

[00:29:16]Next is amphitrichous. Amphi means both side.

[00:29:20]If single single flagella at one end.

[00:29:24]Okay, that we call it as a amphitrichous. Example of this amphitrichous bacteria is Nitrosomonas, Pseudomonas, and Vibrio cholerae.

[00:29:33]Next is peritrichous. Peritrichous means periphery, all over the surface. Okay?

[00:29:39]All over the surface.

[00:29:42]That is your peritrichous. Example, your E. coli is a peritrichous, Salmonella typhi is a peritrichous, Clostridium is a peritrichous type of bacteria. So, first classification we have seen on the basis of morphology. Second classification we've seen in the basis of flagella. Next classification is temperature. You know, there are some bacteria which grow in cold temperature, some are grow in medium range temperature, and some grow in high temperature. So, based upon this, we have classified the bacteria. So, psychrophiles are those bacteria which grow in the temperature around 0 to 15 degree, thermo- uh mesophiles which grow in the temperature range of 20 to 40 degree centigrade, thermophiles which grow in the temperature range 45 to 70 degree centigrade.

[00:30:30]Both your psychrophiles and thermophiles, they are non-pathogenic.

[00:30:34]That means they do not possess any disease.

[00:30:37]But, your thermophiles are But, your mesophiles are pathogenic. So let's see the example psychrophiles example is your saprophytes, major files example is your corynebacterium diphtheriae. Okay, thermophiles that is streptococcus thermophile.

[00:30:55]Okay, these are the classification of this bacteria.

[00:31:01]So on the basis of temperature next classification on the basis of oxygen requirement. How you are going to classify the bacteria on the basis of oxygen requirement first they are called obligate aerobes. Obligate means obedient. They only grow in the presence of oxygen. So they only grow in a aerobic condition around 12 12 to 21% of oxygen. Example is your nicardia nocardia pseudomonas Okay, mycobacteria, brucellis, meningococci and bordetella. These are called obligate aerobes. Next come into the facultative anaerobes. That means they grow in both presence as well as absence of oxygen. They can grow in the presence of oxygen. They can also grow in the absence of oxygen also. If oxygen is not there, then also they can survive. They are obligate anaerobes.

[00:31:55]Example your staphylococcus, your actinomycetis, your E. coli, shigella, salmonella, listeria. These are facultative anaerobes.

[00:32:05]Microaerotolerant very very important many times this from this question has been asked.

[00:32:12]What is microaerophilic aerotolerant?

[00:32:15]They are grow in anaerobic condition.

[00:32:18]Okay, they majorly grow in anaerobic condition, but little amount of oxygen also they can survive around 5% of oxygen. Okay, so that is called as microaerophilic or aerotolerant anaerobes. Example is your staphylococcus spirochetes campylobacter and H. pylori. These are microaerophiles. And last, obligate.

[00:32:39]Obligate means I told you obligate means obedient. Obligate aerobe means only grow in presence of oxygen. Obligate anaerobes means only grow in the absence of oxygen. They can only grow in the absence of oxygen. Example is your Clostridium and Bacteroides.

[00:32:56]I hope everyone is clear up to this.

[00:33:02]Okay? I hope everyone is clear up to this. Next classification.

[00:33:07]Classification based upon the mode of nutrition. How the bacteria is surviving by taking the food. Okay? So, first is autotrophic bacteria. Autotrophic bacteria means these are the bacteria which assimilating inorganic matter into a organic matter. That means comparing preparing their food like a plant. If they converting from inorganic substances into organic food, they are called as autotrophic bacteria.

[00:33:36]So, there are two major type. Either they are photoautotrophs or they are chemoautotrophs.

[00:33:41]Okay? Either they are photoautotrophs or they are chemoautotrophs. So, what is photoautotrophs? If they using light as a energy sources. Photo means light. Yes or no? Photo. Photo means light.

[00:33:59]And chemo means chemical.

[00:34:07]If the organism using light as the energy sources and carbon dioxide as a principal carbon sources, they are called as photoautotrophs. So, example of this, purple sulfur bacteria that is Thiobacillus, purple non-sulfur bacteria is your Rhodopseudomonas, green sulfur bacteria that is your Chlorobium and Chromatium. Okay, these are photoautotrophs. Next is chemoautotrophs. Chemo means chemical.

[00:34:37]If they using chemical sources as a organism using chemical energy sources and carbon dioxide as a principal carbon, they are comes under your chemoautotrophs. So, if you will see the example sulfur bacteria like Thiobacillus and Sulfobolus, nitrogen bacteria that is your Nitrosomonas and Nitrobacteria, hydrogen oxidizing bacteria like your H. pylori and Hydrogenobacter, methanotrophs like Methylomonas, iron bacteria like Ferrobacillus. So, these all are comes under your chemoautotrophs class.

[00:35:13]Okay? Next.

[00:35:15]Heterotrophic bacteria. What is heterotrophic bacteria? They are the bacteria that derive energy by consuming organic compound.

[00:35:24]Heterotrophic bacteria, they derive the energy by consuming the organic compound, but they do not convert organic compound to inorganic. Okay?

[00:35:34]Consuming organic compound, but they do not convert organic to inorganic. In case of autotrophs, they converting inorganic to organic, but in case of heterotrophic bacteria, they consuming organic compound, but they do not convert it organic compound to inorganic. They are parasitic and symbiotic type. Example your E. coli, your Staphylococcus species, your Mycobacterium species. Okay? So, again they are two types, photoheterotrophs and chemoheterotrophs. Organism organism which using light as a energy source and organic compound as the principal carbon source, they are comes under your photoheterotrophs.

[00:36:22]Similarly, if you will talk about chemoheterotrophs, they using chemical as a chemical energy sources, chemical as energy sources, organic substances as a principal carbon sources. They are chemoheterotrophs. Example, most of the animals and most of the fungi comes under this category.

[00:36:40]Photo- photoautotrophs in example is your E. coli and Staphylococcus. Saprophytic bacteria, they are the bacteria that decompose organic compound into inorganic and They are called as saprophytic. They are cellulomonas and Acetobacter.

[00:37:01]Okay?

[00:37:03]Next.

[00:37:06]Next is gram-positive, gram-negative.

[00:37:08]Already we discussed, so again just quickly go through it. Gram-positive is thick.

[00:37:13]Okay, thick cell wall. Gram-negative is thin cell wall. The cell wall is rigid.

[00:37:18]The rigid due to presence of high peptidoglycan. It is elastic due to presence of low peptidoglycan. If you will take about talk about chemical composition, 80% it consisting of peptidoglycan, 20% polysaccharide and teichoic acid is present. Okay?

[00:37:36]Peptidoglycans, 3 to 12% of peptidoglycans, okay? Polysaccharide and lipo proteins are present. Porin protein is also present. So, these are the chemical composition. Next is susceptibility towards the penicillin. You know penicillin bacteria, so sorry, penicillin antibiotic. The gram-positive bacteria is highly sensitive towards the penicillin bacteria, but gram-negative bacteria is low susceptible.

[00:38:01]Flagella having single basal body ring.

[00:38:04]Gram-negative bacteria contains two basal body ring.

[00:38:07]Lipid and lipoprotein content is low.

[00:38:10]Gram-negative bacteria, lipid content is high. Lipopolysaccharide is basically absent, but in case of gram-negative bacteria, lipopolysaccharide is present.

[00:38:19]This is the basic and most important difference between gram positive and gram negative bacteria. This is the fundamental difference, okay? So, you have to remember this, okay? Which will be important for exam point of view. Now, what we are going to talk about right now is the bacterial reproduction.

[00:38:41]Okay, bacterial growth cycle or we call it as a bacterial reproduction.

[00:38:47]Okay? So, here bacteria will going to reproduce where? Inside a culture medium.

[00:38:58]It is grow inside a culture medium. So, it has major phases like lag phase, log phase, stationary phase, and death phase or decline.

[00:39:10]So, lag phase is the phase where initial exposure.

[00:39:19]So, lag phase is the phase where initial exposure of the bacteria to the culture medium. Okay, initial exposure of bacteria to culture medium. So, what happens? So, when when you will be initially just take an example of when you first time leave go into the hostel. So, just example. So, first time you are going to stay in a hostel.

[00:39:49]Okay? So, when you first time go into the hostel, so some students try to accommodate with the hostel condition. Some student who cannot accommodate to the hostel condition, they will leave the hostel. So, that is the the phase of we call it as a accommodation or acclimatization.

[00:40:12]Acclimatization. That means bacteria is try to acclimatize itself inside the culture media where you ex- Now, in this phase bacteria some of the bacteria will die.

[00:40:25]Some [snorts] will try to increase the cell size. Next coming into the picture is now you have spent two to three months in the hostel. Now you make so many friends in the hostel. Now you start enjoying the hostel life. So that phase is your lag phase where exponential growth will be there.

[00:40:49]Exponential growth. Okay, what happens? Your growth will be at highest number. Bacteria will try to reproduce very rapidly by binary fission and other method. Okay, so by consuming all the essential requirement present in the culture media.

[00:41:08]Now one stage will come where the culture media because once bacteria will get using this culture media, automatically it will start depleting.

[00:41:18]So when the depletion start, now growth will be slow down. Okay, now bacteria start it takes start phase. So in the stationary phase, please remember growth is equal to death.

[00:41:35]Okay, growth is equal to death. So let's discuss this phase in detail. So lag phase, this is the phase correspondence to the period of adaptation with the active macromolecular synthesis. The number of bacteria in the lag phase remains stable. Okay, balanced by early reproduction and some cells and some cell and death in others. Next is log phase which is very very important that is exponential phase where bacteria adopted to the new cell division process and the number of bacteria doubles with each generation time. Okay, as the number of bacteria increases exponentially, the logarithmic phase also known as exponential phase.

[00:42:19]So, here in this phase, the reproduction is at highest rate.

[00:42:24]Next, come into the stationary phase. So, what is the stationary phase? The phase the bacteria reproduction and death rate basically equal. Now, bacteria is death rate is equal to the division rate. Okay, so during this phase, nutrition uh nutrition becomes scarce, waste production accumulate, and oxygen and water supply state. This condition lead to growth lead to growth curve into the last phase of the cycle, because it now the bacteria has entered the plateau phase.

[00:43:00]And last year, that is your decline.

[00:43:04]Okay, so what happens in decline? Now, the bacteria is growth stopped. It now bacteria the number of the bacteria start to declining, because the reproduction occurs at the lowest rate. And while the death of the bacteria occurs at the highest rate here, death high, and reproduction low.

[00:43:38]Okay, so number of cell division exceeds the number of cell form.

[00:43:43]Okay?

[00:43:44]Cell dying number of cell dying is increased the number of cell.

[00:43:48]Okay, so now the next important part that we are going to discuss is how bacteria now I will I I talk to you.

[00:43:57]This is the cycle how bacteria reproduce. Now, important thing is how it is reproduce. How bacteria reproduce?

[00:44:06]So, we are going to now discuss. So, bacteria by having very short generation of time, they produce reproduce very So, they produce by asexual as well as sexual type can be classified in the following. So, first is binary fission.

[00:44:23]Binary fission is a asexual method of reproduction. So, the most common type this is basically occurs when bacteria is under a favorable condition. When everything is available, your nutrients nutrient is available, proper temperature is there, proper pH is maintained, so bacteria will reproduce by binary fission. That means one bacteria Okay, it will divide to form two bacteria.

[00:44:52]Okay, this is your binary reproduction.

[00:44:55]So, the bacteria cell first acquire nutrient to the grow, then maximize their cell size, and replicate their DNA.

[00:45:03]First, they acquire the nutrient grow at the maximum size.

[00:45:08]First, it go to the maximum size, then replicate their DNA. New replicate DNA called incipient called an incipient nucleus, they migrate towards the opposite pole, and the transverse septum gets begins and develop into two separate daughter cells. Let's understand it by diagrammatically method. Okay, so this is the bacterial cell.

[00:45:31]Okay, so now what happens? So, first bacteria will increase the cell size cell size to maximum.

[00:45:43]Okay, so now this bacteria DNA will enlarge. So, after enlarging, these two bacteria DNA will move towards the each pole. Once it reach to the each pole, now the cross cell wall will be closed.

[00:45:58]Okay, that process is called a cytokinesis. Cell elongated to cross the cell cross cell wall forms and form formation of daughter cell. This is the process of binary fission.

[00:46:15]Okay? This is the feature of binary fission.

[00:46:20]Next is budding. So, budding is basically bacteria cell develops small swelling called as protuberance or bud on one side. Now, bacteria DNA replicate and one copy enter into the bud. Now, the bud eventually separated develop into a daughter cell. You can see like this.

[00:46:39]So, here bacteria cell this is the DNA DNA replicate come into this. Once it come, it will separated your one DNA will be here, one DNA will be Example is your Rhodomicrobium vannielii. This is the species which reproduce by budding or asexual method.

[00:47:01]Next. Next is endospore formation. This is occurs when bacteria is under unfavorable condition.

[00:47:15]Okay? So, when the condition is not favorable bacteria, now bacteria cannot reproduce or bacteria cannot have the sufficient uh nutrients to grow. So, in that cases, what is going to happen? So, bacteria will reproduce by bacteria will going to reproduce by this endospore formation. So, most important thing to discuss here is endospore is the most resistant structure of the bacteria.

[00:47:43]Endospore is the most resistance structure of Okay, so it has seen that some of the gram-positive bacteria during unfavorable or environmental stress condition, they basically do such type of thing. The cytoplasm became concentrated around the bacterial DNA and he can add resistance wall develops around it. Now it will it will leads to formation of endospore. When the condition became favorable, when the nutrients is available, when the proper water content, proper nutrients only is available, now this endospore will again start to germinate and forms the whole bacteria. This is basically your the concept of endospore formation.

[00:48:43]Okay, this is the concept of endospore formation. Next, that is conjugation.

[00:48:49]Okay, next is your conjugation. So it is the another method of another sexual method where DNA transformation done by contact between donor and recipient. So please remember, so there is a conjugation or formation of this pillars. This is called as cytoplasmic bridge or also called as sex pillars.

[00:49:22]Cytoplasmic bridge or sex pillars. So what happens? Two bacteria come into the contact with each other. There will be a formation of the cytoplasmic bridge.

[00:49:31]Once it will connected, they will transfer the genetic material. Now new bacteria will be formed.

[00:49:38]Okay, so sex pili, so here the sex pili is responsible for the conjugation process. The donor cell develop a sex pillars and attached to the recipient bacteria and transfer it.

[00:49:49]Next is bacterial identification. How you are going to identify bacteria?

[00:49:56]Okay? So, there are different methods.

[00:49:59]This method for identifying bacteria by their cultural character in a specific culture media. Okay? Several [snorts] indicator of bacteria include the shape of the colonies, either they are circular or irregular.

[00:50:11]Shape, size of the colony, either they are micro or they are small or the medium or large.

[00:50:17]Their pigmentation, elevation of colonies, either they are concave or convex or flat or the margin of colony, smooth or rough or dented or wavy. So, these are the Uh on the basis of colony, you can tell the types of bacteria. Next is staining technique. So, staining technique already we discussed Gram staining techniques. Okay? So, Gram staining technique is basically for the detection of Gram positive and Gram negative.

[00:50:45]Crystal violet used as a primary dye.

[00:50:47]Gram's iodine solution after fix the uh staining solution. Okay? Already I have discussed it. Okay? Next is molecular method. This test include bacterial genome and genomic sequences.

[00:51:00]So, you can sequence the genome of the bacteria to know which type of bacteria it is present. Okay? So, it you have to sequence the genome to to tell which type of bacteria is basically uh is this.

[00:51:18]Next.

[00:51:20]Next is your most This includes which technique you are going to do this by this polymerase chain reaction, DNA or RNA probe test or electrophoresis. By this technique, you are going to do this. Next is immunological method. By using this enzyme-linked immunosorbent assay, radioimmunoassay, fluoroimmunoassay, or immunochromatography test. By using specific antigen-antibody principle, you can going to detect. I hope up to this everyone is clear. Things are clear to you. Now we are going to talk about MCQ. First tell me.

[00:52:15]Now we are going to talk about MCQ. I hope up to this everyone is clear. No question at all. So just confirm then I will move to the MCQ part.

[00:52:34]So these are the some bacterial disease and the positive organisms. So tetanus is caused by Clostridium tetani bacteria. Botulism botulinum is caused by Clostridium botulinum. Leprosy is caused by Mycobacterium leprae.

[00:52:49]Brucellosis is caused by Brucella species. Gas gangrene caused by Clostridium perfringens. Diphtheria is caused by Clostridium diphtheriae. Tuberculosis is caused by Mycobacterium tuberculosis.

[00:53:02]Pneumonia is caused by Streptococcus pneumoniae. Epidemic typhus is caused by Rickettsia prowazekii. Whooping cough caused by Bordetella pertussis. Cholera is caused by Vibrio cholerae. Typhoid fever caused by Salmonella typhi.

[00:53:17]Okay. Syphilis caused by Treponema pallidum. Gonorrhea caused by Neisseria gonorrhoeae. Meningitis caused by Neisseria meningitidis. And plague is caused by Yersinia pestis. This table is very very important. Okay, for your exam point of view.

[00:53:32]Okay. Now we will be going to solve some questions. First question. The region where bacterial genome is resides is nucleus, cytoplasm, nucleoid, or ribosome free region.

[00:53:42]>> I jump nucleoid ribosome free region.

[00:53:47]The region where bacterial genome is resides.

[00:53:51]Yes, answer this question.

[00:54:01]So, you know, bacteria does not have specific nucleus. So, this present in a cell uh non nucleated cell. So, that is called as nucleoid. Okay? That is called as nucleoid. Next question. Okay?

[00:54:18]Classification of bacteria. Okay?

[00:54:20]Gram-positive bacteria, spherical shape.

[00:54:25]Okay? Gram-positive bacteria, spherical shape. Uh gram-positive uh sporulating obligative aerobic bacteria, gram-positive rod-shaped non-sporulating bacteria, and gram-positive sporulating rod rod-shaped motile bacteria. So, first, gram-positive spherical non-motile bacteria is your Streptococcus species.

[00:54:46]Gram-positive sporulating obligative anaerobic bacteria is your Clostridium species.

[00:54:52]Next is gram-positive rod-shaped non-sporulating bacteria is Corynebacterium diphtheriae.

[00:55:00]Gram-positive sporulating bacteria is your Bacillus anthracis.

[00:55:05]So, option C is correct.

[00:55:10]C is correct here.

[00:55:12]Next question.

[00:55:14]For the thermophilic microorganism, the minimum growth temperature is one is psycho psycho is 0 to 15°.

[00:55:23]Thermo May psycho then meso meso is 25 to 20 to 45.

[00:55:36]Thermo 45 to 65. So, here minimum growth temperature of required for thermophilic it is 45 degree.

[00:55:48]Okay? Option C is correct.

[00:55:51]Next question. A gram-positive bacterium is differentiated from the gram-negative staining. This is because the cell wall contains lysozyme, teichoic acid, membrane protein, or lipid A.

[00:56:05]Yes, answer this question.

[00:56:40]So, if you will see the gram-positive bacteria contains teichoic acid.

[00:56:46]Okay? Option B is correct answer. Next question. Endotoxin otherwise known as lipopolysaccharide comprise of outermost layer of gram-positive, gram-negative, or virus, or fungi.

[00:56:59]Please note it down.

[00:57:00]Gram-positive bacteria secrete exotoxins. Gram-negative bacteria secrete endotoxins.

[00:57:13]Okay? So, option B here is correct answer.

[00:57:19]Okay? So, next question. So, assertion and reasoning type of question.

[00:57:25]Exotoxin diffuses freely through the bacteria cell wall into the medium.

[00:57:30]Which Which of the organism are going endotoxic they are water soluble and can pass into the surrounding medium.

[00:57:39]In the light of the statement, choose the correct answer from the option given below.

[00:57:45]Both A and R are true. R is the correct explanation. Both A and R are true. R is not the correct explanation. A is true.

[00:57:53]R is false. A is false. R is Answer it.

[00:58:13]So, so you know exotoxins are basically water soluble. Okay? That's why they easily diffuses out from the cell. So, here option A is correct answer. Next question. Which of the following microbial form listed below exhibit highest level of resistance to the physical and chemical method of growth control? I have explained you.

[00:58:36]Which form of bacteria exhibits highest level of resistance?

[00:58:44]Okay? Highest level of resistance. We have just discussed you. So, I told you during this unfavorable condition, bacteria will produce endospore, which is the most resistant structure.

[00:58:57]Okay? So, option B is correct.

[00:59:01]Shall we go next?

[00:59:04]The time required for a bacteria to give rise to two daughter cell under a optimum condition is known as production time, generation time, maturation time, or both A and C.

[00:59:17]The time required for a bacterium to give rise to two daughter cell under a optimum condition is known as production time, generation time, maturation time, or both A and S?

[00:59:36]That is called as generation time.

[00:59:40]What we call? We call it as a generation time. Option B is correct one.

[00:59:45]Next question. The most active stage in the sigmoidal curve of bacteria in which maximum growth is attained The most active stage in the bacteria The most active stage in the sigmoidal curve of bacteria in which maximum growth is attained is decline phase, stationary phase, log phase, or lag phase?

[01:00:20]Maximum growth.

[01:00:21]So, first is lag, and second is log. Log phase is your maximum growth is there.

[01:00:26]So, option So, log phase will be the correct answer.

[01:00:34]So, log phase is your correct answer. Next.

[01:00:38]Last question of this today's class.

[01:00:41]Which of the following You have to match, okay?

[01:00:46]So, yes, you have to match.

[01:00:50]Syphilis Treponema pallidum 1 S Plague Uh C S Plague by Yersinia pestis Okay?

[01:01:13]Uh Kuru CJD is a prion disease. Typhoid by Rickettsia prowazekii.

[01:01:20]4 P 4 P 3 S 3 2r 1q option c Okay.

[01:01:32]So, this completes your bacteria morphological classification identification their reproduction with important questions. Is this clear to everyone?

[01:01:46]Tell me, is this clear to everyone?

[01:02:03]Hello, thank you. Thank you so much. We will be meeting in the next class. Okay, thank you.

[01:03:34]>> Okay, good evening students. I hope screen is visible to all of you and my voice is clear.