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MICRO- ORGANISM
A Micro-Organism or Microbe is an Organism of Microscopic Size, which may exist in its single celled form of as a colony of cells.
(A)CLASSIFICASTION, CHARACTERISTICS OF
MICRO-ORGANISM
The Micro-Organism can be classified on the basis of the Cellular Structure into the Following 2 Categories. i.e. Cellular Micro-Organism Acellular Micro-Organisms
CELLULAR MICRO-ORGANISM The Cellular Micro-Organism are those
Microbes that Posses a Cellular Structure in either the Unicellular or the Multicellular Forms. They have a cell as the Basic Unit of their Body Organization. Ex. Bacteria ,Fungi, Protozoa Helminths
ACELLULAR MICRO-ORGANISM The Acellular types of Microbes Lack
the Cellular Structure in any Form and are Without any types of Cells.
BROAD INDIVIDUATED MICROBIAL CLASSIFICATION
The Micro-Organism can be categorized Broadly into the Following Individualized types Bacteria Viruses Fungi Protozoan Algae
BACTERIA
The Study of Bacteria is Known as Bacteriology. Bacteria are Small Single – Celled Organisms. Bacteria are Found Almost Everywhere on Growth & are Vital to the Planet’s Ecosystems. Bacteria are the Widely Distributed, Very Small, Microscopic, Unicellular, Prokaryotic Microbes that have immense impact of their presence on Earth. Some Bacteria Cause disease. Ex. Salmonella Typhi (Typhoid) Mycobacterium Tuberculosis (Tuberculosis)
VIRUSES These are that Acellular which are smaller in Size than Bacteria. They are Ultramicroscopic in Nature. Viruses are Responsible for causing the various Viral Diseases in plants & Animals. Ex. HIV (AIDS), SARS-CoV2 (Covid-19) FUNGI The Fungi are the Eukaryotic, Unicellular or Multicellular Microbes. They are usually Larger in Size than the Bacteria. The Fungi can be Pathogenic or Non-pathogenic. The Fungi can have two Morphological Types
- Yeasts Ex. Candida Albicans
- Moulds Ex. Aspergillus Fumigatus. PROTOZOANS The Protozoan (Singular Protozoa) are the Unicellular, Eukaryotic, Mostly Parasitic Microbes that Posses Intricate Structure. They may be Free Living or Endo parasitic in Nature. They can be Traced in Normally all habitats on Earth. ALGAE The Algae are the Unicellular or Multicellular Eukaryotic Micro- Organisms that are Photosynthetic in Nature. They are also Known as Blue - Green Algae or Cyanobacteria. They are Normally Found in lakes or other Water Bodies Such as Streams. Their Size can Range from a Single cell Size to the Size of Giant Kelp (A Large Seaweed usually the Brown Algae).
C) VIBRIO’S They are comma shaped curved Rods. Ex. Vibrio Comma D) SPIRILLA They are longer Rigid Rods with Several Curved or Coils. They have a helical Shaped and Rigid Body. Ex. Spirillum Ruprem E) SPIROCHETES They are Slender & Flexous Spiral Forms. F) ACTINOMYCETES The Characteristics shape is due to the presence of Rigid Cell wall. Ex. Streptomyces. They are Branching Filamentous Bacteria Ex. Streptomyces Species G) MYCOPLASMA They are cell wall Deficient Bacteria & hence do Not posses Stable Morphology. They occur as Round or Oval Bodies with interlacing Filaments.
BACTERIAL STRUCTURES
- Flagella 2)Pilli 3)Capsule 4)Plasma Membrane
- Cytoplasm 6)Cell Wall 7)Ribosome 8)Mesosome 9)Inclusion 10)Spores
- FLAGELLA Flagella are long, slender, thin hair like Cytoplasmic Appendages which are responsible for the Motility of Bacteria. These are the Organs of Locomotion. They are 0.01 to 0.02 μm in Diameter, 3 to 20 μm in length. Flagella are made up of a protein – Flagellin. The Flagellum has three Basic Parts. A) Filament B) Hook C) Basal Body Filament is the thin, Cylindrical, Long Outermost Region with a Constant Diameter. Filament is attached to a slightly wider hook. The Basal Body is Composed of a Small Central Rod inserted into a series of Rings Namely M, S, P & L Rings. FLAGELLAR PATTERNS (TYPES OF FLAGELLA) The Different Flagellar Patterns of Arrangement Found in Different Bacterial Cells. They are :-
- Atrichous 2. Monotrichous 3. Lophotrichous
- Amphitrichous 5. Peritrichous 1 ATRICHOUS It Means without Trichous i.e., without any Flagella.
Capsulated Bacteria Produces Smooth Colonies and Non Capsulated Bacteria Produces Rough Colonies on the Surface of Agar Media. FUNCTION They Protect the cell From Drying. They Protects the Bacterial Cell Against Anti-Bacterial Agents & Phages.
- PLASMA MEMBRANE The Cytoplasmic (Plasma) membrane is a thin (5 to 10 nm). It Separates the cell wall and Cytoplasm. It Composed of phospholipids (20 to 30%) and Proteins (60 to 70%). FUNCTION It acts as a Semipermeable Membrane controlling the inflow and outflow of metabolites to and from the Protoplasm. It provides the Mechanical Strength to the Bacterial Cell. It helps in DNA Replication. It contains Enzyme, Permease which plays an Important role in the passage of selective Nutrients through the membranes.
- CYTOPLASM The Bacterial Cytoplasm is a Suspension of Organic, Inorganic Solutes in a Viscous water Solution. The Cytoplasm of Bacteria differs from that of Higher Eukaryotic Micro- Organisms in Not Containing Endoplasmic Reticulum, Golgi Apparatus, Mitochondria & Lysosomes. It contains the Ribosomes, Proteins and other water-Soluble Components & Reserve Material. In Most Bacterial, Extrachromal DNA(Plasmid DNA) is also Present.
- CELL WALL Cell wall is Rigid structure which gives definite shape to cell situated between the capsule and cytoplasmic membrane. It is about 10-20 nm in thickness and constituents 20-30% of dry weight of cell. The cell wall cannot be seen by direct light Microscopy & does not stain easily by different staining Reagents. The cell wall of Bacteria contains diaminopimelic Acid (DAP) , Muramic Acid and Teichoic Acid. These substances are joined together to give rise to a complex polymeric structure known as peptidoglycan or murein or mucopeptide. Peptidoglycan is the major constituent of the cell wall of Gram+ve bacterial cell wall its presence is only 5-10%.
FUNCTION
Cell wall is Involved in Growth & Cell Division of Bacteria. It Gives shape to the Cell. It gives Protection to internal Structure and Acts as Supporting layer. To Prevent Rupture of Bacteria caused by Osmotic pressure differences b/w intra cellular and Extra Cellular Environment. To provide support for flagella. It serves as the sites of Attachment for most Bacterial Viruses.
7) RIBOSOMES
Ribosomes are the Centre of Protein Synthesis. They are slightly smaller than Eukaryotic Ribosomes. The Sedimentation Constant is 70s. This 70s Ribosomes are made up of two Subunits Namely a large Subunits 50s and a small subunit 30s. During Active protein synthesis the Ribosomes are associated with Mrna and Such Associations are called Polysomes.
- MESOSOMES Mesosomes are Respiratory Sites of Bacteria. The Mesosomes are attached to the Bacterial Chromosomes and is involved in DNA segregation during cell Division. They are Predominant in Gram+ve^ Bacteria.
- INCLUSION (INTRA CYTOPLASMIC INCLUSION) Many Species of Bacteria produce cytoplasmic inclusion bodies which Appears as Round Granules. They are made up of either Glycogen or Starch. They Appear Reddish when Stained with Polychrome Methylene Blue or Toluidine Blue.
- SPORE The Process of Endospore formation is known as Sporulation and it may take 4 to 8 hours in a vegetative cell. Endospores are thick – walled, highly refractile bodies that are produced one per cell. Spore are Extremely Resistant to Desiccation, Staining, Disinfecting Chemicals, Radiation and heat. They Remain viable for centuries and help bacteria to survive for long period unfavourable environment. Endospore can Remain dormant for thousand of years.
The normal flora of the human body refers to the microbial community that colonizes on the skin and mucus membrane. Normal flora is sometimes called indigenous microbiota, as they reside within or on the human’s skin surface. DEFINITION The normal flora merely refers to the population of microorganisms like bacteria, fungi and few protists, which typically colonize at the specific anatomical sites of the human body. The surface tissues (skin and mucus membrane) of the human body are generally non-sterile.
TYPES
The human microbiota is primarily classified into two groups:
RESIDENT FLORA
They are fixed-type of microorganisms, which are generally non- pathogenic. Resident microflora confines permanently to the skin’s deeper areas. They can re-establish themselves if disturbed. They cannot be flushed off from the anatomical site. Resident flora is not associated with disease transmission.
TRANSIENT FLORA
They are indeterminate-type of microorganisms, which can be non- pathogenic or potentially pathogenic. Transient microflora confines temporarily to the skin’s superficial layers for hours, days or weeks. They cannot re-establish themselves. They can be flushed off from the anatomical site. Transient flora is closely associated with disease transmission, as they serve as opportunistic microorganisms derived from the environment.
CHARACTERISTIC OF NORMAL FLORA
- Normal flora contains more than 200 bacterial species, among which gram-positive bacteria predominate.
- The factors influencing the normal microflora include age, diet, nutrition, sex, and immune conditions of a person.
- Viruses and parasites do not constitute the normal microflora.
- Under normal conditions, microflora is harmless or even beneficial.
- Any disturbances in the normal flora may harm the host through the consequence of opportunistic microorganisms that may eventually cause disease or an infection.
- A human body is colonized with the normal flora once a neonate or new born body is passed through the mother’s vaginal tract or exposed to the environment.
- A new born baby establishes the oral and nasopharyngeal flora within few hours.
- After one day, resident flora establishes in the lower intestinal tract of the neonate.
Distribution and Occurrence of the Normal Flora
HUMAN SKIN
Starting with the external surfaces, the skin harbours 1000 to 10, microorganisms per square centimetre. A human skin layer possesses the outermost epidermis and inner dermis layer. Many bacterial species exist on the skin’s epidermis layer , which does not penetrate until there is no cut or abrasions over the skin surface. Skin is the largest organ exposed to the environment, and it daily counters with a large number of microbes. Factors like skin’s dryness, low pH and secretion of inhibitory substances discourage microbial colonization. The dry skin restricts microbial growth, as the condition is not favourable to them. The moist regions like groin area possess more normal flora (>10,000). The skin has a normal pH between 3 - 5 that also restrict microbial growth.
The specialized glands within the skin (sweat and oil gland) secrete some
inhibitory substances that discourage bacterial growth.
HUMAN EYE CONJUNCTIVA
INTRODUCTION
The membrane that constitutes the lining of eyelids and eyeball is termed eye conjunctiva. It is a very delicate membrane, which contains sparse microflora due to the following factors: Due to the high moisture content or continuous flow of tears by the eye’s blinking action , the membrane eliminates the microorganisms. The lachrymal secretions include lysozymes that also lyse the microbial cells.
MOUTH
INTRODUCTION
It provides a favourable environment for bacterial growth due to adequate moisture content and dissolved food particles.
INTESTINAL TRACT
To know the intestinal microflora, we need to study all the components of the intestinal tract. Stomach It receives numerous microorganisms from the oral cavity or nasopharynx. The stomach destroys the microbial cells by providing an acidic environment through the secretion of gastric juices (HCl). Lactobacilli and Candida species are evidently seen in the stomach.
SMALL INTESTINE
The duodenum portion possesses gram-positive cocci and bacilli. Jejunum portioninhabits Enterococci , Lactobacilli , Diphtheroids and Cand ida species. Ileum occupies a large number of anaerobic bacteria and the members of Enterobacteriaceae.
LARGE INTESTINE
It has a vast number of microbes, and the faecal matter comprises nearly a hundred billion bacteria per gram wet weight. Thus, a large intestine removes a large number of the microbial population through the peristaltic movement of the villi. Mucus in the large intestine plays a critical role in the removal of microorganisms. The microbial flora, along with the faecal matter, adheres with the mucus layer and consequently rolls up into small masses. At last, the microorganisms in the faeces leave the large intestine by passing through the anus. Bacteroides , Fusobacterium , Bifidobacterium , Eubacterium , and Lactobacillus species are the anaerobes that commonly inhabit the large intestine. Escherichia , Proteus , Klebsiella and Enterobacter species are the facultative anaerobes that reside in the colon. Yeasts ( Candida species ) and protozoan ( Trichomonas hominis ) inhabits the cecum region. Commensals like Entamoeba, Endolimax and Iodamoeba species also reside within the colon. A breastfed and bottle-fed infants have gram-positive bacteria in their intestine until they substitute a liquid food by solid food. Thus, gram- negative bacteria (Bacteroides species) predominate in the intestinal flora of the adult-type diet.
GENITOURINARY TRACT
The excretory system (kidneys, ureters and urinary bladder) is generally sterile, except for the urethra. The urethra of both males and females inhabit Staphylococcus epidermidis , Streptococcus faecalis , Corynebacterium and Neisseria species are significantly present. Afemale vagina inhabits Lactobacilli , Enterococci , Diphtheroids and Candi da albicans. BENEFICIAL EFFECTS The normal flora is associated with the synthesis of vitamin-B complex and vitamin-K. The colonization of the normal flora on the skin prevents the proliferation of pathogenic microbes, as they compete for the same nutrients. They augment the defence mechanism of the human body or elevate the immune system. Microorganisms produce some antibiotic-like substances. For example, bacteria produce bacteriocins. HARMFUL EFFECTS The consequence of opportunistic pathogens causes disease in an immuno-suppressed person. Some microflorae are drug-resistant. A few microflorae may cause confusion in a disease diagnosis.
SIGNIFICANCE
The normal flora serves as antigens, which can significantly induce an antibody-mediated immune response. Other bacteria compete with the normal flora of the human body to invade the nutrients of the host. Any disturbances in the normal flora population make the host cell susceptible to pathogens. Therefore, the study of normal microflora gives us a better understanding of the infections to the specific site. The source of infection can also be determined. We can study the medically important microorganisms excised from the infection site. In simple words, the normal flora of the human body influences the host cell susceptibility and morbidity. (C) PATHOGENESIS & COMMON DISEASES PATHOGENESIS Pathogenesis is the process by which a disease or disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. STAGES 4 stages (1) implantation of virus at the portal of entry (2) local replication
TYPES OF MICROSCOPES The Microscope can be of the following types :- (A) Based Upon the Number of Lenses Used I. Simple Microscope II. Compound Microscope (B) Based Upon the Illuminating Source Used I. Light Microscope II. Electron Microscope (C) Based Upon the Number of Eye Piece Objectives Used I. Monocular Microscope II. Binocular Microscope (A)BASED UPON THE NUMBER OF LENSES USED I. SIMPLE MICROSCOPE: - It is the Microscope in which only one lenses is used. e.g., Magnifying Glass. II. COMPOUND MICROSCOPE: - It is the Microscope in which more than one lens are used. e.g., Compound Light Microscope, Electron Microscope. (B)BASED UPON THE ILLUMINATING SOURCE USED I. LIGHT MICROSCOPE: - This is the Simple or Compound Microscope in which light is used as the illuminating source for seeing the image of the microscope object under microscope. e.g., Bright Field Microscope, Dark Field Microscope, Phase Contrast Microscope and Fluorescent Microscope. II. ELECTRON MICROSCOPE This is the Compound Microscope in which the Electron’s Beam is used as the Illuminating source for seeing the image of the microscopic object under the microscope which has greater magnification and resolution than a light microscope. (C)BASED UPON THE NUMBER OF EYE PIECE OBJECTIVES USED I. MONOCULAR MICROSCOPE It has a Single eye piece objective. II.BINOCULAR MICROSCOPE It has two eye piece objectives.
PARTS OF MICROSCOPE
- Eye Piece
- Body Tube
- Nose - Piece
- Objectives
- Mechanical Stage
- Condenser
- Mirror
- Focusing Knobs A) EYE PIECE The Eye Piece helps to view the object /specimen kept on the stage. It shows the further enlarged image of the object already formed by the objective .The eye-piece contains a lens of varying magnifications that range from 5X to 20X. B) BODY TUBE The microscope tube is attached to the upper side of the “arm” and holds the eye - piece on its top and can be either monocular or binocular type. The length between the nose-piece is known as the mechanical tube length that can vary in different microscopes. C) NOSE - PIECE The Nose- Piece is attached to the lower part of the body tube that rotates its objectives. D) OBJECTIVES The Commonly used objective lenses are of 4X,10X,40X and 100X magnification powers which are attached to the nose-piece. The 100X Objective is also known as the oil immersion objective.
E) MECHANICAL STAGE The slide holding the specimen is put on the stage and moved with the help of the Rotating knobs. F) CONDENSER The condenser lies just below the stage and illuminates the specimen by controlling the quality of light penetrating the specimen from below. G) MIRROR The Mirror is two - sided that helps reflect the natural light by its concave side surface and the artificial light by its plain side surface. It is present on the base of the microscope. H) FOCUSING KNOBS The focusing knobs are of two types, i.e. coarse and fine knobs that helps to adjust the distance between the objective and the specimen slide. The coarse knob helps adjust the view field while the fine knobs ensures a better view of the specimen field. FUNCTION /USE OF MICROSCOPE To magnify Small Objects. To observe an object at the cellular level. It allowing scientists to see the shape of a cell, its nucleus, mitochondria and other organelles. To resolve, or distinguish, fine detail which our eyes alone cannot perceive. To Examine Objects that are too small to be seen by the Naked Eyes. HANDLING OF MICROSCOPE The table on which the microscope is installed must be levelled, sturdy and with appropriate height. Any liquid spills must be avoided on or near the microscope. The light source must be appropriate arranged.
4. ENRICHED MEDIA
5. SELECTIVE MEDIA
6. INDICATOR MEDIA/DIFFERENTIAL MEDIA
7. SUGAR MEDIA
8. TRANSPORT MEDIA
9. ANAEROBIC MEDIA
1. SIMPLE MEDIA
It is like Nutrient Broth consist of peptone ,Meat Extract, Sodium Chloride and water. Nutrient Agar Made by adding 2% Agar in Routine Diagnostic Laboratories. These media support Growth of most Bacteria. Ex. Nutrient Broth =Peptone Water (1%Peptone+ 0.5 Nacl)+100ml water+1% Meat Extract. USES To Grow Non-Fastidious Micro-Organism.
2. COMPLEX MEDIA
These Media has additional Special Ingredients that are Required for the growth of or for Bringing out certain characteristics of certain bacteria. Media that contain some ingredients of unknown chemical composition are complex media. USES To Cultivate all the Fastidious Organisms.
3. SYNTHETIC MEDIA (DEFINNED MEDIA)
These media are prepared from pure chemical substances and the exact composition of the Medium is known. Typically they contain a simple sugar as the carbon and energy source, an inorganic Nitrogen source, Various Mineral salts and if Necessary Growth Factors. Ex. Purified Amino Acids, Vitamins, Purines & Pyrimidines.
4. ENRINCHED MEDIA
In these media, Substances such as Blood , Serum or Egg are Added to a basal Medium. They are used to grow bacteria which are more fastidious in their Nutritional Needs. Enriched Media is always a solid media. Ex. Blood Agar Chocolate Agar Egg Containing Media
- SELECTIVE MEDIA --> The Selective Media are defined as the media that are made in such a way that help in the growth of a selected bacterium usually a pathogen from a mixture of bacterial sample by inhibiting the growth of the contaminants or the unwanted bacteria due the action of certain inhibitory agents already included in the agar based solid medium. The inhibitory agents include antibiotics, chemicals, dyes.
6. INDICATOR MEDIA/DIFFERENTIAL MEDIA--> These type of
Media help to differentiate between the different bacteria
being grown within the same medium on the basis of some
characteristic feature like Colony Color,Size, that becomes
obvious due to the presence of a specific indicator in the
culture medium.
Ex. MacConkey Agar,
Eosin Methylene Blue(EMB),
Mannitol Salt Sugar
