Microbiology Lecture 1 PDF

Dr Sreenivas Sir Lecture 1 19 SEP 2024 Introduction and History of Microbiology Invisible yet invincible: cannot be seen by the naked eye, too strong to be defeated. Definition of microbiology: Microbiology is...

Dr Sreenivas Sir Lecture 1 19 SEP 2024 Introduction and History of Microbiology Invisible yet invincible: cannot be seen by the naked eye, too strong to be defeated. Definition of microbiology: Microbiology is the study of microorganisms (bacteria, viruses, fungi, prions, protozoa and algae) biological entities too small to be seen with the unaided eye. The term was coined by Louis Pasteur (1822-95) (father of microbiology) Antony Van Leeuwenhoek (founding father of microbiology) Branches of Microbiology: can be divided into pure and applied sciences. Pure Microbiology (a) Based on Taxonomic Arrangement (i) Bacteriology (ii) Mycology (iii) Protozoology (iv) Phycology (v) Parasitology (vi) Immunology (vii) Virology (viii) Nematology (b) Based on Integrative Arrangement (i) Microbial Cytology (ii) Microbial Physiology (iii) Microbial Ecology (iv) Microbial Genetics (v) Cellular Microbiology (vi) Evolutionary Microbiology (vii) Generation Microbiology (viii) Systems microbiology (ix) Molecular Microbiology (c) Other (i) Nano Microbiology (ii) Exo Microbiology (iii) Weapon Microbiology Applied Microbiology a. Medical Microbiology b. Pharmaceutical Microbiology c. Industrial Microbiology d. Microbial Biotechnology e. Food and dairy microbiology f. Agricultural Microbiology  g. Veterinary Microbiology h. Environmental Microbiology i. Aquatic Microbiology j. Aeromicrobiology k. Epidemiology History: a. Theurgical theory: Disease followed by death. Occurs due to the curse of the divine spirit. b. Miasmatic theory: Hippocrates in his book “On airs, waters and places”. Elements Qualities Body Fluids Fire Heat Blood Air Cold Phlegm Water Moisture Yellow Bile Earth Dryness Black Bile c. Pore theory: dissymmetry of pores present in the body causes the disease. Asclepiades Obstruction of pores Relaxation of pores ↓ ↓ Acute Diseases Chronic Disease d. Paracelsus Theory: Paracelsus speculated on the role of supernatural forces such as the influence of planets and stars on different organs and the causation of disease. He first identified the role of minerals and chemicals in the treatment of diseases. (syphilis treatment using mercury). e. Spontaneous Generation Theory: Aristotle, Greece. If Pneuma and Vital heat are present, animals originated from soils, plants and other things. Eg. Maggots originated from meat exposed to air and heat. Francisco Redi: Maggots are not produced in the meat covered with gauze. (opposed) John Needham: Supported SG theory with his experiment on chicken broth. Needham boiled the broth in a test tube and sealed them but turbidity was noticed. (supported) Lazzaro Spallanzani: Extensive broth heating up to boiling point and sealing prevent the turbidity. (opposed) Franz Schulze and Theodor Schwann: Supported spallanzani work by introducing air into the broth after passing through a strong acid solution. Schroder and Dusch: used cotton plugs to filter the air on the mouth of the flask and  observe no growth. The Swan Neck/Gooseneck experiment of L. Pasteur SG theory was finally disapproved by L. Pasteur. Pasteur took broth in a flask with a tortuous neck, heated it thoroughly and kept the flask unplugged. Explanation: During heating, germs in the broth die, and germs in the air settle onto the bend of the neck. f. Germ Theory of Infectious Diseases: - Athanasius Kircher: First used low-power microscope - Cornelius Drebbel, Hans and Zacharias Janssen: First compound microscope. - Antony Van Leeuwenhoek: Developed a series of microscope with higher magnification. He referred to the bacteria as "animalcule". (Founding Father of Microbiology) - Jacob Henle: Founder of Germ Theory. The book entitled "On Miasmata and Contagia". - Joseph Lister: use of antiseptics, pure culture technique - Casimir Davaine: coined the term bacteria - Schwann: Father of fermentation. - Walther Hesse & Fannie Hesse: used agar instead of gelatin used by - Robert Koch - Julius Petri: Petri dish - Hans Christian Gram: Gram staining - Elic Metchnikoff: Phagocytosis - Paul Ehrlich: Chemotherapeutic agents - Alexander Flemming: Penicillin - Waksman: Streptomycin Stalwarts (loyal, committed) of Microbiology: a. Edward Jenner: Protection against smallpox if previously exposed to cowpox lesions. b. Louis Pasteur: - Father of Microbiology - Germ Theory of fermentation - Pasteurisation - The germ theory of disease - Vaccine against fowl cholera, anthrax, rabies and Erysipelothrix rhusiopathiae. - Concept of attenuation, and booster dose and coined the term vaccination. c. Robert Koch: - Father of Bacteriology - Solid plate technique for isolation of bacterial pure culture. - Koch postulates and Koch phenomenon. - Discovered causative organisms of anthrax, tuberculosis and cholera. - Fixation of smear by air drying. - Water purification in the prevention of cholera. Koch Postulates: PIRR - The agent must be present in every case of the disease. - The agent must be isolated and cultured in vitro. - The disease must be reproducible when pure culture is inoculated in a susceptible host. - The agent must be recoverable from the experimentally infected host. Koch Phenomenon: The response of a tuberculous animal to reinfection with tubercle bacilli marked by necrotic lesions that develop rapidly due to a hypersensitivity reaction. Milestones in the History of Microbiology 1677 Observed animalcule (Antony Leeuwenhoek) 1796 First scientific smallpox vaccination (Edward Jenner) 1861 Disproved SG Theory (Louis Pasteur) 1862 Supported germ theory of disease (Louis Pasteur) 1867 Antiseptic Surgery (Joseph Lister) 1876 The first proof of germ theory of disease with B.anthracis (Robert Koch) 1881 Growth of bacteria on solid media (Robert Koch) 1882 Koch postulates 1882 Acid-fast stain (Paul Ehrlich) 1884 Gram stain (Christian gram) 1885 First rabies vaccination (Louis Pasteur) 1887 Petri Dish 1892 Discovered viruses (Ivanovski) 1899 Recognised viral dependence on cells for reproduction (Beijerinck) 1900 Mosquito carried yellow fever agent (Walter Reed) 1928 Discovered penicillin (Alexander Fleming) 1975 Hybridoma Technology 1977 DNA Sequencing (Gilbert and Sanger) 1983 PCR (Kary Mullis) 1995 First Microbial Genomic Sequence Published (Haemophilus influenza) Lecture 2 24-SEP’24 Classification and Identification of Bacteria Taxonomy: the science of classification of organisms to establish evolutionary relationships among them. It includes: - Identification - Nomenclature - Classification Father of taxonomy: Carolus Linnaeus - He proposed 2 kingdom classifications. - Kingdom Plantae (organism with cell wall containing cellulose and chlorophyll). - Kingdom Animalia (organism lacking cell wall in their cell). Carolus Linnaeus developed the Binomial system of nomenclature. The Binomial System of nomenclature uses two Latin words to identify a species. Generic Species Capilatised first letter. Lower case. Italicised. Italicised. It may be abbreviated. Never abbreviated. Identification: the process of studying and recording identical and distinguishing features. Nomenclature: a process of assigning names to the various taxonomic rankings of each living organism. Classification: it is the orderly arrangement of organisms into groups preferably in a format that shows evolutionary relationships. Taxon: it is a hierarchical level of classification in which a broad division is divided into smaller divisions. Life>Domain>Kingdom>Phylum>Class>Order>Family>Genus>Species Species: a collection of microbial strains that share many properties and differ significantly from other groups of strains. Strain: it is a basic unit of bacterial taxon. It is a population of microbes descended from a single individual or pure culture. Infra-sub-specific ranks/taxon: - Biovar/biotype: the strains which are having similar biochemical properties. - Morphovar/morphotype: strains which are having similar morphology. - Pathovar/Pathotype: strains which are similar in pathogenicity. - Serovar/serotype: strains which are having similar antigenic properties. - Phagovar/phagotype: strains which are lysed by some phage. Ernst H. Haeckel proposed 3 kingdom classifications: - Kingdom Plantae (Plants and fungi) - Kingdom Animalia (Excluding Animals) - Kingdom Protista (Bacteria) Herbert Copeland proposed 4 kingdom classifications: - Monera Robert H. Whittaker has given 5 kingdom classifications. According to him: - Monera - bacteria - Protozoa - amoeba, seaweeds, diatoms - Fungi - multicellular, filamentous organism - Plantae - an organism that makes food. - Animalia - an organism that ingests food. The three-domain system was given by Carl Woese and George Fox in 1977. Currently, living organisms are divided into 3 super kingdoms. - Eukarya domain (plants, animals, fungi and protista) - Eubacteria (this domain includes bacteria with peptidoglycan cell walls) - Arche (it includes bacteria with unusual cell walls). This domain is further divided into 2 kingdoms: - Crenarchaeota: (Ancient bacteria that produces methane) - Euryarcheota: (Ancient bacteria that grows in high temperatures) Methods of identifying bacteria: - Morphological characteristics: colony, morphology, cell shape and arrangement, cell wall structure and special cellular structure. - Biochemical characteristics/tests: these tests are used to identify specific enzymes and metabolic processes that are characteristic of certain types of bacteria. For example: Catalase which breaks down Hydrogen peroxide can help to identify Staphylococcus bacteria. - Serological test: these tests use specific enzyme-specific antibodies to detect and identify bacteria antigens, for example: ELISA can be used to identify specific strains of E. coli. - Phage typing: it is a method of classifying bacteria based on how they react to a panel of bacteriophages. This method may be summarised as: - Create a lawn. - Introduce phages. - Observe lysis. - Determine phage type. - Sequence amino acid in proteins. - Percentage of G-C pairs in the nucleic acid. Estimated by determining the melting point (temperature of DNA). High GC content means a high melting point. - Number and size of DNA fragments produced by restriction enzymes. - Sequence of bases in 16s-rRNA (ribotypic). Ribotyping compares the sequence of a bacterial 16s-rRNA gene to a database to identify the species. All bacteria have ribosomal RNA genes but the sequence is unique to each species serving as a genetic fingerprint. BERGY’S MANUAL OF SYSTEMATIC BACTERIOLOGY American bacteriologist David Hendricks Bergy in 1923. It is a manual that deals with the identification of bacteria. It has been published in 9 editions. The first 8 editions were published under the name Bergy’s Manual of Determinative Bacteriology. In the 9th edition, it was renamed as Bergy’s Manual of Systematic Bacteriology. The 1st edition contains 4 volumes. - Volume 1: Gram-negative bacteria. - Volume 2: Gram-positive bacteria. - Volume 3: Remaining Gram -ve and about archaebacteria. - Volume 4: Remaining gram +ve filamentous. Actinomycetes and similar types of bacteria. In the first edition, Bergy classified the kingdom prokaryote into 4 divisions: