Introduction of microbiology
Introduction to the science of microbiology
Contents
• Biogenesis and spontaneous generation
• Discovery of microscope
• Louis Pasteur and his contributions
• Robert Koch and his contributions
• Introduction of aseptic methods
• Alexander Flemming and discovery of penicilllin
Intended Learning objectives
At the end of this lecture student will be able to
• Outline the developments in microbiology
• Describe the contributions made by notable microbiologists
• Explain the difference between biogenesis and abiogenesis
• List the Koch postulates
Microbiology
• The study of living organisms that are too small for us to see without a microscope – Microbes or Microorganisms
• Form the basis for all life on earth
• For nearly three quarters of the history of earth, microbes were the only living things on earth
Microorganisms
• Microorganism: refers to any organism that is too small to be seen by the unaided eye
• It also includes some macroscopic forms like some fungi and most of the algae
• Most microorganisms are unicellular
• If multicellular, they lack highly differentiated tissues and organs
Origin of microbial life on earth
• About 3.5 billion years ago, fossil evidence of microbes exist.
• Some of the oldest cells on Earth are single-cell organisms called archaea and bacteria.
• Some began making their own food using carbon dioxide in the atmosphere and energy they harvested from the sun.
• This process produced enough oxygen to change Earth’s atmosphere.
• New oxygen-breathing life forms came onto the scene
History of microbiology
• Ancient Egyptians develop method of embalming
• Ancient Romans develop ideas about contagious particles
• 600 A.D Mayansmake fermented beverage from cacao
• 1348 A.D Black death: Kills 1/3 of European population
• 1590 Janssendevelops compound microscope
• 1665 Robert Hookeviews cork through the microscope, coins the term ‘cell’
• 1668 Franscesco Redi performs the first documented controlled scientific experiments
– Covers meat with cheese cloth, and leaves other pieces of meet uncovered.
– Uncovered meat, exposed to flies, develops maggots.
– Covered meat does not develop maggots.
– Redi concludes that adult flies are necessary for the production of maggots.
– This is the first major blow to the theory of spontaneous generation.
• 1674 Anton von Leeuwenhoek becomes first person to view living microorganisms. This marks the beginning of Microbiology.
• 1735 Linnaeusdevelops a taxonomy and a naming system binomial nomenclature) for organisms.
• 1745 John Needhamshows that boiled broth that cools down overnight becomes richly contaminated with microorganisms. He forcefully argues the microbes must be borne from the broth. He publishes a formal presentation of the Theory of Spontaneous Generation.
Theory of spontaneous generation
• Spontaneous generation, an obsolete theory that states that living organisms can originate from inanimate objects
• Dust creates fleas
• Maggots arise from rotting meat
• Bread or wheat left in a dark corner produces mice
• 1767 Lazzaro Spallanzani performs experiments with boiled and unboiled gravy.
– He shows that boiled gravy will only spoil if exposed to air.
– He concludes that spontaneous generation cannot be correct.
• 1798 Edward Jennerperforms the first vaccinations against smallpox.
• He collects the pus from cowpox blisters on the hands of milkmaids.
• He contaminates a lance with this pus and then cuts the skin of children.
• 1835 Agostino Bassiproves that a fungus is the cause of silkworm disease.
• 1840 Ignaz Semmelweis puts forth the revolutionary idea that physicians should wash their hands when assisting in childbirth.
• 1854 John Snowidentifies contaminated water as the cause of a cholera epidemic in England
• 1857 Louis Pasteur determines that yeast cause fermentation of wine and develops the process of pasteurization that saves the French wine industry.
• This marks the beginning of the Golden Age of
Microbiology--a period of explosive growth of knowledge of microbes (1857-1914).
• 1861 Louis Pasteur provides the final disproof of the theory of spontaneous generation.
• He maintains boiled broth in a swannecked flask, open to the air, for many days without contamination.
• 1861 Louis Pasteur,studying fermentation by yeast, coins the terms ‘aerobic’ and ‘anaerobic’
• 1866 Given the discovery of microscopic organisms, Ernst Haeckel proposes a third Kingdom of Life: The Protista.
• 1867 Joseph Listeruses phenol (carbolic acid) to treat surgical wounds. This reduced infection from surgery dramatically and served as proof that surgical infections are caused by microorganisms.
• 1876 Robert Koch, studying the disease, anthrax, validates the Germ Theory of Disease--the idea that diseases are caused by infectious agents (not by other forces such as evil spirits).
• This is also the first use of the rigorous steps in pathogen identification known as Koch’s Postulates.
• 1879 Neisseridentifies the causative agent of gonorrhea (Neisseria gonorrhoeae).
• This may be the first case where a microbe is implicated as the cause of a chronic disease.
• 1880 Pasteurdevelops a vaccine for chicken cholera. This is the first attenuated vaccine.
• 1881 Kochdevelops the concept of achieving pure cultures using solid media.
• 1882 Hess’working in Koch’s lab, develops agar as a solid medium.
• 1882 Kochidentifies Mycobacterium tuberculosis as the causative agent of tuberculosis.
• 1883 Kochidentifies Vibrio cholerae as the causative agent of cholera.
• 1884 Kochformalizes Koch’s Postulates- -the set of steps required to identify the causative agent of a disease.
Koch Postulates
1. Bacteria can be found in all people with the disease
2. Bacteria can be isolated from the infected site
3. The pure culture inoculated into a susceptible individual produces the symptom of disease
4. The same bacterium can be re-isolated from the intentionally infected animal or human
• 1884 Hans Christian Gram develops the Gram Stain
• 1884 Escherichidentifies Escherichia coli
• 1884 Elie Metchnikoff describes phagocytosis (ingestion of solid materials by cells)
• 1885 Pasteurdevelops a vaccine for rabies
• 1887 Petridevelops the petri plate for use with solid culture media
• 1929 Alexander Fleming discovers the first antibiotic, penicillin.
• Fleming makes this discovery by accident.
• He is searching for antimicrobial chemicals and uses Staphylococcus cultures to test these chemicals.
• He leaves some of these bacterial cultures on the lab bench when he goes on vacation.
• Upon returning, he sees that some of his cultures are contaminated with a fungus called Penicillium.
• He notices that there are no bacteria growing near Penicillium.
Summary
• Microorganism: refers to any organism that is too small to be seen by the unaided eye
• Microbiology is the study of microorganisms
• Anton von Leeuwenhoek becomes first person to view living microorganisms
• Edward Jenner – small pox vaccine
• Robert Koch – laboratory cultivation of organisms, Koch postulates
• Pasteur – theory of biogenesis, rabies and anthrax vaccine, pasteurization
• Hans Christian Gram develops the Gram Stain
• Alexander Fleming discovers the first antibiotic, penicillin
• 1857 Pasteur-Fermentation
• 1861 Pasteur-Disproved spontaneous generation
• 1864 Pasteur-Pasteurization
• 1867 Lister-Aseptic surgery
• 1876 'Koch-Germ theory of disease
• 1879 Neisser-Neisseria gonorrhoeae
• 1881 'Koch-Pure cultures; Finley-Yellow fever
• 1882 ' Koch-Mycobacterium tuberculosis; Hess-Agar (solid) media
• 1883 ' Koch-Vibrio cholerae
• 1884 'Metchnikoff-Phagocytosis; Gram-Gram's staining procedure; Escherich-Escherichia coli
• 1887 Petri-Petri dish
• 1889 Kitasato-Clostridium tetani
• 1890 Von Behring-Diphtheria antitoxin; ' Ehrlich-Theory of immunity
• 1892 Winogradsky-Sullur cycle
• 1898 Shiga-Shigella dysenteriae
• 1908 Ehrlich-Syphilis; Chagas-Trypanosoma cruzi
• 1911 Rous-Tumor-causing virus (1966 Nobel Prize)
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