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Micro1microbiologythescience 1

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  • 1. MICROBIOLOGY: THE SCIENCE
  • 2. WHAT IS MICROBIOLOGY?
    Microbiology is the study of very small living organisms – organisms called microorganisms or microbes.
    Microorganisms that cause disease are called
    pathogens.
    Microorganisms that do not cause disease are
    called nonpathogens.
  • 3. WHY STUDY MICROBIOLOGY?
    1. We have, living on and in our bodies,
    indigenous microflora (or indigenous
    microbiota) and, for the most part, they
    are beneficial to us.
  • 4. 2. Some of the organisms that
    colonize our bodies are known as
    opportunistic pathogens.
    Although such organisms do not usually
    cause us any problems, they have the
    potential to cause infections if they gain
    access to a part of our anatomy where they
    do not belong.
  • 5. 3. Microorganisms are essential for life on
    this planet.
    For example, some microbes produce
    oxygen by the process known as
    photosynthesis.
  • 6. 4. Many microorganisms are involved in the
    decomposition of dead organisms and the
    waste products of living organisms.
    They are referred to as decomposers or
    saprophytes.
  • 7. 5. Some microorganisms are capable of
    decomposing industrial wastes
    (oil spills, for example).
    This is called bioremediation.
  • 8. 6. Many microorganisms are involved in
    elemental cycles.
    The study of the relationships between
    microbes and the environment is called
    microbial ecology.
  • 9. 7. Algae and bacteria serve as food for tiny
    animals.
    Tiny marine plants and algae are called
    phytoplankton, whereas tiny marine
    animals are called zooplankton.
  • 10. 8. Some microorganisms live in the intestinal
    tracts of animals, where they aid in the
    digestion of food and, in some cases,
    produce substances that are of value to
    the host animal.
    For example, the E. coli bacteria that live in
    the human intestinal tract produce
    vitamins K and B1.
  • 11. 9. Many microorganisms are essential in
    food and beverage industries.
    The use of microorganisms in industry is
    called biotechnology.
  • 12. 10. Some bacteria and fungi produce
    antibiotics that are used to treat patients
    with infectious diseases.
    11. Microbes are essential in the field of
    genetic engineering.
  • 13. 12. Microbes have been used as “cell models.”
    The more that scientists learned about
    the structure and functions of microbial
    cells, the more they learned about cells in
    general.
  • 14. 13. Microorganisms cause two categories
    of diseases: infectious diseases and
    microbial intoxications.
    An infectious disease results when a
    pathogen colonizes the body and
    subsequently causes disease.
    A microbial intoxication results when a
    person ingests a toxin that has been
    produced by a microorganism.
  • 15. PIONEERS IN THE SCIENCE OF MICROBIOLOGY
    1. Anton van Leeuwenhoek (1632-1723)
    >He is referred to as the
    “Father of Microbiology.”
    > At various times in his life he was a
    fabric merchant, a surveyor, a wine
    assayer, and a minor city official in
    Delft, Holland.
  • 16. >He created what today are known as
    single-lens microscopes or simple
    microscopes.
    >In many specimens he observed a variety
    of tiny living creatures, which he called
    “animalcules.”
  • 17. >The idea that life can arise spontaneously
    from nonliving material is called the
    theory of spontaneous generation or
    abiogenesis.
    >This theory was debated and tested from
    1650 to 1850.
  • 18. >Louis Pasteur and John Tyndall finally
    disproved the theory of spontaneous
    generation and proved that life can only
    arise from preexisting life.
    >This is called the theory of biogenesis,
    first proposed by a German scientist
    named Rudolf Virchow in 1858.
  • 19. 2. Louis Pasteur (1822-1895)
    >A French chemist, Pasteur
    discovered what occurs during
    alcoholic fermentation.
    >Through his experiments, Pasteur
    dealt the fatal blow to the theory of
    spontaneous generation.
  • 20. >Pasteur discovered forms of life that
    could exist in the absence of oxygen.
    >Pasteur developed a process
    (today known as pasteurization) to kill
    microbes that were causing wine to spoil.
  • 21. >Pasteur discovered the infectious agents
    that caused the silkworm diseases that
    were crippling the silk industry in France.
    >Pasteur made significant contributions to
    the germ theory of disease-the theory
    that specific microorganisms cause
    specific infectious diseases.
  • 22. >Pasteur championed changes in hospital
    practices to minimize the spread of
    disease by pathogens.
    >Pasteur developed vaccines to prevent
    chicken cholera, anthrax, and swine
    erysipelas (a skin disease).
  • 23. >Pasteur developed a vaccine to prevent
    rabies in dogs and successfully used the
    vaccine to treat human rabies.
  • 24. 3. Robert Koch (1843-1910)
    >A German physician, Koch made many
    significant contributions to the germ
    theory of disease.
    He proved that Bacillus anthracis was
    truly the cause of anthrax.
  • 25. >Koch discovered that Bacillus anthracis
    produces spores, capable of resisting
    adverse conditions.
    >Koch developed methods of fixing,
    staining, and photographing bacteria.
  • 26. >Koch developed methods of cultivating
    bacteria on solid media-the Petri dish
    in which to culture bacteria on solid
    media, and agar (a polysaccharide
    obtained from seaweed) as a solidifying
    agent.
    These methods enabled Koch to obtain
    pure cultures of bacteria.
  • 27. The term pure culture refers to a
    condition in which only one type
    of organism is growing on a solid
    culture medium or in a liquid culture
    medium in the laboratory; no other
    types of organisms are present.
  • 28. >Koch discovered the bacterium
    (Mycobacterium tuberculosis) that
    causes tuberculosis and the bacterium
    (Vibriocholerae) that causes cholera.
    >Koch’s work on tuberculin (a protein
    derived from M. tuberculosis) ultimately
    led to the development of a skin test
    valuable in diagnosing tuberculosis.
  • 29. Koch’s Postulates
    An experimental procedure that proves a
    specific microorganism is the cause of a
    specific infectious disease.
    1. A particular microorganism must be found
    in all cases of the disease and must not be
    present in healthy animals or humans.
  • 30. 2. The microorganism must be isolated from
    the diseased animal or human and grown
    in pure culture in the laboratory.
    3. The same disease must be produced when
    microorganisms from the pure culture are
    inoculated into healthy susceptible
    laboratory animals.
  • 31. 4. The same microorganism must be
    recovered from the experimentally infected
    animals and grown again in pure culture.
  • 32. EXCEPTIONS TO KOCH’S POSTULATES
    1. Certain pathogens will not grow in or on
    artificial media in the laboratory (in vitro).
    Such pathogens include viruses, rickettsias,
    chlamydias, and the bacteria that cause
    leprosy and syphilis.
  • 33. 2. Many pathogens are species-specific,
    meaning that they infect only one species
    of animal.
    For example, some pathogens that infect
    humans will only infect humans.
    Because human volunteers are difficult to
    obtain and ethical reasons limit their use,
    the researcher may only be able to observe
    the changes caused by the pathogen in
    human cell cultures.
  • 34. 3. Synergistic infections, which are caused
    by the combined effects of two or more
    different microorganisms, are very difficult
    to reproduce in the laboratory.
  • 35. 4. Certain pathogens become altered when
    grown in vitro.
    Some become less pathogenic, whereas
    others become nonpathogenic.
    Thus, they will no longer infect animals
    after being cultured on artificial media.