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 Mayans
make fermented beverage from cacao
• 1348 A.D Black
death: Kills 1/3 of European population
• 1590 Janssen
develops compound microscope
• 1665 Robert Hooke
views 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 Linnaeus
develops a taxonomy and a naming system binomial nomenclature) for organisms.
• 1745 John Needham
shows 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 Jenner
performs 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 Bassi
proves 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 Snow
identifies 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 Lister
uses 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 Neisser
identifies 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 Pasteur
develops a vaccine for chicken cholera.
This is the first attenuated vaccine.
• 1881 Koch
develops the concept of achieving pure cultures using solid media.
• 1882 Hess’
working in Koch’s lab, develops agar as a solid medium.
• 1882 Koch
identifies Mycobacterium tuberculosis as the causative agent of tuberculosis.
• 1883 Koch
identifies Vibrio cholerae as the causative agent of cholera.
• 1884 Koch
formalizes 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 Escherich
identifies Escherichia coli
• 1884 Elie
Metchnikoff describes phagocytosis (ingestion of solid materials by cells)
• 1885 Pasteur
develops a vaccine for rabies
• 1887 Petri
develops 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)
