Microbiology is the study of microorganisms too small to be seen with the naked eye. Key branches include bacteriology, mycology, immunology and virology. Pioneers like Hooke, van Leeuwenhoek, Schleiden, Schwann, Pasteur, Lister and Koch advanced the field through observations with microscopes, formulation of the cell theory, development of techniques like pasteurization, antisepsis and asepsis, germ theory, and Koch's postulates. Microbes play important roles in environments, human health and industry.

1. What is microbiology
Micro- too small to be seen with the
naked eye.
Bio – life
Logy- study of
Microbiology is the study of all living
organism that are too small to be
visible with the naked eye.

2. Branches of Microbiology
Bacteriology: study of bacteria
Mycology: study of fungi
Immunology: study of immunity
Virology: study of viruses

3. Parasitology: study of protozoa and parasitic
worms
Chemotherapy
 Treatment of disease by using chemical
means
 Antibiotics produced naturally
 Synthetic drugs

4. Benefits
Maintain balance of environment .
Digestion, synthesis of vitamins
Synthesis of chemical products
Recycling sewage
Bioremediation: use microbes to remove toxins
(oil spills)
Normal flora
Genetic engineering

5. Pioneers of Microbiology
Robert Hooke, UK (1665)
 Proposed the Cell Theory
 All living things are composed of cells

6. In 1590 first magnifier glass made by Hans &
Jansen.
First simple microscope made by Galileo
Galilei in1610.
First microscope made by Drebbel in 1618.

7. Pioneers of Microbiology
Antoni van Leeuwenhoek (1673)
 First observed live microorganisms.
Leeuwenhoek was the first to observe
single-celled organisms that later
scientists have applied towards the
discovery of multiple-celled organisms so
without this prior knowledge, the
existence of both single and multiple-
celled organisms probably would not be
known today.

8. Con…
Schleiden and Schwann
 Formulated Cell Theory: cells are the
fundamental units of life and carry out all the
basic functions of living things

9. Pioneers of Microbiology
Louis Pasteur (1822-1895).
 Fermentation (1857)
 Pasteurization: heat liquid enough to kill the
spores of bacteria (1864)
 Vaccine development – rabies
 Proposed aseptic techniques (prevent
contamination by unwanted microbes)
 Director of Pasteur Institute, Paris (1894)

10. Pioneers of Microbiology
Joseph Lister, UK (1867)
 Used phenol (carbolic acid) to disinfect wounds
 First aseptic technique in surgery
Robert Koch (1876)
 Postulates – Germ theory (1876)

11.  Identified microbes that caused anthrax
(1876), tuberculosis (1882) and cholera
(1883)
 Developed microbiological media & streak
plates for pure culture (1881)

12. Koch’s Postulates
The specific causative agent must be found in every
case of the disease.
The disease organism must be isolated from the
lesions of the infected case and maintained in pure
culture.

13. The pure culture, inoculated in to a
susceptible or experimental animal,
should produce the symptoms of the
disease.
The same bacterium should be re-
isolated in pure culture from the
intentionally infected animal.

14. Development of Culture Media
 To enable the isolation of pure cultures
(only one type of organism)

15. Fannie Hesse, the wife of one of Koch’s
assistants, proposed using agar
Not digested by most bacteria
Melts at 100 degrees .
Used today - 2% in solid media
Richard Petri, another of Koch’s
assistants, developed the Petri dish

16. Development of Vaccines and
Antisera
Edward Jenner in 1796 discovered that
cowpox (vaccinia) induced protection against
human smallpox.
 Called procedure vaccination.

17. Charles Chamberland (1851 - 1908)
 identified viruses as disease-causing agents
– Tobacco Mosaic Virus
Elie Metchnikoff (1845 - 1916)
 demonstrated the phagocytic cells in the
blood, thus demonstrating cell-mediated
immunity