Louis Pasteur and Robert Koch made seminal contributions to microbiology in the late 19th century. Pasteur established that microorganisms are responsible for fermentation and cause disease, developed pasteurization to kill pathogens, and produced the first vaccines. Koch introduced techniques like staining and solid media isolation that allowed isolation of specific pathogens, including the anthrax bacillus, tuberculosis bacillus, and cholera vibrios. He established criteria now known as Koch's postulates to prove a microbe's role in causing disease. Together, Pasteur and Koch founded the field of medical microbiology through their pioneering studies of specific microbes.

1. CONTRIBUTION OF LOUIS PASTEUR
AND ROBERT KOCH IN MEDICAL
MICROBIOLOGY

2. Louis pasteur
Father of “Modern Microbiology”
Trained chemist and microbiologist
from France
Developed the concept of fermentation
Lactic acid fermentation is due to a
microorganisms
Yeasts are involved in alcoholic
fermentation

3. ◦ His studies on fermentation of wine led him to take interest in
microbiology. He is known as the founder or Father of Modern
Microbiology.
◦ While studying fermentation of grapes in 1857, Pasteur noted
that alcoholic fermentation of grapes, fruits and grains was
caused by some microbial agents which were then called
ferments by him.
◦ He further noted that different types of fermentations were
brought about by different kinds of ferments-microorganism
(1857).
◦ Pasteur applied the knowledge of his predecessors to his own
research. He and his pupils devised basic principles and
techniques of bacterial cultivation and laid down three
principles.
◦ These are:
1. Every alternation of either wine or beer depends on
development of microorganisms.
2. The microorganisms are brought by the ingredients or
apparatus used in breweries.
3. Whenever beer or wine contains no living organisms, it
remains unchanged.

4. ◦ Discovery of anaerobic life
◦ Proposed germ theory of disease
◦ Pasteur devised the process of destroying bacteria known as pasteurization.
◦ Pasteur in 1897 suggested that mild heating at 62.8˚C for 30 minutes rather than
boiling was enough to destroy the undesirable organisms without ruining the test
of the product, the process was called pasteurization.
◦ Development of methods and techniques of Bacteriology
◦ Studies on Pebrine (silk worm disease), Anthrax, Chickenpox, Cholera and
hydrophobia
◦ Pasteur demonstrated disease of silkworm due to a protozoan parasite.
◦ He developed live attenuated vaccine for the disease.
◦ He demonstrated that the anthrax was caused by bacteria and also discovered
vaccine for the disease.

5. ◦ Pasteur's brilliant and active research for a long period of 30 years (1860-1890)
was acclaimed throughout the world. Some of his important contributions in
microbiology are:
1. Development of methods and techniques for cultivation of microorganisms.
2. Conclusive evidence for microorganisms in disease production.
3. Introduction of sterilization techniques and development of steam sterilizer, hot-
air oven and autoclave. Tyndall (1877), a student of Pasteur, introduced the
method of sterilization by repeated heating (tyndallization).
4. Studies on pebrine (silk worm disease), anthrax, chicken cholera and
hydrophobia. During studies on rabies, though Pasteur could not isolate any
microorganism from man and dog, he reproduced the disease in healthy dogs
in 1881 by intracerebral injection of saliva and brain tissue from an infective
case. He suggested that the causative agent of rabies was too small to be seen
by microscope.

7.  Development of chicken cholera vaccine by pasteur

8. ◦ Discovered the theory of
spontaneous generation. he
pointed that no growth took place
in swan neck shaped flask
because dust and germs has
been trapped on the walls of the
curved neck but if the necks were
broken off so that dust fall directly
down into the flask, microbial
growth commenced immediately.

9.  Robert koch
Robert Koch(1843-1910) was a german
physician and microbiologist
One of main Founder of modern bacteriology
Introduced methods for isolation of pure
culture
 He introduced gelatin as a setting agent in
bacteriological media
 use of solid media for isolation of bacteria
 Staining techniques
Modern medical microbiology began with
Koch's systematic studies on anthrax in 1876
in Germany.

10. ◦ Robert Koch laid the foundation of modern
bacteriological technique- introducing glass slide and
coverslip, examination by hanging drop, fixing and
staining of bacteria, culture on solid media by pour
plate method, disinfection by steam sterilization.
◦ Using these technique, he demonstrated streptococci
and staphylococci as the common cause of wound
disease.
◦ He identified specific causative agent of tuberculosis,
cholera and anthrax and gave experimental support
for the concept of infectious disease. discovered
Anthrax bacillus (1876), Tubercle bacillus (1882) and
cholera vibrios (1883) .

11. Koch’s postulates(1884)
◦ Microorganism can be accepted as the causative agent of an
infectious disease only if following conditions are fulfilled:
◦ Disease agent must be present in every organism suffering from the
disease but should be absent in healthy organism.
◦ It should be possible to isolate the microorganism in its pure culture
from lesion of the disease
◦ The isolated microorganism when introduced into suitable laboratory
animal should produce the similar disease
◦ It should be possible to re-isolate the microorganism in its pure culture
from lesions produced in experimental animals.

13. Koch’s postulates