The bottle filled with a heated infusion and connected with a large spherical bottle and a helical tube. Both were heated and the right tube was closed by melting. The organics remained sterile. Obviously, the germs (molecules or particles) could be destroyed by higher temperature.

1. History of Microbiology

2. SPONTANEOUS GENERATION
Early belief that some forms of life could arise from “vital
forces” present in nonliving or decomposing matter,
abiogenesis. In other words, organisms can arise form non-
living matter.
The belief in the spontaneous generation of life from nonliving
matter was introduced by Aristotle, who lived around 350 BC.
According to Aristotle,
“readily observable that aphids arise from the dew which falls
on plants, fleas from putrid matter, mice from dirty hay.”
This belief remained unchallenged for more than 2000 years.

3. Spontaneous Generation
FRANCESCO REDI - Experiments on Flies
Redi's Question: Where do maggots come from?
Hypothesis: Maggots come from flies.
Experiment: Redi put meat into three separate jars.
Jar-1
• Left open
• Maggots developed
• Flies were observed laying eggs on the meat in the open jar
Jar-2
• Covered with netting
• Maggots appeared on the netting
• Flies were observed laying eggs on the netting
Jar-3
• Sealed
• No maggots developed
First to formally challenge the accepted belief of spontaneous generation.
Francesco Redi, Italian physician,
naturalist & poet, 1626 – 1697.

4. LOUIS JABLOT
In (1645-1723) Jablot conducted an experiment in which he divided a hay
infusion that had been boiled into two containers:
a heated container that was closed to the air and
a heated container that was freely open to the air.
Only the open vessel developed microorganisms.
This further helped to disprove abiogenesis.

5. REDI’S and JABLOT’S
EXPERIMENTS

6. ROBERT HOOKE
One of the most important discoveries of biology occurred in 1665, with the
help of a crude microscope, when Robert Hooke(English scientist) stated
that life’s smallest structural units were cells. He studied fungi as well

7. ANTONY VAN LEEUWENHOEK
• First to observe living
microbes
• His single-lens magnified 50-
300X magnification
• Between 1674-1723 he wrote
series of papers describing his
observations of bacteria,
algae, protozoa, and fungi
(Animalcules)

8. • Antony Van Leeuwenhoek was a Dutch merchant who polished grains of
sand into lenses which were able to magnify 300 times and added a simple
focus mechanism.
• Leeuwenhoek invented the simple (one lens) microscope (in 1673) and
observed the microorganisms.
• Antoni van Leeuwenhoek, the man who first discovered the microbial
world.
• Van Leeuwenhoek viewed rain and pond water, infusions made from
peppercorns, and scrapings from his teeth in the year 1674 and termed the
tiny microorganisms as ‘animalcules’.

9. ANTONY VAN LEEUWENHOEK

10. • After microbial discovery by Leewenhoek, scientists began investigations
about the origin of microbes.
• JOHN NEEDHAM (1749), an Irish priest - observed the appearance of
microorganisms in putrefying meat and interpreted this as spontaneous
generation

11. THEORY OF BIOGENESIS
LA ZARO SPALLAZANI (1729-1799)
•an Italian priest - boiled beef broth for an hour, sealed the flasks and observed
no appearance of microorganisms and disproved the theory of spontaneous
generation and proposed the theory of biogenesis.
•He said that every form of life takes its origin from their parents, germ cells
or seeds.
•This theory of biogenesis was later proved and supported by Louis Pasteur

12. Theodor Schwann (1837a) demonstrated that germs could be destroyed by
heat.
He conducted an experiment :
The bottle filled with a heated infusion and connected with a large spherical
bottle and a helical tube. Both were heated and the right tube was closed by
melting. The organics remained sterile. Obviously, the germs (molecules or
particles) could be destroyed by higher temperature.
Schroder and von Dusch (1854) successfully used a layer of cotton as a
filter for sterilization. First, the organic substance in the middle glass was
heated and after that a flow of air was adjusted by opening the tap and
emptying the left, large bottle slowly. Since then, layers of cotton have been
used frequently to sterilize air in microbiology and biotechnology.
SCHWANN, FRIEDRICH SCHRODER AND VON DUSCH

13. Early experiments showing activities of microorganisms.(b) Theodor Schwann's
experiment with a heated glass spiral (Schwann 1837a, (c) The Schröder and von
Dusch experiment with a glass tube filled with cotton (Schröder and von Dusch
1854).

14. LOUIS PASTEUR (1822 - 1895)
• Disproved abiogenesis
• spontaneous generation of
microbes by preventing “dust
particles” from reaching the
sterile broth
• In 1861 completes experiments
that lays to rest spontaneous
generation.
• Showed microbes caused
fermentation and spoilage

15. • In1858, Pasteur filtered air through a gun-cotton filter and, upon microscopic
examination of the cotton, found it full of microorganisms, suggesting that the
exposure of a broth to air was not introducing a “life force” to the broth but rather
airborne microorganisms.
• Pasteur’s set of experiments( swan neck flask experiments) irrefutably disproved
the theory of spontaneous generation and earned him the prestigious Alhumbert
Prize from the Paris Academy of Sciences in 1862.
• In a subsequent lecture in 1864, Pasteur articulated “Omnevivum ex vivo” (“ life
only comes from life”). In this lecture, Pasteur recounted his famous swan-neck
flask experiment, stating that “life is a germ and a germ is life.”

16. PASTEUR’S EXPERIMENT
Trapped airborne organisms in cotton; he also heated the necks of flasks,
drawing them out into long curves, sterilized the media, and left the
flasks open to the air.
In this way Pasteur disproved the theory of spontaneous generation

17. • In 1861, Louis Pasteur introduced the terms “aerobic” and “anaerobic” in
describing the growth of yeast at the outlay of sugar in the presence or
absence of oxygen.
• In 1876 Robert Koch publishes a paper on his work with anthrax,
pointing explicitly to a bacterium as the cause of this disease. This
validates the germ theory of disease

18. • LOUIS PASTEUR ((1822-1895) Working on souring of wine and beer, found
that alcohol spoilage is due to the growth of undesirable microorganisms,
while the desirable microorganisms produce alcohol by a chemical process
called “fermentation”.
• He observed that more alcohol was produced in the absence of oxygen when
sugar is fermented. The phenomenon was later termed the Pasteur Effect.
• He showed that wine did not spoil, if it is heated to 50-600C for a few
minutes. This method is called “pasteurization”, now widely used in dairy
units to kill pathogenic microorganisms in milk.
• He is a founder of “germ theory of disease”, as he visualized that diseases are
caused by microorganisms.

19. • LOUIS PASTEUR (1822-1895) He invented steam sterilizer, autoclave
and hot air oven and also established the importance of cotton wool plugs
for protection of culture media from aerial contamination. He differentiated
between aerobic and anaerobic bacteria and coined the term “anaerobic” to
refer to the organisms that do not require oxygen for growth.
• LOUIS PASTEUR (1822-1895) Working on “pebrine” - a silk-worm
disease caused by a protozoan, showed that infection can be controlled by
choosing worms free from the parasite for breeding.
• He developed the process of “attenuation”, during his work on “chicken
cholera” in fowls. He found old cultures would not kill the animals as fresh
cultures did. This attenuation is now used in protective vaccination against
diseases

20. •LOUIS PASTEUR (1822-1895) Pasteur showed that the anthrax disease
in cattle and sheep is caused by a bacterium. He cultivated anthrax
organisms in sterile yeast water and showed that these cultures can
produce disease when inoculated into healthy animals.
•He developed a live attenuated anthrax vaccine by incubation at 40-42C,
which protects animals against anthrax.

21. • LOUIS PASTEUR (1822-1895) Pasteur developed a vaccine against rabies
(hydrophobia), which made greatest impact in medicine. He obtained the
causative agent of rabies by serial intracerebral passage in rabbits and the vaccine
was prepared by drying pieces of spinal cord.
• In 1888, Pasteur Institute was established for mass antirabic treatment. Pasteur
gave the general term “vaccine” (vacca=cow) in honour of Jenner’s cowpox
vaccine, to various materials used to induce active immunity.

22. ROBERT KOCH (1843-1912) He was a German doctor, who later became the professor of
hygiene and Director of Institute of Infective Diseases at Berlin. He perfected many
bacteriological techniques and is known as “Father of Practical Bacteriology”.
ROBERT KOCH (1843-1912)
He discovered rod shaped organisms in the blood of animals that died of anthrax.
He experimentally obtained the anthrax organisms in pure culture on slide by inoculation of
infected blood into the aqueous humour of a bullock’s eye. He observed multiplication of
bacteria and spore formation. He injected these spores into mice and reproduced the
disease.
He found that in certain conditions, the anthrax bacillus forms spores, which can survive.
He passed anthrax bacilli, from the blood of an infected animal, from one mouse to another
through 20 generations, and found that they bred true.

23. ROBERT KOCH (1843-1912) He introduced staining techniques by preparing dried
bacterial films (smears) on glass slide and stained them with aniline dyes for producing a
better contrast under microscope. He discovered tubercle bacillus (Mycobacterium
tuberculosis), which is popularly called as Koch’s bacillus. He discovered Vibrio
cholera, the causative agent of cholera disease.
ROBERT KOCH (1843-1912) He developed pure culture techniques by introducing
solid media. The use of agar-agar obtained from dried sea weeds (Geladium sp,) in the
preparation of solid bacteriological media was first suggested by Frau Hesse, the wife of
Koch’s student. Koch isolated bacteria in pure cultures on these solid media. It
revolutionized bacteriology.

24. ROBERT KOCH (1843-1912) He discovered “old tuberculin”. Koch noted that
when tubercle bacilli or its protein extract was injected into a guinea pig already
infected with the bacillus, an exaggerated reaction took place and the reaction
remained localized. This is popularly called “Koch phenomenon” and it is a
demonstration of cell mediated immunity. The tuberculin test is based on Koch
phenomenon. He erroneously thought that protein extracted from tubercle bacilli,
called “old tuberculin”, could be used in the treatment of tuberculosis.
ROBERT KOCH (1843-1912)Koch did a series of experiments to fulfill the
criteria laid by his teacher Henle to establish the causative role between a
particular micro-organism and a particular disease. They are popularly known as
Koch’s postulates (Henle-Koch’s postulates).

25. Henle-Koch’s Postulates..
1.A specific organism should be found constantly in association with the disease.
2.The organism should be isolated and grown in a pure culture in the laboratory.
3.The pure culture when inoculated into a healthy susceptible animal should produce
symptoms/lesions of the same disease.
4.From the inoculated animal, the microorganisms should be isolated in pure culture.
5.An additional criterion introduced is that specific antibodies to the causative
organism should be demonstrable in patient’s serum.

26. JOSEPH LISTER (1827-1912)He is popularly known as “Father of antiseptic
surgery”.
He was deeply interested in the prevention of postoperative sepsis. He chose
carbolic acid (phenol) and used as spray on the wound or during surgery. It
saved millions of lives from the jaws of death due to wound infections.
ALEXANDER FLEMMING (1881-1955)He was an English scientist who
worked at St. Mary’s hospital in London. Flemming was associated with two
major discoveries – Lysozyme and Penicillin.
In 1922, he discovered lysozyme by demonstrating that the nasal secretion has
the power of dissolving or lysing certain kinds of bacteria.

27. ALEXANDER FLEMMING (1881-1955)In 1929, Flemming made an
accidental discovery that the fungus Penicillin notatum produces penicillin.
Flemming was culturing Staphylococci in petridishes and some of his cultures
were contaminated with a mold, subsequently identified as Penicillium
notatum.
In 1945, Flemming, Florey and Chain shared the Nobel prize in Physiology
and Medicine for the discovery of penicillin.

28. EDWARD JENNER (1749-1823) Edward jenner was an English physician, who
discovered a safe and efficient vaccination against small pox, which ultimately led
to the eradication of small pox (variola).
Jenner observed that diary workers, exposed to occupational cowpox infection, was
immune to smallpox. He proved experimentally that resistance to smallpox can be
induced by injecting cowpox material (vaccinia) from disease pustules into man
EDWARD JENNER (1749-1823) Pasteur gave the general term “vaccine”
(vacca=cow) in honour of Jenner’s cowpox vaccine, to various materials used to
induce active immunity. Jenner published his findings in 1798 in a pamphlet “An
inquiry into the cause and effect of variola vaccine”

29. PAUL EHRLICH (1854-1915) He was a German bacteriologist, who pioneered the
technique of chemotherapy in medicine.
From his discovery that certain tissues have a specific affinity, he reasoned that
organisms causing diseases could be selectively killed with chemical drugs. This led
him to produce “arsphenamine” (an arsenic compound), the first synthetic drug,
which destroyed the syphilis microbe in the body
Erhlich observed that organic arsenicals killed trypanosomes in an infected
animal, but, if smaller doses were administered, the trypanosomes acquired
tolerance to the drug. Therefore, he aimed at “therapia magna sterilans”, i.e., the
introduction of a single dose of chemotherapeutic agent sufficient to kill the
parasite in the blood. He also observed that drug would undergo certain changes
in the body after which it would produce the desired action