The document outlines the history of microbiology, highlighting key figures and theories from ancient beliefs in spontaneous generation to modern understandings of microorganisms. It describes significant experiments and contributions from scientists like Louis Pasteur, Robert Koch, and Alexander Fleming, which established foundational concepts in microbiology, including germ theory and the development of vaccines. The document covers various eras, including the discovery era, golden era, and modern era, detailing advances in understanding bacteria, viruses, and the role of microorganisms in health and disease.

1. HISTORY OF
MICROBIOLOGY
BY- SANCHIT
DHANKHAR

2. MICROBIOLOGY
Scientific study of organisms (both eukaryotes
and prokaryotes) and agents too small to be seen
clearly by the unaided eye.
Microbiology is the study of microorganisms / microbes which is visible only
with a microscope.
Derived from the Greek word “mikros” - ‘small’
and “bios” - ‘life’.
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3. The diverse group of organisms includes algae, archae, bacteria,
cyanobacteria, fungi, protozoa, viruses.
Most of the microorganisms are harmless.
99% are good. Eg: Cynobacteria (blue green algae)
1% are bad. Eg: Pathogens
MICROBIOLOGY
Discovery Era Transition Era Golden Era Modern Era
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4. __________ __________ DEBATE
The belief in the spontaneous
generation of life from nonliving
matter was introduced by
Aristotle, who lived around 350
BC.
According to Aristotle, it was:
“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. Aristotle: 384 – 322 B.C.
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5. THEORY OF SPONTANEOUS
GENERATION
Formation of life from non living things-
ABIOGENESIS.
Aristotle suggested that flies and maggots developed
from decaying organic matter.
Epicuris suggested that worms and other animals
originated from soil and manure by the action of sun
and rain.
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6. Theory of Spontaneous generation was disproved
by Francesco Redi,Lazzaro Spallanzani,Louis
Pasteur and Theodore Schwann.They argued
that life originated from “pre existing life only”-
BIOGENESIS.
Francesco Redi took 3 containers filled with
meat particles.1st was kept unclosed,2nd covered
with paper and 3rd was covered with cork or
guaze.After inhibition the 1st container had
maggot being produced because flies were
attracted by the odour of the meat and they laid
eggs after some days developed to maggots.2nd
and 3rd container did not contain maggots.
Francesco red
(1626 - 1697)
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7. Redi’s experiment proving that maggots
are not spontaneously produced in rotten
meat.
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8. In 13th century, Rogen Bacon described that the disease
caused by a minute “seed” or “germ”.
Antony Van Leeuwenhoek (1632 – 1723)
Descriptions of Protozoa, basic types of bacteria,
yeasts and algae.
Father of Bacteriology and protozoology.
In 1676, he observed and described microorganisms
such as bacteria and protozoa as “Animalcules”.
The term microbe is used by Sedillot in 1878.
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9. SPONTANEOUS GENERATION DEBATE
ANTON VAN ___________: “ANIMALCULES”
(PRONOUNCED LAY-WHEN-HOOK)
As a tailor, used lenses to examine cloth. It was
probably this that led to his interest in lens making.
He assembled hundreds of microscopes, some of
which magnified objects 270 times.
As he looked at things with his microscopes, he
discovered “micro” organisms - organisms so tiny
that they were invisible to the naked eye.
He called these tiny living organisms “animalcules”.
He first described bacteria and the protozoans.
1632 - 1723
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10. TRANSITION ERA:
John Needham (1713 – 1781)
Supporter of the spontaneous generation theory.
He proposed that tiny organism(animalcules) arose
spontaneously on the mutton gravy.
He covered the flasks with cork as done by Redi, Still the
microbes appeared on mutton broth.
Lazzaro spallanzai (1729 – 1799)
He demonstrated that air carried germs to the culture medium.
He showed that boiled broth would not give rise to microscopic
forms of life.
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11. THE CONTROVERSY OVER SPONTANEOUS
GENERATION
JOHN NEEDHAM & LAZZARO SPALLANZANI
The Question:
What causes tiny living things to appear in decaying broth?
Needham’s Hypothesis: Spontaneous generation.
Spallazani’s Hypothesis: Microbes come from the air. Boiling will kill them.
Needham >
Spallazani >
French
chemist Louis
Pasteur’s
design of this
experiment settled the
argument. Click here for
an animation and quiz.
1713 - 1781
1729 - 1799
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12. GOLDEN ERA:
Louis Pasteur
He is the father of Medical Microbiology.
He pointed that no growth took place in swan neck shaped tubes because dust and germs had
been trapped on the walls of the curved necks but if the necks were broken off so that dust
fell directly down into the flask, microbial growth commenced immediately.
Pasteur in 1897 suggested that mild heating at 62.8°C (145°F) for 30 minutes rather than
boiling was enough to destroy the undesirable organisms without ruining the taste of the
product, the process was called Pasteurization.
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13. He invented the processes of
pasteurization, fermentation and the
development of effective vaccines
( rabies and anthrax).
Pasteur demonstrated diseases of
silkworm was due to a protozoan parasite.
Contributions of Loius pasteur:
He coined the term “microbiology”, aerobic, anaerobic.
He disproved the theory of spontaneous germination.
He demonstrated that anthrax was caused by bacteria and
also produced the vaccine for the disease. 13

14. John Tyndall (1820 - 1893)
He discovered highly resistant bacterial structure, later
known as endospore.
Prolonged boiling or intermittent heating was necessary
to kill these spores, to make the infusion completely
sterilized, a process known as Tyndallisation.
Lord Joseph Lister (1827-1912)
He is the father of antiseptic surgery.
Lister concluded that wound infections
too were due to microorganisms.
He also devised a method to destroy microorganisms
in the operation theatre by spraying a fine mist of
carbolic acid into the air.
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15. Robert Koch (1893-1910)
He demonstrated the role of bacteria
in causing disease.
He perfected the technique of isolating
bacteria in pure culture.
Robert Koch used gelatin to prepare
solid media but it was not an ideal because
(i) Since gelatin is a protein, it is digested by many
bacteria capable of producing a proteolytic exoenzyme
gelatinase that hydrolyses the protein to amino acids.
(ii) It melts when the temperature rises above 25°C.
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16. Fanne Eilshemius Hesse (1850 - 1934)
One of Koch's assistant first proposed
the use of agar in culture media.
It was not attacked by most bacteria.
Agar is better than gelatin because of its
higher melting pointing (96°c) and solidifying
(40 – 45°c)points.
Richard Petri (1887)
He developed the Petri dish (plate), a container used for
solid culture media.
1786 Miller produced first classification of Bacteria.
1838-1839 Schwann and Schleiden proposed the Cell Theory.
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17. Alexander Flemming
He discovered the penicillin from
penicillium notatum that destroy
several pathogenic bacteria.
1835-1844 Bassi discovered that Silkworm disease was caused by Fungus.
1847-1850 Semmelweis introduced Antiseptics to prevent diseases.
Paul Erlich (1920)
He discovered the treatment of syphilis by using arsenic
He Studied toxins and antitoxins in quantitative terms & laid foundation of
biological standardization.
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18. In 1884,Metchnikoff,Father of Cellular immunity
described Theory of Phagocytosis.Hans Christian
Gram,introduced the Gram staining technique for the
differentiation of Gram positive and Gram negative
bacteria.
In 1887 Richard Julius Petri developed Petri
dish(plate).
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19. 1887-1890 Winogradsky studied sulfur and nitrifying
bacteria.
Beijerinck in 1889 isolated root nodule bacteria.In
1899 he proved that Tobacco mosaic disease was
caused by Virus.
In 1895 Bordet discovered Complement.
In 1902 Landsteiner discovered Blood Grouping.
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20. Alexander Fleming discovered Lysozyme in 1921.In
1929 he discovered Penicillin.
In 1928 Griffith discovered Bacterial Transformation.
In 1937 Chatton divided living organisms into
Prokaryotes and Eukaryotes.
In 1941 Beadle and Tatum proposed One-gene-one-
enzyme Theory. 20

21. In 1953 Watson and Crick proposed DNA double
helix.
In 1961 Jacob and Monad proposed lac operon.
In 1970 Arber and Smith discovered restriction
endonucleases.
In 1977 Woese divided Prokaryotes into Bacteria and
Archaea.
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22. In 1979 Insulin was synthesised using Recombinant DNA.
In 1982 Recombinant Hepatitis B vaccine was developed.
First genetic engineered vaccine was approved for human
use in 1986.
In 1997 the largest known bacterium,Thiomargarita
namibiensis was discovered.
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23. GERM THEORY OF
FERMENTATION
The anaerobic enzymatic conversion of organic compounds
especially carbohydrates to simpler compounds especially to
ethyl alcohol producing energy in the form of ATP-
Fermentation.
Louis Pasteur defined fermentation as “life without air”.He
proved that microorganisms are involved in fermentation.
Theodore Schwann demonstrated that yeast causes
fermentation and produces alcohol.
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24. GERM THEORY OF
DISEASE
Germ theory states that infectious diseases are caused by
microbes.
Robert Koch showed that microbes caused diseases.He
proved that Anthrax was caused by Bacillus anthracis
Von Plenciz not only stated that living organisms or
agents are the cause of diseases but suspected that different
germs were responsible for different diseases.
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25. GERM THEORY OF
PASTEURISATION
Pasteurisation is the process of heating milk or wine or other
fluids to moderate temperature for a definite time which kills
pathogenic bacteria and considerably delays other bacterial
growth.
Introduced by Louis Pasteur in 1866 to sterilise wine.
Undesirable secondary fermentations caused the wine
diseases which could be prevented by Pasteurisation.
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26. IMPORTANT DISCOVERIES:
Bacteria:
Hansen (1874) – Leprosy bacllus
Neisser (1879) – Gonococcus
Ogston (1881) – Staphylococcus
Loeffler (1884) – Diphtheria bacillus
Roux and Yersin – Diphtheria toxin
Viruses:
Beijerinck (1898) - Coined the term Virus for filterable infectious agents.
Pasteur developed Rabies vaccine.
GoodPasteur - Cultivation of viruses on chick embryos.
Charles Chamberland, one of Pasteur’s associates constructed a porcelain bacterial filter.
Twort and d’Herelle - Bacteriophages.
Edward Jenner - Vaccination for Smallpox.
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27. MODERN ERA:
Nobel Laureates
Years Nobel laureates Contribution
1901 Von behring Dipth antitox
1902 Ronald Ross Malaria
1905 Robert koch Tb
1908 Metchnikoff Phagocytosis
1945 Flemming Penicillin
1962 Watson,Crick Structur DNA
1968 Holley,Khorana Genetic code
1997 Pruisner Prions
2002 Brenner, Hervitz Genetic regulation of organ
development &cell death
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28. THANK YOU
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