This presentation describe the discovery of microbial world. Theory of Abiogenesis and Biogenesis and Contribution of scientist in the field of Microbiology

1. Microbiology: Historical
perspective
Unit- I (B.sc)
Presented by: Simran S Sonule.

2. Content
+ Introduction
+ Discovery of Microbes
+ Theory of Biogenesis and Abiogenesis
+ Contributions of Scientists

3. Introduction
+ Microbiology is the study of micro-organisms or microbes that
are too small to be visible through naked eye.
+ Microbes/Microorganisms is an organism of microscopic size
which may exist in its single-celled form or as a colony of cells.
+ Microorganisms are found in a wide range of environments,
including the poles and the equator, deserts, geysers, rocks,
and the deep oceans.
+ Some are adapted to extreme temperatures, some to high
pressure, and a few to high radiation environments.
+ Microbes play a vital role in human culture and health in a
variety of ways, including the fermentation of meals, the
treatment of sewage, and the production of fuel, enzymes, and
other bioactive compounds.
+ Microbes matter because they affect every aspect of our
lives they are in us, on us and around us.

4. Discovery of Microbes
+ The existence of microbes was discussed for centuries before their discovery in the
seventeenth century.
+ By the sixth century BC, the Jains of modern-day India had proposed the presence of
small beings known as nigodas. These nigodas are supposed to be born in clusters, to
live anywhere, including the bodies of plants, animals, and humans, and to survive for only
a fraction of a second.
+ Roman scholar Marcus Terentius Varro in a first-century BC describe about the unseen
creatures that cause diseases called animalia minuta in book entitled On Agriculture.
+ .Since microbes were too small to be seen by the naked eye, their discovery had to wait
until the invention of the microscope.

5. + In 1660, Robert Hooke made a compound microscope and draw the first drawing
of cell in a piece of cork.
+ He published Micrographia in 1665 in which his compound microscope
was described and pictured.
+ He unfortunately couldn't discover the bacteria probably because he studied
opaque objects in dry state under reflected light-conditions. Under these
conditions observation of bacteria is difficult.
+ In 1674, Antony van Leeuwenhoek was the first to observe bacteria and
protozoa.
+ He created more than 250 simple microscopes as a hobby of lens grinding. The
magnifying power of some of those microscopes was as high as 300X, sufficient
enough to visualize microorganisms.
+ One day he observed the rain water collected in earthen pot through his lens. To
his surprise he observed a minute creatures moving here and there which he
named as 'Little animalcules'.
+ He was also the first to observe microscopic images of muscle fibers, bacteria,
spermatozoa, red blood cells, gouty tophi crystals and blood flow in capillaries.
+ Because of his extraordinary contribution in the field of microbiology he is
considered as Father of Microbiology.

6. Theory of Abiogenesis and Biogenesis
Theory of Abiogenesis
+ Spontaneous generation theory is an obsolete scientific belief that stated that living organisms could arise from nonliving
substances and that this process occurred naturally.
+ It was proposed that certain species, such as fleas, might develop from inanimate substance such as dust, or that
maggots could evolve from dead flesh.
+ Van Helmont (1577-1644) devised a method for manufacturing mice. He recommended putting some wheat grains with
soiled linen and cheese into an appropriate receptacle and leaving it undisturbed for a time in an attic or stable. Mice
would then appear.
+ Aristotle, a Greek philosopher and naturalist, devised the notion, which maintained sway until the 17th century.
+ Aristotle’s Work: Aristotle proposed that life arose from nonliving material if the material contained pneuma (“vital heat”).
As evidence, he noted several instances of the appearance of animals from environments previously devoid of such
animals, such as the seemingly sudden appearance of fish in a new puddle of water.
+ In his sexual theory of reproduction, he believed that the male semen and female matter were refinements that
were produced by bodies as a result of their proportions of heat, ingested food and were a byproduct of the elements
earth and water.
+ Yet, he believed that creatures arose from spontaneous generation and not sexual reproduction. He came to
the conclusion that whether a life form arose from sexual reproduction or spontaneous generation, they were a result of
interaction between vital heat and elemental matter.

7. Controversy over Spontaneous Generation:
+ Francesco Redi and Lazzaro Spallanzani then challenged this theory in the 17th and 18th centuries, but it was
still not discredited. It was not until the work of Louis Pasteur and John Tyndall in the 19th century that this
theory was finally disproved.
+ Francesco Redi opposed the theory of Spontaneous
generation.
+ In 1668, Francesco Redi performed one experiment to
know the truth of formation of maggots forming
spontaneously from meat exposed to warmth and air.
+ He performed experiment and the results were files get
attracted by the meat went to the both the sets of jar but
these couldn't go up to the meat pieces where jars were
covered with gauze but could reach up to the meat pieces
in the jars not covered with gauze and laid eggs there,
from where maggots were developed.
+ Thus meat itself did not turn into maggots as opposed to
the doctrine of abiogenesis/spontaneous generation.

8. + John Needham supported theory of Spontaneous
generation
+ John Needham, an English biologist, did an experiment to
prove spontaneous generation in 1745 with boiled broths.
+ He infused a broth by mixing plant and animal matter and
boiled it in the belief that it would kill all the microorganisms.
He sealed the broth and left it for a few days.
+ He observed that the broth had become cloudy and that it has
microscopic organisms in it. He reiterated the spontaneous
generation theory and many of his peers believed him.
However, in reality, the broth was not boiled vigorously so as
to kill all the microorganisms.
+ Lazzaro Spallanzani criticized Needham's finding
and opposed the theory of spontaneous generation.
+ In 1768, an Italian biologist named Lazzaro Spallanzani retried
Needham's experiment. He vigorously cooked broths infused
with animal and plant materials. He kept one of the jars closed
and the other open to the air. According to his findings, the
sealed jar was clear and free of development. He then
discovered that air was the medium that was introducing
microbes into the flask.
+ Scientists' doubts regarding the spontaneous generation
theory had grown by this point.

9. Disapproving the theory
+ Louis Pasteur opposed the theory of Spontaneous generation.
+ In 1864, Louis Pasteur performed the Goose neck flask experiment and ended the controversy over Spontaneous generation
and proved that it is the theory of biogenesis which is correct.
+ For the experiment, he used goose flasks with twisted necks and boiled meat broth in them. The flask was designed in such a
way that it allowed air to pass from outside to within while preventing microbes from entering. If any microbes entered the
flask, they would get caught in the flask's twisted neck.
+ As long as the flask was kept intact, the broth remained clear for an extended period of time. When the flask neck broke,
microbes entered the broth, causing it to become cloudy.
+ He predicted right that sterilized broth in his goose-neck flasks would stay sterile as long as the goose necks remained intact.
However, if the necks are broken, microbes will be introduced, contaminating the flasks and permitting microbial development
within the broth.

10. Contributions of Scientists
John Tyndall:
+ In 1876 John Tyndall, an English Physicist supported the Pasteur's view and
carried out his experiment 'Dust free box experiment' to prove the fact that dust
particles carry the microorganism in the air and disapproved the theory of
Spontaneous generation.
+ He discovered the thermoresistant phases of bacteria. He performed several
experiments and concluded that there are two phases in some bacteria. In
one phase, these are relatively thermolabile(destroyed by boiling for 5 minutes)
and in other phase these are thermoresistant(required very long time for
destruction).
+ He introduced Tyndallization:
+ Tyndallization is a multi-step technique which is effective for destroying bacteria
spores. In this procedure products are placed in steam exposure at 100°C in a
steam sterilizer for 20-45 minutes, followed by overnight incubation at 37°C, and
this cycle is repeated next two days. Spores, if present, germinate into
vegetative bacteria during the incubation period and get destroyed
during steaming on the second and third days.

11. Louis Pasteur
+ Louis Pasteur (December 27, 1822 -September 28, 1895) French chemist and microbiologist who was one of
the most important founders of medical microbiology.
+ He is known as Father of Microbiology and Father of Immunology.
+ He is regarded as one of the three main founders of Bacteriology, together with Ferdinand Cohn and Robert
Koch.
+ He was the Director of the Pasteur Institute, established in 1887, till his death.
+ Pasteur also made significant discoveries in chemistry, most notably on the molecular basis for
the asymmetry of certain crystals and racemization
Contributions in the field of Microbiology:
+ In 1864 he solved the controversy over Spontaneous generation by performing Goose -neck flask experiment.
+ In 1857-1876 he discovered the causes of 'Diseases of Wine and Beer'
+ He introduced Pasteurization process: a method for preventing the growth of undesirable organisms however
allowing the growth of desirable yeasts in the fermentation medium by heating the medium for few minutes at
50-60°C.
+ He also discovered various other fermentative processes: Working for more than 20 years in fermentative
processes he concluded that different organisms are required for different fermentations.
+ Pasteur laid foundation for all microbiological techniques through his research on lactic and alcoholic
fermentation.
+ He discovered anaerobes: Microorganism that can live only in the absence of oxygen.
+ He isolated microorganism responsible for Silkworm disease. Silkworm disease called pebrine which was
caused by Protozoa.

12. + Contribution in the field of Immunology:
+ He performed Chicken-Cholera Experiment: Two groups of chickens were inoculated; one
that had been given the old culture and one group that had not. Those chickens that had
been given the old culture survived, those that had not died. The chickens that had been
inoculated with the old culture had become immune to chicken cholera. Pasteur believed
that their bodies had used the weaker strain of germ to form a defense against the more
powerful germs in the fresher culture. Pasteur had found a way of producing the resistance
without the risk of the disease.
+ He applied the Chicken-Cholera expt. principle to prepare the Anthrax Vaccine and got the
success.
+ After this he made another successful attempt to prepare the Rabies(hydrophobia)
Vaccine. Louis Pasteur’s initial efforts to isolate the rabies virus proved unsuccessful as
the virus remained invisible. Viruses could not be seen due to the poor resolution of the
microscopes used. The virus was not seen until almost a century later, in 1962, with the
advent of electron microscopy. Louis Pasteur then attempted to develop a vaccine with
attenuated virulence. He suspended sections of spinal cord from rabid rabbits inside flasks
to dry in a moisture-free atmosphere. Virulence gradually declined until finally
disappearing. Louis Pasteur injected these spinal cord sections into rabid dogs, followed
by preparations of increasing virulence. They did not develop rabies.
+ Then, in July 1885, Joseph Meister, a 9-year-old boy from France, was severely bitten by a
rabid dog. With Joseph facing almost certain death, his mother took him to Paris to see
Pasteur because she had heard that he was working to develop a cure for rabies. Pasteur
took on the case, and alongside two physicians, he gave the boy a series of injections over
several weeks. Joseph survived and Pasteur shocked the world with a cure for a
universally lethal disease. This discovery opened the door to the widespread use of
Pasteur’s rabies vaccine around 1885, which dramatically reduced rabies’ deaths in
humans and animals. This milestone transformed Pasteur into a legend.

13. Robert Koch
+ Heinrich Hermann Robert Koch (11 December 1843 – 27 May 1910) was a
German physician and microbiologist.
+ He is known for his role in identifying the specific causative agents of deadly infectious diseases
including tuberculosis, cholera and anthrax.
+ His discovery of the anthrax bacterium (Bacillus anthracis) in 1876 is considered as the birth of
modern bacteriology. Thus he is regarded as one of the main founders of modern bacteriology.
+ Koch developed many innovative techniques in microbiology. He was the first to use the oil
immersion lens, condenser, and microphotography in microscopy.
Contribution of Robert Koch in the field of Microbiology:
+ He proved 'Germ theory of diseases' which stated that germs are responsible for the diseases.
+ He investigated the cause of Anthrax in Germany got the success isolating the microorganism
responsible for it from the blood of cattle that had died from Anthrax. It was a bacteria.
+ He discovered bacteria responsible for Tuberculosis disease and proved that it is not inherited and
people get the disease due to infection.
+ He also discovered Vibrio cholerae(bacteria) in India(Calcutta) as a causative agent for Cholera
disease.
+ Later, he also discovered microorganism responsible for various diseases such
as Gonorrhea, Typhoid, Leprosy, etc.

14. + He devised a treatment method: Used old tuberculin for treatment of Tuberculosis.
+ He introduced several Microscopic treatment: Use of oil for higher magnification,
introduced new techniques like smearing and fixing of bacterial cultures on glass slide,
introduced staining methods.
+ He proposed Koch's Postulates:
1)The microorganism must be found in abundance in all organisms suffering from
the disease, but should not be found in healthy organisms.
2) The microorganism must be isolated from a diseased organism and grown in
pure culture.
3) The cultured microorganism should cause disease when introduced into a
healthy organism.
4) The microorganism must be reisolated from the inoculated, diseased
experimental host and identified as being identical to the original specific causative agent.
+ He introduced Pure culture techniques: He realized that the development of simple
methods for obtaining pure cultures of bacteria was the vital requirement for the
growth of new science. He introduced Streak plate method for isolating bacteria. He
devised Slant cultures which are used for storing pure cultures for a moderately long
term. He then introduced Pour plate method for isolating bacteria.

15. Sergei Winogradsky
+ Sergei Winogradsky, was born in Russia in 1856 and was to become a
founder of modern microbiology and microbial ecology.
+ He made lot of contribution in the field of Soil microbiology.
+ He isolated the first pure cultures of the nitrifying bacteria and confirmed
that they carried out the separate steps of the conversion of ammonia to
nitrite and of nitrite to nitrate. This led directly to the concept of the cycles
of sulfur and nitrogen in Nature.
+ Discovered and isolated nitrogen fixing bacteria in soil that make nitrates
available to green plants.
+ He is best known for the discovery of Chemoautotrophy the process by
which organisms derive energy from a number of different inorganic
compounds and obtain carbon from carbon dioxide.
+ Invented the Winogradsky column: Winogradsky column is a closed
column inside which a diverse microbial community is cultured. The setup
is quite simple, consisting of a combination of pond mud, water, an organic
carbon source (e.g. shredded newspaper), calcium (e.g. crushed
eggshells), and sulfur (e.g. gypsum). By exposing the column to light, all
the ‘ingredients’ necessary to support a diverse microbial community are
available. Different regions within the column will receive different amounts
of light, and oxygen / nutrient concentrations. The result is that diverse
species communities become established in close proximity to one
another. To the naked eye this appears as a (living) mosaic of colors.

16. Joseph lister
• Joseph Lister, (April 5, 1827— February 10, 1912), British surgeon and medical
scientist who was the founder of antiseptic medicine and a pioneer in preventive
medicine.
• He is known as Father of Antiseptic Surgery.
• As a surgeon he promoted the concept of antiseptics by introducing carbolic acid
(modern-day phenol) as a sterilizer for surgical equipment, patients'
skins, sutures, surgeons' hands, and wards. Lister's work reduced post-
operative infections and made surgery safer for patients, earning him the title of
"Father of Modern Surgery."
• He devised techniques to improve post-surgery survival rates. His most
significant discovery, however, was recognizing that putrefaction in wounds is
produced by germs, which relates to Louis Pasteur's then-novel germ theory
of fermentation.

17. Contribution of other Scientist in the field of Microbiology
+ Edward Jenner (17 May 1749 – 26 January 1823) was an English physician and scientist who pioneered the
concept of vaccines and created the smallpox vaccine, the world's first vaccine.
+ Sir Ronald Ross (13 May 1857 – 16 September 1932) was a British medical doctor who received the Nobel Prize
for Physiology or Medicine in 1902 for his work on the transmission of malaria, becoming the first British Nobel
laureate, and the first born outside Europe. His discovery of the malarial parasite in the gastrointestinal tract of
a mosquito in 1897 proved that malaria was transmitted by mosquitoes, and laid the foundation for the method
of combating the disease.
+ Élie Metchnikoff, (May 16, 1845—July 16, 1916, Paris, France), Russian-born zoologist and microbiologist who
received (with Paul Ehrlich) the 1908 Nobel Prize for Physiology or Medicine for his discovery in animals of amoeba-
like cells that engulf foreign bodies such as bacteria—a phenomenon known as phagocytosis and a fundamental part
of the immune response.
+ Martinus Willem Beijerinck (16 March 1851 – 1 January 1931) was a Dutch microbiologist and botanist who was
one of the founders of virology and environmental microbiology. He is credited with the discovery of viruses, which
he called "contagium vivum fluidum" In 1898, he published results on the filtration experiments demonstrating
that tobacco mosaic disease is caused by an infectious agent smaller than a bacterium.Nitrogen fixation, the
process by which diatomic nitrogen gas is converted to ammonium ions and becomes available to plants, was also
investigated by Beijerinck. Beijerinck discovered the phenomenon of bacterial sulfate reduction, a form of anaerobic
respiration.

18. Thank you