1. Fundamentals of Microbiology
Outlines
Development of Microbiology
Significance of Studying Microbiology
Prokaryotic and Eukaryotic cell structure
Bacterial Taxonomy
Bacterial cell Structure
Bacterial Nutrition and Growth
Bacterial Genetic
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Objectives
• Upon completion of this unit of instruction, the student will be able
to:
Discuss the historical background of Microbiology
Discuss the significance of studying Microbiology
Classify medically-significant bacteria according to their
phenotype and genotype
Identify external and internal structural components of bacteria
Discuss bacterial genetics
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Objectives….
Discuss bacterial metabolism and growth
Describe types of disinfection, decontamination and
sterilization
Prepare and apply disinfectants and antiseptics
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CHAPTER I: INTRODUCTION
Microbiology:
• is a subject which deals with living organisms that are
individually too small to be seen with the naked eye.
• It considers the microscopic forms of life and deals about their
• Reproduction and physiology
• participation in the process of nature
• helpful and harmful relationship with other living things
• significance in science and industry
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Subdivisions of Microbiology
Sub divisions of microbiology
Bacteriology – which deals with bacteria
Mycology- which deals with fungi
Phycology - Which deals with Algae.
Protozoology – which deals with Protozoa.
Helminthology –which deals with worms
Virology -studies about viruses
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Division of Microbiology
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Medical Bacteriology
 It involves the study of pathogens, the disease caused by them,
and the body’s defenses against disease.
• It is also concerned with
• Epidemiology, transmission of pathogens
• disease prevention measures, and
• aseptic techniques and treatment of infectious diseases
• Immunology and production of vaccines.
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HISTORICAL BACKGROUND
 Man kind has always been affected by diseases which were
originally believed to be visitations by the gods and meant to punish
evil doers.
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History
Discovery
era
Transition
era
Golden
era
Modern
era

History…
• Hippocrates:
• father of medicine
• observed that ill health resulted due to changes in air, winds,
water, climate, food, nature of soil and habits of people.
• Varro (117-26 BC) : formulated a theory that
• diseases were caused by animated particles invisible to
naked eye
• which were carried in the air and acquired via the mouth
and nose into the body.
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Background …
• Fracastoro (1478–1553 G.c):
proposed that the agent of communicable diseases were
living things.
Could be transmitted by direct contact with humans and
animals.
Indirectly by objects
But no proofs due to lack of experimental evidence.
• Antony van leeuwehoek ( 1632-1723 G.c)
Father of microbiology, observed “animalcules” using
simple microscope with one lense.
He was the first who properly described the different
shapes of bacteria.
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Question raised - where did they originate?
Leeuwenhoek was not concerned about the origin of Mos.
 many other scientists were searching for an explanation for
spontaneous appearance of living things from
decaying meat
stagnating ponds
fermenting grains and infected wounds
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Background…

History…
• On the bases of this observation, two major theories
were formulated.
1. Theory of Abiogenesis
2. Theory of Biogenesis
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Theory of Abiogenesis:
• Theory of Abiogenesis:
• deals with the theory of spontaneous generation
• stating that living things originated “spontaneously” from non-
living things.
• Aristotle (384-322 BC):
• The founder of a theory spontaneous generation.
• He observed spontaneous existence of fishes from dried ponds,
when the pond was filled with rain.
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Theory of Biogenesis:
• Theory of Biogenesis:
• States that life comes from pre-existing life.
• Francesco Redi (1626-1697):
• He is the scientist who first tried to set an experiment to
disprove spontaneous generation.
• Utilized jars containing meat.
• Some were covered, some were not.
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Theory of Biogenesis…
• He observed that the flies laid eggs on uncovered jar from
which the maggots developed but not from covered jars.
• He said maggots did not developed from meat but from flies
egg.
• Results not accepted for microscopic organisms.
• Introduced experimental procedure to disproof spontaneous
generation.
• The controversy on spontaneous generation took 200 years.
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F. Redi ‘s experiment
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Figure 1 Redi experiment jars

Theories of …
• John Needham (1749)-Utilized infusion broth prepared by
boiling meat, grain, etc. to extract nutrients.
• Lazzaro Spallanzani (1776)- used boiled broth
• Turbidity indicated growth.
• Louis pasture (1822- 1895) :
• He was the scientist who disproved the theory of abiogenesis
once and for all.
• In his experiment he filtered air through cotton plug.
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Theory of…
• He placed plug in infusion broth, broth became cloudy -
organisms present in the air.
• He designed
a large curved flask or
swan-necked or
pasture goose neck flask and placed a sterile infusion
broths.
• Flasks remained sterile unless tilted or neck broken.
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 Luis Pasteur’s experiment
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In ‘A’ air freely moved through the tube, but dust particles were trapped in the curved portion of
the flask. And no microbial growth was observed

Therefore, Pasteur proved that microorganisms entered to the
broth with the air and micro organisms did not evolve
spontaneously.
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Other major contribution of Louis Pasteur
1. Microbial theory of fermentation
2. Principles and practices of sterilization and
pasteurization
3. Control of disease of silk worm
4. Development of vaccines against anthrax and rabies
5. Discovery of streptococci.
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The Germ Theory of diseases
• Robert Koch
• He established an experimental procedure to prove the germ
theory of disease in 1876.
• The theory states that specific disease is caused by specific
pathogen.
• The scientific procedure is known as Koch’s Postulate.
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Koch’s Postulate:
 proof of germ theory of disease.
 A Mo can be accepted as a causative agent of an infectious
disease only if the following conditions are satisfied.
1. The specific causative agent must be found in every case of
the disease but absent from health organism.
2. The suspected micro-organism must be isolated and grown
in pure culture.
3. Inoculation of a sample of the culture into a healthy
organism, susceptible animal must produce the same disease.
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Koch’s Postulate:
4. The disease organism must be isolated from the
inoculated animal. E.g.
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Fig 2. Koch’s postulate
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Exceptions to Koch’s postulate
• Many healthy people carry pathogens but do not exhibit symptoms
of the disease.
• Some microbes are very difficult or impossible to grow in vitro (in
the laboratory) in artificial media. E.g. Treponema pallidum.
• Many pathogens are species specific. E.g. Brucella abortus cause
abortion in animals but not in humans.
• Certain diseases develop only when an opportunistic pathogen
invades imuno-compromised host.
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Major achievements of Robert Koch
• use of solid medium in bacteriology
• Discovery of causative agents of
tuberculosis and cholera
• Koch’s postulate
• Luis Pasture has also developed the germ
theory of diseases.
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Significance of Studying Microbiology
• WHY STUDY MICROBIOLOGY?
• MOs have a tremendous impact on all life
• They are physical and chemical makeup of our planet.
• Microorganisms have a close association with humans.
• They are in us, on us, and nearly everywhere around us.
• One reason for studying microbiology is that MOs are part of the
human environment and are therefore important to human health.
• MOs are essential to the web of life in every environment.
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Significance…
• Microorganisms:
capture energy from sunlight
decompose dead organisms, waste material, and even some
kinds of industrial wastes.
make nitrogen available to plants
maintain the balance of nature
synthesize antibiotics, vaccines
are the major tools of genetic engineering
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Significance…
certain microbes cause disease.
Studying microbiology is provides insight into life processes in all
life-forms.
• In general, Microorganisms are part of the human environment
and are therefore important to human health and activities.
• The study of microorganisms provides insight into life
processes in all forms of life.
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