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MICROBIOLOGY
What
is
Microbiology
Study of:
Organisms of microscopic size
Classification
Morphology
Physiology
Metabolism
Distribution in nature
Relationship to each other and other living organisms
Why to study the
Subject
Distribution in Nature:
• Omnipresent: nearly everywhere in Nature

• Grow where they get food moisture and temperature suitable for
growth
• Air
• Soil
• Oceans
• Food we eat
• Surfaces of our body and inside alimentary canal
Effects on Human beings:
Microorganisms

Beneficial
Food

Harmful
Food spoilage

Bread, Wine, Cheese, Yoghurt,
Vinegar

Diseases

Industrial applications
Enzymes, Amino
acids, Vitamins, Antibiotics, Vacc
ines, Pharmaceutical
industries, Sewage treatment

Agriculture
Recycling of elements, Nitrifying
bacteria

Bacterial
Viral
Fungal
Microbiology includes study of

Bacteria

Fungi

Viruses
Protozoa

Algae
Five Kingdom classification of Organisms:
Living Organisms

Monera

Protista

Fungi

Bacteria

Protozoa, A
lgae

Yeasts
Molds

Plantae

Animalia
Basic structural and functional unit of life: Cell
Prokariyotic cell

Eukariyotic cell

Organisms

Bacteria

Algae, Fungi, Protozoa,
Plants, Animals

Size

1-4 µm

>5 µm

Nucleus

Nuclear membrane absent,
Nucleolus absent

Nucleus bounded by
nuclear membrane,
Nucleolus present

Cell wall

Peptidoglycan present

Peptidoglycan absent

Plasma membrane

Sterols absent, Cytoplasmic
streaming absent

Sterols present, Cytoplasmic
streaming present

Membrane-enclosed
organelles

Absent

Present

Ribosome

70 S

80 S
Microbiology: Introduction & history
Characteristics of
major groups of
Microorganisms
Bacteria
Size:
0.2-1.5 by 3-5 µm
Important Characteristics:
• Prokaryotic
• Unicellular
• Simple Internal structure
• Grow on artificial laboratory media
• Reproduction asexual (mostly simple cell division)

Practical significance:
• Some cause diseases
• Some perform role in natural cycling of elements and increase soil
fertility
• Manufacture of valuable compounds in Industry
Microbiology: Introduction & history
Viruses
Size:
0.015-0.2 µm
Important Characteristics:
• Do not grow on artificial media
require living cells within which they reproduce
• Obligate parasites
• Electron microscopy required to observe
Practical significance:
• Cause diseases in humans animals plants
• Also infect microorganisms
Microbiology: Introduction & history
Fungi (Yeasts)
Size:
5.0-10.0 µm
Important Characteristics:
• Eukaryotic
• Unicellular
• Grow on artificial laboratory media
• Reproduction asexual (cell division/ budding) or sexual
Practical significance:
• Some cause diseases
• some are used as food supplements
• Manufacture of alcoholic beverages
Microbiology: Introduction & history
Fungi (Molds)
Size:
2.0-10.0 µm by several mm
Important Characteristics:
• Eukaryotic
• Multicellular
• Many distinctive structural features
• Cultivated on artificial laboratory media
• Reproduction asexual or sexual

Practical significance:
• Decomposition of many materials
• Industrial production of many chemicals like antibiotics
• Can cause diseases
Microbiology: Introduction & history
Protozoa
Size:
2.0-200 µm
Important Characteristics:
• Eukaryotic
• Unicellular
• Some cultivated on laboratory media while some are intracellular
parasites
• Reproduction asexual or sexual

Practical significance:
• Some cause diseases
• Food for aquatic animals
Microbiology: Introduction & history
Algae
Size:
1.0 µm to several centimeters
Important Characteristics:
• Eukaryotic
• Unicellular or Multicellular
• Photosynthetic
• Most occur in aquatic environments
• Reproduction asexual or Sexual

Practical significance:
• Production of food in aquatic environments
• Source of food and in Pharmaceuticals
• Some produce toxic substances
Microbiology: Introduction & history
History
Varo & Columella [1st century BC]: Diseases caused by
invisible organisms (Animalia minuta)
Girolamo Fracastorius of verona [1546]: Living germs
(contagium vivum) cause infectious diseases

Von Plenciz [1762]: Each disease caused by different agent
Kircher [1659]: reported finding minute worms in blood of
plague patients.
Antonie Van Leeuwenhoek [1632-1723]:
• 1st to observe and describe single celled
organisms, “animalcules”, we now refer to as
microorganisms.
• Described different morphological forms of
bacteria
• 1st to record observations of muscle
fibers, bacteria, spermatozoa and blood flow in
capillaries (small blood vessels).
Microbiology: Introduction & history
Robert Hooke [1678]:
• Developed Compound microscope
• 1st to coin the term ‘Cell’
Microbiology: Introduction & history
Earliest discovery of pathogenic role of microorganism:
Augustino Bassi [1835]:
Muscardine diseases of silk worms was caused by a fungus.

Oliver Holmes [1840] & Ignaz Semmelweis [1846]:
 Concluded that puerperial sepsis was transmitted by
contaminated hands of obstetricians, nurses and medical
students.
 This could be prevented by washing hands in antiseptic
solutions.
Edwerd Jenner:
• Observed that the milk maids who had milder form of cowpox
were not prone to Smallpox.
• After observing cases of cowpox and smallpox for few years, In
1796 he removed the fluid of a cowpox from milkmaid and
inoculated James Phipps, an eight-year-old boy, who soon came
down with cowpox.
• Six weeks later, he inoculated the boy with smallpox. The boy
remained healthy.
• Jenner had proved his theory that the pus in the blisters which
milkmaids received from cowpox protected milkmaids from
smallpox.
Louis Pasteur [1822-1895]:

Father of Microbiology
• Trained chemist from France
• Established that Fermentation
caused by microbial agents

was

• Demonstrated anaerobic fermentation by
both bacteria and yeasts (bacteria
produce acid and yeast produce alcohol)
• Developed pasteurization to prevent spoilage of wine by
bacteria
• Noted that different types of fermentations were associated with
different kinds of microbes
• Development of methods and techniques of Bacteriology
• proved that microbes arise only from their like
• Introduction of sterilization techniques: development of steam
sterilizer, autoclave and hot-air oven
• Studies on Anthrax, Cholera and hydrophobia
• Introduced live attenuated (weakened) vaccines
[Accidental observation: chicken cholera bacillus cultures left for
several weeks lost their pathogenicity but retained their ability to
protect the chickens from infection]
Chicken
inoculated

Pure culture of
chicken Cholera
bacteria
8 weeks old

Remains
Healthy
After several weeks…

Chicken
previously
inoculated

Fresh virulent
culture of
chicken Cholera
bacteria

Chicken
which is not
previously
inoculated

Remained
Healthy

Died
• Then he attenuated anthrax bacillus by incubation at high
temperatures (42 C-43 C) and proved that inoculation of such
bacilli in animals introduced protection against anthrax
• He coined
preparations.

the

term

‘Vaccine’

for

such

prophylactic

• While working on rabies, he could not isolate any
microorganism from dog and man but suggested that causative
agent of rabies was too small to be seen by microscope.
Spontaneous generation versus Biogenesis
• Aristotle (384-322 BC) proposed that animals might originate
spontaneously from soil, plants or other unlike animals.
• His influence was strongly felt even in the 17th century

• In 1668, Francesco Redi disproved such generation of
organisms from non-living things
John Needham (1745):
heated Nutrient Fluids and poured them into flasks and covered
with corks → fluid turned turbid showing presence of
microorganisms.

Spallanzani (1765):
Similar to Needham’s Experiments
Boiled the beef broth for hour and then immediately sealed flasks
No growth was observed in the broth
Louis Pasteur (1861)
• finally disproved spontaneous generation after many years of
debate
• Boiled broth in swan-necked flasks
Microbiology: Introduction & history
Joseph Lister [1827-1912]:
Father of Antiseptic surgery
• Professor of surgery
• Applied Pasteur’s work and introduced
Antiseptic techniques in Surgery
• Use of Carbolic acid in Antiseptic
surgery

• Resulted in drop in morbidity and
mortality due to surgical sepsis
Robert Koch [1843-1910]:
Father of Bacteriology
• Introduced methods for isolation of
pure culture

• use of solid media for isolation of
bacteria
• Staining techniques

• discovered
Anthrax
bacillus
(1876), Tubercle bacillus (1882) and
cholera vibrios (1883)
Koch’s postulates
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.
Microbiology: Introduction & history
Paul Ehrlich [1854-1915]:
Father of Chemotherapy
• Applied stains to cells and tissues for
study of their functions.

• Reported the
tubercle bacillus

acid-fast

nature

of

• Discovered Salvarsan (derivative of
arsenic) sometimes called as ‘Magic
Bullete’
• Salvarsan: capable
spirochetes of syphilis.

of

destroying

• Gave rise to new branch of medicine:
‘Chemotherapy’
• In 1892, Ivanovsky removed the bacteria from diseased tobacco
plant extract using some filters.
• This extract was responsible for producing tobacco mosaic
disease in healthy plant
• Beijerinck (1898) confirmed these findings and coined the term
‘Virus’ for such filterable infectious agents.

• Loeffler & Frosch (1898):
Foot and mouth disease of cattle
caused by similar filter-passing
viruses.
• Landsteiner & Popper (1909):
Virus responsible for Poliomyelitis
• Ruska (1934):
introduced Electron microscope
Alexander Fleming [1928]:
• Discovery of 1st Antibiotic
• Accidentally discovered Penicillin produced by a fungus
Penicillium

• Left his Staphylococcus culture on an agar plate for 2 weeks →
went on vacation → came back & found mold on his plate which
prevented bacterial growth
Microbiology: Introduction & history
Elie Metchnikoff:
• Described how Leukocytes ingest disease producing bacteria in
the body
• Called such cells ‘Phagocytes’ & the process ‘Phagocytosis’
• Suggested that Phagocytes are the body’s 1st & most important
line of defense against infection.
Thank
You

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Microbiology: Introduction & history

  • 2. What is Microbiology Study of: Organisms of microscopic size Classification Morphology Physiology Metabolism Distribution in nature Relationship to each other and other living organisms
  • 3. Why to study the Subject Distribution in Nature: • Omnipresent: nearly everywhere in Nature • Grow where they get food moisture and temperature suitable for growth • Air • Soil • Oceans • Food we eat • Surfaces of our body and inside alimentary canal
  • 4. Effects on Human beings: Microorganisms Beneficial Food Harmful Food spoilage Bread, Wine, Cheese, Yoghurt, Vinegar Diseases Industrial applications Enzymes, Amino acids, Vitamins, Antibiotics, Vacc ines, Pharmaceutical industries, Sewage treatment Agriculture Recycling of elements, Nitrifying bacteria Bacterial Viral Fungal
  • 5. Microbiology includes study of Bacteria Fungi Viruses Protozoa Algae
  • 6. Five Kingdom classification of Organisms: Living Organisms Monera Protista Fungi Bacteria Protozoa, A lgae Yeasts Molds Plantae Animalia
  • 7. Basic structural and functional unit of life: Cell Prokariyotic cell Eukariyotic cell Organisms Bacteria Algae, Fungi, Protozoa, Plants, Animals Size 1-4 µm >5 µm Nucleus Nuclear membrane absent, Nucleolus absent Nucleus bounded by nuclear membrane, Nucleolus present Cell wall Peptidoglycan present Peptidoglycan absent Plasma membrane Sterols absent, Cytoplasmic streaming absent Sterols present, Cytoplasmic streaming present Membrane-enclosed organelles Absent Present Ribosome 70 S 80 S
  • 10. Bacteria Size: 0.2-1.5 by 3-5 µm Important Characteristics: • Prokaryotic • Unicellular • Simple Internal structure • Grow on artificial laboratory media • Reproduction asexual (mostly simple cell division) Practical significance: • Some cause diseases • Some perform role in natural cycling of elements and increase soil fertility • Manufacture of valuable compounds in Industry
  • 12. Viruses Size: 0.015-0.2 µm Important Characteristics: • Do not grow on artificial media require living cells within which they reproduce • Obligate parasites • Electron microscopy required to observe Practical significance: • Cause diseases in humans animals plants • Also infect microorganisms
  • 14. Fungi (Yeasts) Size: 5.0-10.0 µm Important Characteristics: • Eukaryotic • Unicellular • Grow on artificial laboratory media • Reproduction asexual (cell division/ budding) or sexual Practical significance: • Some cause diseases • some are used as food supplements • Manufacture of alcoholic beverages
  • 16. Fungi (Molds) Size: 2.0-10.0 µm by several mm Important Characteristics: • Eukaryotic • Multicellular • Many distinctive structural features • Cultivated on artificial laboratory media • Reproduction asexual or sexual Practical significance: • Decomposition of many materials • Industrial production of many chemicals like antibiotics • Can cause diseases
  • 18. Protozoa Size: 2.0-200 µm Important Characteristics: • Eukaryotic • Unicellular • Some cultivated on laboratory media while some are intracellular parasites • Reproduction asexual or sexual Practical significance: • Some cause diseases • Food for aquatic animals
  • 20. Algae Size: 1.0 µm to several centimeters Important Characteristics: • Eukaryotic • Unicellular or Multicellular • Photosynthetic • Most occur in aquatic environments • Reproduction asexual or Sexual Practical significance: • Production of food in aquatic environments • Source of food and in Pharmaceuticals • Some produce toxic substances
  • 23. Varo & Columella [1st century BC]: Diseases caused by invisible organisms (Animalia minuta) Girolamo Fracastorius of verona [1546]: Living germs (contagium vivum) cause infectious diseases Von Plenciz [1762]: Each disease caused by different agent Kircher [1659]: reported finding minute worms in blood of plague patients.
  • 24. Antonie Van Leeuwenhoek [1632-1723]: • 1st to observe and describe single celled organisms, “animalcules”, we now refer to as microorganisms. • Described different morphological forms of bacteria • 1st to record observations of muscle fibers, bacteria, spermatozoa and blood flow in capillaries (small blood vessels).
  • 26. Robert Hooke [1678]: • Developed Compound microscope • 1st to coin the term ‘Cell’
  • 28. Earliest discovery of pathogenic role of microorganism: Augustino Bassi [1835]: Muscardine diseases of silk worms was caused by a fungus. Oliver Holmes [1840] & Ignaz Semmelweis [1846]:  Concluded that puerperial sepsis was transmitted by contaminated hands of obstetricians, nurses and medical students.  This could be prevented by washing hands in antiseptic solutions.
  • 29. Edwerd Jenner: • Observed that the milk maids who had milder form of cowpox were not prone to Smallpox. • After observing cases of cowpox and smallpox for few years, In 1796 he removed the fluid of a cowpox from milkmaid and inoculated James Phipps, an eight-year-old boy, who soon came down with cowpox. • Six weeks later, he inoculated the boy with smallpox. The boy remained healthy. • Jenner had proved his theory that the pus in the blisters which milkmaids received from cowpox protected milkmaids from smallpox.
  • 30. Louis Pasteur [1822-1895]: Father of Microbiology • Trained chemist from France • Established that Fermentation caused by microbial agents was • Demonstrated anaerobic fermentation by both bacteria and yeasts (bacteria produce acid and yeast produce alcohol) • Developed pasteurization to prevent spoilage of wine by bacteria • Noted that different types of fermentations were associated with different kinds of microbes • Development of methods and techniques of Bacteriology • proved that microbes arise only from their like
  • 31. • Introduction of sterilization techniques: development of steam sterilizer, autoclave and hot-air oven • Studies on Anthrax, Cholera and hydrophobia • Introduced live attenuated (weakened) vaccines [Accidental observation: chicken cholera bacillus cultures left for several weeks lost their pathogenicity but retained their ability to protect the chickens from infection] Chicken inoculated Pure culture of chicken Cholera bacteria 8 weeks old Remains Healthy
  • 32. After several weeks… Chicken previously inoculated Fresh virulent culture of chicken Cholera bacteria Chicken which is not previously inoculated Remained Healthy Died
  • 33. • Then he attenuated anthrax bacillus by incubation at high temperatures (42 C-43 C) and proved that inoculation of such bacilli in animals introduced protection against anthrax • He coined preparations. the term ‘Vaccine’ for such prophylactic • While working on rabies, he could not isolate any microorganism from dog and man but suggested that causative agent of rabies was too small to be seen by microscope.
  • 34. Spontaneous generation versus Biogenesis • Aristotle (384-322 BC) proposed that animals might originate spontaneously from soil, plants or other unlike animals. • His influence was strongly felt even in the 17th century • In 1668, Francesco Redi disproved such generation of organisms from non-living things
  • 35. John Needham (1745): heated Nutrient Fluids and poured them into flasks and covered with corks → fluid turned turbid showing presence of microorganisms. Spallanzani (1765): Similar to Needham’s Experiments Boiled the beef broth for hour and then immediately sealed flasks No growth was observed in the broth Louis Pasteur (1861) • finally disproved spontaneous generation after many years of debate • Boiled broth in swan-necked flasks
  • 37. Joseph Lister [1827-1912]: Father of Antiseptic surgery • Professor of surgery • Applied Pasteur’s work and introduced Antiseptic techniques in Surgery • Use of Carbolic acid in Antiseptic surgery • Resulted in drop in morbidity and mortality due to surgical sepsis
  • 38. Robert Koch [1843-1910]: Father of Bacteriology • Introduced methods for isolation of pure culture • use of solid media for isolation of bacteria • Staining techniques • discovered Anthrax bacillus (1876), Tubercle bacillus (1882) and cholera vibrios (1883)
  • 39. Koch’s postulates 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.
  • 41. Paul Ehrlich [1854-1915]: Father of Chemotherapy • Applied stains to cells and tissues for study of their functions. • Reported the tubercle bacillus acid-fast nature of • Discovered Salvarsan (derivative of arsenic) sometimes called as ‘Magic Bullete’ • Salvarsan: capable spirochetes of syphilis. of destroying • Gave rise to new branch of medicine: ‘Chemotherapy’
  • 42. • In 1892, Ivanovsky removed the bacteria from diseased tobacco plant extract using some filters. • This extract was responsible for producing tobacco mosaic disease in healthy plant • Beijerinck (1898) confirmed these findings and coined the term ‘Virus’ for such filterable infectious agents. • Loeffler & Frosch (1898): Foot and mouth disease of cattle caused by similar filter-passing viruses. • Landsteiner & Popper (1909): Virus responsible for Poliomyelitis • Ruska (1934): introduced Electron microscope
  • 43. Alexander Fleming [1928]: • Discovery of 1st Antibiotic • Accidentally discovered Penicillin produced by a fungus Penicillium • Left his Staphylococcus culture on an agar plate for 2 weeks → went on vacation → came back & found mold on his plate which prevented bacterial growth
  • 45. Elie Metchnikoff: • Described how Leukocytes ingest disease producing bacteria in the body • Called such cells ‘Phagocytes’ & the process ‘Phagocytosis’ • Suggested that Phagocytes are the body’s 1st & most important line of defense against infection.