Transcript Introduction and Historical landmarks in the development of

 Microbiology is a science that deals with the
study of living organisms and agents that are too
small to be seen clearly by the naked eye.
 Greek – ‘Mikros’ means small, ‘Bios‘ means life
and ‘Logos’ means science.
Development of Microscope
 In
1590, Zacharias Janssen, developed a
prototype of the present day telescope and the
compound microscope.
 Galileo also constructed a microscope
 Anton Van Leeuwenhoek (1632 – 1723)
 constructed simple microscope
 could magnify up to 300 times
 His descriptions of animalcules were made from
1673.
 Robert Hooke (1665) compound microscope
Robert Hooke’s compound microscope
Theory of Spontaneous
generation
 Italian physician Francesco Redi disproved this
theory in 1688 (Maggots over meat)
 Italian Priest and naturalist Lazzaro Spallanzani
(1729 – 1799) (Microbes not found in heated
broth)
 Louis Pasteur (1822 – 1895), a French Chemist
 John Tyndall (1820 – 1893) , English Physicist.
 swan-neck-flask experiment of Louis Pasteur in
1861 conclusively disproved the theory of
spontaneous generation
Francesco Reddi
Spallanzani ‘s work
 Spallanzani put broth into four flasks
 Flask 1 was left open - Microbes found
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Flask 2 was sealed
- Microbes found
 Flask 3 was boiled and then left open -Microbes found
 Flask 4 was boiled and then sealed- Microbes not
found
Pasteur’s Swan neck flask
Germ theory of Disease
 Agostino Bassi, in 1835 was the first
demonstrate that microorganism cause disease
 1867,
Joseph Lister, introduced antibiotic
principles
 carbolic acid as antiseptic
 Robert Koch - His criteria for providing casual
relationship between a microorganism and a
specific disease are known as Koch’s
postulates
Koch’s postulates
• The microorganism must be present in very case
of the disease but absent from healthy host
• The suspected microorganism must be isolated
and grown in a pure culture
• The same disease must result when the isolated
microorganism is inoculated into a healthy host
• The same microorganism must be isolated again
from the experimentally diseased host
Other contributions of Koch
• Robert Koch also developed techniques to grow
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bacteria on solid media
On sterile surfaces of cut, boiled potatoes
Gelatin to solidify liquid medium
Fannie Eilshemius Hesse suggested the use of agar
as a solidifying agent
Agar is not digested by most bacteria
Agar remains solid until temperature reaches above
98oC and medium solidifies at around 44oC
Richard Petri developed the Petridish for cultivation
of bacteria
Robert Koch
• Vaccination
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was successfully used against
smallpox by Edward Jenner
Elie Metchnikoff discovered some blood
leucocytes that could engulf disease causing
bacteria
Phagocytes, phagocytosis
Winogradsky, Beijerinck ecological role of
microorganisms role of microorganisms in
carbon, nitrogen and sulfur cycles
enrichment – culture technique
Other significant developments in
microbiology
• 1796 – Edward Jenner – Vaccination – Smallpox
• 1873 – John Lister - obtained pure culture of
bacteria by serial dilution
• 1881 – Paul Ehrlich - Staining of bacteria with
methylene blue
• 1881 – 1883 – Robert Koch – Simple methods
for isolation and maintenance of microorganisms
on chemically defined solid medium
• 1884 – Hans Christian Gram – differential
staining
 1884 – Elie Metchnikoff – Phagocytosis – WBC
engulfing foreign particles
 1884 – Charle Chamberland – Invention of
bacterial filters for sterilization of liquids.
Invention of autoclave
 1892 – Iwanowski – observed filterable particles
(virus)
 1929 – Alexander Fleming – Antibiotics penicillin
 1860 to 1910 - Golden Age of Microbiology.
Grouping and Description of
living organisms
 Prokaryotic cells
 lack a true membrane – delimited nucleus; All
bacteria
 Eukaryotic cells
 Cells that have a membrane enclosed nucleus
Description of Microorganisms
 Bacteria
 prokaryotes, unicellular organisms binary fission.
Size 0.1 µ m to 18 µ m
 Viruses
 infectious agents having a simple organization
protein coat single type nucleic acid (either RNA /
DNA), Size ranges from 20 to 350 nm
 Fungi
 eukaryotic, spore-bearing organisms absorptive
nutrition
 Algae
 Algae are eukaryotic lack roots and leaves have
chlorophyll
 Protozoa
 eucaryotic protist, not multicellular
Classification of Living
organisms
 All organisms were earlier classified into two
groups
 Plants and animals
 third kingdom called Protista, Haeckel (1866)
consisting of unicellular organisms
 Copeland (1956) created a fourth kingdom
Monera, unicellular prokaryotic bacteria
 fifth kingdom Mycetae created by Whittaker
(1969) accommodate fungi
 Robert H. Whittaker in 1969, placed organisms
into five kingdom based on three major criteria
 Cell type (Procaryotic / Eucaryotic)
 Level of organization (Solitary / colonial; Uni or
multicellular)
 Nutritional type
Kingdom : Monera or Procaryote
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All procaryotes
Kingdom : Protista
 Unicellular or colonical eucaryotic organisms that lack
Protozoa, lower fungi and smaller algae
Kingdom : Fungi
Kingdom : Animalia
 Multicellular animals with ingestive nutrition
Kingdom : Plantae
 Multicellular plants with walled eucaryotic cells and
photosynthesis
Cavalier – Smith’s classification
• Empire : Bacteria
• Kingdom – Eubacteria
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Arahaebacteria
• Empire : Eucaryota
• Kingdom - Archaozoa
Protozoa
Chromista
Plantae
Fungi
Animalia
 Carl Woese comparison of RNA sequences,
developed a three domain or empire
classification
 Eubacteria, Archaebacteria, Eucaryotes, which
are placed above kingdom level.
 bacterial classification on the basis of similarities
 Bergey’s Manual of Systematic Bacteriology
(1984)
 prokaryotes
are grouped on basis of
characteristics Gram stain, morphology motility,
structural features distinguishing physiological
features
 Nowadays organisms are grouped on a genetic
basis nucleotide sequences of the small subunit
ribosomal RNA (rRNA)
 C. Woese developed the phylogenetic tree of
prokaryotes
 16S rRNA of 30S ribosomes
conserved sequences
yield highly