Chapter 1
The Microbial World and You
What are microorganisms?
Too small to be seen with the unaided eye
True cellular forms
Ubiquitous
Both helpful and problematic
Scope and Relevance of Microbiology
First living organisms on the planet
Live everywhere life is possible
Largest component of Earth's biomass
Ecosystems depends on their activities
Why study microbes?
Recycling vital elements
Bioremediation
Agriculture
Biotechnology/ Genetic engineering
Food microbiology
Industrial Microbiology
Normal microbiota
Disease causing microorganisms
Common Ancestor
Gave rise to 3 Domains
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Two prokaryotic
Bacteria and Archaea
One eukaryotic
Eukarya
Prokaryotes
Asexual; unicellular, no membrane bound organelles
Archaea
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Not known to be human pathogens
Usually found in extreme environments
Bacteria
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Some pathogenic
Multiple morphological and physiological differences
from archaea
Rod Shaped Bacteria
Round Archaea
Many Klebisella pneumoniae cells
Methanococcus janaschii, with
numerous flagella attached to one side
Eukaryotes
Unicellular or multicellular
Sexual and asexual reproduction
Multiple membranous organelles
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Algae
Unicellular or multicellular
Photosynthetic
High morphological diversity
Not pathogenic
Cymatopleura
Volvox
Macrocystis pyrifera
Gelidium pulchrum
Alexandrium tamarense
•Fungi
•Unicellular or multicellular
•Absorb nutrients from their environment
•Primarily opportunistic pathogens
Saccharomyces
cerevisiae
Rhizopus
Aspergillus
flavus
Amanita
muscaria
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Protozoa
Unicellular
Most are mobile
 Pseudopods, Flagella, Cilia
Absorb nutrients from environment or live as
parasites
Manyare pathogenic
Amoeba
Giardia lamblia
Paramecium
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Helminths
Multi-cellular animals
Flatworms and round worms
Many are pathogenic
Only some life stages
microscopic
Taenia taeniformis
Necator americanus
Viruses
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Obligatory intracellular
parasite
No true cellular organization
Living or non-living???
HIV virus on the surface of
a CD4+ cell
Bacteriophages
Size in the Microbial World
History of Microbiology
Robert Hooke -1665
Anton van Leeuwenhoek 1673
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"animalcules"
Schleiden and Schwann1838/39
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Cell theory
Spontaneous Generation
Franscesco Redi – 1668
John Needham – 1745
Lazzaro Spallanzani - 1765
Rudolf Virchow -1855
Louis Pasteur – 1861
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Aseptic techniques
Golden Age of
Microbiology
(1874 – 1914)
Support theories that invisible agents cause
disease
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Ignaz Semmelweis - 1840
Childbed fever
Joseph Lister - 1867
Aseptic surgery
John Tyndall
Microbes in dust, some heat resistant
Germ Theory of Disease
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Pasteur
Fermentation (1857) and pasteurization (1864)
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Robert Koch - 1876
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Walther Hesse – 1882
Vaccination
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Edward Jenner – 1798
Smallpox vaccine
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Louis Pasteur – 1880
Avirulence
Rabies vaccine
Chemotherapy
1908, Paul Ehrlich
Salvarsan – treatment for syphilis
1928, Alexander Fleming
Discovered properties of penicillin
1935-36, Gerhard Domagk & Ernest Fourneau
Development of sulfa drugs
1940, Selman Waksman
Isolated antibiotic from Streptomyces
1940, Howard Florey & Ernest Chain
Preformed clinical trials and mass produced
penicillin
Problems with modern chemotherapeutics
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Toxicity
Resistance
Lack of adequate anti- viral drugs
Infectious disease remains a threat

750 million cases each year in US
Emerging diseases
Factors associated with emerging disease
 Microbial evolution
 Changing human behavior/lifestyles
 Complacency of human population
 Population expansion/global travel