This document provides an overview of the history and relevance of microbiology. It discusses how microbiology is the study of microorganisms that cannot be seen with the naked eye. It outlines the diversity of microorganisms and their ubiquitous nature. The document also describes the development of the field from early theories of disease to the acceptance of germ theory in the late 19th century. This included the development of tools like microscopes and experiments that disproved spontaneous generation. The impact of microorganisms on human health and ecosystems is also summarized.

1. Relevance and History of
Microbiology
General Microbiology
BIO 211
Dr. Miller

2. Objectives
Introduction to Microbiology
• Learn the scope and range of microbiology study
(ubiquity and diversity)
• Describe broad taxonomic classifications of
microorganisms
• Understand the importance of microorganisms
and the effect they have on human populations
• Describe the advent of the microbiology field
from a historical perspective

3. What is microbiology?
1. Micro: too small to be seen with the naked
eye
2. Bio: life
3. Logy: study of
In general microbiology is the study of
microorganisms

4. Microorganisms are DIVERSE!!!
• Microorganisms are found across every
taxonomic group
– Bacteria (Bacteria and Archaea)
– Fungi (Fungi/Myceteae)
– Protozoa (Protista)
– Algae (Protista)
– Parasites (Animalia)
– Viruses ( ? )

5. System of Classification
• Five Kingdom system
http://www.davidlnelson.md/Cazadero/C
azImages/FiveKingdoms%20Animals2.jpg

6. System of Classification
• Three Domain System

7. System of Classification
• Six Kingdom System

8. System of Classification
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Humans E. coli (6 Kingdom)
Eukarya Bacteria/Eubacteria
Animalia Bacteria/Eubacteria
Chordata Proteobacteria
Mammalia Gama Proteobacteria
Primates Enterobacteriales
Hominidae Enterobacteriaceae
Homo Escherichia
H. sapiens E. coli

9. Microorganisms are UBIQUITIOUS!!!
• Microorganisms are found nearly everywhere
– On/in bodies
– On surfaces
– In the air
– In water
– In extreme environments: deep sea thermal
vents, polar ice caps, sulfur and salty lakes

10. Microorganisms are IMPORTANT!!!
(positive)
1. Nutrient production and energy flow
– Engage in photosynthesis
– Produce oxygen
– Food chain
2. Decomposition and nutrient recycling
– Recycle chemical elements and direct them back to natural
cycles of living organisms.
3. Biotechnology/Genetic Engineering
– Can be manipulated to produce proteins for our use (i.e.
insulin, human growth hormone)
– Used as a genetic model organism
4. Bioremediation
– Used to restore stability or clean up pollutants

11. Microorganisms are IMPORTANT!!!
(negative)
Impact on Human Health
• Only 1% of known bacteria cause human disease
• Annual world wide death toll from infections is 12
million people
– 3 million from malaria alone

12. Worldwide Infectious Disease

13. • Notice how many deaths are caused by microorganisms
• Notice the difference between the US and worldwide
Today we understand the impact microorganisms have on our
life. Historically their importance was not recognized!

14. Historical Perspective
• 400 B.C. Hippocrates
– Medicine is distinct from theology and philosophy
– Set forth ethical standards for the practice of medicine
• 100 B.C. Roman scholars
– Proposed that tiny animals entered the mouth and nose
to cause disease
• Disease, infection, and death was recognized as
contagious and perhaps even caused by “minute
bodies” or “foul foreign earthly bodies” however, their
study was inhibited due to a lack of scientific tools.
– 542-1650 A.D. The Black Death (bubonic plague) killed 10s
of millions of people in the Mediterranean and Europe.
Jewish population less affected due to Hebrew sanitation
laws

15. Spontaneous Generation
• Existed ~300B.C. through the mid 1800s
• Theory that microorganisms arose from non-
living things (seeing is believing)
– Maggots from dead meat
– Bacteria from old broth
• As long as people believed that living could
arise from non-living there was no need to
understand how diseases were transmitted
and controlled!!!

16. Beginning of Microbiology
• Scientists (and others) began to change
traditional ideas about disease and
microorganisms in the mid 1600s
1. Tools
• Anton van Leeuwenhoek (Dutch merchant): 1670s. 1st
lenses and later the 1st to examine/document living
microorganisms
• Robert Hooke (English scientist): Used a compound
microscope . Coined the term cell.
2. New hypothesis (theory): Germ Theory of Disease
• Microorganisms can invade other organisms and cause
disease
• Met with lots of resistance from the scientific community
(previous theory lasted for 2100 years)

17. Germ Theory of Disease
Proponents
• Francesco Redi (Italian physician): 1688
http://biology.clc.uc.edu/graphics/bio104/redi.jpg
http://www.rmutphysics.com/CHARUD/scibook/bio
2/chapter6/image/spallanzani-experiment.jpg
• John Needham
(English priest): 1748
• Lazzaro Spallanzani
(Italian priest): 1760s
• Challenges spontaneous generation
• Tested decaying meat’s ability to produce
maggots
• Challenges spontaneous generation
• Boiled broth and sealed it

18. Germ Theory of Disease
Proponents
• Ignaz Philipp Semmelweis (Austrian
physician): 1847
– Introduced hand washing practices
– Childbed fever
• (decrease the mortality rate from 35% to 1%)
– Largely ignored during his lifetime
• Joseph Lister (English surgeon): 1867
– Introduced phenol as a disinfectant
– Decrease post-operative infections

19. Germ Theory of Disease
Proponents-The Final Blow
http://3.bp.blogspot.com/_wYOqE4H4V6U/Rdo8-
Y1pj8I/AAAAAAAAACQ/hsehi4O0DV0/s200/1_6.gif
• John Tyndall (English
physicist): 1860s
• Louis Pasteur (French
chemist): 1861
• Swan neck flasks
• Placed sealed flasks of boiled infusions in
an airtight box. After the dust settled
he removed the covers from the flasks.
The flasks remained sterile.
First evidence against spontaneous
generation was in 1688. Wasn’t
finally accepted by the scientific
community until 1861.

20. Other Significant Events in
Microbiology History
• 1796: Edward Jenner introduces cowpox
vaccination for smallpox
• 1838 & 1839: Schwann and Schleiden
propose cell theory
– Plants and animals are made up of cells
– These cells are essential to the structure and
function of organisms
• 1884: Hans Christian Gram develops the
Gram stain technique

21. Other Significant Events in
Microbiology History
1876: Identifies Bacillus
anthracis as the causative agent
of anthrax
1882: Identifies
Mycobacterium tuberculosis as
the causative agent of
tuberculosis
1884: Develops Koch’s
postulates. Still used today in
identifying causative agents of
disease
1857: Developed pasteurization
1861: Refuted spontaneous
generation
1881: Developed anthrax vaccine
1885: Developed rabies vaccine
Louis Pasteur
Robert Koch

22. Other Significant Events in
Microbiology History
• 1903: Wright and others discover antibodies
• 1929: Alexander Fleming discovers the first antibiotic
(penicillin)
• 1953: Watson and Crick propose DNA double helix
• 1954: Jonas Salk develops polio vaccine
• 1976: First whole genome to be sequenced (RNA virus)
• 1979: Smallpox is officially declared eradicated
• 1983: HIV is isolated and identified
• 1990: First human gene therapy
• 1995: First bacterial genome is sequenced
• 2002: Infectious poliovirus is made from basic chemicals
SIGNIFICANT findings are still being made today!

23. Conclusions
• Microorganisms span all taxonomic kingdoms
• Microorganisms can be found everywhere
• Microorganisms have vast impact on the environment,
the ecosystem, and human life (give examples)
• Our current understanding of microbiology is the result
of the work of thousands of microbiologists over
hundreds of years
• The advent of the microscope is what really began the
study of microbiology
• The Golden Era of Microbiology resulted in huge
advancements in this field
• Great achievements are still being reached today

24. Suggested Reading
• Chapter 4: Prokarytoic cells