Lecture 1 – An Overview of Microbiology
Introduction to Microbiology
- Microbiology is the study of microorganisms (or microbes)
- Microbes are microscopic
o Through most of their lifespan
o Can only be seen through a microscope
o Less than about 1 mm across
o About 10 M to 10 M in size
- Six major groups of microbes
- In 1990, infectious diseases were the biggest killer
- In 2004, lower respiratory infections are in the top 10 but mostly in elderly due to
improvements in public health
- Discovery of microbes
o Hooke observes small eukaryotes (1600)
o Leeuwenhoek discovers bacteria (1676)
Developed lenses to look at fibers of the cloth
Developed powerful lenses to look at bacteria
- Microbes are living organisms
o Microbes arise only from other microbes
No spontaneous generation
o Redi shows that flies do not spontaneously generate (1688)
o Pasteur shows that microbes do not grow in liquid until introduced from outside
Long curved neck doesn’t allow bacteria to fall inside
Broken neck allows bacteria to fall inside and grow in medium
Discovered the germ theory of disease
- Germ theory of disease
Germs can infect and grow on food
Can germs infect and grow on people?
Do germs cause disease?
o Hypothesis is testable
Are germs found in infected tissue?
Can transmission of germs cause disease?
o Pasteur’s Theory
Transmission of germs cause disease o Scientific Theories
Explain many known observations
Provide framework for understanding
Can be tested further
- Koch’s postulates
o Provides means of testing hypothesis
Does this germ cause that disease?
o Organisms must meet criteria