Intro to Microbiology
A Brief History of Microbiology
The Microbes of Microbiology
Updated 1/2011
What is Microbiology?
Why should we study
Microbiology?
Why should we study Micro?
Help protect us from
pathogens by taking up
space and activating
our immune system.
Make us healthy by
producing vitamins.
Can be
used to
produce
food,
medicines,
and more.
Microbes form the base
10X more bacteria Help
of the food chain.
than our own cells plants
http://www.tutorvista.com/science/pictures-of-food-webs
absorb
nutrients
and grow
faster
http://www.cof.orst.edu/cof/teach/for442/cinfof.htm
Conclusion:
Understanding microbes is
vital for other study of life!
Advances in microbiology have
followed advances in technology
And vice-versa…
The Early Years of Microbiology
Anton van Leeuwenhoek (Dutch)
Began making and looking through
simple microscopes
 Examined water, semen, teeth
scrapings ~1683

 Visualized
tiny animals, fungi, algae,
and single celled protozoa;
“animalcules”
By end of 19th century, these
organisms were called
microorganisms
http://www.history-of-the-microscope.org/anton-van-leeuwenhoek-microscope-history.php
The Golden Age of Microbiology
Scientists searched for answers to four
questions
Is spontaneous generation of microbial life
possible?
 What causes fermentation?
 What causes disease?
 How can we prevent infection and disease?

Is Spontaneous Generation of
Microbial Life Possible?
Aristotle proposed spontaneous generation
living things can arise from nonliving matter
 Explained many observations

Theory came under challenge in 17th
century
Redi’s Experiments (late 1600s)
 Needham’s Experiments (mid 1700s)
 Spallanzani’s Experiments (1799)
 Pasteur’s Experiments (mid 1800s)

Redi’s
Experiments
Meat exposed to
flies developed
maggots, when
meat is kept isolated maggots do not develop

Conclusion: Animals only come from other animals.
After Leeuwenhoek discovered microbes scientists
assumed that microbes arose spontaneously


Thought they were too small/simplistic to reproduce
Incorrect conclusions misled scientists.
The Scientific Method
Debate over spontaneous generation led in part to
development of scientific method




Observations lead a scientist to ask questions about
some phenomenon
The scientist generates hypothesis (potential answer to
question)
The scientist designs and conducts experiment to test
hypothesis
Based on observed results of experiment, scientist either
accepts, rejects, or modifies hypothesis
Louis Pasteur
Performed a similar
experiment to Spallanzani
Instead of completely sealing his flasks he bent
the necks which allowed air to enter but
prevents contamination
 Flasks remained pure until they were exposed to
dust

 Conclusion:
Microbes in the flask are the progeny of
microbes on the dust
Pasteur also researched
Fermentation and Infection
Cell Theory
Pasteur’s evidence and conclusions led to the
cell theory.
The cell is the fundamental unit of Life.
 All organisms are made of cells.
 All cells come from previously existing cells.

What Causes Disease?
Pasteur developed germ theory of disease

Microbes are responsible for disease
Robert Koch studied causative agents of
disease
Anthrax
 Examined colonies
of microorganisms
 Developed
Koch’s Postulates

Koch’s Postulates
1. Suspected causative agent must be
found in every case of the disease and
be absent from healthy hosts(a)
2. Agent must be isolated and grown
outside the host(b).
3. When agent is introduced into a
healthy(c), susceptible host, the host
must get the disease(d).
4. Same agent must be re-isolated from
diseased experimental host(e,f)
http://media.wiley.com/Lux/26/8326.nfg002.jpg
Laboratory Microbiology Advances
by Koch and Others
Simple staining techniques
First photomicrograph of bacteria
First photomicrograph of bacteria in diseased tissue
Techniques for estimating CFU/ml
Use of steam to sterilize media
Use of Petri dishes
Aseptic techniques
Bacteria as distinct species
How Can We Prevent Infection
and Disease?
Semmelweis and handwashing
Lister’s antiseptic technique
Nightingale and nursing
Snow and epidemiology – infection control
and epidemiology
Jenner’s vaccine – field of immunology
Ehrlich’s “magic bullets” – field of
chemotherapy
The Modern Age
of Microbiology
What are the basic chemical reactions of life?

Biochemistry
How do genes work?

Microbial genetics, Molecular biology, Recombinant DNA
technology, Gene therapy
What role do microorganisms play in the
environment?

Environmental microbiology
How do we defend against disease?

Serology, Immunology, Chemotherapy
Meet the Microbes!
Microorganisms we will study:

Fungi, Protozoa, Algae, Bacteria, Archaea,
certain Animals
Non-living particles are also included:

Viruses, virons, prions
No plants!
Fungi
Eukaryotic (have membrane-bound nucleus)
Obtain food from other organisms
Possess cell walls of chitin
Examples:
Molds – multicellular; have hyphae; reproduce by
sexual and asexual spores
 Yeasts – unicellular; reproduce asexually by
budding; some produce sexual spores
 [Mushrooms – not discussed in Microbiology]

Protozoa (Protist)
Single-celled eukaryotes
Similar to animals in their
nutritional needs and
cellular structure
Most reproduce asexually;
some sexually
Sometimes classified by
type of movement
Pseudopods
Cilia
Flagella
Algae (Protist)
Unicellular or
multicellular
Photosynthetic
Categorized by:
Pigmentation
 storage products
 cell wall composition

Bacteria and Archaea
Unicellular and lack nuclei
Much smaller than eukaryotes
Found everywhere there is sufficient
moisture; some found in extreme
environments

Use every type of metabolism
Reproduce asexually
Two Groups of
Prokaryotes
Bacteria


Cell walls contain peptidoglycan
(some lack cell walls)
most do not cause disease and
some are beneficial
Archaea


cell walls composed of polymers
other than peptidoglycan
Some live in extreme
environments, none identified
that cause disease
Methanopyrus kandleri Copyright K.O.Stetter and
R.Rachel, Univ. Regensburg, Germany
Other Microbes of Importance
Animals


Eukaryotic, multicellular,
heterotrophs
Parasites or vectors for other
diseases
Viruses


Non-cellular infectious
particles
DNA or RNA in a protein
coat
http://health.enotes.com/images/neurolo
gical-disorders/gend_02_img0088.jpg
Viroids


Smaller than viruses
RNA without protein or
protein genes
Prions

Infectious proteins
http://universe-review.ca/I11-45-viroid.jpg