Download Lecture Objectives: Why study microbiology? What is microbiology

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Lecture Objectives:
Why study microbiology?
What is microbiology?
Roots of microbiology
Why study microbiology?
ENVIRONMENTAL
MEDICAL
APPLIED SCIENCE
BASIC SCIENCE
The science of microbiology
Microbiology can be highly interdisciplinary
Molecular Bio
Physiology
Genetics
Biochem.
Microbiology
Geology
Ecology
Chemistry
Engineering
Computer Sci.
What is Microbiology
• Study of life too small to be seen
unaided by eye
! Need a microscope to see
them
<0.1 mm too small to see
•Using techniques of microbiology
!Isolate microorganisms
!Study their characteristics
Where to find microbes?
Ex. 1. In nature:
Where to find microbe?
Ex. 2. In your intestines:
Characteristics of a living organism
All living organisms are composed of one or
more cells—the cell theory of life.
Viruses are not cellular, and are not
considered to be living organisms. They are
still considered a microorganism.
Characteristics of life
Cell: The fundamental unit of living organisms with
characteristic functions and structures.
Cell functions:
1. Metabolism—biochemical reactions catalyzed by
enzymes
2. Reproduction
Characteristics of life
3. Differentiate
! Formation of a spore; part of cell life cycle.
4. Communicate
! Or interact by means of chemicals released or taken
up
Characteristics of life
5. Movement
! Living organisms are often capable of self-propulsion
6. Evolve
! Cells evolve to display different or new biological
properties.
Characteristics of life
Cells have structures:
• Cytoplasm—aqueous fluid containing
enzymes, organelles, chemicals
• Nuclear area with DNA
• Cell membrane (plasma membrane)—
boundary between cell and environment
Classifying life
Three domains of organisms are now
recognized:
• Bacteria – numerous and diverse
• Archaea – many live in extreme environments
• Eukarya – fungi, algae, protozoa, plants,
animals
Figure 1.6 Tree of Life
Prokaryotes
Figure 1.7 Drawings of representative microorganisms, as they appear by light microscopy
Classifying life: Eukaryotes
• We are eukaryotes
• Some are big some are small.
• Hallmarks of eukaryotes:
! Nuclei
! Membrane bound organelles
• Some microbial eukaryotes:
! Yeast
! Fungi
! Protozoa
! Diatoms
Classifying life: Archaea
• Archaea are microorganisms
• No nuclei
• Different than bacteria
! To be discussed later.
• Often live in extreme
environments
• Mostly non-pathogenic
methanoarchaea
Classifying life: Bacteria
• Bacteria are microorganisms
• Most are harmless
• No nucleus
• Pathogenic:
! Escherichia coli (E. coli)
! Streptococcus (strep throat)
! Yersinia pestis (plague)
! Salmonella (food poison)
• Non-pathogenic:
! Thermus aquaticus (PCR)
! Lactobacillus (dairy products)
! Nitrosomonas (fish aquariums)
Nitrifying bacteria
Let’s define a “microorganism”
• Microorganism:
! Can be eukaryotic, archaeal, or
bacterial.
• Prokaryotes:
! Lack membrane-bound nucleus
! Self replicate
• We will focus is on the Prokaryotes
! Bacteria and Archaea
virus
prokaryote
Nucleus
2 !m
History of microbiology
• Infectious diseases, population control, and
antiquity.
! Cholera, syphilis, casualties of war, trade.
• Black Death
! 1331
History of microbiology
• How did people figure out that
there were microbes?
• Major break through was when
people could see
microorganisms.
• Antony van Leeuwenhoek (16321723)
! Built the first solar light
microscope in 1676.
! Magnification 300X
Antony van Leeuwenhoek
• “Average” guy with extreme
curiosity.
• Excellent eye-sight
• Key player in advancing the
field of microbiology
• He saw the unseen for the
first time! E.g.:
! Corpuscle
! Bacteria
! Spermatozoa
! Algae
• He reported his observations
too. In sometimes painful
details.
Antony van Leeuwenhoek
• First observation of
growing microorganisms.
• Also anaerobic growth
• Experimented with pepper
water in open and sealed
glass tubes.
• Used is microscope to
make is observations.
http://www.microscopy-uk.org.uk
Microbes and disease
• Greek physician Galen said
disease was caused by
imbalance of 4 humours:
!
!
!
!
• Pasteur and Sterilization.
Blood
Phlegm
Yellow bile
Black bile
• Fracastoro: 1478-1553 (Italy)
! Wrote about spread of disease
! Proposed epidemics were
spread by tiny “spores”.
• During the mid 1800’s there
were hints that a transferable
or infectious agent caused
disease.
• Along came Robert Koch
! Showed, without a doubt,
that anthrax was caused
by a bacterium.
www.encyclopedia.com
John Snow and epidemiology
• British epidemiologist around 1850
• Proposed that cholera might come from
water
• Used surveys and maps
• Linked the disease to sewage in water
• Therefore cholera must have come from
sewage.
• Still couldn’t prove that is was a caused
by a microorganism!
Robert Koch--from modest doctor to pioneering microbiologists
• He was the first to prove that a microbe caused disease.
• In the blood of animals dying of anthrax there was always one type
of bacterium: Bacillus anthracis
• But, did these bacteria cause the disease? Or did something else
cause the disease and then this bacterium came along; take
advantage of the weakened animal; and grow?
• Supplemental Reading on Web Page from Microbe Hunters
Koch’s Postulates
Koch’s Postulates: Defined
1. The suspected pathogenic organism should be
present in all cases of the disease and absent from
healthy animals
2. the suspected organism should be grown in pure
culture
3. Cells from a pure culture of the suspected organism
should cause disease in a healthy animal
4. The organism should be re-isolated and shown to be
the same as the original.
Koch’s Postulates: Part II
1. Blood of diseased animal.
2. Injected into healthy animal
3. Found same bacterium in
the blood
4. Repeat
5. What’s the problem:
• How do you know
disease comes from one
bacterium?
• 109 cells/ml.
• Is there only 1 type in
there?
• How do we address this
problem?
• We need a way to separate
individual bacteria.
• Then we need to culture the
isolate and then repeat
postulate #3.
• Solution:
! Dilute sample to one cell
! Use Koch’s method for
isolating individual bacteria
! The streak plate
• This was another major
advancement in the field of
microbiology
The Streak Plate
• Need a solid surface to keep bacteria from
moving away.
! Agar, petri dish
• Means of separating cells.
! Sterile stick or metal loop
• Sterilization method
! Heat
Once all these techniques were developed, Koch went
on to isolate the bacteria that caused Anthrax,
Tuberculosis, and Cholera. He received the 1905 Nobel
Prize for the Tb work
Study Questions:
1.
Why was the microscope key to microbiology?
2.
What are the 6 characteristics of living cells? Which characteristics are
universal?
3.
Which of the 3 Domains contain microorganisms? How do
microorganisms within these domains differ and how are they the
same?
4.
What are Koch's postulates and how are they used?
5.
What is pure culture, and why is so important for microbiology? What
would be different if Koch didn't start with a pure culture?
6.
How did solid media help with obtaining pure cultures?
7.
What is sterile technique, and why is it important? In other words,
what would happen if sterile techniques weren't used?