Transcript Main Themes in Microbiology

Main Themes in
Microbiology
Chapter 1
Humans are
outnumbered
• We have ~ 10 trillion cells in our
body
– We have 100 trillion foreign cells
in/on our body!!
– Tiny life forms are called
microorganisms
What is a
microorganism?
• Could be…
– Bacteria
– Viruses
– Protists
• Protozoa and algae
– Helminthes
• Worms
What is microbiology?
• Microbiology is a special area of
biology that deals with tiny life
forms not readily observed
without magnification
– Little guys are called:
• Microorganisms
• Microbes
• Germs
• Bugs
Can I do this for a
living?
• Geomicrobiologist- roles of
microbes in the development of
the earth’s crust
• Marine microbiologist- study the
oceans and its smallest
inhabitants
• Medical technologists- do tests
to diagnose pathogenic
microbes and their diseases
• Nurse epidemiologists- analyze
the occurrence of infectious
diseases in hospitals
• Astrobiologist- study the
possibility of organisms in
space
What do we focus on?
• Genetics
• Physiology
– Appearance and survival
•
•
•
•
+ and – characteristics
Environmental interaction
Host interaction
Uses in industry/agriculture
How long have these
guys been around?
• Practically forever!
– Life on Earth started 3.5 billion
years ago!
• Prokaryotes came first
• Then eukaryotes
Good or bad?
• Both!
• We’ve been using
microorganisms for thousands
of years!
Good Microbes
• Yeast (microscopic fungi) =
bread
• Penicillin (moldy bread) = first
aid
Biotechnology
• Industry applications
– Bacteria that can mine metals!
Genetic Engineering
• Manipulates genetics to make
new products and genetically
modified organisms
– Microbes can make drugs,
hormones, and enzymes
Bioremediation
• Fixing environmental problems
with microorganisms
Bad Microbes
• Pathogens- agents that cause
disease
– Over 2000 types of microbes that
cause disease!
– WHO says over 10 BILLION
infections caused by microbes
worldwide
Bad microbes
• Malaria
– Actually a microbe (protist)
Malaria Prevention
• Malaria nets
cost $3-5
• 1/3 world
population
makes <$1/day
• Which kid will
sleep under the
net tonight?
The subtle side of
microbes
Associated with
• Gastric ulcers
– Heliobacter
• Cancer
– HPV
– Hepatitis viruses
• Diabetes
– coxsackievirus
• schizophrenia
• MS
• OCD
• Coronary artery
disease
• Infertility
– Chlamydia
General Microbe
Characteristics
• TINY
• Millimeters (mm), micrometers
(µm), and nanometers (nm)
• Prokaryotic or eukaryotic
• 1 or a few cells
• Free-living—live independently
• Parasitic—microbes harbored
and nourished inside host
• Could be viruses
– NOT ALIVE
– NOT CELLS
– Small amount of hereditary
material wrapped up in a protein
coating
– “Obligate intracellular parasites”
* Viroids are smaller
viruses
Adenovirus
Rhinovirus
Rhinovirus
Where does life come
from?
• Meat makes maggots
• Shrooms spring from spruce
• Rats from rotting refuse
Spontaneous Generation
• The idea that life can arise from
non-living matter
– Aka abiogenesis
• Competing theory—biogenesis
– Life can only arise from living
things of a similar nature
•
How can we prove or disprove this
hypothesis?
Francesco Redi (1668)
Hypothesis: Flies produce maggots
on meat. Lay small eggs
Set up a controlled experiment to
test his hypothesis
Found that by keeping flies away
from meat, no maggots appear
Variables
1. Controlled variable:
Jar, meat, location, temperature, time
2. Independent or Manipulative variable:
Gauze covering the meat jars
3. Dependant (responding) variable:
Whether maggots appear
John Needham – 1745
Hypothesis: spontaneous generation
occurs under the right conditions
– Boiled chicken broth and then sealed
flask (thought heat would kill)
– “Animalcules” swarmed after a few days
– Therefore, he felt his hypothesis was
right.
What was wrong with
Needham’s hypothesis? Was
it flawed?
He assumed all the animalcules
would be killed by heat
Louis Jablot
• Hypothesis: even microscopic
organisms must have parents
• Boiled hay infusions very similar
to Needham’s work
• However, his uncovered WAS
contaminated with growth
Lazzaro Spallanzani
• 1776
• Attempted to disprove
Needham’s work.
• Took 4 flasks with broth in them
–
–
–
–
Left open – went cloudy
Sealed but not boiled – went cloudy
Boiled but left open – went cloudy
Sealed then boiled – stayed clear
• Microbes were not found in this
one but in all the other ones
What would have been
Spallanzani’s hypothesis?
Microorganisms form not from air
but from other microorganisms.
When broth was boiled and then
sealed, no air could get in for
organisms to reproduce.
What was wrong with what
Spallanzani assumed?
No air
Louis Pasteur - 1859
Tested Spallanzani’s work by using a
curved neck flask to prevent microbes
from entering flask but would let air in
Microbes collecting in bend
Boiled broth of control and experimental
flasks.
Result: No growth in curved neck flask.
Pasteur’s broth in the curved necked flask
stayed sterile for years until he tilted it and
the airflow carried the microbes into the broth
Conclusion
Contamination is due to microbes
in the air.
Spontaneous generation theory
died here!!
John Tyndall
Heated hay infusions for various times.
Found 2 kinds of bacteria –
1. Those readily killed by heating
2. Heat resistant forms (endospores)
**Between 1875 – 1918, most of the
disease-causing bacteria were
identified.
The Microscope
 Antonie von Leeuwenhoek
The Microscope
 Leeuwenhoek looked
at a drop of water and
saw moving things
 Called them
“animacules”

Bacteria and protozoa
The Pillar of Science: The scientific
method
 Origin in the 1600s…enough of the superstition!!
The Scientific Method
1.
Ask a question
Do some research
2.
3.
4.
5.
6.
7.
Propose a hypothesis
Conduct a controlled experiment
Collect data and make observations
Analyze data
Make a conclusion
Possibly, write a theory
Scientific method
• NEEDS a testable hypothesis
• Use the deductive approach
▫ If…then (because)
• Test, test, and retest that hypothesis!
Do you know where bees come from?
Recipe for Bees
1. Kill a bull during the first thaw of winter
2. Build a shed
3. Place the dead bull on branches and herbs
inside the shed
4. Wait for summer. The decaying body of the
bull produces bees
Words from a Roman poet about 2000 years ago
Know the jargon
 Hypothesis- tentative explanation for what has
been observed
 Theory- very well supported idea
 Many hypotheses and experiments
 NOT A “FACT
 Law- principle of science
 Super accurate
Germ theory of disease

Louis Pasteur
◦ Human diseases could
arise from infection

Robert Koch
◦ Koch’s Postulates
 Verified germ theory
 Showed anthrax caused
by bacterium
Aseptic Technique
Joseph Lister
 Goal: reduce microbes in a medical setting
and preventing wound infections

◦ No handwashing prior to surgery before
Lister!!
Taxonomy
 What’s in a name?
 Taxonomy- formal system for organizing,
classifying, and naming organisms
 Carl von Linnie
 Aka Carolus Linnaeus
 Standardized
 Keeps names short and consistent
 Binomial system of nomenclature
Binomial Nomenclature
•a two name system for writing scientific names.
•The genus name is written first (always Capitalized).
•The species name is written second (never capitalized).
•Both words are
italicized if typed or underlined if hand written.
Example:
Smith john (print)
Smith john (written)
Felis concolor or F. concolor
Which is the genus? The species?
The major classification levels,
from most general to most specific
(several of these have subdivisions)
A group at any level is a taxon.
Categories within Kingdoms
Kingdoms are divided into groups called phyla
Phyla are subdivided into classes
Classes are subdivided into orders
Orders are subdivided into families
Families are divided into genera
Genera contain closely related species
Species is unique
Phylogeny
 Natural relatedness of organisms
 Related by evolution—theory that all life descended,
with modification, from one common ancestor
Evidence
Morphology similar structures in organisms
Physiology similar functions of organisms
Genetics similar DNA in organisms
 Dumpy Kings Play Cards On Fat Green Stools
•Domain
•Kingdom
•Phylum
•Class
•Order
•Family
•Genus
•Species
Kingdoms and Domains
Originally, 2 kingdoms
Plantae and Animalia
Then 3 (Protista)
…and 4 (Add the Bacteria—
kingdom Monera)
…finally 5 (Fungi!)
5 kingdom system
Associated with Robert
Whittaker
Based on the morphology
and physiology-type of
evidence
The domain system
Now we look at molecular biology
How do DNA, proteins, rRNA
compare?
Bacteria Kingdom split into two:
 Domain Bacteria
 Domain Archaea
3 domain system
Domain eukarya—
 the eukaryotes
Domain archaea—
 prokaryotes that live in extreme
environments
Domain bacteria—
 “traditional” prokaryotes
 What is classification?
 Why is classifying living things
important?
 What is taxonomy?
 Describe binomial
nomenclature.
 Who developed a system for
naming living organisms?
 What is a scientific name of an
organism and how is it written?
 Kingdom
 Family
 Phylum
 Genus
 Class
 Species
 Order
 What are the seven classification
groups?
 Kings Play Cards On Fat Green
Stools