2. 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
3. MICROORGANISMS
They are very minute organisms that are
too small to be seen with the naked eye.
They are observed with the use of a
magnifying device called the microscope
“Germ” refers to a rapidly growing cell
4. How long have these guys
been around?
Practically forever!
Life on Earth started 3.5 billion years ago!
Prokaryotes came first
Then eukaryotes
5.
6. Origins of Microorganisms
• Bacteria-like organisms have existed on earth for about 3.5
billion years
• Prokaryotes (pre-nucleus): Simple cells
• Eukaryotes (true nucleus): Complex cells
7. 7
Characteristics of Microbes
• Two cell lines
– Prokaryote – microscopic, unicellular organisms,
lack nuclei and membrane-bound organelles
– Eukaryote – unicellular (microscopic) and
multicellular, nucleus and membrane-bound
organelles
• Viruses
– Acellular, parasitic particles composed of a
nucleic acid and protein
10. Lifestyles of Microorganisms
• Majority live a free existence, are relatively
harmless and often beneficial
• Many microorganisms have close associations
with other organisms
– Parasites
– Hosts
10
11. 11
Historical Foundations of Microbiology
• Thousands of microbiologists, 300 years
• Prominent discoveries include:
– Microscopy
– Scientific method
– Development of medical microbiology
– Microbiology techniques
12. 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
13. 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
14. 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
15. 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.
16. What was wrong with Needham’s
hypothesis? Was it flawed?
He assumed all the animalcules would be killed
by heat
17. 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
18.
19. 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
20. 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.
22. Louis Pasteur - 1859
Tested Spallanzani’s work by using a
curved neck flask to prevent microbes from entering
flask but would let air in
Boiled broth of control and experimental flasks.
Result: No growth in curved neck flask.
Microbes collecting in bend
23. 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
25. 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.
26. 26
Antonie van Leeuwenhoek (1632-1723)
• Dutch linen merchant
• First to observe living
microbes
• Single-lens magnified
up to 300X
Insert figure 1.8
28. Good or bad?
Both!
We’ve been using microorganisms for thousands of
years!
29. Good Microbes
Yeast (microscopic fungi) = bread
Penicillin (moldy bread) = first aid
30. Biotechnology and Bioremediation
• Biotechnology- when humans manipulate microorganisms
to make products in an industrial setting
– Genetic engineering- create new products and genetically
modified organisms (GMOs)
– Recombinant DNA technology- allows microbes to be
engineered to synthesize desirable proteins (i.e. drugs,
hormones, and enzymes)
• Bioremediation- introducing microbes in to the
environment to restore stability or clean up toxic pollutants
– Oil spills (recently seen with Gulf spill).
– Chemical spills
– Water and sewage treatment
32. Genetic Engineering
Manipulates genetics to make new products and
genetically modified organisms
Microbes can make drugs, hormones, and enzymes
38. 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
44. The Pillar of Science: The scientific
method
Origin in the 1600s…enough of the superstition!!
• Approach taken by scientists to explain a
certain natural phenomenon
45. The Scientific Method
1. Ask a question
Do some research
2. Propose a hypothesis
3. Conduct a controlled experiment
4. Collect data and make observations
5. Analyze data
6. Make a conclusion
7. Possibly, write a theory
46. The Development of Medical
Microbiology
• Early experiments led to the realization that
microbes are everywhere
• This discovery led to immediate applications
in medicine
– Germ theory of disease: resulted in the use of
sterile, aseptic, and pure culture techniques
46
47. 47
Louis Pasteur (1822-1895)
• Showed microbes caused
fermentation and spoilage
• Disproved spontaneous
generation of microorganisms
• Developed pasteurization
• Demonstrated what is now
known as Germ Theory of
Disease
Insert figure 1.11
48. 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
49. 49
Robert Koch (1843-1910)
• Established Koch’s
postulates - a sequence of
experimental steps that verified the
germ theory
• Identified cause of anthrax,
TB, and cholera
• Developed pure culture
methods
Insert figure 1.12
50.
51. 51
Discovery of Spores and Sterilization
• John Tyndall and Ferdinand Cohn each
demonstrated the presence of heat resistant
forms of some microbes.
– Cohn determined these forms to be heat-
resistant bacterial endospores.
• Sterility requires the elimination of all life
forms including endospores and viruses.
52. 52
Development of Aseptic Techniques
• The human body is a source of infection
– Dr. Oliver Wendell Holmes – observed that
mothers of home births had fewer infections
than those who gave birth in hospitals
– Dr. Ignaz Semmelweis – correlated infections
with physicians coming directly from autopsy
room to maternity ward
53. 53
• Joseph Lister – introduced aseptic
techniques reducing microbes in medical
settings and preventing wound infections
– Involved disinfection of hands using chemicals
prior to surgery
– Use of heat for sterilization
55. • Taxonomy: organizing, classifying, and naming
living things
– Formal system originated by Carl von Linné
Aka Carolus Linnaeus
• Concerned with:
– Classification – orderly arrangement of organisms into
groups
– Nomenclature – assigning names
– Identification – determining and recording traits of
organisms for placement into taxonomic schemes
55
56. •a two name systemfor writing scientificnames.
•The genus name is writtenfirst (always Capitalized).
•The species name is written second (never capitalized).
•Bothwords are
italicized if typedor underlined if hand written.
Example: Smith john (print)
Smith john (written)
Felisconcoloror F. concolor
Binomial Nomenclature
57. 57
Levels of Classification
• Domain - Archaea, Bacteria, & Eukarya
• Kingdom
• Phylum or Division
• Class
• Order
• Family
• Genus
• Species
58.
59. 59
The Origin and Evolution of
Microorganisms
• Phylogeny: natural relatedness between groups of
organisms
• Evolution
– All new species originate from preexisting species
– Closely related organism have similar features because they
evolved from common ancestral forms
• Evolution usually progresses toward greater
complexity
60. Phylogeny
Natural relatedness of organisms
Related by evolution—theory that all life descended,
with modification, from one common ancestor
64. Bacteria and Archaea
◦ Unicellular and lack nuclei
◦ Much smaller than
eukaryotes
◦ Found everywhere there is
sufficient moisture; some
found in extreme
environments
◦ Reproduce asexually
◦ Two kinds
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
65. Not independently living
cellular organisms
Much simpler than cells-
basically a small amount of
DNA or RNA wrapped in
protein and sometimes by a
lipid membrane
Individuals are called a
virus particle or virion
Depend on the infected
cell’s machinery to multiply
and disperse
66. Algae
◦ Unicellular or
multicellular
◦ Photosynthetic
◦ Simple reproductive
structures
◦ Categorized on the basis
of pigmentation, storage
products, and
composition of cell wall
67. Fungi
◦ Eukaryotic (have membrane-
bound nucleus)
◦ Obtain food from other
organisms
◦ Possess cell walls
◦ Composed of
Molds – multicellular; have
hyphae; reproduce by sexual
and asexual spores
Yeasts – unicellular;
reproduce asexually by
budding; some produce
sexual spores
68. Protozoa
◦ Single-celled eukaryotes
◦ Similar to animals in nutrient
needs and cellular structure
◦ Live freely in water; some live
in animal hosts
◦ Asexual (most) and sexual
reproduction
◦ Most are capable of
locomotion by
Pseudopodia – cell
extensions that flow in
direction of travel
Cilia – numerous, short,
hairlike protrusions that
propel organisms through
environment
Flagella – extensions of a
cell that are fewer, longer,
and more whiplike than
cilia
