I. Microorganism Diversity
A. Bacteria
1. Constitute a large domain of prokaryotic
microorganisms
2. Are unicellular, filamentous, or colonial
3. Typically they a few micrometers in length
4. They have a wide range of shapes, ranging
from rods, to spheres and spirals
5. Bacteria were among the first life forms to
appear on Earth, and are present in most
habitats on the planet
6. They have cell walls composed of
peptidoglycan
B. Archaea
1. In the past they were included as a type
of bacteria because they are similar in size
and shape
2. Are unicellular, filamentous, or colonial
3. Archaea were among the first life forms to
appear on Earth, and are present in most
habitats on the planet
4. Many members are “extreme” microorganisms
-hyperthermophiles
-extreme halophiles
-methanogens
5. They have cell walls that lack peptidoglycan
C. Fungi
1. Unicellular, filamentous and multicellular
2. Eukaryotic
-complex in structure
-membrane-bound nucleus
-membrane-bound organelles
3. Includes the molds, yeast, mushrooms
4. Cell wall composed of chitin
5. Reproduce by spores and budding
6. Nutrition by absorption
D. Algae
1. Unicellular, colonial, filamentous and multicellular
2. Composed of eukaryotic cells
3. Cell wall composed of cellulose
or silicon dioxide
4. Compose phytoplankton
5. Nutrition by photosynthesis
E. Protozoa
1. Unicellular
2. Composed of eukaryotic cells
3. Animal-like
4. No cell wall
5. Nutrition by ingestion
F. Helminths
1. Multcellular
2. Eukaryotic
3. Parasitic flatworms and roundworms
4. Nutrition by parasitism by feeding off
living hosts
G. Viruses
1. Acellular
2. Smaller than bacteria
3. Obligate intracellular parasites
4. Outside of the living cells, viruses cannot move, grow or reproduce
5. Inside the cell they can reproduce themselves
II. Classification
A. Binomial Nomenclature System
1. Carolus Linnaeus (1735) Father of Taxonomy
2. Based on a two name system: genus and species
3. Used worldwide
4. Used for Economy, Clarity, Uniqueness, Stability
5. Capitalize first letter in genus name; italicize both words
Micrococcus luteus: micro = small; coccus = spherical; luteus = yellow
Escherichia coli : Escherichia = Theodor Escherich; coli = colon
Staphylococcus aureus: staphylo = cluster; coccus = spherical; aureus = golden
B. Five Kingdom System- Robert H. Whitaker
1. Monera
2. Protista
3. Fungi
4. Plantae
5. Animalia
C. Three Domain System- Carl R. Woese
1. Bacteria
2. Archaea
3. Eukarya
D. Taxonomic Hierarchy
Taxonomic Ranking
1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species
Homo sapiens
Escherichia coli
Eukarya
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
sapiens
Bacteria
Proteobacteria
Enterobacteriales
Enterbacteriaceae
Escherichia
coli
III. The Discovery of Cells and Microorganisms
A. Robert Hooke 1665
1. Observed microorganisms for the first time with a microscope
2. Coined the term “cell”
B. Anton van Leeuwenhoek 1670’s
1. Microscope lens grinder who accidentally discovers microorganisms in a
drop of water
2. Using his own microscopes, he observed sperm cells, bacteria, and red
blood cells
IV. The Golden Age of Microbiology
A. Major Accomplishments
1. Louis Pasteur and Robert Koch both led the way
2. Significant developments- lasted from 1857 to 1914 (57 years)
-germ theory of disease established
-use of disinfectants introduced
-improved surgical techniques
-role of immunity established and vaccines to immunize against diseases
-microbiology culture techniques
B. Spontaneous Generation
Francesco Redi- maggots come from flies
C. Louis Pasteur- Microorganisms Come from Microorganisms- Biogenesis
1. Demonstrated that microorganisms are everywhere
2. Disproved spontaneous generation of microorganisms
Swan-necked Flask Experiment
D. Fermentation Discovered (1857)
1. Pasteur was asked by the wine and beer making
merchants to find out why the beverages were spoiling
2. Discovered that bacteria was contaminating vats of wine
and beer which ended up with sour-tasting acetic acid
(vinegar)
3. Discovered that yeast was responsible for fermentation
4. Developed the technique Pasteurization as a way to control
unwanted the bacteria
5. Linked food and beverage spoilage to microorganisms
6. Considered the Father of Microbiology
E. What Causes Disease?
1. The Germ Theory of Disease
-Pasteur was called upon by French merchants to determine
the cause of silkworm disease
-found that a protozoan was the cause of silkworm disease
-for the first time a microorganism was linked to a particular
disease
-this ushered in the germ theory of disease
2. Pasteur developed vaccines for cholera and rabies
3. His remarkable breakthroughs in the causes and
preventions of diseases
4. Edward Jenner was the first to develop a vaccine
against smallpox
3. Robert Koch
-became famous for isolating Bacillus anthracis; the pathogen that
causes antrax (1877); Mycobacterium tuberculosis, the tuberculosis
bacillus (1882); Vibrio cholerae (1883), the causative agent of cholera,
culture techniques, and for the development of Koch's postulates
-awarded the Nobel Prize in Physiology or Medicine for his
tuberculosis findings in 1905
-considered one of the founders, of microbiology, along with Louis
Pasteur
-he inspired major figures later to come such as Paul Ehrlich and
Gerhard Domagk
Koch’s Postulates
Isolate
Incubate
Infect healthy animal
Identify
4. Joseph Lister was the first to use disinfectants
-he studied the disinfectant, carbolic acid (phenol)
-carbolic acid had been in use as a means of deodorizing
sewage
-Lister sprayed carbolic acid on surgical instruments, surgical incisions
and on the dressings placed on wounds
-he found that carbolic acid solution swabbed on wounds reduced the
incidence of gangrene
-he suggested surgeons wear clean gloves and wash their hands before
and after surgery with 5% carbolic acid
F. Birth of Modern Chemotherapy: Dreams of a “Magic Bullet”
1. The “magic bullet”
-treatment of disease by using chemical substances is called
chemotherapy
-chemotheraphy drugs are synthetic or naturally produced
substance
2. Paul Ehrlich (1910)
-developed salvarsanm a compound containing arsenic 606, the first
chemotherapy drug
-it was the magic bullet that targeted Treponema pallidum, the
microorganism that causes syphilis
-awarded the Nobel Prize
3. Gerhard Paul Domagk (1930’s)
-discovered protonsil, a sulfonamide drug
-effective against streptococci diseases
-awarded the Nobel Prize
4. Alexander Fleming (1928)
-discovered the antibiotic penicillin
-penicillin was isolated from the fungus, Penicillium notatum
-received the Nobel Prize in Physiology or Medicine in 1945
V. Methods of Culturing and Media Classification
A. Media Classification
1. Physical state of media
a. liquid
b. semisolid
c. solid
2. Media types
a. chemically defined
-also called synthetic media
-all the chemicals used are known
-formula known
-does not contain any yeast, animal or plant tissue
b. complex media
-contains a carbon source such as glucose for bacterial growth
-various salts needed for bacterial growth
-non synthetic
-contains yeast, animal or plant tissue
-formula unknown
3. Types of Media for Microbial Growth
a. general purpose media
-nutrient agar (NA)
-nutrient broth (NB)
c. selective media
-selects the growth of one microorganism over another
d. differential media
-distinguishes one microorganism from another
-eosin-methylene blue (EMB) -selective and differential
-MacConkey agar (MCK ) -selective and differential
-Hektoen Enteric agar (HE) -selective and differential
-manitol salt agar (MSA -selective and differential
-blood agar plate (BAP) -differential
-NaCl agar -selective
1. Hektoen Enteric Agar (HEK)
-is a selective and differential media primarily used to recover Salmonella and
Shigella from patient specimens.
-contains indicators of lactose fermentation and H2S production; as well as
inhibitors to prevent the growth of gram positive bacteria
-Salmonella produces black colonies, whereas Shigella produces translucent
green colonies, the color of the agar
-sugars in media usually include lactose, sucrose, and salicin
3. Eosin Methylene Blue (EMB)
-lactose fermentation produces acids, which lower the pH and
encourages dye absorption by the colonies, which are now colored purpleblack and display "nucleated colonies“- colonies with dark centers
-lactose non-fermenters may increase the pH by deamination of proteins
which ensures that the dye is not absorbed- the colonies will be colorless
-is a slightly selective stain for Gram-negative bacteria is a blend of two
stains, eosin and methylene blue in the ratio of 6:1
Alpha and Beta Hemolysis
Gamma Hemolysis
B. Comparative Sizes of Microorganisms
VII. Microscopy
A. Factors Affecting Microscopy
1. Magnification
2. Resolution
B. Brightfield Microscope
1. Microscope parts
2. Lens system
-the refractive index is the light-bending ability of a
medium
-the light may bend in air so much that it misses the
small high-magnification lens
-immersion oil is used to keep light from refracting
C. Darkfield Microscope
D. Phase Contrast microscope
E. Electron Microscope
SEM (scanning electron microscope)
TEM (transmission electron microscope)
F. Preparing Smears for Staining
1. Smear preparation
2. Heat fixing
3. Staining
-stains are salts composed of positive or negative ions
-basic dyes
attracted to slightly negative bacteria
stains bacteria
crystal violet, methylene blue, malachite green, safranin
-acidic dyes
negative stain
does not stain bacteria
nigrosin, India ink, eosin
G. Simple Staining
1. Used to highlight microorganisms
2. Mordants are sometimes used to intensify stain
H. Differential Staining
1. Gram stain
crystal violet, mordant, decolorizer,
safranin
2. Acid-fast stain
carbolfuschin, decolorizer,
methylene blue
3. Endospore stain
malachite green, safranin
I. Special Staining
1. Capsule stain
2. Flagella stain