Download notes - introduction to bacteria 2010

ORIGIN OF LIFE
THE CELL
ALL LIVING THINGS ON EARTH ARE
CHARACTERIZED BY CELLULAR
ORGANIZATION, HOMEOSTATSIS, GROWTH,
HEREDITY AND OTHER LIFE FUNCTIONS.
THE PROKARYOTIC CELL
THE EARLIEST CELL
 WHAT DOES PROKARYOTIC MEAN?
 CELL LACKING A TRUE NUCLEUS and
MEMBRANE BOUND ORGANELLES
 BACTERIA REFLECT THE IDEA OF A
PROKARYOTIC CELL
Taxonomy the Science of
Classification
 Due to the great number and diversity of organisms, biologists use
the characteristics of different organisms to describe specific
forms of life and identify new ones.
 Classification: is the grouping of related organisms
 Carolus Linneaus is credited with foundings of Taxonomy – He
originated the binomial nomenclature system. Ie. Genus and
species
 Also established a hierarchy of taxonomic ranks – KPCOFGS
– the highest level being the Kingdoms
 He established a 2 kingdom system – plant and animal
Classification
 Since Linnaeus
1. 6 kingdom system
2. Microorganisms were identified due to tools such as
the light microscope and staining techniques
3. Recently 1956- bacteria were placed in the kingdom
Monera and considered Prokaryotic cells
 Monera (Archaebacteria and Eubacteria)
Classification of Bacteria
Bacteria have been classified into 33 groups
1.
2.
3.
4.
Morphology: size, shape,
arrangement of cells,
motility, presence of cellular
structures
Staining: gram + and –
Growth: characteristics in
solids and liquids, colony
morphology, pigments
Nutrition: autotrophic,
heterotrophic, chemotrophic
(C, N, S etc) fermentative
5.
6.
7.
Physiology: requirements –
temp, pH, aerobic,
anaerobic, salt, antibiotic
sensitivity and resistance
Biochemistry: cellular
components, nature of the
cell wall, ribosomes,
reaction to biochemicals
(carbs, lipids etc.)
Genetics: percentage of
DNA bases
CLASSIFICATION OF BACTERIA


Archaebacteria
“ARCHAE” – ANCIENT


DISCOVERED IN HARSH
ANAEROBIC ENVIRONMENTS 

Contain unusual lipids in their cell
membranes and lack
peptidoglycan in the cell wall


Gram + and -, motile and
nonmotile, various shapes
Ex. METHANOGENS, HALOPHILES &

THERMOACIDOPHILES

Eubacteria
TODAY’S TYPICAL
BACTERIA
Contain a cell membrane and
cell wall that contains
peptidoglycan
Mostly gram -, both anaerobic
and aerobic, motile and nonmotile, various shapes
Heterotrophic, photosynthetic
and chemosynthetic
Ex.
Yellowstone – hot
springs (hydrogen
sulfide) energy source
E. coli, Salmonella typhi,
cyanobacteria (blue-green
algae), Rhizobium,
Micrococcus luteus etc.
IDENTIFICATION
SHAPE
 COMMON BACTERIA HAVE
3 SHAPES
 COCCI
 BACILLI
 SPIRILLA
 VIBRIO (comma shaped)
 SPIROCHETES (corkscrew)
GROWTH PATTERN
 3 COMMON cocci
PATTERNS
 STAPHYLO- cluster
 STREPTO – chain –
cocci and bacilli
 DIPLO – Two
 TETRAD - four
THE BACTERIA


The prokaryotic cell is a
small one room
compartment
Components of cell
1.
2.
3.
4.
5.
6.
Capsule (glycocalyx)
Cell wall
Cell membrane
Cytoplasm
DNA (chromosome)
Pili (conjugation or
fimbriae)
7. Ribosomes
8. Flagella
9. Inclusion (granules) energy storage of
lipids
10. Plasmid
Bacteria
Pili:
a. Fimbriae –
attachment pili
b. Conjugation or sex
pili – attach two
cells and allow the
transfer of genetic
material
fimbriae
Conjugation –
attach two cells
to transfer DNA
Staining Techniques used
to classify bacteria
Based on certain cellular structures of the
prokaryotic cell, stains and techniques can
be used to identify a bacterium.
1. Simple Stain: adheres to the cell wall of the
structure to identify morphology
2. Differential Stain:
-Gram stain (cell wall characteristics)
-Negative stain (capsule)
3. Special Stain:
-Schaeffer-fulton spore technique (endospores)
-Flagellum staining
Bacteria: Negative Stain
Capsule: protective, thick, slimy
structure outside the cell wall
-A polysaccharide substance called
glycocalyx
- prevents drying
- prevents phagocytosis by host
- serve as a binding/adhesion
mechanism
 Produced as a defense mechanism
and contributes to virulence or
intensity of disease.
 Capsule not often visible - Negative
staining allows one to view this
specialized structure
Negative Staining technique –
Live bacteria is stained. This
creates a halo affect around
the cell. (Pink-red cell,
capsule does not stain
because of dark background.
Bacteria: Gram Staining and the cell wall
 Most bacteria are encased by
a strong cell wall
 PEPTIDOGLYCAN: consists
of carbohydrates and
polypeptide units
 Protect cell, maintain
shape, prevent
excessive water intake
 Some antibiotics and
chemicals interfere with
the production of
peptidoglycan synthesis
of some bacteria – destroy
cell
Bacteria: Gram Staining and the cell wall
GRAM STAINING (CLASSIFICATION
TECHNIQUE)
 GRAM STAINING is a staining
technique that will be detected in
the cell wall of some disease
causing bacteria.
 Bacterial Smear can either be
Gram + or Gram –
 Gram + have a thick layered
cell wall will reflect a purple
color
 Gram – do not retain the
staining dye because of a lipid
layer and will not retain the
purple dye. Will reflect a pink
color
Bacteria: Schaeffer-Fulton
Spore Technique
Endospores
1. Specialized resting cells that
survive extreme heat, toxins,
radiation, disinfectants and
chemicals
2. Primary function is to ensure the
survival of the bacterium through
times of stress
3. Extremely hard to destroy but
burning and autoclaving can do
this
4. Endospores can be seen with a
simple stain but the SchaefferFulton Spore Technique is used
to make spores more visual.
(spores stain a greenish color)
Schaeffer-Fulton Spore Stain
- a heat fixed smear is covered
with malachite green and
steam heated for 10 min. The
slide is then counterstained
with saffranin
Endospores
Spores outside