Chaper 3 The Prokaryotes
Section 1 Bacteria
Section 2 Actinomycetes
Section 3 Cyanobacteria
Section 4 Archaeobacteria
Section 5 Other prokaryotes
Size,Shape,and Arrangement of Bacterial Cells
Most bacteria fall within a range
from 0.2 to 2.0 μm in diameter
and from 2 to 8μm in length.
They have a few basic shapes-spherical coccus
(plural,cocci,meaning berries),rod-shaped
bacillus (plural,bacilli,meaning little staffs),and
spiral.
Cm = 10-2 meter
mm = 10-3 meter
μm = 10-6 meter
nm = 10-9 meter
Bacteria
The thousands of species of bacteria are
differentiated by many factors,including
morphology (shape),chemical composition
(often detected by staining reactions),
nutritional requirements,biochemical
activities,and source of energy (sunlight or
chemicals).
How to identify an unknown bacterial species?
Arrangement of Spherical Bacterial Cells
diplococci
streptococci
tetracocci
sarcinae
staphylococci
Spherical
coccus
The Micrococcaceae
The family Micrococcaceae contains gram-positive
cocci,0.5-2.5 μm in diameter,that divide in more than
one plane to form regular or irregular clusters of cells,
All are aerobic or facultatively anaerobic,The
peptidoglycan di-amino acid is L-lysine,
The three most important genera are:
Micrococcus
Staphylococcus
Streptococcus
Micrococcus – aerobic,gram-positive,
catalase positive,cell arranges mainly in pairs,
tetrads,or irregular clusters,nonmotile,They
are often yellow,orange or red in colour
Staphylococcus - facultatively anaerobic,gram-
positive,usually form irregular clusters,nonmotile,
catalase positive but oxidase negative,ferment
glucose anaerobically.
staphylococcistaphylococci
Streptococcus - facultatively anaerobic or
microaerophilic,catalase negative,gram-positive,
Cell arranges in pairs or chains,usually nonmotile,
A few species are anaerobic rather than facultative,
Bacilli divide only across their short axis,so there
are fewer groupings of bacilli than of cocci,
Rod-shaped bacteria
Diplobacilli
streptobacilli
Single bacillus
Coccobacillus
Clostridium botulinus
C,butyricum
C,aceticum
C,tetani
C,putrificum
Bacillus subtilis,
B,Mycoides
B,Pastturii
B,megaterium
B,Thuringiensis
B,Anthracis
B,Botulinus
B,cereus
Spore-forming rod shaped bacteria
Almost all Spore-forming bacteria are Gram+
Clostridium – AnaerobicBacillus – Aerobic
Nonspore - forming rod shaped bacteria
Most nonspore – forming rod shaped bacteria are Gram-
Representatives:
Escherchia coli
Alcaligenes
Proteus
Flavobacteria
Pseudomonas
Rhizobium
Azotobacter
Vibrio,Spirillum and Spirochete
Some bacteria are shaped like
long rods twisted into spirals
or helices; they are called
vibrios (like commas or
incomplete spirals),spirilla if
rigid and spirochetes when
flexable.
vibrio
spirillum
spirochete
Actinomycetes
Actinomycetes are filamentous bacteria,Their
morphology resembles that of the filamentous fungi;
however,the filaments of actinomycetes consist of
procaryotic cells,Some actinomycetes resemble molds
by forming externally carried asexual spores for
reproduction.
Filamentous,High G + C content,Gram-positive
(63 – 78% GC)
Chain of
conidiospores
Agar
surface
Substrate
mycelium
Aerial hyphae
The cross section of an actinomycete colony showing the substrate
mycelium and aerial mycelium with chains of conidiospores
Various types of
spore-bearing
structures on the
streptomyces
Representive genera:
Streptomyces
Nocardia
Actinomyces
Micromonospora
Streptosporangium
Actinoplanes
Frankia
Over 500 distinct antibiotic
substances have been shown
to be produced by
streptomycete.
Most antibiotics are efficient
against different bacteria.
More than 50 antibiotics
have been used in human
and veterinary medicine,
agriculture and industry
AntibioticsActinomycetes
Chain of
conidiospores
Agar
surface
Substrate
mycelium
Aerial hyphae
The cross section of an actinomycete colony showing the substrate
mycelium and aerial mycelium with chains of conidiospores
Various types of spore-bearing
structures on the streptomycesStreptomyces spores,
called conidia,are not
related in any way to the
endospores of Bacillus
and Clostridium because
the streptomycete spores
are produced simply by
the formation of cross-
walls in the multinucleate
sporophores followed by
separation of the
individual cells directly
into spores,
Ecology and isolation of Streptomyces:
Alkaline and neutral soils are more favorable for
the development of Streptomyces than are acid soils,
Streptomyces require a lower water potential for
growth than many other soil bacteria,
Media often selective for Streptomyces contain the
usual assortment of inorganic salts
The method of a serial dilutions for viable counting
The streptonycetes are a large group of
filamentous,gram positive bacteria that
form spores at the end of aerial filaments.
They have the highest GC percentagein
the DNA base composition of any bacteria
known.
Many clinically important antibiotics
have come from Streptomycetes species
Concept:
Cyanobacteria
The cyanobacteria have typical prokaryotic cell
structures and a normal gram-negative cell wall,
They range in diameter from about 1 – 10 μm and
may be unicellular or form filaments,
They have chlorophyll and carry out oxygen-
producing photosynthesis,much as plants and the
eukaryotic algae do,
Filamentous Cyanobacterium,
Anabaena sp,
(SEM x5,000)
Nonfilamentous
cyanobacteria
The morphological diversity of the cyanobacteria is considerable,
Both unicellular and filamentous forms are known,and
considerable variation within these morphological types occurs.
Heterocysts have intercellular connections with adjacent
vegetative cells,and there is mutual exchange of materials
between these cells,with products of photosynthesis moving
from vegetative cells to heterocysts and products of nitrogen
fixation moving from heterocysts to vegetative cells.
Photosynthesis
Nitrogen fixation
Main function of Cyanobacteria
The nutrition of cyanobacteria is simple,Vitamins are
not required,and nitrate or ammonia is used as
nitrogen source,
Nitrogen-fixing species are common,
Most species tested are obligate phototrophs,However,
some cyanobacteria are able to grow in the dark on
organic compounds,using the organic material as both
carbon and energy source.
Physiology of
cyanobacteria:
Problems:
Many cyanobacteria produce potent
neurotoxins,and during water blooms when
massive accumulations of cyanobacteria
may develop,animals ingesting such water
may succumb rapidly,
Aseptic technique
Streak plate
Pour plate
Spread plate
Archaeobacteria differ from eubacteria in a number
of other ways,For example,their cell walls never
contain peptidoglycan,they often live in extreme
environments,and they carry out unusual metabolic
processes.
The Archaebacteria
1,The methanogens,strict anaerobes that produce
methane (CH4) from carbon dioxide and
hydrogen.
2,Extreme halophiles,which require high
concentrations of salt for survival.
3,Thermoacidophiles,which normally grow in hot,
acidic environments.
Archaebacteria include three groups:
Methanogenic bacteria are strict anaerobes that
obtain energy by converting C02,H2,formate,
acetate,and other compounds to either methane
or methane and C02,
C02 + 4 H2 CH4 + 2 H2O
CH3 C00 H C02 + CH4
Sewage treatment plants use the methane
produced to generate heat and electricity,
and methanogenesis may eventually serve
as a major source of pollution-free energy.
extremely thermophilic bacteria are
gram-negative,aerobic,irregularly lobed
spherical bacteria with a temperature
optimum around 70-80 0C and a pH
optimum of 2 to 3,Their cell wall contains
lipoprotein and carbohydrates but lacks
peptidoglycan.
Their most distinctive characteristic is their
requirement of a high concentration of sodium chloride
for growth,They are aerobic chemoheterotrophs with
respiratory metabolism and require complex nutrients,
usually proteins and amino acids,for growth,
Extreme halophilic bacteria:
Other prokaryotes
Rickettsia
Chlamydia
Mycoplasma
Bdellovirio
1,0.2-0.5μm in diameter,obligate intracellular
parasites,The majority of them are gram-
negative and multiply only within host cells,
2,Binary fission within host cells.They lack the
enzymatic capability to produce sufficient
amounts of ATP to support their reproduction,
They obtain the ATP from host cells.
3,Many species of them cause disease in
humans and other animals.
Rickettsia
They are obligate intracellular parasites,
unable to generate sufficient ATP to support
their reproduction.
gram-negative and cell divides by binary
fission
They Chlamydia cause human respiratory and
genitourinary tract disease,and in birds they
cause respiratory disease.
Chlamydia
Diameter=0.1-0.25 μm,They lack cell wall,are
bounded by a single triple-layered membrane.
They are the smallest organisms capable of
self-reproduction,
The colony is,fried egg” appearance.
Several of them cause diseases in humans,
(pneumonia,respiratory tract disease)
Mycoplasma
Bdellovirio
See Movie for the detail of
infection and reproduction
Movie
Classification of bacteria
MORPHOLOGICAL CHARACTERISTICS
DIFFERENTIAL STAINING
NUCLEIC ACID HYBRIDIZATION
GENETIC RECOMBINATION
NUMERICAL TAXONOMY
Fungi Plants Animals
Protista
Prokaryotae
Five-kingdom system is a commonly accepted system of classification
Archaebacteria Eubacteria
Eukaryotes
The taxonomic classification scheme for bacteria may be found
in Bergey's Manual of Systematic Bacteriology,In Bergey's
Manual,bacteria are divided into four divisions,Three divisions
consist of eubacterial cells,and the fourth division consists of the
archaeobacteria,Each division is divided into classes;
Classes are divided into orders;families; genera; species.
Bacterial species is defined simply as a population of
cells with similar characteristics,
strain is a group of cells all derived from a single cell.
MORPHOLOGICAL CHARACTERISTICS
Morphological characteristics are useful in
identifying bacteria,For example,differences in
such structures as endospores or flagella can be
helpful.
However,many microorganisms appear too
similar to be classified by their structures.
DIFFERENTIAL STAINING
(for example Gram staining) Most
bacteria are either gram-positive or gram-
negative,But not useful in identifying either
the wall-less bacteria or the archaeobacteria
with unusual walls.
NUCLEIC ACID HYBRIDIZATION
GENETIC RECOMBINATION
Section 1 Bacteria
Section 2 Actinomycetes
Section 3 Cyanobacteria
Section 4 Archaeobacteria
Section 5 Other prokaryotes
Size,Shape,and Arrangement of Bacterial Cells
Most bacteria fall within a range
from 0.2 to 2.0 μm in diameter
and from 2 to 8μm in length.
They have a few basic shapes-spherical coccus
(plural,cocci,meaning berries),rod-shaped
bacillus (plural,bacilli,meaning little staffs),and
spiral.
Cm = 10-2 meter
mm = 10-3 meter
μm = 10-6 meter
nm = 10-9 meter
Bacteria
The thousands of species of bacteria are
differentiated by many factors,including
morphology (shape),chemical composition
(often detected by staining reactions),
nutritional requirements,biochemical
activities,and source of energy (sunlight or
chemicals).
How to identify an unknown bacterial species?
Arrangement of Spherical Bacterial Cells
diplococci
streptococci
tetracocci
sarcinae
staphylococci
Spherical
coccus
The Micrococcaceae
The family Micrococcaceae contains gram-positive
cocci,0.5-2.5 μm in diameter,that divide in more than
one plane to form regular or irregular clusters of cells,
All are aerobic or facultatively anaerobic,The
peptidoglycan di-amino acid is L-lysine,
The three most important genera are:
Micrococcus
Staphylococcus
Streptococcus
Micrococcus – aerobic,gram-positive,
catalase positive,cell arranges mainly in pairs,
tetrads,or irregular clusters,nonmotile,They
are often yellow,orange or red in colour
Staphylococcus - facultatively anaerobic,gram-
positive,usually form irregular clusters,nonmotile,
catalase positive but oxidase negative,ferment
glucose anaerobically.
staphylococcistaphylococci
Streptococcus - facultatively anaerobic or
microaerophilic,catalase negative,gram-positive,
Cell arranges in pairs or chains,usually nonmotile,
A few species are anaerobic rather than facultative,
Bacilli divide only across their short axis,so there
are fewer groupings of bacilli than of cocci,
Rod-shaped bacteria
Diplobacilli
streptobacilli
Single bacillus
Coccobacillus
Clostridium botulinus
C,butyricum
C,aceticum
C,tetani
C,putrificum
Bacillus subtilis,
B,Mycoides
B,Pastturii
B,megaterium
B,Thuringiensis
B,Anthracis
B,Botulinus
B,cereus
Spore-forming rod shaped bacteria
Almost all Spore-forming bacteria are Gram+
Clostridium – AnaerobicBacillus – Aerobic
Nonspore - forming rod shaped bacteria
Most nonspore – forming rod shaped bacteria are Gram-
Representatives:
Escherchia coli
Alcaligenes
Proteus
Flavobacteria
Pseudomonas
Rhizobium
Azotobacter
Vibrio,Spirillum and Spirochete
Some bacteria are shaped like
long rods twisted into spirals
or helices; they are called
vibrios (like commas or
incomplete spirals),spirilla if
rigid and spirochetes when
flexable.
vibrio
spirillum
spirochete
Actinomycetes
Actinomycetes are filamentous bacteria,Their
morphology resembles that of the filamentous fungi;
however,the filaments of actinomycetes consist of
procaryotic cells,Some actinomycetes resemble molds
by forming externally carried asexual spores for
reproduction.
Filamentous,High G + C content,Gram-positive
(63 – 78% GC)
Chain of
conidiospores
Agar
surface
Substrate
mycelium
Aerial hyphae
The cross section of an actinomycete colony showing the substrate
mycelium and aerial mycelium with chains of conidiospores
Various types of
spore-bearing
structures on the
streptomyces
Representive genera:
Streptomyces
Nocardia
Actinomyces
Micromonospora
Streptosporangium
Actinoplanes
Frankia
Over 500 distinct antibiotic
substances have been shown
to be produced by
streptomycete.
Most antibiotics are efficient
against different bacteria.
More than 50 antibiotics
have been used in human
and veterinary medicine,
agriculture and industry
AntibioticsActinomycetes
Chain of
conidiospores
Agar
surface
Substrate
mycelium
Aerial hyphae
The cross section of an actinomycete colony showing the substrate
mycelium and aerial mycelium with chains of conidiospores
Various types of spore-bearing
structures on the streptomycesStreptomyces spores,
called conidia,are not
related in any way to the
endospores of Bacillus
and Clostridium because
the streptomycete spores
are produced simply by
the formation of cross-
walls in the multinucleate
sporophores followed by
separation of the
individual cells directly
into spores,
Ecology and isolation of Streptomyces:
Alkaline and neutral soils are more favorable for
the development of Streptomyces than are acid soils,
Streptomyces require a lower water potential for
growth than many other soil bacteria,
Media often selective for Streptomyces contain the
usual assortment of inorganic salts
The method of a serial dilutions for viable counting
The streptonycetes are a large group of
filamentous,gram positive bacteria that
form spores at the end of aerial filaments.
They have the highest GC percentagein
the DNA base composition of any bacteria
known.
Many clinically important antibiotics
have come from Streptomycetes species
Concept:
Cyanobacteria
The cyanobacteria have typical prokaryotic cell
structures and a normal gram-negative cell wall,
They range in diameter from about 1 – 10 μm and
may be unicellular or form filaments,
They have chlorophyll and carry out oxygen-
producing photosynthesis,much as plants and the
eukaryotic algae do,
Filamentous Cyanobacterium,
Anabaena sp,
(SEM x5,000)
Nonfilamentous
cyanobacteria
The morphological diversity of the cyanobacteria is considerable,
Both unicellular and filamentous forms are known,and
considerable variation within these morphological types occurs.
Heterocysts have intercellular connections with adjacent
vegetative cells,and there is mutual exchange of materials
between these cells,with products of photosynthesis moving
from vegetative cells to heterocysts and products of nitrogen
fixation moving from heterocysts to vegetative cells.
Photosynthesis
Nitrogen fixation
Main function of Cyanobacteria
The nutrition of cyanobacteria is simple,Vitamins are
not required,and nitrate or ammonia is used as
nitrogen source,
Nitrogen-fixing species are common,
Most species tested are obligate phototrophs,However,
some cyanobacteria are able to grow in the dark on
organic compounds,using the organic material as both
carbon and energy source.
Physiology of
cyanobacteria:
Problems:
Many cyanobacteria produce potent
neurotoxins,and during water blooms when
massive accumulations of cyanobacteria
may develop,animals ingesting such water
may succumb rapidly,
Aseptic technique
Streak plate
Pour plate
Spread plate
Archaeobacteria differ from eubacteria in a number
of other ways,For example,their cell walls never
contain peptidoglycan,they often live in extreme
environments,and they carry out unusual metabolic
processes.
The Archaebacteria
1,The methanogens,strict anaerobes that produce
methane (CH4) from carbon dioxide and
hydrogen.
2,Extreme halophiles,which require high
concentrations of salt for survival.
3,Thermoacidophiles,which normally grow in hot,
acidic environments.
Archaebacteria include three groups:
Methanogenic bacteria are strict anaerobes that
obtain energy by converting C02,H2,formate,
acetate,and other compounds to either methane
or methane and C02,
C02 + 4 H2 CH4 + 2 H2O
CH3 C00 H C02 + CH4
Sewage treatment plants use the methane
produced to generate heat and electricity,
and methanogenesis may eventually serve
as a major source of pollution-free energy.
extremely thermophilic bacteria are
gram-negative,aerobic,irregularly lobed
spherical bacteria with a temperature
optimum around 70-80 0C and a pH
optimum of 2 to 3,Their cell wall contains
lipoprotein and carbohydrates but lacks
peptidoglycan.
Their most distinctive characteristic is their
requirement of a high concentration of sodium chloride
for growth,They are aerobic chemoheterotrophs with
respiratory metabolism and require complex nutrients,
usually proteins and amino acids,for growth,
Extreme halophilic bacteria:
Other prokaryotes
Rickettsia
Chlamydia
Mycoplasma
Bdellovirio
1,0.2-0.5μm in diameter,obligate intracellular
parasites,The majority of them are gram-
negative and multiply only within host cells,
2,Binary fission within host cells.They lack the
enzymatic capability to produce sufficient
amounts of ATP to support their reproduction,
They obtain the ATP from host cells.
3,Many species of them cause disease in
humans and other animals.
Rickettsia
They are obligate intracellular parasites,
unable to generate sufficient ATP to support
their reproduction.
gram-negative and cell divides by binary
fission
They Chlamydia cause human respiratory and
genitourinary tract disease,and in birds they
cause respiratory disease.
Chlamydia
Diameter=0.1-0.25 μm,They lack cell wall,are
bounded by a single triple-layered membrane.
They are the smallest organisms capable of
self-reproduction,
The colony is,fried egg” appearance.
Several of them cause diseases in humans,
(pneumonia,respiratory tract disease)
Mycoplasma
Bdellovirio
See Movie for the detail of
infection and reproduction
Movie
Classification of bacteria
MORPHOLOGICAL CHARACTERISTICS
DIFFERENTIAL STAINING
NUCLEIC ACID HYBRIDIZATION
GENETIC RECOMBINATION
NUMERICAL TAXONOMY
Fungi Plants Animals
Protista
Prokaryotae
Five-kingdom system is a commonly accepted system of classification
Archaebacteria Eubacteria
Eukaryotes
The taxonomic classification scheme for bacteria may be found
in Bergey's Manual of Systematic Bacteriology,In Bergey's
Manual,bacteria are divided into four divisions,Three divisions
consist of eubacterial cells,and the fourth division consists of the
archaeobacteria,Each division is divided into classes;
Classes are divided into orders;families; genera; species.
Bacterial species is defined simply as a population of
cells with similar characteristics,
strain is a group of cells all derived from a single cell.
MORPHOLOGICAL CHARACTERISTICS
Morphological characteristics are useful in
identifying bacteria,For example,differences in
such structures as endospores or flagella can be
helpful.
However,many microorganisms appear too
similar to be classified by their structures.
DIFFERENTIAL STAINING
(for example Gram staining) Most
bacteria are either gram-positive or gram-
negative,But not useful in identifying either
the wall-less bacteria or the archaeobacteria
with unusual walls.
NUCLEIC ACID HYBRIDIZATION
GENETIC RECOMBINATION
