The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
The Purple Bacteria, also called Proteobacteria is the
largest and most physiological diverse of all bacteria
Bacteria














Purple and Green (Anoxygenic Phototrophic Bacteria)
Cyanobacteria
Prochlorophytes
Chemolithotrophs: Nitrifying Bacteria
Chemolithotrophs: Sulfur- and Iron-Oxidizing Bacteria
Chemolithotrophs: Hydrogen-Oxidizing Bacteria
Methanotrophs and Methylotrophs
Sulfate and Sulfur-Reducing Bacteria
Homoacetogenic Bacteria
Budding and Appendaged (Prosthecate) Bacteria
Spirilla
Spirochetes
Gliding Bacteria
Sheathed Bacteria
Bacteria


















Pseudomonads
Free-Living Aerobic Nitrogen-Fixing Bacteria
Acetic Acid Bacteria
Zymomonas and Chromobacterium
Vibrio and Related Genera
Facultatively Aerobic Gram-Negative Rods
Neisseria and other Gram-Negative Cocci
Rickettsias
Clamydias
Gram-Positive Bacteria: Cocci
Lactic Acid Bacteria
Endospore-Forming Gram-Positive Rods and Cocci
Mycoplasmas
High GC Gram-Positive Bacteria: “Actinomycetes”
Coryneform Bacteria
Propionic Acid Bacteria
Mycobacteria
Filamentous Actinomycetes
Facultatively Aerobic Gram-Negative Rods
Enteric Bacteria







Gamma Purple bacteria
Gram-negative straight rods
Facultative aerobes
Nonsporulating
Motile by peritrichous flagella or nonmotile
Large number of strains have been isolated
Identification is now based on computer analysis of a
large number of diagnostic tests carried out using
miniaturized rapid diagnostic media kits and
immunological and nucleic acid probes
Facultatively Aerobic Gram-Negative Rods
Butanediol-Producing, peritrichous
Enteric Bacteria Erwinia carotovora,
and its biochemical pathway for
formation of butanediol from two
molecules of pyruvate
Fermentation products
are the key to separate
the enteric bacteria
Two Broad Patterns of Fermentations
 Mixed-Acid Fermenters:  Butanediol Producers
Proteus
 Citrobacter
 Edwardsiella
 Salmonella
 Escherichia
 Shigella

Klebsiella
 Enterobacter
 Serratia
 Erwinia
 Hafnia

Facultatively
Aerobic GramNegative Rods
A simplified key to identify
the main genera of enteric
bacteria
Escherichia




Universal inhabitants of the intestinal tract
Play nutritional role (synthesizing vitamins)
Consume O2, render the large intestine anoxic
Some are pathogenic




Diarrhea
Children’s nurseries
Urinary infections
Enterotoxin
Shigella
 Very similar to E. coli
 Commonly pathogenic to humans



Gastroenteritis (bacillary dysentery)
Endotoxin
Neurotoxin
 Transmitted by Food and Waterborne
Routes
Salmonella
 Salmonella and Escherichia are related
 The two have 45-50% of their DNA sequences in common
 Usually pathogenic


Typhoid fever
Gastroenteritis
• O antigen:cell wall (somatic) antigen,
lipopolysaccharide
• H antigen: flagellar antigen,
Proteus
 Rapid motility
 Production of enzyme urease
 Cause diseases:



Urinary tract infection
Enteritis
Kidney infection
Yersinia
 Y. pestis: causal agent of bubonic plague
 Y. pseudotuberculosis: causal agent of a
tuberculosis-like disease of the lymph nodes
in animals (rarely in human)
 Y. enterocolitica: causal agent of an intestinal
infection (also occasionally systemic
infections) in humans and animals
Neisseria and Other Gram-Negative Cocci




Beta purple bacteria
Lack of motility
Nonfermentative aerobic metabolism
Have five genera:





Neisseria (Neisseria gonorrhoeae)
Moraxella
Kingella
Psychrobacter
Acinetobacter
Rickettsias
 Gram-negative (Alpha purple)
 Coccoid or rod-shaped
 Obligate intracellular parasites:
 Typhus Fever
 Rocky Mountain Spotted
Fever
 Q Fever (by Coxiella burnetii)
 Transmitted by arthropod
vectors or by aerosols
(Coxiella Burnetii)
 Close relationship with
Agrobacterium tumefaciens
 Representatives: Rickettsia,
Rochalimaea, Coxiella
Chlamydias
 Obligate parasites
 Three species:
 C. psittaci (psittacosis)
 C. trachomatis (trachoma)
 C. pneumoniae
 probably have the simplest
biochemical abilities of all
cellular organisms
What are the differences between
Richettsia, Chlamydias and Viruses?
Gram-Positive Bacteria: Cocci
 Clostridium (endospore formers)
 Lactic Acid Bacteria
 Most are Gram-Positive Cocci
 Actinomycetes
 Propionibacterium
Gram-Positive Bacteria: Cocci
Sarcina
 Staphylococcus: facultative aerobe,
produce acid from glucose both aerobically
and anaerobically, low GC ratios, common
parasites of human and animals,
occasionally cause diseases
 Micrococcus: obligate aerobe, high GC
ratios.
 Sarcina: obligate anaerobes, extremely
acid-tolerant (pH 2). Sarcina ventriculi can
grow in stomach of human, causing pyloric
ulcerations
Staphylococcus
Gram-Positive Bacteria: Cocci: Deinococcus
 Resistant to radiation and
dessication
 Most are bright red and
pink in color
 Cell walls consist of several
layers
 Deinococcus radiodurans
are more resistant to
radiation than bacterial
endospore, also resistant to
mutagenic chemicals.
 Isolated from near atomic
reactors.
Lactic Acid Bacteria








Gram-positive
Non-motile
Non-sporulating
Lactic acid as a major or sole product of
fermentative metabolism
Obtain energy only through substrate-level
phosphorylation
Anaerobes, but aerotolerant
Homofermentative group: produces only lactic
acid as sole product
Heterofermentative group: produces ethanol,
CO2 and lactic acid
The fermentation of
glucose in homofermentative
and heterofermentative lactic
acid bacteria
Lactic Acid Bacteria
 Genera:






Streptococcus
Leuconostoc
Pediococcus
Lactobacillus
Enterococcus
Lactococcus
All the above genera grow
in chains.
Many are used for the food
industry.
Lactic Acid Bacteria
 Picture above:
 Lactobacillus acidophilus
 Picture in the middle:
 Lactobacillus brevis
 Picture on the bottom:
 Lactobacillus delbrueckii
Endopsore-Forming Gram-Positive Rods and Cocci
 Bacillus and Clostridium are better studied
 Bacillus: aerobic and facultatively aerobic
 B. popilliae and B. thuringiensis produce insect larvicides
(biological insecticides)
 Clostridium: strictly anaerobic
 Some Clostridium sugar and produce butyric acid
 Some Clostridium produce acetone and butanol
 Some Clostridium ferment cellulose to ethanol, it is
industrially significant, could be used to turn waste cellulose
into motor fuel
 Most produce one spore except polyendosporus
Endopsore-Forming Gram-Positive Rods and Cocci
 B. popilliae and B. thuringiensis produce insect
larvicides (biological insecticides)
 Toxic parasporal crystal in B. thuringiensis
Endopsore-Forming Gram-Positive Rods and Cocci
 Clostridum species have various spore
location in the bacterial cells.
 Bottom left: Clostridium cadaveris
 Bottom middle: Clostridium sporogenes
 Bottom right: Clostridum bifermentans
Formation of fermentation
products from the butyric
acid group of clostridia
Endopsore-Forming Gram-Positive Rods and Cocci
 Sporosarcina is unique among endospore
formers as the cells are cocci instead of rods.
 Sporosarcina ureae can decomposes urea to
CO2 and NH3. Causing pH increase
Mycoplasma
 Microorganisms without cell walls that do
not revert to walled organsims
 The smallest organisms capable of
autonomous growth
 Resistant to osmotic pressure and penicillin
Due to lack of rigidity,
mycoplasma has various growth
morphologies. In agar, it appears
as fried egg shape
High GC Gram-Positive Bacteria: “Actinomycetes”






Most are gram-positive
Rod-shaped to filamentous
Aerobic
Generally nonmotile in the vegetative phase
Form a subdivision of gram-positive bacteria
Contain a large variety of bacteria:




Coryneform group of bacteria
Propionic acid bacteria
Obligate anaerobes
Actinomycetes
Coryneform Bacteria
 Gram-positive, aerobic
 Nonmotile, rod-shaped
 Forming irregular-shaped, clubshaped or V-shaped cells
 Main genera:
 Corynebacterium
 Arthrobacter
 Corynebacterium: extremely diverse
group of bacteria, including animal
and plant pathogens
 Arthrobacter: soil organisms,
ditinguished from Corynebacterium
by a cycle of development from rod
to sphere and back to rod.
Coryneform Bacteria
 Arthrobacter: soil organisms, ditinguished
from Corynebacterium by a cycle of
development from rod to sphere and
back to rod.
Propionic Acid Bacteria




Gram-positive, pleomorphic
Nonsporulating rods
Nonmotile and anaerobic
Ferment lactic acid, carbohydrates and
polyhydroxy alcohols
 Produce propionic acid, succinic acid, acetic
acid and CO2
 Grow slowly
 First discovered as inhabitants of Swiss cheese
Mycobacterium
 Rod-shaped
 Acid-alcohol fastness (due to mycolic acid)
 Gram-positive, but not ready stained due to
high surface lipid content
 Pleomorphic (branching or filamentous)
 Many form yellow carotenoid pigments
 Mycobcterium tuberculosis grows slowly
 Other like Mycobacterium smegmatis grows
fast.
Mycobacterium
 The fuchsin dye
probably combines
with the mycolic
acid via ionic
bonds between
COO- and NH2+
Mycobacterium
 Characteristic colony morphology of
mycobacterium
M. tuberculosis
M. avium
Filamentous Actinomycetes








A large group of filamentous bacteria
Usually gram-positive, forming branching filaments
Most form spores
Have high GC content of 63-78%
Streptomyces important
Streptomyces are primarily soil organisms
Streptomyces produces earthy odor (geosmins)
Streptomyces: most important antibiotic producers
Filamentous Actinomycetes
 A young colony of an actinomycete of the
genus Nocardia
Filamentous Actinomycetes
 Several spore-bearing
structures of actinomycetes:
Streptomyces.
Filamentous Actinomycetes
 Stages in the conversion of a streptomycete’s
aerial hypha into spores (conidia)
Various types
of spore-bearing
structures in the
streptomycetes
Filamentous Actinomycetes
 Typical
appearance of a
streptomycete
growing on agar
slants
 The colors are
due to the
production of
pigments
Filamentous Actinomycetes
 Antibiotic
action of soil
microorganis
ms on a
crowded plate
streptomycetes
Bacillus
To reach the peak, you have to
begin from each brick
SEE YOU HERE
Microbiology
Molecular Biology
Biochemistry
Physics
Chemistry
Mathematics General Biology
May the new century bring YOU
many successes and happinesses