The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom I,Proteobacteria
? Purple Phototrophic Bacteria
? The Nitrifying Bacteria
? Sulfur- and Iron-Oxidizing Bacteria
? Methanotrophs and Methylotrophs
? Pseudomonas and Pseudomonads
? Acetic Acid Bacteria
? Free-Living Aerobic Nitrogen-Fixing Bacteria
? Neisseria,Chromobacterium,and Relatives
? Enteric Bacteria
? Vibrio and Photobacterium
? Rickettsia
? Spirilla
? Sheathed Protesbacteria,Sphaerotilus and Leptothrix
? Budding and Prosthecate/Stalked Bacteria
? Gliding Myxobacteria
? Sulfate- and Sulfur-Reducing Proteobacteria
The Purple Bacteria,also called Proteobacteria is the
largest and most physiological diverse of all bacteria
Purple and Green (Anoxygenic Phototrophic) Bacteria
? Purple Bacteria,
? Bacteriochlorophylls a,b
? Anoxygenic photosynthesis
? One photosystem
? Green Bacteria:
? Bacteriochlorophylls c,d or e
? Anoxygenic photosynthesis
? One photosystem
? Cyanobacteria:
? Bacteriochlorophyll a
? Oxygenic photosynthesis
? Two photosystems
Purple and Green (Anoxygenic Phototrophic) Bacteria
Bacteriochlorophylls
? Bacteriochlorophylls differ
in substituents on various
parts of the porphyrin ring;
? The various modifications
lead to changes in the
absorption spectra of the
bacteriochlorophylls;
? From the long-wavelength
maximum,the identification
of the bacteriochlorophyll
can be made.
Purple and Green (Anoxygenic Phototrophic) Bacteria
Classification
? Anoxygenic phototrophic bacteria are classified
based on their bacteriochlorophylls and
photosynthetic membrane systems into three major
groups:
? Purple Bacteria (Nonsulfur purple,Purple sulfur bacteria)
? Green Bacteria (Green sulfur,green nonsulfur bacteria)
? Heliobacteria
? Anoxygenic phototrophic bacteria also produce
carotenoid pigments,Therefore,the colors of the
bacteria are the combination of bacterio-
chlorophylls and carotenoid pigments
Purple and Green (Anoxygenic Phototrophic) Bacteria
Classification
Purple and Green (Anoxygenic Phototrophic) Bacteria
Carotenoids
Carotenoid-less
mutant,the actual
Bchl a color
Carotenoid-less
mutant
Purple and Green (Anoxygenic Phototrophic) Bacteria
Photosynthetic Membrane Systems
Differences between green and purple bacteria in the Photosynthetic Membrane Systems
In purple bacteria,photosynthetic pigments are parts of the internal membane (lamellae).
In green bacteria,photosynthetic apparatus consists of a series of cylindrically shaped
structures called chlorosomes underlaying and attached to the cytoplasmic membrane.
In heliobacteria,bacteriochlorophyll is associated with the cytoplasmic membrane
Purple bacteria
Green Bacteria
Heliobacteria
Purple and Green (Anoxygenic Phototrophic) Bacteria
Nonsulfur purple bacteria
? can only used sulfide at a low concentration;
? have great photoheterotrophic abilities;
? some have ability to utilize methanol as sole carbon
source for phototrophic growth;
? most are active N2 fixers.
Rhodospirilum fulvum
Rhodopseudomonas acidophila
Rhodobacter sphaeroides
Rhodopila globiformis
Rhodocyclus purpureus
Rhodomicrobium vannielii
Purple and Green (Anoxygenic Phototrophic) Bacteria
Purple sulfur bacteria
? deposit sulfur and oxidize it to sulfate,
? commonly found in anoxic zones of lakes as well as
in sulfur springs,
? Ectothiorhodospira deposits sulfur externally,grows
halophilically and at high pH,found in saline lakes,
saltern,and bodies of water high in salt,
? limited ability to utilize organic compounds as C
source for phototrophic growth
? Thiocapsa grows chemoorganotrophically on
acetate
Purple and Green (Anoxygenic Phototrophic) Bacteria
Purple sulfur bacteria
Chromatium okenii
Thiospirillum jenense
Thiocapsa Thiopedia rosea
Chemolithotrophs,Nitrifying Bacteria
? Bacteria able to grow chemolithotrophically at the
expense of reduced inorganic nitrogen compounds
? (1) Nitrosifying bacteria:
? NH3 + O2 NO2- + H+ + H2O
? (2) Nitrifying bacteria:
? NO2- + O2 NO3-
? No chemolithotroph is known that will carry out the
complete oxidation of ammonia to nitrate
? (1) Nitrosomonas,Nitrosococcus,Nitrosospira
? (2) Nitrobacter,Nitrospira,Nitrococcus
? They are members of the purple bacteria
Chemolithotrophs,Sulfur- and Iron-Oxidizing Bacteria
? Members of purple bacteria
? Have ability to grow chemolithotrophically on
reduced sulfur compounds
? Only six genera,Thiobacillus,Thiosphaera,
Thiomicrospira,Thermothrix,Beggiatoa and
Sulfolobus (Archaea) have been cultured.
? Two groups,neutrophilic and acidophilic
? The acidophilic group can grow
chemolithotrophically using ferrous iron as electron
donor
? Thiobacillus ferrooxidans has been used for leaching
Chemolithotrophs,Hydrogen-Oxidizing Bacteria
? Capable of growing with H2 as sole electron donor and
O2 as electron acceptor,
? Many of them can also grow autotrophically using
Calvin cycle to fix CO2,
? All contain hydrogenase for binding H2 and use it to
produce ATP,
? Can grow both chemoorganotrophs and
chemolithotrophs,
? Most are obligate aerobes,but prefer microaerobic
conditions when growing chemolithotrophically on H2,
? Some can grow on CO,
? Best studied Alcaligenes eutrophus,or Ralstonia
eutropha
Methanotrophs and Methylotrophs
? Methanotrophs,
? utilize methane,and/or a few other one-carbon
compounds as sole source of carbon
? aerobes (Purple Bacteria)
? widespread in nature in soil and water
? possess methane monooxygenase
? obligate C1 utilizers
? contain large amount of sterols in internal membrane
? Methylotrophs:
? utilize methane and other one-carbon compounds as
electron donors for energy generation and as sole
sources of carbon
? many can utilize organic acids,ethanols and sugars
Methanotrophs and Methylotrophs
Classification
? Based on internal cell structure and carbon
assimilation pathway:
? Type I,ribulose monophosphate cycle,lack a
complete TCA cycle
? Type II,Serin pathway
Methylosinus,Type II Methylococcus capsulatus,Type I
Methanotrophic Symbionts of Animals
? Intact mussels as well as isolated mussel
gill tissue consume methane at high rates
in the presence of O2 due to symbiotic
methanotrophic bacteria presence.
Symbiotic methanotrophs in the gill tissue of a marine mussel living
near hydrocarbon seeps in the Gulf of Mexico
Gliding Bacteria
? No flagella but can move when in contact with surfaces
? Gram-negative,purple bacteria,some are Bacteroides-Flavobacterium
? Myxobacteria can form multicellular structures called fruiting bodies
Beggiatoa
Thioploca
Filamentou sulfur-oxidizing
bacteria in a small stream
Sulfur-oxidizing bacteria
Gliding Bacteria
Gliding Bacteria,Leucothrix
? Chemoorganotrophic,requires both H2S and an organic compounds for growth
? Form gonidia under unfavorable conditions
? May aggregate to form rosette when gonidia have high concentration
Leucothrix mucor
Gliding Bacteria,Fruiting Myxobacteria
Myxococcus fulvus
Mellitangium erectum
Myxococcus stipitatus
Chondromyces crocatus
Stigmatella aurantiaca
Exhibit the most
complex behavioral
patterns and life
cycles of all known
prokaryotes
Gliding Bacteria,Fruiting Myxobacterium
Gliding myxobacterium
Stigmatella aurantiaca
Have rather large
chromosome size
Rely on lysis of other
bacteria for nutritions
Myxospores are more
resistant to drying,
sonic vibration,UV
and heat.
Usually colored by
carotenoid pigments
Gliding Bacteria
Gliding Bacteria
? Myxobacteria have distinct growth morphology
Myxococcus xanthus on agar
Myxococcus fulvus
slime tracks on agar
Fruiting body of
stigmatella aurantiaca
Gliding Bacteria
Fruiting body formation in Chondromyces crocatus
Early stage
Stalk formation
Three stages in head formation
Mature fruiting bodies
Sheathed Bacteria
? Filamentous organisms with a unique life cycle involving
formation of flagellated swarmer cells within a long tube or
sheath
? Under unfavorable conditions,the swarmer cells move out and
become dispersed to new environments,leaving behind the empty
sheath
Sphaerotilus natansActive growth stage
Swarmer cells leaving the sheath
Swarmer cell
Pseudomonads
? Purple bacteria (Proteobacteria),gram-negative
? Polar flagella,aerobic,grow at neutral pH mesophilically
? Chemoorganotrophic,never show a fermentative metabolism
? P,aeruginosa is opportunistic pathogen,some are plant pathogens
Pseudomonas have broad substrate
utilization,some produce polyhydroxy-
butyrate and some synthesize medium-
chain-length polyhydroxyalkanoates,
have been studied in our lab
The Entner-Doudoroff pathway,
the major means of glucose catabolism
in pseudomonads
Free-Living Aerobic Nitrogen-Fixing Bacteria
? Large,gram-negative,obligately aerobic rods,capable of fixing N2 nonsymbiotically
? Azotobacter has the highest respiratory rate of any living organism (purple bacteria)
? Azotobacter cells are very large,almost the size of yeasts,produce cysts
Vegatative cells of Azotobacter vinelandii
Cysts
Azotobacter cysts have low
endogenous respiration and are
resistant to desiccation,
mechanical disintegration,and
UV as well as ionizing radiation
however,they are not especially
heat-resistant
Free-Living Aerobic Nitrogen-Fixing Bacteria
? Major genera,Azotobacter,Azomonas,
Azospirillum and Beijerinckia,Derxia
Colonies of Beijerinckia species growing on a carbohydrate-containing medium
Derxia gummosa encased in slime
Free-Living Aerobic Nitrogen-Fixing Bacteria
? Acid-tolerant,free-living N2-fixing Bacteria
Acid-tolerant,free-living N2-fixing bacteria
Beijerinckia indica
Derxia gummosa
PHB
Acetic Acid Bacteria
? Purple bacteria,gram-negative,aerobic,motile rods,tolerance to low pH
? Carry out incomplete oxidation of alcohols,leading to the accumulation of organic
acids as end products
? With ethanol as a substrate,acetic acid is produced
Acetobacter aceti on calcium carbonate agar
containing ethanol as energy source,The clearing
around the colonies due to the dissolution of calcium
carbonate by the acetic acid produced by the bacteria
Classified as Gluconobacter
Can carry out incomplete
oxidation of higher alcohol
and sugars:
Glucose Gluconic acid
Galactose Galactonic acid
Arabinose Arabonic acid
Sorbitol Sorbose
Ascobic acid
Zymomonas and Chromobacterium
? Facultatively aerobic gram-negative rods,beta purple bacteria
? Chromobacterium violaceum produces a purple pigment violacein,a water-insoluble
pigment that has antibiotic properties and is produced only from tryptophan
? Zymomonas carries out fermentation of sugar to ethanol,used in beverage industry.
A large colony of Chromobacterium violaceum
growing among other colonies on an agar plate
Pigment violacein produced by
various species of the genus
Chromobacterium
Vibrio and Related Genera
Gram-negative,facultatively aerobic rods and curved rods
that possess a fermentative metabolism
Most are aquatic,
The Group contains Vibrio,Aeromonas,Photobacterium
Some can emit light (luciferase),these are associated with fish.
and Plesiomonas
Sulfate- and Sulfur-Reducing Bacteria
Representative Sulfate-reducing and sulfur-reducing bacteria
Most are Delta Purple Bacteria
Desulfovibrio desulfuricans
Desulfonema limicola
Desulfobacter postgatei
Desulfobulbus propionicus
Desulfosarcina variabilis
Desulfuromonas acetoxidans
Sulfur-reducing bacteria
Sulfate-Reducing Bacteria
? Strict anaerobes,
? Divided into two broad physiological subgroups:
? Genera in Group I (Desulfovibrio,Desulfomonas,
Desulfotomaculum,Desulfobulbus)
? utilize lactate,pyruvate,ethanol,or certain fatty acids as
carbon and energy sources,reducing sulfate to hydrogen
sulfide
? Genera in Group II (Desulfococcus,Desulfosarcina,
Desulfonema,Desulfonema)
? specialize in the oxidation of fatty acids,particularly
acetate,reducing sulfate to sulfide
? Growth and reduction of sulfate by Desulfotomaculum in certain
canned foods leads to a type of spoilage called sulfide stinker,
? Habitants of anoxic aquatic and terrestrial environments
Sulfur-Reducing Bacteria
? Able to reduce elemental sulfur to sulfide
? Unable to reduce sulfate to sulfide
? Obligate anaerobes
? Utilize only sulfur as an electron acceptor
? Also referred to as dissimilatory sulfur-
reducing bacteria
? Members of the genus Desulfuromonas can
grow anaerobically by coupling the oxidation of
substrates such as acetate to ethanol to the
reduction of elemental sulfur to hydrogen
sulfide
Homoacetogenic Bacteria
? Obligate anaerobes
? Gram-positive
? CO2 as a terminal electron acceptor
? Acetate as the sole product of anaerobic respiration
? Acetyl-CoA pathway convert CO2 to acetate
? Typical species,Acetobacterium woodii and
Clostridium aceticum
Homoacetogenic Bacteria
Mechanism of
autotrophy in
homoacetogenic,
sulfate-reducing
and methanogenic
bacteria
Reactions of the Acetyl-CoA Pathway
Budding and Appendaged (Prosthecate) Bacteria
Asticcacaulis biprosthecum Ancalomicrobium adetum
Ancalochloris perfilievii
Stella
Budding and Appendaged (Prosthecate) Bacteria
? Contain various kinds of cytoplasmic extrusions:
? Stalk
? Hyphae
? Appendages
? These kinds of extrusions,which are smaller in diameter
than mature cell,contain cytoplasma,and are bounded by
the cell wall,are called prosthecae (singular prostheca)
? Unequal cell growth,such as polar growth
? Majority is purple bacteria except Planctomyces and Pirella
which are unusual as their cell walls consist mainly of
protein
? Most are aquatic,many live attach to surfaces using
prosthecae
? A stalk is usually a prostheca except in Planctomyces
Budding and Appendaged (Prosthecate) Bacteria
Contrast between cell division
in conventional bacteria and in
budding and stalked bacteria
Budding and Appendaged (Prosthecate) Bacteria
A Caulobacter rosette,The five cells are
attached by their stalks (prosthecae)
Budding and Appendaged (Prosthecate) Bacteria
Stages in the Hyphomicrobium cell cycle
Budding and Appendaged (Prosthecate) Bacteria
Physiology and Ecology
? Hyphomicrobium is a methylotrophic bacteria,widespread in
freshwater,marine and terrestrial habitates.
Photomicrographs of cells of
Hyphomicrobium
Spirilla,Bdellovibrio
? Preying on other bacteria
? Attack and develop intraperiplasmically
? A wide variety of gram-negative bacteria
can be attacked by a single Bdellovibrio
species
? Gram-positive cells are not attacked
? Obligate aerobe,purple bacteria (delta
group)
Spirilla,Bdellovibrio bacteriovorus
Developmental Cycle
SpirillaSpirillum volutans
Spirillum volutans
Spirosoma linguale
Intestinal spirillum
Purple bacteria
Gram-negative
The genus Spirillum
includes only S,volutans
Spirillum volutans is a
large bacteria,micro-
aerobic
Azospirillum lipoferum is a
nitrogen-fixing organism,It
can form a loose symbiotic
relationship with tropical
grasses and grain crops
Aquaspirillum magnetotacticum
has magnetotaxis ability
Spirilla
? Aquaspirillum
magnetotacticum
contains particles of
Fe3O4 (magnetite)
called magnetosomes
arranged in a chain
Auqasirillum magnetotacticum
Spirilla,Bdellovibrio
Bdellovibrio bacteriovorus
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:
? Proteus
? Citrobacter
? Edwardsiella
? Salmonella
? Escherichia
? Shigella
? Butanediol Producers
? Klebsiella
? Enterobacter
? Serratia
? Erwinia
? Hafnia
Facultatively
Aerobic Gram-
Negative 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
Kingdom II,Gram-Positive Bacteria
? Nonsporulating,Low GC,Gram-Positive Bacteria
? Endospore-Forming,Low GC,Gram-Positive
Bacteria
? Cell-Wall Less Low GC,Gram-Positive Bacteria,
The Mycoplasmas
? High GC,Gram-Positive Bacteria,Coryneform
and Propionic Acid Bacteria
? High GC,Gram-Positive Bacteria,Mycobacterium
? Filamentous,High GC,Gram-Positive Bacteria,
the Actinomycetes
Gram-Positive Bacteria,Cocci
? Clostridium (endospore formers)
? Lactic Acid Bacteria
? Most are Gram-Positive Cocci
? Actinomycetes
? Propionibacterium
Gram-Positive Bacteria,Cocci
? 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
Sarcina
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 Clostridia consume sugar and produce butyric acid
? Some Clostridia produce acetone and butanol
? Some Clostridia 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,club-
shaped 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,
distinguished 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
microorganisms
on a crowded
plate
streptomycetes
Bacillus
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom III,Cyanobacteria,
Prochlorophytes and Chloroplasts
Cyanobacteria,Diversity
? A large and heterogeneous group of phototrophic bacteria
? Oxygenic phototrophs,Bergey’s Manual has divided them into 5 major groups
? Contain unsaturated fatty acids with two or more double bonds instead of one in
other bacteria.
Unicellular Gloeothece
Colonial Dermocarpa
Filamentous,Oscillatoria Filamentous heterocystous Anabaena
Filamentous branching Fischerella
Similar to gram-positive bacteria.
All cyanobacteria have chlorophyll a
All have biliprotein pigments:
Phycobilins,or Phycoerythrin
Cyanobacteria
Structural variations,gas vesicles and heterocysts
? Gas vesicles,provide flotation,so the cells
will remain where there is most light.
? Heterocysts,rounded,distributed regularly
along a filament or at one end of a filament,
are the sole sites of nitrogen fixation in
heterocystous cyanobacteria
Heterocysts in
cyanobacterium
Anabaena
Prochlorophytes
? Prokaryotic oxygenic phototrophs that contain
chlorophyll a and b but do not have phycobilins.
? Resemble both cyanobacteria and the plant chloroplast.
The first prochlorophyte discovered
is Prochloron,has extensive thylakoid
membrane system similar to chloroplast
Filamentous prochlorophyte Prochlorothrix
Prochlorophytes,cyanobacteria and
the plant chloroplasts share a common ancestor
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom IV,Chlamydia
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?
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom V,Planctomyces/Pirella
? Planctomyces,A phylogenetically unique
stalked bacterium
? Planctomyces is a stalked bacterium
? The stalk is made of protein only,no cell wall
? They lack peptidoglycan wall,have protein wall
? A budding bacterium
? Typical facultatively aerobic chemoorganotrophs
? Aquatic inhabitant.
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom VI,
Bacteroids/Flavobacteria
?Bacteroides
?Flavobacterium
?Cytophaga
Bacteroides
? Obligately anaerobic,Non-sporing
? Commensals,inhabitant of human
intestinal tract and other animals
? The most important anaerobic
bacteria associated with human
infections
? Synthesize sphingolipids (commonly
found in mammalian tissues)
Flavobacteria
? Aquatic habitates (both fresh water
and marine)
? Mostly they are glucose utilizers
? Only F,meningitis is pathogenic
Cytophaga
? Long,slender rods
? Move by gliding
? digest polysaccharides (cellulose,
agar,chitin) using membrane
banded cellulase
? Obligately aerobic
? Cause fish diseases.
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom VII,Green Sulfur Bacteria
?Chlorobium
?Other Green Sulfur Bacteria
Purple and Green (Anoxygenic Phototrophic) Bacteria
Green sulfur bacteria
? Morphologically diverse (nonmotile rods,spirals,spheres,motile
filamentous gliding,prosthecae);
? Some living planktonically in lakes possess gas vesicles;
? Strictly anaerobic;
? Obligate phototrophic;
? Most can assimilate simple organic substances (acetate,propionate,
pyruvate and lactate)for phototrophic growth provided that a
reduced sulfur compound is present as a sulfur source;
Chlorobium limicola
Pelodictyron clathratiforme
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom VIII,Tightly Coiled
Bacteria,The Spirochetes
Spirochetes
? Typically slender,flexuous,helical in shape,often rather long
? Axial fibrils or axial filaments are attached to the cell poles and
wrapped around the coiled protoplasmic cylinder.
? Both the axial fibrils and the protoplasmic cylinder are
surrounded by a three-layered membrane called the outer sheath
or outer cell envelope
Spirochaeta stenostrepta
Spirochaeta plicatilis
Treponema pallidum
causes syphilis diseases
Spirochetes
? Arrangement of the protoplasmic cylinder,axial fibrils,and external sheath
? The manner in which the rotation of the rigid axial fibril can generate rotation.
Spirochaeta zuelzerae
Spirochetes,Classification
? Six genera (based on habitat,pathogenicity,and morphological,
physiological characteristics):
? Spirochaeta
? Cristispira
? Treponema (Host in human,causes sexual disease syphilis)
? Leptospira (L,Interrogans causes nephritis and jaundice)
? Leptonema
? Borrelia (B,recurrentis causes relapsing fever)
Cristispira
Spirochetes
? Morphology of Treponema saccharophilum
Treponema saccharophilum
Kingdom IX,Deinococci
?Deincoccus
?Thermus
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.
Thermus aquaticus
? Thermophilic chemoorganotrophic
? Tag DNA polymerase
? Ornitine is present in place of
diaminopimelic acid in cell wall.
? Aerobic
Kingdom X,The Green Nonsulfur Bacteria
?Chloroflexus
?Heliothrix
Purple and Green (Anoxygenic Phototrophic) Bacteria
Green nonsulfur bacteria
? Chloroflexus has been given the designation green nonsulfur
bacterium;
? able to grow chemoorganotrophically in the dark under aerobic
conditions;
? able to grow phototrophically on a wide variety of sugars,amino
acids,and organic acids;
? able to grow phototrophically with H2S or H2 and CO2;
? best grow photoheterotrophically;
Chloroflexus aurantiacus
Oscillochloris
Oscillochloris
Purple and Green (Anoxygenic Phototrophic) Bacteria
Heliobacteria
? Phylogenetically separate group of anoxygenic phototrophic
bacteria that contain bacteriochlorophyll g;
? Consisting of
? Heliobacterium
? Heliophilum
? Heliobacillus
? Strictly anaerobic phototrophs;
? Unable to grow by respiratory means;
? Similarity between Bchl g and Chlorophyll a (modified form of
hydroxychlorophyll a);
Heliobacillus mobilis
Purple and Green (Anoxygenic Phototrophic) Bacteria
A Comparison of electron flow in green sulfur,heliobacteria and purple bacteria
Bchl a Bchl g
Purple and Green (Anoxygenic Phototrophic) Bacteria
Ecology
Purple sulfur bacteria
from a stratified lake
Green sulfur bacteria
from a stratified lake
Purple and Green (Anoxygenic Phototrophic) Bacteria
Ecology
Vertical stratification
of purple sulfur
bacteria (Amoebabacter
purpureus in a
CanadianLake
A syringe sampling
device that can collect
water at intervals
The phototrophic bacterium
forms a layer just at the top
of the anoxic zone
Membrane filters
through which
were passed water
samples taken at
varying depth
Purple and Green (Anoxygenic Phototrophic) Bacteria
Ecology
Massive accumulation of purple sulfur
bacteria,Thiopedia roseopersicinia in a
spring in Madison,The green color is
from cells of alga Spirogyra
Cross-section through a bacterial mat,
top,cyanobacteria;
pink,phototrophic purple sulfur bacteria
black,sulfate-reducing bacteria
peach,Bchl b containing cells of Thiocapsa
Kingdom XI,XII,and XIII,
Hyperthermophiles
? Thermotoga and Thermodesulfobacterium
? Aquifex and Relatives
Thermotoga
? rod-shape hyperthermophilic
? growth optimal 80oC,maximal 90oC
? contain sheath-like envelope
? non-sporing
? anaerobic fermentative
chemoorganotroph
? isolated from terrestrial hot springs
and marine hydrothermal vents
Thermodesulfobacterium
? Thermophilic
? Sulfate-reducing bacteria
? Growth optimal 70oC
? The most thermophilic of all known sulfate-
reducing bacteria
? Ether-linked lipids in the cell membrane,
contain features of both the Archaea and the
Bacteria
Aquifex
? Obligately chemolithotrophic
? Autotrophic hyperthermophile
? Grow optimal at 85oC,maximal 95oC
? The most thermophilic of all known bacteria
? Utilize H2,S0 or S2O32- as electron donors
? O2 or NO3- as electron acceptors
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Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom I,Proteobacteria
? Purple Phototrophic Bacteria
? The Nitrifying Bacteria
? Sulfur- and Iron-Oxidizing Bacteria
? Methanotrophs and Methylotrophs
? Pseudomonas and Pseudomonads
? Acetic Acid Bacteria
? Free-Living Aerobic Nitrogen-Fixing Bacteria
? Neisseria,Chromobacterium,and Relatives
? Enteric Bacteria
? Vibrio and Photobacterium
? Rickettsia
? Spirilla
? Sheathed Protesbacteria,Sphaerotilus and Leptothrix
? Budding and Prosthecate/Stalked Bacteria
? Gliding Myxobacteria
? Sulfate- and Sulfur-Reducing Proteobacteria
The Purple Bacteria,also called Proteobacteria is the
largest and most physiological diverse of all bacteria
Purple and Green (Anoxygenic Phototrophic) Bacteria
? Purple Bacteria,
? Bacteriochlorophylls a,b
? Anoxygenic photosynthesis
? One photosystem
? Green Bacteria:
? Bacteriochlorophylls c,d or e
? Anoxygenic photosynthesis
? One photosystem
? Cyanobacteria:
? Bacteriochlorophyll a
? Oxygenic photosynthesis
? Two photosystems
Purple and Green (Anoxygenic Phototrophic) Bacteria
Bacteriochlorophylls
? Bacteriochlorophylls differ
in substituents on various
parts of the porphyrin ring;
? The various modifications
lead to changes in the
absorption spectra of the
bacteriochlorophylls;
? From the long-wavelength
maximum,the identification
of the bacteriochlorophyll
can be made.
Purple and Green (Anoxygenic Phototrophic) Bacteria
Classification
? Anoxygenic phototrophic bacteria are classified
based on their bacteriochlorophylls and
photosynthetic membrane systems into three major
groups:
? Purple Bacteria (Nonsulfur purple,Purple sulfur bacteria)
? Green Bacteria (Green sulfur,green nonsulfur bacteria)
? Heliobacteria
? Anoxygenic phototrophic bacteria also produce
carotenoid pigments,Therefore,the colors of the
bacteria are the combination of bacterio-
chlorophylls and carotenoid pigments
Purple and Green (Anoxygenic Phototrophic) Bacteria
Classification
Purple and Green (Anoxygenic Phototrophic) Bacteria
Carotenoids
Carotenoid-less
mutant,the actual
Bchl a color
Carotenoid-less
mutant
Purple and Green (Anoxygenic Phototrophic) Bacteria
Photosynthetic Membrane Systems
Differences between green and purple bacteria in the Photosynthetic Membrane Systems
In purple bacteria,photosynthetic pigments are parts of the internal membane (lamellae).
In green bacteria,photosynthetic apparatus consists of a series of cylindrically shaped
structures called chlorosomes underlaying and attached to the cytoplasmic membrane.
In heliobacteria,bacteriochlorophyll is associated with the cytoplasmic membrane
Purple bacteria
Green Bacteria
Heliobacteria
Purple and Green (Anoxygenic Phototrophic) Bacteria
Nonsulfur purple bacteria
? can only used sulfide at a low concentration;
? have great photoheterotrophic abilities;
? some have ability to utilize methanol as sole carbon
source for phototrophic growth;
? most are active N2 fixers.
Rhodospirilum fulvum
Rhodopseudomonas acidophila
Rhodobacter sphaeroides
Rhodopila globiformis
Rhodocyclus purpureus
Rhodomicrobium vannielii
Purple and Green (Anoxygenic Phototrophic) Bacteria
Purple sulfur bacteria
? deposit sulfur and oxidize it to sulfate,
? commonly found in anoxic zones of lakes as well as
in sulfur springs,
? Ectothiorhodospira deposits sulfur externally,grows
halophilically and at high pH,found in saline lakes,
saltern,and bodies of water high in salt,
? limited ability to utilize organic compounds as C
source for phototrophic growth
? Thiocapsa grows chemoorganotrophically on
acetate
Purple and Green (Anoxygenic Phototrophic) Bacteria
Purple sulfur bacteria
Chromatium okenii
Thiospirillum jenense
Thiocapsa Thiopedia rosea
Chemolithotrophs,Nitrifying Bacteria
? Bacteria able to grow chemolithotrophically at the
expense of reduced inorganic nitrogen compounds
? (1) Nitrosifying bacteria:
? NH3 + O2 NO2- + H+ + H2O
? (2) Nitrifying bacteria:
? NO2- + O2 NO3-
? No chemolithotroph is known that will carry out the
complete oxidation of ammonia to nitrate
? (1) Nitrosomonas,Nitrosococcus,Nitrosospira
? (2) Nitrobacter,Nitrospira,Nitrococcus
? They are members of the purple bacteria
Chemolithotrophs,Sulfur- and Iron-Oxidizing Bacteria
? Members of purple bacteria
? Have ability to grow chemolithotrophically on
reduced sulfur compounds
? Only six genera,Thiobacillus,Thiosphaera,
Thiomicrospira,Thermothrix,Beggiatoa and
Sulfolobus (Archaea) have been cultured.
? Two groups,neutrophilic and acidophilic
? The acidophilic group can grow
chemolithotrophically using ferrous iron as electron
donor
? Thiobacillus ferrooxidans has been used for leaching
Chemolithotrophs,Hydrogen-Oxidizing Bacteria
? Capable of growing with H2 as sole electron donor and
O2 as electron acceptor,
? Many of them can also grow autotrophically using
Calvin cycle to fix CO2,
? All contain hydrogenase for binding H2 and use it to
produce ATP,
? Can grow both chemoorganotrophs and
chemolithotrophs,
? Most are obligate aerobes,but prefer microaerobic
conditions when growing chemolithotrophically on H2,
? Some can grow on CO,
? Best studied Alcaligenes eutrophus,or Ralstonia
eutropha
Methanotrophs and Methylotrophs
? Methanotrophs,
? utilize methane,and/or a few other one-carbon
compounds as sole source of carbon
? aerobes (Purple Bacteria)
? widespread in nature in soil and water
? possess methane monooxygenase
? obligate C1 utilizers
? contain large amount of sterols in internal membrane
? Methylotrophs:
? utilize methane and other one-carbon compounds as
electron donors for energy generation and as sole
sources of carbon
? many can utilize organic acids,ethanols and sugars
Methanotrophs and Methylotrophs
Classification
? Based on internal cell structure and carbon
assimilation pathway:
? Type I,ribulose monophosphate cycle,lack a
complete TCA cycle
? Type II,Serin pathway
Methylosinus,Type II Methylococcus capsulatus,Type I
Methanotrophic Symbionts of Animals
? Intact mussels as well as isolated mussel
gill tissue consume methane at high rates
in the presence of O2 due to symbiotic
methanotrophic bacteria presence.
Symbiotic methanotrophs in the gill tissue of a marine mussel living
near hydrocarbon seeps in the Gulf of Mexico
Gliding Bacteria
? No flagella but can move when in contact with surfaces
? Gram-negative,purple bacteria,some are Bacteroides-Flavobacterium
? Myxobacteria can form multicellular structures called fruiting bodies
Beggiatoa
Thioploca
Filamentou sulfur-oxidizing
bacteria in a small stream
Sulfur-oxidizing bacteria
Gliding Bacteria
Gliding Bacteria,Leucothrix
? Chemoorganotrophic,requires both H2S and an organic compounds for growth
? Form gonidia under unfavorable conditions
? May aggregate to form rosette when gonidia have high concentration
Leucothrix mucor
Gliding Bacteria,Fruiting Myxobacteria
Myxococcus fulvus
Mellitangium erectum
Myxococcus stipitatus
Chondromyces crocatus
Stigmatella aurantiaca
Exhibit the most
complex behavioral
patterns and life
cycles of all known
prokaryotes
Gliding Bacteria,Fruiting Myxobacterium
Gliding myxobacterium
Stigmatella aurantiaca
Have rather large
chromosome size
Rely on lysis of other
bacteria for nutritions
Myxospores are more
resistant to drying,
sonic vibration,UV
and heat.
Usually colored by
carotenoid pigments
Gliding Bacteria
Gliding Bacteria
? Myxobacteria have distinct growth morphology
Myxococcus xanthus on agar
Myxococcus fulvus
slime tracks on agar
Fruiting body of
stigmatella aurantiaca
Gliding Bacteria
Fruiting body formation in Chondromyces crocatus
Early stage
Stalk formation
Three stages in head formation
Mature fruiting bodies
Sheathed Bacteria
? Filamentous organisms with a unique life cycle involving
formation of flagellated swarmer cells within a long tube or
sheath
? Under unfavorable conditions,the swarmer cells move out and
become dispersed to new environments,leaving behind the empty
sheath
Sphaerotilus natansActive growth stage
Swarmer cells leaving the sheath
Swarmer cell
Pseudomonads
? Purple bacteria (Proteobacteria),gram-negative
? Polar flagella,aerobic,grow at neutral pH mesophilically
? Chemoorganotrophic,never show a fermentative metabolism
? P,aeruginosa is opportunistic pathogen,some are plant pathogens
Pseudomonas have broad substrate
utilization,some produce polyhydroxy-
butyrate and some synthesize medium-
chain-length polyhydroxyalkanoates,
have been studied in our lab
The Entner-Doudoroff pathway,
the major means of glucose catabolism
in pseudomonads
Free-Living Aerobic Nitrogen-Fixing Bacteria
? Large,gram-negative,obligately aerobic rods,capable of fixing N2 nonsymbiotically
? Azotobacter has the highest respiratory rate of any living organism (purple bacteria)
? Azotobacter cells are very large,almost the size of yeasts,produce cysts
Vegatative cells of Azotobacter vinelandii
Cysts
Azotobacter cysts have low
endogenous respiration and are
resistant to desiccation,
mechanical disintegration,and
UV as well as ionizing radiation
however,they are not especially
heat-resistant
Free-Living Aerobic Nitrogen-Fixing Bacteria
? Major genera,Azotobacter,Azomonas,
Azospirillum and Beijerinckia,Derxia
Colonies of Beijerinckia species growing on a carbohydrate-containing medium
Derxia gummosa encased in slime
Free-Living Aerobic Nitrogen-Fixing Bacteria
? Acid-tolerant,free-living N2-fixing Bacteria
Acid-tolerant,free-living N2-fixing bacteria
Beijerinckia indica
Derxia gummosa
PHB
Acetic Acid Bacteria
? Purple bacteria,gram-negative,aerobic,motile rods,tolerance to low pH
? Carry out incomplete oxidation of alcohols,leading to the accumulation of organic
acids as end products
? With ethanol as a substrate,acetic acid is produced
Acetobacter aceti on calcium carbonate agar
containing ethanol as energy source,The clearing
around the colonies due to the dissolution of calcium
carbonate by the acetic acid produced by the bacteria
Classified as Gluconobacter
Can carry out incomplete
oxidation of higher alcohol
and sugars:
Glucose Gluconic acid
Galactose Galactonic acid
Arabinose Arabonic acid
Sorbitol Sorbose
Ascobic acid
Zymomonas and Chromobacterium
? Facultatively aerobic gram-negative rods,beta purple bacteria
? Chromobacterium violaceum produces a purple pigment violacein,a water-insoluble
pigment that has antibiotic properties and is produced only from tryptophan
? Zymomonas carries out fermentation of sugar to ethanol,used in beverage industry.
A large colony of Chromobacterium violaceum
growing among other colonies on an agar plate
Pigment violacein produced by
various species of the genus
Chromobacterium
Vibrio and Related Genera
Gram-negative,facultatively aerobic rods and curved rods
that possess a fermentative metabolism
Most are aquatic,
The Group contains Vibrio,Aeromonas,Photobacterium
Some can emit light (luciferase),these are associated with fish.
and Plesiomonas
Sulfate- and Sulfur-Reducing Bacteria
Representative Sulfate-reducing and sulfur-reducing bacteria
Most are Delta Purple Bacteria
Desulfovibrio desulfuricans
Desulfonema limicola
Desulfobacter postgatei
Desulfobulbus propionicus
Desulfosarcina variabilis
Desulfuromonas acetoxidans
Sulfur-reducing bacteria
Sulfate-Reducing Bacteria
? Strict anaerobes,
? Divided into two broad physiological subgroups:
? Genera in Group I (Desulfovibrio,Desulfomonas,
Desulfotomaculum,Desulfobulbus)
? utilize lactate,pyruvate,ethanol,or certain fatty acids as
carbon and energy sources,reducing sulfate to hydrogen
sulfide
? Genera in Group II (Desulfococcus,Desulfosarcina,
Desulfonema,Desulfonema)
? specialize in the oxidation of fatty acids,particularly
acetate,reducing sulfate to sulfide
? Growth and reduction of sulfate by Desulfotomaculum in certain
canned foods leads to a type of spoilage called sulfide stinker,
? Habitants of anoxic aquatic and terrestrial environments
Sulfur-Reducing Bacteria
? Able to reduce elemental sulfur to sulfide
? Unable to reduce sulfate to sulfide
? Obligate anaerobes
? Utilize only sulfur as an electron acceptor
? Also referred to as dissimilatory sulfur-
reducing bacteria
? Members of the genus Desulfuromonas can
grow anaerobically by coupling the oxidation of
substrates such as acetate to ethanol to the
reduction of elemental sulfur to hydrogen
sulfide
Homoacetogenic Bacteria
? Obligate anaerobes
? Gram-positive
? CO2 as a terminal electron acceptor
? Acetate as the sole product of anaerobic respiration
? Acetyl-CoA pathway convert CO2 to acetate
? Typical species,Acetobacterium woodii and
Clostridium aceticum
Homoacetogenic Bacteria
Mechanism of
autotrophy in
homoacetogenic,
sulfate-reducing
and methanogenic
bacteria
Reactions of the Acetyl-CoA Pathway
Budding and Appendaged (Prosthecate) Bacteria
Asticcacaulis biprosthecum Ancalomicrobium adetum
Ancalochloris perfilievii
Stella
Budding and Appendaged (Prosthecate) Bacteria
? Contain various kinds of cytoplasmic extrusions:
? Stalk
? Hyphae
? Appendages
? These kinds of extrusions,which are smaller in diameter
than mature cell,contain cytoplasma,and are bounded by
the cell wall,are called prosthecae (singular prostheca)
? Unequal cell growth,such as polar growth
? Majority is purple bacteria except Planctomyces and Pirella
which are unusual as their cell walls consist mainly of
protein
? Most are aquatic,many live attach to surfaces using
prosthecae
? A stalk is usually a prostheca except in Planctomyces
Budding and Appendaged (Prosthecate) Bacteria
Contrast between cell division
in conventional bacteria and in
budding and stalked bacteria
Budding and Appendaged (Prosthecate) Bacteria
A Caulobacter rosette,The five cells are
attached by their stalks (prosthecae)
Budding and Appendaged (Prosthecate) Bacteria
Stages in the Hyphomicrobium cell cycle
Budding and Appendaged (Prosthecate) Bacteria
Physiology and Ecology
? Hyphomicrobium is a methylotrophic bacteria,widespread in
freshwater,marine and terrestrial habitates.
Photomicrographs of cells of
Hyphomicrobium
Spirilla,Bdellovibrio
? Preying on other bacteria
? Attack and develop intraperiplasmically
? A wide variety of gram-negative bacteria
can be attacked by a single Bdellovibrio
species
? Gram-positive cells are not attacked
? Obligate aerobe,purple bacteria (delta
group)
Spirilla,Bdellovibrio bacteriovorus
Developmental Cycle
SpirillaSpirillum volutans
Spirillum volutans
Spirosoma linguale
Intestinal spirillum
Purple bacteria
Gram-negative
The genus Spirillum
includes only S,volutans
Spirillum volutans is a
large bacteria,micro-
aerobic
Azospirillum lipoferum is a
nitrogen-fixing organism,It
can form a loose symbiotic
relationship with tropical
grasses and grain crops
Aquaspirillum magnetotacticum
has magnetotaxis ability
Spirilla
? Aquaspirillum
magnetotacticum
contains particles of
Fe3O4 (magnetite)
called magnetosomes
arranged in a chain
Auqasirillum magnetotacticum
Spirilla,Bdellovibrio
Bdellovibrio bacteriovorus
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:
? Proteus
? Citrobacter
? Edwardsiella
? Salmonella
? Escherichia
? Shigella
? Butanediol Producers
? Klebsiella
? Enterobacter
? Serratia
? Erwinia
? Hafnia
Facultatively
Aerobic Gram-
Negative 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
Kingdom II,Gram-Positive Bacteria
? Nonsporulating,Low GC,Gram-Positive Bacteria
? Endospore-Forming,Low GC,Gram-Positive
Bacteria
? Cell-Wall Less Low GC,Gram-Positive Bacteria,
The Mycoplasmas
? High GC,Gram-Positive Bacteria,Coryneform
and Propionic Acid Bacteria
? High GC,Gram-Positive Bacteria,Mycobacterium
? Filamentous,High GC,Gram-Positive Bacteria,
the Actinomycetes
Gram-Positive Bacteria,Cocci
? Clostridium (endospore formers)
? Lactic Acid Bacteria
? Most are Gram-Positive Cocci
? Actinomycetes
? Propionibacterium
Gram-Positive Bacteria,Cocci
? 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
Sarcina
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 Clostridia consume sugar and produce butyric acid
? Some Clostridia produce acetone and butanol
? Some Clostridia 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,club-
shaped 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,
distinguished 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
microorganisms
on a crowded
plate
streptomycetes
Bacillus
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom III,Cyanobacteria,
Prochlorophytes and Chloroplasts
Cyanobacteria,Diversity
? A large and heterogeneous group of phototrophic bacteria
? Oxygenic phototrophs,Bergey’s Manual has divided them into 5 major groups
? Contain unsaturated fatty acids with two or more double bonds instead of one in
other bacteria.
Unicellular Gloeothece
Colonial Dermocarpa
Filamentous,Oscillatoria Filamentous heterocystous Anabaena
Filamentous branching Fischerella
Similar to gram-positive bacteria.
All cyanobacteria have chlorophyll a
All have biliprotein pigments:
Phycobilins,or Phycoerythrin
Cyanobacteria
Structural variations,gas vesicles and heterocysts
? Gas vesicles,provide flotation,so the cells
will remain where there is most light.
? Heterocysts,rounded,distributed regularly
along a filament or at one end of a filament,
are the sole sites of nitrogen fixation in
heterocystous cyanobacteria
Heterocysts in
cyanobacterium
Anabaena
Prochlorophytes
? Prokaryotic oxygenic phototrophs that contain
chlorophyll a and b but do not have phycobilins.
? Resemble both cyanobacteria and the plant chloroplast.
The first prochlorophyte discovered
is Prochloron,has extensive thylakoid
membrane system similar to chloroplast
Filamentous prochlorophyte Prochlorothrix
Prochlorophytes,cyanobacteria and
the plant chloroplasts share a common ancestor
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom IV,Chlamydia
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?
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom V,Planctomyces/Pirella
? Planctomyces,A phylogenetically unique
stalked bacterium
? Planctomyces is a stalked bacterium
? The stalk is made of protein only,no cell wall
? They lack peptidoglycan wall,have protein wall
? A budding bacterium
? Typical facultatively aerobic chemoorganotrophs
? Aquatic inhabitant.
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom VI,
Bacteroids/Flavobacteria
?Bacteroides
?Flavobacterium
?Cytophaga
Bacteroides
? Obligately anaerobic,Non-sporing
? Commensals,inhabitant of human
intestinal tract and other animals
? The most important anaerobic
bacteria associated with human
infections
? Synthesize sphingolipids (commonly
found in mammalian tissues)
Flavobacteria
? Aquatic habitates (both fresh water
and marine)
? Mostly they are glucose utilizers
? Only F,meningitis is pathogenic
Cytophaga
? Long,slender rods
? Move by gliding
? digest polysaccharides (cellulose,
agar,chitin) using membrane
banded cellulase
? Obligately aerobic
? Cause fish diseases.
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom VII,Green Sulfur Bacteria
?Chlorobium
?Other Green Sulfur Bacteria
Purple and Green (Anoxygenic Phototrophic) Bacteria
Green sulfur bacteria
? Morphologically diverse (nonmotile rods,spirals,spheres,motile
filamentous gliding,prosthecae);
? Some living planktonically in lakes possess gas vesicles;
? Strictly anaerobic;
? Obligate phototrophic;
? Most can assimilate simple organic substances (acetate,propionate,
pyruvate and lactate)for phototrophic growth provided that a
reduced sulfur compound is present as a sulfur source;
Chlorobium limicola
Pelodictyron clathratiforme
The Bacteria
Phylogenetic tree of the major lineages
of Bacteria based on 16S ribosomal RNA
Sequence comparisons
Kingdom VIII,Tightly Coiled
Bacteria,The Spirochetes
Spirochetes
? Typically slender,flexuous,helical in shape,often rather long
? Axial fibrils or axial filaments are attached to the cell poles and
wrapped around the coiled protoplasmic cylinder.
? Both the axial fibrils and the protoplasmic cylinder are
surrounded by a three-layered membrane called the outer sheath
or outer cell envelope
Spirochaeta stenostrepta
Spirochaeta plicatilis
Treponema pallidum
causes syphilis diseases
Spirochetes
? Arrangement of the protoplasmic cylinder,axial fibrils,and external sheath
? The manner in which the rotation of the rigid axial fibril can generate rotation.
Spirochaeta zuelzerae
Spirochetes,Classification
? Six genera (based on habitat,pathogenicity,and morphological,
physiological characteristics):
? Spirochaeta
? Cristispira
? Treponema (Host in human,causes sexual disease syphilis)
? Leptospira (L,Interrogans causes nephritis and jaundice)
? Leptonema
? Borrelia (B,recurrentis causes relapsing fever)
Cristispira
Spirochetes
? Morphology of Treponema saccharophilum
Treponema saccharophilum
Kingdom IX,Deinococci
?Deincoccus
?Thermus
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.
Thermus aquaticus
? Thermophilic chemoorganotrophic
? Tag DNA polymerase
? Ornitine is present in place of
diaminopimelic acid in cell wall.
? Aerobic
Kingdom X,The Green Nonsulfur Bacteria
?Chloroflexus
?Heliothrix
Purple and Green (Anoxygenic Phototrophic) Bacteria
Green nonsulfur bacteria
? Chloroflexus has been given the designation green nonsulfur
bacterium;
? able to grow chemoorganotrophically in the dark under aerobic
conditions;
? able to grow phototrophically on a wide variety of sugars,amino
acids,and organic acids;
? able to grow phototrophically with H2S or H2 and CO2;
? best grow photoheterotrophically;
Chloroflexus aurantiacus
Oscillochloris
Oscillochloris
Purple and Green (Anoxygenic Phototrophic) Bacteria
Heliobacteria
? Phylogenetically separate group of anoxygenic phototrophic
bacteria that contain bacteriochlorophyll g;
? Consisting of
? Heliobacterium
? Heliophilum
? Heliobacillus
? Strictly anaerobic phototrophs;
? Unable to grow by respiratory means;
? Similarity between Bchl g and Chlorophyll a (modified form of
hydroxychlorophyll a);
Heliobacillus mobilis
Purple and Green (Anoxygenic Phototrophic) Bacteria
A Comparison of electron flow in green sulfur,heliobacteria and purple bacteria
Bchl a Bchl g
Purple and Green (Anoxygenic Phototrophic) Bacteria
Ecology
Purple sulfur bacteria
from a stratified lake
Green sulfur bacteria
from a stratified lake
Purple and Green (Anoxygenic Phototrophic) Bacteria
Ecology
Vertical stratification
of purple sulfur
bacteria (Amoebabacter
purpureus in a
CanadianLake
A syringe sampling
device that can collect
water at intervals
The phototrophic bacterium
forms a layer just at the top
of the anoxic zone
Membrane filters
through which
were passed water
samples taken at
varying depth
Purple and Green (Anoxygenic Phototrophic) Bacteria
Ecology
Massive accumulation of purple sulfur
bacteria,Thiopedia roseopersicinia in a
spring in Madison,The green color is
from cells of alga Spirogyra
Cross-section through a bacterial mat,
top,cyanobacteria;
pink,phototrophic purple sulfur bacteria
black,sulfate-reducing bacteria
peach,Bchl b containing cells of Thiocapsa
Kingdom XI,XII,and XIII,
Hyperthermophiles
? Thermotoga and Thermodesulfobacterium
? Aquifex and Relatives
Thermotoga
? rod-shape hyperthermophilic
? growth optimal 80oC,maximal 90oC
? contain sheath-like envelope
? non-sporing
? anaerobic fermentative
chemoorganotroph
? isolated from terrestrial hot springs
and marine hydrothermal vents
Thermodesulfobacterium
? Thermophilic
? Sulfate-reducing bacteria
? Growth optimal 70oC
? The most thermophilic of all known sulfate-
reducing bacteria
? Ether-linked lipids in the cell membrane,
contain features of both the Archaea and the
Bacteria
Aquifex
? Obligately chemolithotrophic
? Autotrophic hyperthermophile
? Grow optimal at 85oC,maximal 95oC
? The most thermophilic of all known bacteria
? Utilize H2,S0 or S2O32- as electron donors
? O2 or NO3- as electron acceptors
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