Download 3/2/12 Proteobacteria

Figure 17.1
Deferribacter
Cytophaga
Flavobacteria
Spirochetes
Planctomyces/
Pirellula
Verrucomicrobiaceae
Green sulfur
bacteria
Deinococci
Green nonsulfur
bacteria
Chlamydia
Cyanobacteria
Thermotoga
Actinobacteria
Firmicutes and Mollicutes
Gram-positive
bacteria
Thermodesulfobacterium
Nitrospira

Aquifex





© 2012 Pearson Education, Inc.
See Figure 17.2
Proteobacteria
17.1 Phylogenetic Overview of Bacteria
• Proteobacteria (Figure 17.2)
– A major lineage (phyla) of Bacteria
– Includes many of the most commonly
encountered bacteria
– Most metabolically diverse of all Bacteria
• Chemolithotrophy, chemoorganotrophy,
phototrophy
– Morphologically diverse
– Divided into five classes
• Alpha-, Beta-, Delta-, Gamma-, Epsilon-
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Figure 17.2
16S rRNA Gene Tree of Proteobacteria Proteobacterial
Classes
Bacillus
Nitrosococcus
Thermochromatium
Acidithiobacillus
Beggiatoa
Gamma
Pseudomonas
Vibrio
Escherichia
Methylobacter
Gallionella
Nitrosomonas
Methylophilus
Derxia
Beta
Ralstonia
Spirillum
Rhodocyclus
Thiobacillus
Neisseria
Methylobacterium
Nitrobacter
Rhodopseudomonas
Beijerinckia
Alpha
Paracoccus
Azotobacter
Rickettsia
Acetobacter
Zeta
Mariprofundus
Campylobacter
Sulfurimonas
Epsilon
Thiovulum
Wolinella
Desulfosarcina
Desulfovibrio
Delta
Myxococcus
Nitrospina
Major metabolisms
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Chemolithotrophy
Anoxygenic phototrophy
Methylotrophy
Sulfur compounds (H2S, S0, etc.)
Ferrous iron (Fe2)
Sulfate reduction
Nitrogen fixation
Ammonia (NH3) or nitrite (NO2)
Hydrogen (H2)
17.2 Purple Phototrophic Bacteria
• Purple phototrophic bacteria
– Carry out anoxygenic photosynthesis; no O2
evolved
– Contain bacteriochlorophylls and carotenoid
pigments (Figure 17.3)
– Produce intracytoplasmic photosynthetic
membranes with varying morphologies
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Figure 17.3
© 2012 Pearson Education, Inc.
Figure 17.4
© 2012 Pearson Education, Inc.
17.2 Purple Phototrophic Bacteria
• Purple sulfur bacteria
– Use hydrogen sulfide (H2S) as an electron
donor for CO2 reduction in photosynthesis
– Sulfide oxidized to elemental sulfur (S0) that is
stored as globules either inside or outside
cells
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Figure 17.5
© 2012 Pearson Education, Inc.
17.2 Purple Phototrophic Bacteria
• Purple sulfur bacteria (cont’d)
– Many can also use other reduced sulfur
compounds, such as thiosulfate (S2O32)
– All are Gammaproteobacteria
– Found in illuminated anoxic zones of lakes and
other aquatic habitats where H2S accumulates,
as well as sulfur springs (Figure 17.6)
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Figure 17.6
© 2012 Pearson Education, Inc.
17.2 Purple Phototrophic Bacteria
• Purple nonsulfur bacteria (Figure 17.7)
– Organisms able to use sulfide as an electron
donor for CO2 reduction
– Most can grow photoheterotrophically using
light as an energy source and organic
compounds as a carbon source
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Figure 17.7
© 2012 Pearson Education, Inc.
17.3 The Nitrifying Bacteria
• Nitrifying bacteria
– Able to grow chemolithotrophically at the expense
of reduced inorganic nitrogen compounds
– Nitrification (oxidation of ammonia to nitrate)
occurs as two separate reactions by different
groups of bacteria
– Many species have internal membrane systems
that house key enzymes in nitrification
– Highest numbers in habitats with large amounts of
ammonia
– Most are obligate chemolithotrophs and aerobes
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Figure 17.8
Reaction: NH3  1 12 O2
Reaction: NO2 
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1
2
NO2  H2O
O2
NO3
17.4 Sulfur- and Iron-Oxidizing Bacteria
• Sulfur-oxidizing bacteria
– Grow chemolithotrophically on reduced sulfur
compounds
– Some obligate chemolithotrophs possess special
structures that house Calvin cycle enyzmes
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Figure 17.9
© 2012 Pearson Education, Inc.
Figure 17.10
© 2012 Pearson Education, Inc.
17.5 Hydrogen-Oxidizing Bacteria
• Hydrogen-oxidizing bacteria
– Most can grow autotrophically with H2 as sole
electron donor and O2 as electron acceptor
(“knallgas” reaction)
– Contain one or more hydrogenase enzymes
that use H2 either to produce ATP or for
reducing power for autotrophic growth
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Figure 17.13
© 2012 Pearson Education, Inc.
17.6 Methanotrophs and Methylotrophs
• Methanotrophs
– Use CH4 and a few other one-carbon (C1)
compounds as electron donors and source of
carbon
– Widespread in soil and water
– Obligate aerobes
– Morphologically diverse
– Contain extensive internal membrane systems for
methane oxidation
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Figure 17.14
© 2012 Pearson Education, Inc.
17.7 Pseudomonas and the
Pseudomonads
• All genera within the pseudomonad group are
– Straight or curved rods with polar flagella
– Chemoorganotrophs
– Obligate aerobes
• Species of the genus Pseudomonas and
related genera can be defined on the basis of
phylogeny and physiological characteristics
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Figure 17.16
© 2012 Pearson Education, Inc.
17.7 Pseudomonas and the
Pseudomonads
• Pseudomonads
– Nutritionally versatile
– Ecologically important organisms in water and
soil
– Some species are pathogenic
• Includes human opportunistic pathogens and
plant pathogens
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17.8 Acetic Acid Bacteria
• Acetic acid bacteria
– Organisms that carry out complete oxidation
of alcohols and sugars
• Leads to the accumulation of organic acids as
end products
– Motile rods
– Aerobic
– High tolerance to acidic conditions
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17.8 Acetic Acid Bacteria
• Acetic acid bacteria (cont’d)
– Commonly found in alcoholic juices
• Used in production of vinegar
– Some can synthesize cellulose
– Colonies can be identified on CaCO3 agar
plates containing ethanol
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Figure 17.17
© 2012 Pearson Education, Inc.
17.10 Neisseria
• Neisseria and their relatives can be isolated
from animals, and some species of this group
are pathogenic
– N. gonorrheae and N. meningitidis
– Some of the most naturally competent bacteria
known
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Figure 17.21
© 2012 Pearson Education, Inc.
17.11 Enteric Bacteria
• Enteric bacteria (Figure 17.22)
– Phylogenetic group within the
Gammaproteobacteria
– Facultative aerobes
– Motile or nonmotile, nonsporulating rods
– Possess relatively simple nutritional
requirements
– Ferment sugars to a variety of end products
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Figure 17.22
© 2012 Pearson Education, Inc.
17.11 Enteric Bacteria
• Escherichia
– Universal inhabitants of intestinal tract of
humans and warm-blooded animals
• Synthesize vitamins for host
– Some strains are pathogenic
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17.11 Enteric Bacteria
• Salmonella and Shigella
– Closely related to Escherichia
– Usually pathogenic
– Salmonella characterized immunologically by
surface antigens
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17.11 Enteric Bacteria
• Proteus
– Genus containing rapidly motile cells; capable
of swarming (Figure 17.24)
– Frequent cause of urinary tract infections in
humans
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Figure 17.24
© 2012 Pearson Education, Inc.
17.12 Vibrio, Aliivibrio, and Photobacterium
• The Vibrio group
–
–
–
–
Cells are motile, straight or curved rods
Facultative aerobes
Fermentative metabolism
Best-known genera are Vibrio, Aliivibrio, and
Photobacterium
– Most inhabit aquatic environments
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Figure 17.26
© 2012 Pearson Education, Inc.
17.13 Rickettsias
• Rickettsias (Figure 17.27)
– Small, coccoid or rod-shaped cells
– Most are obligate intracellular parasites
– Causative agent of several human diseases
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Figure 17.27
© 2012 Pearson Education, Inc.
17.13 Rickettsias
• Wolbachia (Figure 17.28)
– Genus of rod-shaped Alphaproteobacteria
– Intracellular parasites of arthropod insects
• Affect the reproductive fitness of hosts
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17.14 Spirilla
• Spirilla (Figure 17.29)
– Group of motile, spiral-shaped Proteobacteria
– Key taxonomic features include
•
•
•
•
•
Cell shape and size
Number of polar flagella
Metabolism
Physiology
Ecology
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17.14 Spirilla
• Spirilla
– Bdellovibrio
•
•
•
•
•
Prey on other bacteria (Figure 17.31)
Two stages of penetration (Figure 17.32)
Obligate aerobes
Members of Deltaproteobacteria
Widespread in soil and water, including
marine environments
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Figure 17.31
© 2012 Pearson Education, Inc.
Figure 17.32
Release of progeny
Prey lysis
(2.5–4 h
postattachment)
Bdellovibrio
Prey
cytoplasm
Elongation
of Bdellovibrio
inside the
bdelloplast
Prey
40–60 min
Attachment
5–20 min
Bdelloplast
Penetration
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Prey periplasmic
space
17.16 Budding and Prosthecate/Stalked
Bacteria
• Budding and Prosthecate/Stalked Bacteria
– Large and heterogeneous group
– Primarily Alphaproteobacteria
– Form various kinds of cytoplasmic extrusions
bounded by a cell wall (collectively called
prosthecae; Figure 17.35)
– Cell division different from other bacteria
(Figure 17.36)
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Figure 17.36
I. Equal products of cell division:
Binary fission: most bacteria
II. Unequal products of cell division:
1. Simple budding: Pirellula, Blastobacter
2. Budding from Hyphae: Hyphomicrobium, Rhodomicrobium,
Pedomicrobium
3. Cell division of stalked organism: Caulobacter
4. Polar growth without differentiation of cell size:
Rhodopseudomonas, Nitrobacter, Methylosinus
© 2012 Pearson Education, Inc.