Figure 17.1 Deferribacter Cytophaga Flavobacteria Spirochetes
Planctomyces/ Pirellula Verrucomicrobiaceae Green sulfur bacteria
Deinococci Green nonsulfur bacteria Chlamydia Cyanobacteria
Thermotoga Actinobacteria Gram-positive bacteria Firmicutes and
Mollicutes Thermodesulfobacterium Figure 17.1 Some major phyla of
Bacteria based on 16S ribosomal RNA gene sequence comparisons.
Nitrospira Aquifex See Figure 17.2 Proteobacteria 2012 Pearson
Education, Inc. 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- 2012 Pearson
Education, Inc. Proteobacterial Classes
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 Ralstonia Beta
Spirillum Rhodocyclus Thiobacillus Neisseria Methylobacterium
Nitrobacter Rhodopseudomonas Beijerinckia Alpha Paracoccus
Azotobacter Rickettsia Acetobacter Mariprofundus Zeta Campylobacter
Figure 17.2 Phylogenetic tree of some key genera of Proteobacteria.
Sulfurimonas Epsilon Thiovulum Wolinella Desulfosarcina
Desulfovibrio Delta Myxococcus Nitrospina Major metabolisms
Chemolithotrophy Anoxygenic phototrophy Sulfur compounds (H2S, S0,
etc.) Methylotrophy Ferrous iron (Fe2) Sulfate reduction Ammonia
(NH3) or nitrite (NO2) Nitrogen fixation Hydrogen (H2) 2012 Pearson
Education, Inc. 17.2 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
2012 Pearson Education, Inc. Figure 17.3 Figure 17.3 Photograph of
liquid cultures of phototrophic purple bacteria showing the color
of species with various carotenoid pigments. 2012 Pearson
Education, Inc. Figure 17.4 Figure 17.4 Membrane systems of
phototrophic purple bacteria as revealed by the electron
microscope. 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 2012 Pearson Education, Inc. Figure 17.5 Figure 17.5
Bright-field and phase-contrast photomicrographs of purple sulfur
bacteria. 2012 Pearson Education, Inc. 17.2 Purple Phototrophic
Bacteria
Purple sulfur bacteria (contd) 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) 2012 Pearson Education, Inc. Figure 17.6
Figure 17.6 Blooms of purple sulfur bacteria.
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 2012 Pearson Education, Inc. Figure
17.7 Figure 17.7 Representatives of several genera of purple
nonsulfur bacteria. 2012 Pearson Education, Inc. 17.3 The
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
2012 Pearson Education, Inc. Reaction: Reaction: NH3 1 O2 NO2 H2O
NO2 O2 NO3 1 2 1 2
Figure 17.8 Reaction: 2 1 NH3 1 O2 NO2 H2O Figure 17.8 Nitrifying
bacteria. Reaction: 2 1 NO2 O2 NO3 2012 Pearson Education, Inc.
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 2012 Pearson Education,
Inc. Figure 17.9 Figure 17.9 Nonfilamentous sulfur
chemolithotrophs.
2012 Pearson Education, Inc. Figure 17.10 Figure 17.10 Filamentous
sulfur-oxidizing bacteria.
2012 Pearson Education, Inc. 17.5 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 2012 Pearson Education, Inc.
Figure 17.13 Figure 17.13 Hydrogen bacteria.
2012 Pearson Education, Inc. 17.6 Methanotrophs and
Methylotrophs
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 2012 Pearson Education, Inc. Figure
17.14 Figure 17.14 Methanotrophs.
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 2012 Pearson
Education, Inc. Figure 17.16 Figure Typical pseudomonad colonies
and cell morphology of pseudomonads. 2012 Pearson Education, Inc.
17.7 Pseudomonas and the Pseudomonads
Nutritionally versatile Ecologically important organisms in water
and soil Some species are pathogenic Includes human opportunistic
pathogens and plant pathogens 2012 Pearson Education, Inc. 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 2012 Pearson
Education, Inc. 17.8 Acetic Acid Bacteria Acetic acid bacteria
(contd)
Commonly found in alcoholic juices Used in production of vinegar
Some can synthesize cellulose Colonies can be identified on CaCO3
agar plates containing ethanol 2012 Pearson Education, Inc. Figure
17.17 Figure Colonies of Acetobacter aceti on calcium carbonate
(CaCO3) agar containing ethanol as electron donor. 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 2012 Pearson Education, Inc.
Figure 17.21 Figure 17.21 Chromobacterium and Neisseria.
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 2012 Pearson Education, Inc. Figure 17.22 Figure 17.22
Butanediol producer.
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 2012 Pearson Education, Inc. 17.11 Enteric Bacteria
Salmonella and Shigella
Closely related to Escherichia Usually pathogenic Salmonella
characterized immunologically by surface antigens 2012 Pearson
Education, Inc. 17.11 Enteric Bacteria Proteus
Genus containing rapidly motile cells; capable of swarming (Figure
17.24) Frequent cause of urinary tract infections in humans 2012
Pearson Education, Inc. Figure 17.24 Figure 17.24 Swarming in
Proteus.
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 2012 Pearson Education, Inc. Figure 17.26 Figure
Bioluminescent bacteria and their role as light organ symbionts in
the flashlight fish. 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 2012 Pearson
Education, Inc. Figure 17.27 Figure 17.27 Rickettsias growing
within host cells.
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 2012
Pearson Education, Inc. 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 2012 Pearson Education, Inc. 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 2012
Pearson Education, Inc. Figure 17.31 Figure 17.31 Attack on a prey
cell by Bdellovibrio.
2012 Pearson Education, Inc. Figure 17.32 Release of progeny Prey
lysis (2.54 h postattachment)
Bdellovibrio Prey cytoplasm Elongation of Bdellovibrio inside the
bdelloplast Prey Attachment 4060 min 520 min Figure Developmental
cycle of the bacterial predator Bdellovibrio bacteriovorus.
Bdelloplast Prey periplasmic space Penetration 2012 Pearson
Education, Inc. 17.16 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) 2012 Pearson Education,
Inc. Equal products of cell division:
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 Figure Cell division in different
bacteria. 4. Polar growth without differentiation of cell size:
Rhodopseudomonas, Nitrobacter, Methylosinus 2012 Pearson Education,
Inc.