Phylogenetic tree of the major lineages (phyla) of
Bacteria based on 16S ribosomal RNA sequence
comparisons
Phylum 1: Proteobacteria (2086)
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Purple phototrophic Bacteria
The nitrifying Bacteria
Sulphur and iron oxidizing Bacteria
Hydrogen oxidizing Bacteria
Methanotrophs and methylotrophs
Pseudomonas and the Pseudomonads
Acetic acid Bacteria
Free living aerobic nitrogen fixing Bacteria
Neisseria and Chromobacterium
Enteric Bacteria
Vibrio and photobacterium
Rickettsia
Spirilla
Sheathed proteobacteria
Budding and prosthecate/stalked Bacteria
Gliding Myxobacteria
Sulphate and sulphur reducing proteobacteria
Non-photosynthetic proteobacteria
Light microscopy of stained
bacteria
Escherichia coli,
gram negative,
glucose fermenting
facultative aerobe
TEM of E. coli with intact
flagella. Courtesy of
Peggy S. Hayes, Centers
for Disease Control
http://www.geocities.com/CapeCanaveral/3504/gallery.htm
Fermentative rods and vibrios
Enteric bacteria
Vibrio and related genera
Pasteurellea and Hemophilus
Zymomonas
Chromobacterium
Enteric bacteria
Relatedness among the enteric bacteria. Numbers indicate DNA/DNA
reassociation values, a measure of the relatedness among the various genera.
Mixed-acid fermentation
Mixed-acid fermentation of glucose by Escherichia coli. Pyruvate produced by
glycolysis (the Embden-Meyerhof pathway) is catabolized to a mixture of products,
high in acids. Acids are shown here and in Figure 19.3 in their nonionized form.
2,3-Butanediol fermentation
In the butanediol
variation of mixed-acid
fermentation, more
neutral products are
formed, as well as a
higher ratio of CO2 to
H2.
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The human digestive system
Escherichia coli (Bacteria)
Found in the intestines of humans and
animals, this bacterium is usually harmless,
but some strains can cause food poisoning
and more serious illnesses. Most outbreaks
involve contaminated beef that was not cooked
thoroughly. The strain known as O157:H7 is
considered a potential biological weapon.
» Sequenced by: University of Wisconsin E.
coli K-12 Abstract
University of Wisconsin E. coli O157:H7
EDL933 Abstract
Genome Information Research Center E. coli
O157:H7 Abstract
University of Wisconsin E. coli UPEC-CFT073
Abstract
» Related GNN article: Researchers sequence
strain of E. coli linked to disease
» Image: Courtesy The Donnenberg
Laboratory.
Fig. 1. Scanning electron micrograph
showing microcolonies
of EPEC displaying the characteristic
localized adherence
pattern of adherence to HEp-2 cells.
Fig. 2. High power scanning
electron micrograph of EPEC
displaying localized adherence to
HEp-2 cells. Note the elongated
microvilli to which the bacteria
appear to attach.
This screenshot shows the
complete genome of Yersinia
pestis (top) versus Escherichia
coli versus Salmonella typhi
versus Salmonella typhimurium
(bottom). The comparisons
were done with tblastx.
Yersinia pestis
Yersinia pestis (Bacteria)
The dynamic plague bacterium
evolved from harmless stomach bug
to blood-borne pathogen in a
relatively short amount of time. Y.
pestis is transmitted to humans by
fleas that feed on the blood of
infected animals such as rats,
causing bubonic plague. When
transmitted by air through respiratory
droplets, the bacterium causes the
more severe and often fatal
pneumonic plague.
» Sequenced by: Sanger Institute Y.
pestis CO92 Abstract
University of Wisconsin Y. pestis KIM
Abstract
Erwinia carotovora (Bacteria)
This pathogen infects potatoes throughout the
world. It causes the diseases “blackleg” in
developing tubers and “soft rot” in harvested
potatoes. Infected potatoes have mushy spots
with black borders and can have a foul odor.
» Sequenced in 2004 by The Wellcome Trust
Sanger Institute E. carotovora subsp.
atroseptica Abstract
» Image: Courtesy Gary D. Kleinschmidt,
University of California Statewide IPM Program
Vibrio
Vibrio cholerae (Bacteria)
The bacterium that causes cholera, unlike other pathogens, has not
one but two chromosomes. This may give it a competitive
advantage in diverse environments. The rod-shaped bacterium was
given the Latin name Vibrio because it possesses a flagellum and
appears to vibrate.
Vibrio parahaemolyticus (Bacteria)
V. parahaemolyticus causes food-borne gastroenteritis, which
inflames the stomach and small intestine. Most people recover
completely from the illness by drinking plenty of fluids. The
bacterial pathogen is a growing concern in North America,
particularly in places where seafood is popular.
Vibrio vulnificus (Bacteria)
Found in warm coastal waters, this bacterium is related to the
cholera pathogen and can cause a severe and potentially fatal
illness. Infections tend to occur through eating raw or improperly
cooked shellfish, particularly oysters, or exposing open wounds
to seawater containing the organism
Oxidative rods and cocci
Pseudomonads
Azotobacter and other free living nitrogen fixing bacteria
Rhizobium and Bradyrhizobium: Symbiotic nitrogen fixing bacteria
Agrobacterium
Vinegar bacteria: Acetobacter and Gluconobacter
Legionella
Neisseria and related bacteria
Rickettsia
Pseudomonas
aeruginosa
Figure 19.6 Pseudomonas
Figure 19.10 Azotobacter
Development of root nodules in Rhizobiumplant symbiosis
Diagram showing attachment and
invasion in development of a root
nodule in a leguminous plant.
Rhizobium attaches to the root hair of a
susceptible plant, enters, and forms an
infection thread as it moves into the root
cells. Factors contributed by both the
bacterium and the root result in nodule
formation.
Crown galls
Agrobacterium tumefaciens
(Bacteria)
Found in soil worldwide, this
bacterium infects the roots of plants
and can cause fatal tumors in
hundreds of species, including
walnut trees and ornamental plants
such as roses. It causes disease by
transferring its own DNA into plant
cells. In the laboratory, researchers
use the bacterium experimentally to
add genes to plants.
» Sequenced by: Cereon Genomics
A. tumefaciens C58 (Cereon)
Image:
Courtesy
Martha Hawes