Characterizing and Classifying prokaryotes chapter 11

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Characterizing and Classifying prokaryoteschapte
r 11
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Prokaryotes

• Most diverse group of organisms
• Habitats
• All possible habitats are exploited by some sort
  of prokaryote
• Only a few capable of colonizing humans and
  causing disease

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Morphology of Prokaryotic Cells
Figure 11.1
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Arrangements of Prokaryotic Cells

• Result from two aspects of division during binary
  fission
• Planes in which cells divide
• Separation of daughter cells

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Arrangements of Cocci Diplococci
Figure 11.6a
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Arrangements of Cocci Streptococci
Figure 11.6b
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Arrangements of Cocci Tetrads
Figure 11.6c
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Arrangements of Cocci Staphylococci
Figure 11.6e
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Arrangements of Bacilli Single Bacillus
Figure 11.7a
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Arrangements of Bacilli Diplobacilli
Figure 11.7b
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Arrangements of Bacilli Streptobacilli
Figure 11.7c
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Arrangements of Bacilli V-Shape and Palisade
Figure 11.7d
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Endospores

• Produced by Gram-positive bacteria
• Bacillus and Clostridium are examples
• Each vegetative cell transforms into one
  endospore
• Each endospore germinates to form one vegetative
  cell
• Constitute a defensive strategy against hostile
  or unfavorable conditions
• Endospores are not reproductive structures

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Modern Prokaryotic Classification

• Three domains of Life
• Archaea (prokaryote)
• Bacteria (prokaryote)
• Eukarya (eukaryote)

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Archaea
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Features of Archaea

• Prokaryotes (no membrane bound nucleus)
• Lack Peptidoglycan in their cell walls
• Genome is circular DNA
• Histone proteins are present
• Ribosomes are more similar to bacteria than
  eukaryotes
• Many occupy "extreme' environments. Extremophiles
• Not known to cause disease in humans or animals

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Halophiles

• Inhabit extremely saline habitats
• Depend on greater than 9 NaCl to maintain
  integrity of cell walls
• Many contain red or orange pigments protection
  from visible and UV light
• Extreme Halophiles require very high salt (not
  just tolerant)
• Most require at least 9 NaCl
• Most require 12-23 NaCl for optimal growth
• Almost all can grow at 32 NaCl
• Most studied Halobacterium salinarium

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Extreme Halophiles
Seawater evaporation ponds
Great salt lake
African soda lake high alkalinity, high salinity
SEM of halophiles
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Methanogens

• Convert carbon dioxide, hydrogen gas, and organic
  acids to methane gas
• Largest group of archaea
• Convert organic wastes in pond, lake, and ocean
  sediments to methane
• Some live in colons of animals are one of
  primary sources of environmental methane

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Methanogens

• CH4 (methane producers)
• Strict anaerobes
• Example genus Methanococcus

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Methanogens

• Methanogen habitats

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Hyperthermophiles

• Most are obligate anaerobes
• Most require S? as part of their metabolic scheme
• Example Genera
• Sulfolobus Thermococcus Pyrolobus
• Hyperthermophiles require temperatures over
  80ºC
• Heat stable biomolecules

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Hyperthermophile Habitats
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Bacterial groups
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Phototrophic Bacteria

• Photoautotrophs
• Five groups (often grouped by color)
• Blue-green bacteria (cyanobacteria)
• Chlorophyll a (oxygenic photosynthesis)
• Green sulfur bacteria bacteriochlorophyll
• Green nonsulfur bacteria
• Purple sulfur bacteria
• Purple nonsulfur bacteria

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Phototrophic Bacteria
Table 11.1
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Low G C Gram-Positive Bacteria

• Clostridia
• Mycoplasma
• Bacillus
• Listeria
• Lactobacillus
• Streptococcus
• Staphylococcus

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High G C Gram-Positive Bacteria

• Includes rod-shaped cells and filamentous
  bacteria
• Corynebacterium
• Mycobacterium
• Actinomycetes
• Actinomyces
• Nocardia
• Streptomyces

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Actinomycetes
Figure 11.17
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Gram-Negative Proteobacteria

• Largest and most diverse group of bacteria
• More diseases are caused by this group than any
  other.
• Five distinct classes
• Alphaproteobacteria
• Betaproteobacteria
• Gammaproteobacteria
• Deltaproteobacteria
• Epsilonproteobacteria

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Alphaproteobacteria

• Nitrogen fixers
• Azospirillum
• Rhizobium
• Nitrifying bacteria
• Nitrobacter
• Purple nonsulfur phototrophs
• Pathogenic alphaproteobacteria
• Rickettsia
• Brucella
• Ehrlichia
• Caulobacter

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Betaproteobacteria

• Pathogenic betaproteobacteria
• Neisseria
• Bordetella
• Nonpathogenic betaproteobacteria
• Thiobacillus
• Spirillum

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Gammaproteobacteria

• Purple sulfur bacteria
• Intracellular pathogens
• Legionella
• Coxiella
• Methane oxidizers
• Facultative anaerobes
• Family Enterobacteriaceae
• Pseudomonads
• Pseudomonas
• Azotobacter
• Azomonas

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Deltaproteobacteria

• Bdellovibrio
• Myxobacteria

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Epsilonproteobacteria

• Campylobacter
• Helicobacter

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Other Gram-Negative Bacteria

• Chlamydias
• Chlamydia
• Spirochetes
• Treponema
• Borrelia
• Bacteroids
• Bacteroides