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Chapter 19- Archaeal Diversity
Microbiology: An evolving science
33
Microbiology
04/15/2012

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Term
Archaea
Definition

psychrophiles

hyperthermophiles

halophiles

acidophiles

methanogens

abundant in moderate habitats

lack pathogens

Term
Traits
Definition
archaeal signatures such as:
cell membrane lipids
cell wall components
certain metabolic pathways
certain genome features
Term
Lipids
Definition

different from those of bacteria and eukaryotes
have ether links (R-O-R), not ester links.
branched chains of lipids made from isoprenoid units with no unsaturations

can form monolayers due to tetraethers

Term
FIGURE 19.2
Definition
Term
Cell Walls
Definition
pseudopeptidoglycan in methanogens (N-acetyltalosaminuronic acid) resistant to lysozyme; different crossbridge types causing penicilin resistance
Term
Genomes
Definition

unique features of archaea
have reverse gyrase, maintaining positive supercoiling
similar to bacteria in:

circular genome
gene size and density
presence of operons

similar to eukaryotes in:
presence of histone homologs

Term
Phylogeny
Definition

includes two phyla:
crenarchaeota
euryarchaeota

 

Term
Crenarchaeota
Definition

name means "scalloped archaea"
irregular shape

have crenarchaeol

shows wide range of temperature

hyperthermophiles, thermophiles, mesophiles and psychrophiles

Term
euryarchaeota
Definition
greater range of metabolism
methanogens, halophiles, acidophiles and alkalinophiles
Term
FIGURE 19.5
Definition
Term
Crenarchaeol
Definition
distinctive tetraether lipid synthesized by crenarchaeotes
Term
crenarchaeota
Definition

example: Desulfurococcales

Ignicoccus islandicus: enormous periplasm
example: Ignicoccus hospitalis

Figure 19.36

Term
Barophilic hyperthermophiles
Definition
grow near hydrothermal vents on ocean floor (feature black smoker)
Example: Pyrodictium abyssi
found in abyss of sea
Term
Sulfolobales
Definition

species that respire by oxidizing sulfur

found within hot springs

 

example: :Sulfolobus solfataricus
a double extremophile that grows at 80 deg. C with pH of 3
oxidizes H2S to sulfuric acid

 

Term
Mesophiles and Psychrophiles
Definition

grow in ocean
abundance varies according to season and increases with depth

likely predominant crenarchaeotes on Earth

Term
Psychrophile
Definition
"cold-loving"
Term
Mutualistic symbiosis
Definition
Cenarchaeum symbiosum inhabits the sponge Axinella mexicana
Term
Euryarchaeota
Definition

dominated by Methanogens
means broad-ranging archaea

poisoned by molecular oxygen and require complete anaerobiosis

substrates include:
carbon dioxide and acetic acid

Term
Methanogens
Definition

include four classes:
thermophiles and mesophiles found in all, display diversity of cell forms (rods, cocci or spirals)

have rigid cell walls made up of pseudopeptidoglycan, proteins or sulfated sugars

Term
Filamentous methanogens
Definition
form chains of large cells
Term
Methanosaeta
Definition
performs key functions in treatment of sewage waste; traps bacteria into residual sludge
Term
Anaerobic habitats
Definition
methanogens grow in anaerobic soil, landfills, animal digestive tracts, marine sediments
Term
Halophiles
Definition

high salt environments
photopigments color salterns which are used for salt production

colored red by bacterioruberin, protect them from light

adapt to high external NaCl by maintaining high intracellular KCl

Term
Haloarchaeal Habitats
Definition

Thalassic lakes
Athalassic lakes
Solar salterns
Brine pools beneath oceans

Alkaline soda lakes
Antarctic brine lakes
Underground salt deposits
Salted foods

Term
Retinal-Based Photoheterotrophy
Definition
Rhodopsins capture light energy
Term
Bacteriorhodopsin
Definition
pumps out H+
Term
Halorhodopsin
Definition
pumps in Cl-
Term
Bacteriorhodopsin and Halorhodopsin
Definition
both increase proton motive force using proton gradient to pump out Na+
Term
Phototaxis
Definition
respond to light, but not just any light. Signals flagellum
Term
FIGURE 19.31!
Definition
Term
Thermophiles
Definition
Thermococcales Figure 19.33A
Term
Thermococcales
Definition
includes Pyrcoccus growing at 105 degrees C; anaerobes, sulfur used as a terminal electron acceptor

SMITH'S favorite, may be on test.
Term
Nanoarchaeota
Definition

Nanoarchaeum equitans

obligate symbiont of Ignicoccus hospitalis (crenarchaeote)