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Flashcards in Eukaryotic species Deck (16):

phylogenetically, archaea are split into ____ phyla




-extremely halophilic archaea
-key genus: halobacterium
-have a requirement for high salt concentrations
-typically require at least 1.5 (~9%) NaCL for growth
-found in solar salt evaporation ponds and salt lakes where the salt concentration approaches saturation
-found in great salt lake (Utah), dead sea, as well as soda lakes that are highly alkaline hypersaline environments
-posses adaptations to life in highly ionic environments


euryarchaeota: extremly halophilic archaea: water balance

-halophiles need to maintian osmotic balance
-this is usually achieved by accumulation or synthesis of compatible solutes
-halobacterium species instead pump large amounts of K+ into the cell from the environment
-intracellular K+ concentration exceeds extracellular Na+ concentration and positive water balance is maintained


Euryarchaeota: extremely halophilic archaea unique feature

-found in some haloarchaea is light-driven synthesis of ATP using bacteriorhodopsin(reason the cells are pink)
-cytoplasmic membrane proteins that can absorb light energy and pump protons across the membrane to make ATP
-cannot fix CO2
-they are photoheterotrophs


Euryarchaeota: methanogenic archaea
key genera

methanobacterium, methanosarcina


Euryarchaeota: methanogenic archaea why are they termed methanogens

because they are the only microbe capable of significant methane production
-produce the bulk of CH4 in the atmosphere (important green house gas)


Euryarchaeota: methanogenic archaea

-strict anaerobes, found in many diverse anaerobic environments
ex. cows gut; sewage sludge


Euryarchaeota: methanogenic archaea
deomstrate diversity of ______ chemistries

cell wall
-pseudomurein (eg methanobacterium) similar in structure to peptidoglycan (less similar in composition) only the methanobacteriales family has this type of cell wall
-most other types of methanogens have a S-layer made of protein of glycoprotien as their cell wall


Euryarchaeota: methanogenic archaea
substrates for methanogens

-obligate anaerobes that use a very limited rage of substrates: H2 + CO2, formate, acetate, methanol
-ex, members of genus methanobacteium can use H2 + CO2 but not methanol or acetate, members of methanosarcina can use acetate, methanol, but only some use H2+CO2
-other compounds (eg glucose) can be converted to methane, but only in cooperative reactions between methanogens and other anaerobic bacteria)


thaumarchaeota and nitrification in archaea:
key genus



thaumarchaeota growth

grows chemolithotrophically by aerobically oxidizing ammonia
-uses CO2 as its only carbon source
-can grow at very low levels of ammonia


thaumarchaeota is indigenous to ...

open ocean water where they are major player in ammonia oxidation
-others are involved in nitrification in soils



-ex. nanoarchaeum equitans
-one of the smallest cellular organisms (~0;4 um)
-obligate symbiont of the crenarchaeote ignicoccus
-contains one of the smallest genomes known
-lacks genes for all but core molecular processes
-depends upon host for most of its cellular needs


Korarchaeota and the secret filament

-ex. korarchaeum cryptofilum
-obligately anaerobic chemoorganotroph
-cells are long thin filaments
-lacks many core genes
-depends on other members of hot springs community and cannot yet be grown in pure culture



-most are hyperthermophiles
-found in extreme heat environments
-others are found in extreme cold environments
-chemoorganotrophs or chemolithotrophs
-some species can respire aerobically
-some species carry out anaerobic respiration
-NO-3, S^0, Fe3+ as electron acceptors
-H2 electron donor


Crenarchaeota example sulfolobus

-grows in sulfur rich acidic hot springs pH 2
-aerobic chemolithotrophs that oxidize reduced sulfur or iron
-the crenarchaeota contain several representatives which have an optimum growth temperature above 100 c from deep sea hydrothermal vents including:
geogemma barossii (aka strain 121) can grow up to 121 c