4.2: Diversity of Archaea Flashcards
(22 cards)
what’s the biggest and best studied phylum of archaea?
Euryarchaeota
what are the two groups within the phylum euryarchaeota?
- haloarchaea
- methanogens
what’s an example of haloarchaea within the phylum euryarchaeaota? describe what they are and where they’re found
Halobacterium salinarum
* absolute requirement for high salt concentrations:
-typically need at least 1.5 (~9%) NaCl for growth
* found in: solar salt evaporation ponds, and salt lakes, where salt concentration approaches saturation
* ex. Great Salt Lake (Utah), Dead Sea
* And soda lakes (highly alkaline hypersaline lakes.)
what are the adaptations do halophiles have to live in highly ionic enivironments?
- Halophiles need to maintain osmotic balance
-usually achieved by accumulation or synthesis of compatible solutes (solutes that don’t interfere with metabolism, not sodium), results in a net inflow of water -halobacterium salinarium pumps large amounts of K+ into the cell from the environment - K+ conc. inside the cell exceeds Na+ conc. outside the cell, so now since there’s more salt inside, water flows into the cell, even in a very salty environment.
- Some haloarchaea have a unique system for generating energy:
-light-driven synthesis of ATP without the use of chlorophylls
-instead they use a pigment called bacteriorhodopsin (instead of using an ETC to generate the PMF, like in aerobic respiration which requires oxygen as the final e- acceptor, they generate it with this bc salty environments often oxygen poor)
Describe how bacteriorhodopsin works
- Integral membrane protein
- absorbs light energy and pumps protons across the membrane to make a PMF
- PMF is used to generate a PMF
- They do not fix CO2
- ie. Photoheterotrophy (use sunlight to get energy but can’t fix co2 so must eat carbon source)
what is the only genus of microbes capable of methane production?
Methanogens
True or false bacteriorhodopsin is in bacteria
False, it’s misnamed it’s in archaea
what’s an example of archaea in the genus Methanogens, what do they do?
Methanobacterium, they produce the bulk of CH4 in the atmosphere (important green house gas)
what is the metabolic style of Methanogens and where are they found?
- strict anaerobes
- found in many diverse anaerobic environments
- ex. cow’s gut; sewage sludge
Methanogens demonstrate diversity of cell wall types most have what type? but what do Methanobacterium have?
- Most have a S-layer (like most archaea in general) made of protein or glycoprotein; some have a thick polysaccharide cell wall
- Methobacterium has a cell wall made of pseudomurein
-Peptidodoglycan like polymer
-lacks N-acetyl muramic acid
-sugars are linked by B-1,3 glycosidic bonds instead of B-1,4.
describe the phylum Crenarchaeaota
- smaller well studied phylum of archaea
- found in extremely hot environments:
-boiling hot springs, deep ocean vents - other representatives are found in extremely cold environments
- include chemoorganotrophs (eats organic) or chemolithotrophs (eats inorganic, must be autotroph to get carbon from CO2)
- most use sulfur in their metabolism
describe an example of Crenoarchaeota
- ex: Sulfolobus acidocaldarius (remember since crenarchaeota use sulfur and think cald like scald =hot, in hot springs)
- grows in sulfur-rich acidic hot springs (~90 C, pH 2)
- hyperthermophile and acidophile
- aerobic chemolithotroph that oxidizes reduced sulur or iron
- example: 2S + 3O2 + 2H2O > 2H2SO4
True or false all Crenoarchaeaota are extremophiles
False most in this phylum are but not all, there are lots of archaea that aren’t extremophiles
describe an example of crenarchaeota that cannot be grown in pure culture? why can’t it?
- Canditatus: ‘Korarchaeum cryptofilum’
- hyperthermophile
- lacks many core genes (genes for processes we assume would be required for independent living microbes)
- bc it depends on other members of hot springs community, it cannot yet be grown in pure culture (can’t grow on its own)
describe Nanoarchaeum equitans
- one of the smallest cellular organisms (~0.4 um)
- famous for being an obligate parasite 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
what’s the exception to the statement that archaea are never pathogenic
Nanoarchaeum equitans is an obligate parasite (of the crenarchaeote ignicoccus)
* so archaea are never pathogenic to humans or other organisms, but they can be to other archaea.
what prokaryotic lineage is most closely related to eukaryotes, and what specific species is most closely related to eukaryotes
- the Asgard superphylum of archaea
- ‘Prometheoarchaeum syntrophicum’ MK-D1
Describe the Asgard Superphylum of Archaea
- Prokaryotic lineage most closely related to eukaryotes
- eukaryote-like genomic features (like DNA is packaged with histones)
- genes encode proteins once thought to be unique to eukaryotes
- may represent the ‘missing link’ between archaea and eukarya
- studied bc it could have characteristics in common with the ancestor that first engulfed an Alphaproteobacterium (creating endosymbiont)
what was the first cultured Asgard archaean named, when was it described? and how was it described
- ‘Prometheoarchaeum syntrophicum’ MK-D1
- described in Jan 2020
- anaerobic extremely slow-growing, small coccus (~0.5 um diameter)
- morphologically complex with unique protrusions, but no visible organelles
- degrades amino acids through ‘syntrophy’ (means it needs to work with other organisms can’t do it alone).
where was the first cultured Asgard archaean ‘Prometheoarchaeum syntrophicum’ MK-D1 isolated from?
Isolated from deep sea sediment (where it’s cold and grows slowly which is good for studying evolution.)
what do the unique protrusions on asgard archaea ‘Prometheoarchaeum syntrophicum’ MK-D1 suggest?
suggests protrusions are beginning of endocytosis ( so they might do this like animal cells do).
where is ‘Prometheoarchaeum
syntrophicum’ MK-D1 placed on the phylogenetic tree of life?
within the phylum ‘Lokiarchaeota’
