Archaeal Diversity Flashcards
1
Q
what are two main bracnhes of prokaryotes and what traits are shared and whats different
A
- bacteria and archaea
- both have 70S ribosomes, complex cell walls, majority have circular genomes in compact nucleoid, share metabolic traits
*deep branching bacteria phyla have archaeal genes (ex; bacteria extremeophiles have similar cell walls to achaea)
- differeneces: acheae have rRNA gene sequence, membrane lipids (ether-lnked isoprenoid lipids forming mono/bilayers) cell walls have pseudopeptidoglycan (not peptidoglycan), domain archaea lack animal/plant pathogens
2
Q
Archaea look like bacteria but are not, explain
A
- just as closely related to bacteria as they are form eukaryotes
- diverged from evolutionary branch that gave rise to eukaryotes
- many live in extreme conditions - extremeophiles
- grow within a wider range of temperature, osmolarity, pH and other environmental conditions then other prokaryotes or eukaryotes
- share some traits with eukaryotes - enzymes for transcription and DNA replication
3
Q
describe domain archaea phylogeny
A
- phylogeny is based on small subunit SSU 16S eRNA and genome sequences
- archaeal genomes include large portions derived from bacteria by horizontal gene transfer
*suggests archaeal gneomes are highly recombinogenic
4
Q
what are nanoarchaea
A
- nanoarchaeum equitans
- contain the smallest genome among archaea
- coccoid cells ~1% the volume of an E.coli cell
- lacks many genes required for biomass biosynthesis
- obligate symbiont of the archean ignicoccus hospitalis (host)
- only grows when attached to host, optimal growth at 90 C (hyperthermophilic)
- host and symbiont genomes have been sequenced revealing extensive coevolution
5
Q
what are Crenarchaeota and Euryarchaeota phyla
A
crenarchaeota:
- grows in wide range of temperature, pH
- can be psychrophiles, mesophiles, thermophiles and hyperthermophiles
- can be found in diverse habitats
- diversity in cell structure including cell-wall less acidophilic extremophiles
Euryarchaeota
- shows a greater range of metbaolism - methanogens, haophilic heterotrophs, acidophils, alkaliphiles
6
Q
A
7
Q
What is Sulfolobus
A
- a Crenarchaeota
- easily lab cultured and well studied (unlike most achaea)
- motile by flagella
- no cell walls; only an S layer of glycoprotein
- membrane cocytoplasmic membrane hmainly of tetraethers
- acidophilic hyperthermophils (grows as 80-90 C, pH of 2.0)
- also an acidophile aerobe; oxidizes sulfur to sulphuric acid (lithotroph)
8
Q
what are psychrophiles
A
- type of crenarchaeota
- largely uncultured so little understood
- live in permanntly cold, near freezing water or in water under fozen sea
- dissolved solutes in lower freezing point of water. enable microbial growth - growth cannot oxxur in frozen water
- some barophiles (adapted to high atmospheric pressues) are also psychrophiles bc the average temp at ocean floor (high pressure env) is 2 C
9
Q
describe crenarchaeota mesophiles
A
- can be visualized with red fluorescent dye
- mesophiles and heterotrophs
associated with tomato plant?
10
Q
describe acidophiles as archaeal extremists
A
- ex: ferroplasma acidiphilum
- oxidizes sulfur from FeS2 to form H2SO4
- generates pH of 0
has no cell wall
- can be found in acid mine tailing
11
Q
describe barophilic vent hyperthermophiles
A
- the most extreme hyperthermophiles are barophiles adapted to grow near hydrothermal vents at ocean floor
- temp and presure contribute to water temp over 400 degrees
- as water cools FeS precipitates and supports microbial growth
12
Q
describe the pyrodictium species
A
- barophilic vent hyperthermophiles
- vent adapted members of the desulfurococcales include pyrodictium species
- genome shows evidence of ‘mixed heritage’ with genes from all 3 domains (bacteria, archaea and eukarya)
- reduce sulfur to H2S, either with molecular hydrogen or organic comp
- Grow as flat, disk shaped cells that can be as thin as 0.1 um (allow fro rapid exchange of materials)
- cell disks are interconnected by periplasmic extensions called cannulae
*sharing periplasmic contents between cells
13
Q
how can you study bacteria form extreme environments?
A
- to study hyperthermophiles from black smoker vents requires specialized equipment (expensive)
- a robotic system that has a collection arm plus a prussurized device - when samples are collected the high pressue and temp is maintained
14
Q
describe haloarchaea
A
- salt loving archaea extremists
- the main inhabitants of high salt environments are members of Haloarchaea
- most are phototrophs
*photopigments of haloarchaea color salterns, which are used for salt production
*most are red due to bacterioruberin which protects cells from light
- reuqire at least 1.5 M NaCl
15
Q
describe the phylum euryarchaeota
A
- euryarchaeota means “broad-ranging archaea”, includes a vast array of species
- phylum is dominated by methanogens ie: Biogenic Methane Production
- generate methane form CO2 and small nutrient molecules
Basic reaction: CO2+ 4H2à CH4 + 2H2O
- some are obligate endosymbionts of protozoa - the protozoa are themselves symbionts in termite guts
- some emthanogens are part of the natural microbiota of animal/human large intestines
- methanogens serve a key energetic role in ecosystems by providing anaerobic H2 removal through production of methane
*major participants in global biogeochemical cycle
19
Q
describe methane production in bovine rumen
A
- numerous methanogens also grow within the digestive fermentation chambers of animals such as termites and cattle
- cattle support mathanogenesis within thier rumen and reticulum
- bovine methanogensis diverts carbon from meat production and it makes a sig contriubtion to global methane
20
Q
how have methanogens been harnessed to make clean methane
A
- methanobacterium palustre can convert electrical current directly to methane at 80% efficienct
- carbon in methanobacterium - produced methane ceoms from the atmosphere not fossil fules
- methane is a greenhouse gas but when produced by bacteria it is carbon neutral (easily harvested, stored and piped for distribution)
