The Archaea Flashcards
How many similar cell wall types to gram stain negative/positive are there in the Archaea?
Over 7
Saccharolobus solfataricus
- moderate acidophile, growing at optimum pH 4.5.
- extreme thermophile, growing at, optimum 87 °C.
- can use O2 or Fe(III) as terminal electron acceptors for respiration, producing H2O and Fe(II), respectively.
- weak chemolithoautotrophic growth on molecular hydrogen as electron donor.
- grows well on complex organics (yeast extract, peptone etc) and on sugars (sucrose, lactose, maltose, D-(+)-glucose, D-(-)-fructose, D-(-)-arabinose, L-(+) arabinose).
- cannot use pyrite (FeS2 ), tetrathionate (S4O6 2-) or
elementary sulfur (S8) as electron donors – Sulfolobus spp. can. - isolated from a fumarole at the Campi Flegrei (Phlegraean Fields), west of Naples.
- similar wall structure to Halobacterium spp.
Methanopyrus kandleri
Explain kandleri strain 116 temperature it grows in and where it was isolated from?
originally meaning ‘derived from wood-alcohol.
Methanopyrus, methane-producing thermophile.
* hyperthermophile. Most strains grow at 110 °C – Mps. kandleri strain 116 grows at 122°C very well. Dies below 80 °C.
* originally isolated from 2 km depth in Gulf of California from chimney of a ‘black smoker’. Strain 116 is from ‘black smoker’ fluid in the Kairei hydrothermal field.
* strict obligate anaerobe – killed by even a trace of molecular oxygen.
* methanogenic – uses H2 as electron donor for respiration and CO2 as electron acceptor for respiration, yielding methane.
* CO2 is the C-source but fixed into biomass by a pathway similar to the Wood-Ljungdahl pathway – not the CBB cycle.
* must be grown at 20 MPa (197 atm) – obligate barophile.
* cells are long rods and have a cell membrane, a layer of pseudomurein (pseudopeptidoglycan) and an S-layer.
Pseudomurein is like Gram-stain-negative peptidoglycan but with N-acetylmuramic acid replaced with N-acetyltalosaminuronic acid (TalaNAc).
Methanobrevibacter oralis
Where is it found normally?
Where can it grow?
What does its cell wall comprise of?
- isolated from Homo sapiens L. dental plaque just below the gum line. Strict obligate anaerobe – 50 μm thickness of dental plaque is enough to give anoxia. Probably the dominant species of the Archaea in the human mouth.
- increases in numbers during periodontal disease and in implantitis.
- produces methane from CO2/H2 just like Mps. kandleri.
- grows optimally at 37 °C. Usually grown under 80% H2, 20% CO2.
- does not grow in vitro without addition of fecal extract or sterilised rumen fluid to grow. Nickel (Ni2+) ions required for growth – needed for the hydrogenase enzyme.
- branched chain volatile fatty acids (BCVFAs) stimulate growth. These are produced by Bacteria fermenting sugars and proteins and our cell membrane lipids etc during periodontal disease etc.
- other Methanobrevibacter spp. have been found in Human mouth, human colon, human feces (and sewage containing it), pig colon, cattle rumen and feces, termite gut, goose feces, rotting cottonwood trees.
- cell wall comprises one cell membrane and then layers of pseudomurein, glutaminylglycan (L-glutamine,
N-acetylglucosamine, N-acetylgalactosamine) and heteropolysaccharides (polysaccharides with multiple
sugars instead of just one like in amylose or glycogen etc).
Halobacterium salinarum
What survival mechanism does it use to be an obligate aerobe?
- grows at very high salinities (much higher than in seawater) – partly by filling the cell with KCl to reduce osmotic stress. Most of proteins contain acid-side-chain amino acids to help them stay soluble at high salt levels.
- found in salterns, hypersaline lakes, on salt-fish and on salted hides.
- 0.1 M Mg2+ required for growth. Grows at 3.0-5.2 M NaCl.
- moderate thermophile, growing 20-55 °C, optimally at 50 °C.
- oxidises amino acids using oxygen as the terminal electron acceptor for respiration.
Whilst an obligate aerobe, it has a survival mechanism – using photo-driven proton translocation. Bacteriorhodopsin (cf. rhodopsin in the eyes of Mammalia) based on retinaldehyde that changes shape and transfers protons from inside of the cell to outside when hit by photons. These flow back into the cell via normal ATP synthesis systems.
- owing to high UV-stress in shallow salt ponds, it contains α-bacterioruberin (a carotenoid-alcohol) – makes the cells bright cerise to red and provides protection from UV light and from reactive oxygen species.
- single cell membrane (doubled-headed ether lipid monolayer) plus an S-layer.
Haloquadratum walsbyi
observed cells in saturated brine samples from Egypt.
* record holding extreme halophile – grows at 6.2 M NaCl (i.e. a saturated solution).
* moderate thermophile, growing 25-45 °C, optimally at 45 °C.
* cells are square and flat (2 × 2 × 0.2 μm) – can form large sheets of cells.
* very difficult to grow in pure culture – forms tiny colonies on agar and very low growth in liquid culture.
* contains gas vesicles that allow it to move up and down water column. Does not have any other means of motility.
* obligate aerobe – mainly grows on pyruvate, D-glucose and glycerol. Also uses the bacteriorhodopsin system similar to Hbm. salinarum.
* when salterns reach their highest salinity, Hbm. salinarum tends to die back and Hqr.walsbyi takes over as dominant species.
* owing to high UV-stress in shallow salt ponds, it contains bacterioruberin (a carotenoid alcohol pigment) – makes the cells pale pink.
* similar wall structure to Hbm. salinarum.
Thermococcus gammatolerans
Thermococcus, heat-loving berry.
gammatolerans, tolerating high doses of γ-radiation.
* isolated from a deep-sea hydrothermal vent chimney in Guaymas Basin at > 2,000 m depth.
* hyperthermophile (55-95 °C, optimum 88 °C).
* optimum growth at 0.3 M NaCl.
* obligate anaerobe that ferments proteins, amino acids etc. Can also respire sulfate (cf. Desulfovibrio vulgaris in Gram-stain-negative Bacteria). Grown under 20 % CO2 in N2.
* isolated based on ability to resist a 30,000 Gy dose of γ-radiation (λ = 1.8 pm) from 137Cs.
* cell wall similar to Halobacterium spp.: cell membrane (monolayer of double-headed ether lipids) and S-layer.
Acidiplasma aeolicum
- grows at pH 0.5 – extreme acidophile and at 45 °C, moderate thermophile (range 15-65°C).
- isolated from Vulcano Island from a shallow hydrothermal pool.
- cells are pleomorphic (coccoid, rod-like, blob-like, selenoid (not solenoid!) and oftenbranching)
- chemolithoheterotroph – grows on multi-C compounds (amino acids, D-(+)-glucose) but also oxidises Fe2+ to Fe3+ or S4O6 2- (tetrathionate) to sulfuric acid to obtain extra electrons for respiration – means more biomass per mole of multi-C compound that without the extra electrons – evolutionary advantage.
- can also grow anaerobically, on multi-C compounds, respiring ferric iron (Fe3+) as terminal electron acceptor.
- single cell membrane, no S-layer. Majority of membrane lipids are galactolipids– note these are archaeal doubleheaded ether galactolipids, not to be confused with chloroplast single-headed ester galactolipids.
Ph is 7 inside cell because it pumps out acid.
What is the protein used to pump protons at the expense of photons in Halobacterium ?
bacteriorhodopsin
