Life living in anthropocentrically extreme environments

Life living in anthropocentrically extreme environments

Life living in anthropocentrically
extreme environments:
Temperature
pH (Acidity or Alkalinity)
Salinity (Osmotic Stress)
Radiation
Barometric Pressure
Halophilic
Archaea
Life in hypersaline habitats.
Not just tolerant of high salt but require
it for physiological function.
Need a minimum of 1.5 M NaCl (or
other salt); Live in 2-7 M NaCl; where
seawater is 0.7 M NaCl.
Alkaliphilic Natronobacteria
Mostly Chemoheterotrophs; depend on
oxygenic photosynthetic green algea
Dunaliella and anoxygenic
phtosynthetic purple bacteria
Ectothiorhodospira and
Halorhodospira.
Few are partially photoheterotrophic at
low oxygen (need ATP supplement)
(Halobacterium salinarum)
Halobacterium Phototrophy
See
Box20.1
(p 462)
Why the
purple
membrane?
Thermoplasmatales
(cell wall-less; extreme acidophiles)
• Thermoplasma:
– Thermophile as well (likes 55 ºC)
– Chemoheterotroph
• Ferroplasma:
– Chemolithoautotroph;
– Autotrophic by oxidizing Fe(II)
– Acid mine drainage archaea
• Picrophilus:
– Most extreme acidophile (0.6 pH optimum)
Hyperthermophiles
• Thermococcales (Euryarchaeota):
– Anaerobic sulfur reducing chemoheterotroph.
– Flagellated motility
– Temperature optimum 88-100 ºC
• Archaeoglobales (Euryarchaeota):
– Anaerobic sulfate reducers
– Temperature optimum 83 ºC
Cultured Crenarchaeota
Hyperthermophiles
Submarine
volcanic
Acidic
terrestrial
volcanic
Terrestrial
volcanic
The unique archaeal morphology of Pyrodictium;
disc-like cells with network of intertwined threadlike appendages.
Bacterial “Extremophiles”
Thermophilic chemolithoautotroph
Thermophilic chemoheterotroph
Radiation tolerance 10,000x humans.