Lecture 2: High temperatures Flashcards
upper temperature limits for growth
- Vascular plants & mosses = 35/40 degrees
- u dont find photosynthetic organisms above 73 degrees C as chlorophyll is destroyed
- heterotrophic bacteria = 70 degrees C
- archaea = 110 degrees C
- record growth for archaea = 115 degrees C
high temperature environments may be high
high pressure environments
chlorophyll is destroyed at
73 degrees C
- limiting photosynthetic organisms
top temp found for archaea GROWTH
= 115 degrees C
as you increase temp, oxygen solubility
decreases (is low)
-organisms often use mechanisms not requiring O2
Hot springs = Yellowstone National Park
- extensively studied
- large caldera (volcanic crater) with extensive geothermal activity
- surrounding environments can be v cold so extreme & localised temperature gradients are set up
hydrology of yellowstone =
- water enters through fissures
- water is heated far above normal boiling point due to intense pressure
- water boils at 92 degrees C due to altitude
- water boils near ground surface as pressure reduces
- – MINERAL RICH, LOW pH
hot springs difficult to study:
- obv v hot
- protected areas i.e grand prismatic spring
- lots of variety within them though so are some accessible ( Octopus Spring, not v big, access)
What organisms do we find in Hot environments (i.e. hot springs)
- Archaea
- Sulfolobus acidocaldarius (75-80 DC)
- many other species
- Bacteria
- Cyanobacteria
What organisms do we find in Hot environments (i.e. hot springs) BELOW 73 DC
- photosynthetic organisms
- - i.e cyanobacteria
What organisms do we find in Hot environments (i.e. hot springs) ABOVE 73 DC
Heterotrophs (using fixed C from environments) Lithotrophs (Chem energy) BACTERIA & ARCHAEA
– lithotrophs ==> dont need light so found in rocks etc
what are the problems faced by organisms at high temperatures
- membran stability
- DNA stabilibty (double helix unravels)
- enzyme denaturation
- Nutrition
- Chlorophyll is denatured at 73DC
- -O2 solubility is LOW
- -organic content is often LOW
- -inorganic content may be very HIGH
adaptions: lipid composition
- -thermophilic bacteria = have membranes composed of largely saturated lipids (ester linked)
- Archaea = either-linked lipids, EXTREMEOPHILIC (100DC+) archaea = tetra-ether linked lipids
Adaptions: DNA
- increased salt concentrations increase DNA helix stability
- DNA gyrases cause DNA to be tightly super-coiled
- Archaea contain histone-like proteins (like euk, unlike bacteria)
- histones bind and condense DNA
adaptions: Thermostable enzymes
- extremeophilic micro-organisms have enzyme adapted to high temperatures
- The thermotolerant DNA polymerase essential for PCR was attained from a bacteria (Thermus aquaticus)
- organic solutes within the cell can increase thermostability
