BACK TO 1h: CRUNCH TIME
PRESENTING THE FINDINGS
and Eric led off with an introduction and history of the extremophile
organisms of Yellowstone. They related how in the 1960s a bacteriologist
named Thomas Brock began to look for bacteria in a warm creek downstream
from a hot spring, and ended up finding organisms that thrived in
the near-boiling water at the creek's source. The organism he found,
Thermus aquaticus, was the first of the Archaea, ancient microorganisms
now widely regarded as a separate kingdom of life. Subsequent discoveries
have shown that Archaeans inhabit some of the most extreme environments
on Earth. In addition to thermoacidophilic Archaeans, such as those
found in Yellowstone, there are halophiles (thriving in very salty
environments, such as the Dead Sea) and methanogens (which live in
with his summary of how the acidity level (measured in pH) affects
living organisms. In Yellowstone, the acidic hot pots have pH levels
that range from 2 (as acid as lemon juice) to 4 (as acid as tomatoes).
In many of these hot springs, the thermoacidophilic prokaryotes Sulfolobus
or Acidianus, of the domain Archaea, are the only known inhabitants.
These organisms oxidize elemental sulfur to sulfuric acid and use
this energy to grow atrophically, and use carbon dioxide as their
Tom spoke about
the question: how hot can the surroundings be for living organisms?
He said that, in general, plants and animals can survive temperatures
higher than 50 degrees Celsius (122 F), but find it difficult or impossible
to grow in environments that are constantly that high. Microorganisms
are different - they can grow in temperatures well above 50 Celsius,
in fact up to 115 Celsius, which is past the boiling point of water
at sea level. Only the organisms in the domain Archaea are able to
Tom pointed out
that the organisms that live in the Yellowstone hot pots, Sulfolobus
acidocaldarius and pyrobacterium brockii, thrive in high temperatures
but aren't found if temperatures drop below around 160-175 F.
Jamie then showed
some pictures taken during the field trip to the hot pots, and briefly
explained the scientists' purpose and collection procedures.
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