Wednesday, April 8, 2009
If you can't take the heat...
On page 69, Carroll talks about the hot springs of Yellowstone National Park and one of its inhabitants, the Thermus aquaticus. He notes that the Thermus aquaticus's habitat is made up of water with a temperature of 163 degrees Fahrenheit! Although he does state the benefit made possible to us (think PCR), he neglects to mention the type of life forced to live by the bacterium itself. How does such a high temperature help it? How does it hurt it? If removed from its current habitat and placed into a much colder one, how would this affect the way the Thermus aquaticus is forced to live (what kind of changes in its lifestyle would it be forced to undertake)?
Subscribe to:
Post Comments (Atom)
Based on Kinetic-Molecular Theory, being functionally stable at extremely high temperatures is definitely a selective advantage for thermophiles, including thermus aquaticus. At higher temperatures, the speed of molecules increases, causing chemical reactions to occur much faster. In particular, DNA replication is sped up, meaning high temperatures effectively allow thermus aquaticus to asexually reproduce quicker than non-thermophilic bacteria. Faster reproduction allows for more mutations in the DNA. This causes the species as a whole to be much more adaptable to its environment. Also, thermus aquaticus is a chemotroph, so it uses chemosynthesis to synthesize food. Chemosynthesis relies on the oxidation of inorganic molecules, such as hydrogen sulfide. Geysers and hot springs such as those found in Yellowstone Park are rich in sulfur. As a thermophile, thermus aquaticus is able to exploit this environment for chemosynthesis. As far as disadvantages of adapting to the high temperatures of this environment go, thermus aquaticus is not resistant to high temperatures but rather confined to them. The bacterium cannot survive in temperatures below 120°F, so it is restricted only to its current extremely hot environment. If removed from its current habitat and placed into a much colder one, it would die. However, if it is placed in an environment around 120°F, which is cold relative to its usual habitat, thermus aquaticus would not perform as effectively as a species. Its chemical reactions would slow and reproduction would be less frequently. The bacterium would have to adapt to living in colder environments. Mutations that alter its thermophilic tendencies would be selectively chosen through natural selection. Eventually, it would probably resemble bacteria that had never adapted to high temperature conditions.
ReplyDeleteWithin the hot springs, you would find a great amount of the bacteria thermus aquaticus. This bacteria made the process of PCR (polymerase chain reactions or a process used to quickly replicate samples of DNA) available when it introduced an enzyme called Mullis. This bacteria is also greatly researched because it can live in harsh temperatures.
ReplyDeleteI think that one of the most important parts affected by heat in any cell is enzymes. Enzymes at great heats become denatured and they can no longer complete their assigned tasks. This organism, living in high temperatures, would need to use enzymes that could function at 163 degrees Fahrenheit. Even higher heat could affect the enzymes but at this heat the enzymes would therefore help the bacteria. in order to thrive in this environment the bacteria has made many modifications to its lifestyle and physical structures, such as internally and molecularly changing temperatures, acidic pH levels, and/or high salinity levels. The bacteria uses the oxidation of inorganic molecules like methane, hydrogen gas or hydrogen sulfide to change nutrients into organic mater and obtain food. This is opposed to other bacteria that use sunlight to obtain energy. If the bacteria was taken into a colder environment then the RNA polymerase is affected and the cell would initially not survive. The may adaptations made by this organism are being questioned. Many scientists believe that thermus aquaticus is related to the beginning of the Earth, where environments like the one in Yellowstone National Park where very common.
sources:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=524896
http://www.wyomingnews.com/articles/2007/08/17/outdoors/01out_08-15-07.txt
Thermus aquaticus is classified as a thermopile in the domain Bacteria. Generally thermopiles operate optimally at temperatures of 60 to 108 degrees Celsius and are usually found in hot springs, hydrothermal vent systems, sediment from volcanic islands, and deep sea hydrothermal vents. Thermus aquaticus specifically proliferates best at 70 degrees Celsius but can survive at a range between 50 to 80 degrees Celsius. Environmental factors surrounding Thermus aquaticus and other thermopiles have selectively chosen characteristics that allow it to operate best at such high temperatures, making it necessary for Thermus aquaticus to live in hot water environments.
ReplyDeleteThe main adaptation of Thermopiles to be able to survive and operate at temperatures over 100 degrees Fahrenheit is mostly due to extremozymes, or enzymes that are tuned to work best at high temperatures compared to other enzymes that would regularly denature at such extreme environments. The ability of the extremozymes to maintain its structural shape comes from several different factors. First extremozymes fold themselves into the necessary functioning structural shape more tightly than other regular enzymes to maintain shape. As well several chemical bonds located on the outer surfaces of the extremozymes retain the shape and keep them intact. Another adaptation is the less or restricted use of very flexible and bendable amino acid glycine, an amino acid that is commonly found in the polypeptide chains of enzymes. By using less of this particular amino acid, the extremozymes are able to stay increasingly rigid and structurally stiff. Thermopiles also incorporate the use of chaperonin proteins that are able to latch on disintegrating extremozymes and refold it back to active functioning structures. There adaptations that could have evolved extremely early in the origins of the earth have allowed Thermus aquaticus and other thermopiles to survive in high temperatures to the point that it could not survive otherwise at lower, less optimal temperatures. Extreme environments are the norm for these organisms.
Thermopiles also are characterized with the ability to use sulfate reduction, a respiration metabolic pathway unique to thermopiles as they derive their energy from inorganic molecules. As users of chemosynthesis at extremely high temperatures, Thermus aquaticus require high activation energy for the extremozyme activity that is usually made up for by the surrounding high temperatures. By relocating Thermus aquaticus and other thermopiles to colder environments, their adaptation to (as Nikil stated) temperatures synonymous with higher kinetic molecular energy will work against them with high activation energy requirements in lower temperature settings. Metabolism at high temperatures is just one example of how Thermus aquaticus has environmental adapted to the extremely hot environment to actually work optimally at such temperatures; therefore, Thermus aquaticus could not adopt a lifestyle in colder climates and does benefits from living in its optimal environment of hot temperatures.
http://www.microbeworld.org/know/hot.aspx
http://en.wikipedia.org/wiki/Thermus_aquaticus
http://serc.carleton.edu/microbelife/extreme/extremeheat/
http://www.biochemsoctrans.org/bst/032/0172/0320172.pdf
I like the valuable info you provide to your articles.
ReplyDeleteI will bookmark your blog and take a look at again here frequently.
I am reasonably sure I will be informed many new stuff proper right here! , Best of luck for the next!
You can check my site best geyser in INdia
Greate pieces. Keep posting such kind of information on your blog.
ReplyDeleteIm really impressed by it.
Hello there, You’ve done an incredible job.
I will definitely digg it and personally recommend to my friends.
I’m sure they’ll be benefited from this site.
how many bottles of water are in a gallon
i did not understand what kind of post this is
ReplyDeleteHow many fluid ounces are in a gallon of Water?