Carnobacterium pleistocenium Emma Schmittzehe
It all started five years ago in a permafrost tunnel near Fox, Alaska. NASA astrobiologist Dr. Richard Hoover went to the Cold Region Research and Engineering Laboratory (CRREL) tunnel looking for “psychrophiles”, organisms which live only at extremely low temperatures. The tunnel was carved by the Army Corps of Engineers in the mid 1960s, preparing for the construction of the Trans-Alaska Oil Pipeline in early 1970. Hoover, a researcher at NASA’s Marshall Space Flight Center in Huntsville, Alabama, went to this tunnel in 1999 and 2000. He studied ice taken from this tunnel with his collaborator, microbiologist Dr. Elena Pikuta of the University of Alabama in Huntsville. Hoover and Pikuta studied the samples at the National Space Science and Technology Center, the research consortium which is operated by NASA and the Alabama universities.
Initially Hoover thought that the samples from the ice were diatoms, which are microscopic, golden-brown algae. This unique new life form was not diatoms, but a collection of bacterial cells which were more than 30 millennia old. They then thought the organism was a psychrophile, but as soon as the ice thawed, these bacteria ‘came to life’. Further testing of the bacteria revealed that they are “psychrotolerant”, not psychrophiles (not an organism which thrives only at low temperatures, but an organism which is able to tolerate deep cold that resumes normal activity when the temperature rises.
The newly discovered bacterium was named Carnobacterium pleistocenium. This was the first fully described, validated species to be found alive in the ancient ice. The ancient ice was actually Pleistocene ice; this bacterium had been frozen near the end of the Pleistocene Age (1.8 million years ago to about 11,000 years ago), which is where it got its species name. These psychrotolerant organisms were frozen in the ice for about 32,000 years. They were found to have close similarities to the Carnobacterium alterfunditum, which is how they got their genus name. These bacteria are facultative anaerobes; they are gram positive, motile, rod-shaped cells. They are about 0.6-0.7 x 0.9-1.5µm in size. They are catalase-negative chemoorganoheterotrophs, they use some sugars and proteins as substrates of proteolysis. They can grow at temperatures ranging from 0oC to 28oC, with an optimum temperature of 24oC. They do not require NaCl to grow, but growth was observed from 0% to 5% NaCl, with optimal growth at 0.5% NaCl. They were also observed to grow at pHs ranging from 6.5-9.5, with an optimum of 7.3-7.5. C. pleistocenium has metabolic end product of acetate, ethanol, and CO2. They are sensitive to ampicillin, tetracycline, chloramphenicol, rifampicin, kanamycin, and gentamicin.
Many people think of illnesses and decay when they think of bacteria, but of the approximately 7,000 discovered bacteria, less than 1% of bacteria are dangerous to human. There are actually more bacteria which are actually valuable to humans; they have many uses including culturing wine and dairy products. NASA and partner organizations study extremophiles in order to help prepare robotic probes and in time for human explorations in searching other planets for life. The discovery of this organism is exciting for NASA; it leads to the possibility of organisms like this living on Mars or Europa. This bacterium also presents the possibility of medical breakthroughs. The enzymes and proteins this bacteria have enable it to ‘come back to life’ after long periods of dormancy. This may hold the key to long-term, cryogenic storage of cells, tissues, and possibly even complex life forms. Living cultures of C. pleistocenium have been deposited in the American Type Culture Collection, the Microbial Collection at Pasteur Institute, and the Japan Collection of Microorganisms in Saitiama, Japan.
Pikuta, E., Marsic, D., Bej, A., Tang, J., Krader, P., & Hoover, R. Carnobacterium pleistocenium sp. nov., a novel psychrotolerant, facultative anaerobe isolated from permafrost of the Fox Tunnel in Alaska. <http://ijs.sgmjournals.org/cgi/content/abstract/55/1/473>
Roy, Steve. NASA Astrobiologist Identifies New ‘Extreme’ Life Form. <http://www1.nasa.gov/centers/marshall/news/news/releases/2005/05-020.html>
NASA Scientists Find Life Thriving at ‘Extremes.’ <http://www.rednova.com/news/display?id=131221>
Ancient bacteria gets busy after thawing out. <http://www.scienceblog.com/cms/node/7086>
Carnobacterium pleistocenium. <http://en.wikipedia.org/wiki/Carnobacterium_pleistocenium>
Bacteria Frozen for 32,000 Years Comes to Life. <http://www.ens-newswire.com/ens/feb2005/2005-02-24-05.asp>
Hammes, W., Weiss, N. & Holzapfel, W. Lactobacillus and Carnobacterium. <http://et.springer-ny.com:8080/prokPUB/chaphtm/070/COMPLETE.htm>
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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