Saturday, July 16, 2011

Arsenic and Life

Arsenic (As) can be found in many dangerous synthetic chemicals. Such chemicals consist of pesticides, wood treatment, and so on. So this may go without saying that arsenic can be very dangerous, especially for multi-cellular organisms like humans. When arsenic (a metalloid) is introduced into a human body it interferes with cellular longevity by isolating specific metabolic enzymes through allosteric inhibition (Oremland, 2005). Many undeveloped nations have had a long standing problem with arsenic contaminated water sources. Arsenic poisoning can cause many unpleasant symptoms as well as death. Scientists however, have now trained certain bacterium to live on a purely arsenic diet. This new ability may lead to an answer to the arsenic contamination problem for many people around the world. The bacterium strain GFAJ-1 usually likes to dine on phosphorus, but scientists over a period of time isolated the bacteria from anything but arsenic and the full scope of adaptation was then observed (Overbye, 2010). NASA and astrobiologists everywhere are also excited by this new discovery in the ability for life to thrive. If an organism can live solely on arsenic, then what else or where else could it live? Life, it seems, could be more easily facilitated than once assumed. Mono Lake in California is where this survivalist bacterium calls home. Geomicrobiologist Felisa Wolfe-Simon and her team sought out Mono Lake because of its already high concentration of arsenic (Overbye, 2010). After scooping the bacterium out of the lake with the mud Simon and her team continued feeding the bacterium more and more arsenic until it had replaced the environment with the element. Simon decided to use this bacterium as a starting point, since after many millions of years living in arsenic contaminated water the assumption was that the bacteria would have some evolutionary resistance or appeal to the element (Overbye, 2010). After also introducing radioactively stained arsenic to the bacteria; under a microscope the team could observe the arsenic already embedding itself with in the DNA of the organism (Overbye, 2010). This was a monumental finding as not only did it consume arsenic, but also used in replacement of other elements (phosphorus) in its basic biological processes. Carbon, Sulfur, Nitrogen, Hydrogen, Phosphate, and Phosphorus are the five known elements essential for life; though these elements are still vital, it now seems that they can however be replaced (Oremland, 2005). Arsenic is positioned just below phosphorus in the periodic table, and the two elements can play a similar role in chemical reactions. For example, the arsenate ion, AsO34-, has the same geometric structure and bonding sites as phosphate. It is so similar that it can actually get inside cells by hijacking phosphate's transport mechanism (Oremland, 2005). It is no doubt that this new discovery will lead to many more interesting searches for other life forms who defy our limited view of how and where life can survive. This is also a step in the right direction for the creation many new poison eating microbes that may be able to assist humanity in living long enough to maybe, one day finally find life elsewhere in the universe.



Oremland, R. (2005). Arsenic, microbes and contaminated aquifers. Trends in Microbiology,13(2), 45-49.

Overbye, D. (2010, December 2). Microbe finds arsenic tasty; redefines life. The New York Times.

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