Extremophile bacteria suggests new possible life systems?!
Life (as we know it!) is mostly composed of 6 elements – carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. These six elements make up all the viable organic compounds in the organisms – nucleic acids, proteins, and lipids – the bulk of living matter.
In theory it is possible that some other elements in the periodic table could serve the same functions as the “core” 6 elements.
There is a category of organisms (almost all of them are bacteria) called Extremophiles, which could not only survive, but “feel just perfect” in conditions far from those considered as “normal” for the rest of the living beings. All of the known extremophile bacteria could live in highly severe conditions – very low or very high temperatures, highly acidic (low pH values) and similar, but there was none that could replace one of the core elements with alternative and to use it for building it’s structural and functional units. You can read more about extremophiles in Life on the Edge!
Recently, a new Halomonadaceae extremophile bacteria, strain GFAJ-1 was isolated from Mono Lake in California, US. The bacterium is capable to substitutes phosphorus with arsenic to sustain its growth. The researchers prove that this organism synthesize arsenate containing macromolecules that normally contained phosphate – mostly proteins and nucleic acids.
What I come up with, based on these findings is that these “abnormal” substitutions could be triggered just because of the extreme conditions, in which these organisms live. As we know that the conditions on distant planets differ to much from the “normal” conditions on Earth, I can imagine that similar to this extremophile bacteria organisms could be considered as quite normal on other planets and vice versa!
Do you think than on the distant planet HD 189733 b, arsenate utilizing living forms will be classified as “extremophile bacteria“, or they will be considered as normal?