"Alien bacteria found on earth"

One of my fave topics in science is astrobiology. Which is simply the study of potential life elsewhere in the universe.

The idea that life is elsewhere in the universe seems very obvious to me, but I never cease to be surprised by human arrogance with regards to this subject. There are still many scientists out there who believe that its possible life only exists here on earth!

Our understanding of life is completely based upon our experience and observations here on earth, and its refreshing to see that new research is demonstrating that some of the previous prerequisites for life are not always valid, even here on earth. Recently NASA scientists have found a type of bacteria that is like no other found thus far. They describe it as "Alien bacteria" simply because it is so different to what our experience of life is thus far.

All life on earth contains genetic information which is encoded in DNA (Or some primitive viruses, RNA). DNA has a well known structure consisting of the elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. NASA have now found a bacteria which was isolated from Mono Lake, California. They have found that in order to maintain growth this bacteria will replace the normally essential element Phosphorus with the element Arsenic. This is highly surprising in two ways.

Firstly, it demonstrates that the structure of DNA and hence the genetic code may be subject to change. This really opens up the possibility that the "Information of life" may be passed in different types of "DNA" - perhaps DNA is just a family of biological molecules which are capable of coding genetic information.

Secondly, Arsenic is normally toxic to life on earth and yet this new bacteria is thriving on it and using it as part of its chemical make-up.

The concept of Darwinian evolution has demonstrated the importance of the environment in the progression of life in earths history. I now think it is quite likely that this has more far reaching consequences than we previously thought and it may be possible that there is life out there in the universe in places we would no doubt class to be inhospitable, due to extreme temperatures, pressures, or lack of specific compounds such as water.

The abstract for the NASA article may be found here