It's life, but not as we know it
4 December 2010
First published in the Daily Telegraph on 4 December 2010.
Bacteria are the true rulers of the Earth.
Their numbers, activities and diversity are far greater than any other group of organisms and they have an amazing capacity to make a living in the most unlikely environments.
Bacteria that tolerate high concentrations of toxins, such as arsenic, are not unusual and have been long studied for their possible role in cleaning upcontaminated sites.
Bacteria that can 'breathe' using arsenic compounds instead of oxygen are also known, although these are rare and only found in environments very rich in arsenic, such as Mono Lake in California, USA.
The new NASA results are revolutionary because they show that functional DNA and other cellular components can be made using arsenic instead of phosphorous. And further, living things can thrive in the absence of phosphorous, previously thought essential for all life. The significance of this finding for the existence of life on other planets is threefold.
Firstly, it demonstrates the incredible ability of life to adapt to apparently inhospitable environments.
Secondly, it shows planets lacking phosphorous can still potentially support life.
Finally, it makes us rethink questions such as: "What is life and how will we recognise it if we find it elsewhere in the galaxy?"
Dr Nick Coleman is a lecturer in microbiology in the School of Molecular Bioscience at the University of Sydney. His research is in the area of microbial biotechnology.
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