Tenacity of Life

A final point regarding the prokaryotes relates to their tenacity and ability to survive for long periods of time. There are many examples of bacteria being revived after long term storage, but perhaps none any more dramatic than those from the Antarctic permafrost, where soils that have been permanently frozen for 3 million years or more have yielded copious numbers of living bacteria. Dr. David Gillichinsky and his colleagues from Puschino, Russia, have been drilling in such sites for many years now, and a number of organisms have been “revived” from their carefully collected samples. It is not unusual to find 10⁶ to 10⁷ (1 to 10 million) viable bacteria from each gram of permafrost. These are not cold loving (psychrophilic) bacteria that have adapted to these freezing conditions, but simply mesophilic organisms that have been trapped within this icy storage facility for millions of years.

So, as we are poised to proceed to other celestial bodies in search of life, we find that our definition of habitability is quite different from what we adhered to just a few years ago. In response to this, we must: a) consider that the physical and chemical conditions tolerant to life are broader than we once thought; b) examine the potential energy sources available and look carefully for life forms utilizing any such energy; and, c) be prepared for subtle, single-celled life that may not be obvious at first glance, even looking in places where life might have been preserved as dormant forms.

Contributed by: Dr. Kenneth Nealson