Mythbusting thriller science: Space bacteria #4

(This is a follow-up on earlier mythbusting posts about Michael Crichton’s Andromeda Strain.)

There’s news in astrobiology this week.

The search for extraterrestrial life is focused on microorganisms, which are the life form we’re most likely to find in our solar system.  Scientists involved in the search make certain assumptions about what life on other planets would be like in order to design ways of detecting it.  Those assumptions are based on what we know about life on Earth.  For example, it’s widely assumed that water is an absolute requirement for life.

Another assumption has been that the element phosphorus is also essential.  Certainly that has been true of life on Earth; phosphorus (bound to oxygen in the form of phosphate) is a necessary structural component of DNA and RNA.

But a paper just published in the journal Science reveals that bacteria isolated from an arsenic-rich environment–exotic Mono Lake in California east of Yosemite National Park–can survive and grow in a laboratory after substituting arsenic for phosphorus.

Arsenic is normally toxic precisely because its chemical properties are similar to phosphorus (As sits directly below P in the periodic table); it can sneak in as a substitute for phosphorus and then fail to do the job properly.  The new research suggests substitution may not always be fatal.

The bacteria called GFAJ-1 from Mono Lake adapted to steadily increasing concentrations of arsenic.  Their ability to survive on arsenic raises the possibility that living cells might do the same in arsenic-rich alien environments like the moon.

Read the article in the Washington Post

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