Better know a prokaryote

This column, which will be switching off with Leanne Grieves’ “Zoological investigations,” will strive to pique your interest in the world of the microscopic, bringing you strange tales of wonder and amazing diversity, but first, a little explanation of the term “prokaryote”.

The prokaryotes, which include bacteria, archaea and viruses, are possibly the most diverse and misunderstood organisms on our planet, but also some of the most important, being at the heart of so many of the things that keep this green rock going — decomposition, to name just one. Their name roughly translates from Greek to “pre-nucleus,” referring to the fact that prokaryotes don’t even have the decency to keep their genetic material bunched up in a membrane bound vesicle like us humans, who are proud members of the eukaryotes — which stands for “true nucleus.”

While there are several interesting prokaryotes for us to discuss, possibly the most interesting — to those who grew up watching Star Wars at least — is a little bacterium known as Deinococcus radiodurans.

We’ll get the boring stuff out of the way first. The little buggers are spherical in shape and 1-2 micrometres across (that’s 1/1000th of a milimetre). They are not disease-causing and enjoy hanging out in soil. So what’s so special about these bacteria you might ask? Well they can withstand about 10 times the amount of ionizing radiation as Escherichia coli — or E. coli as it is commonly known — and 2,000 times the amount of radiation as you or me.

How this diminutive organism became the most radiation resistant thing on the planet is a hotly debated subject among D. radiodurans researchers, and while some believe that it is a byproduct of a highly evolved and efficient DNA repair system, others have speculated that the evolutionary process which would have brought about such a radical ability could have only developed in the harshness of outer space, where cosmic rays and radiation are abound.

While we may never know how D. radiodurans evolved its ability to survive nuclear bombardment, its discovery has lent credibility to the camp of scientists, which included the late Francis Crick, — 10 points if you can email me with what he discovered without checking — who believe in panspermia, or the theory that life on our planet had its origins elsewhere in the universe, and flew here through the cold radioactive darkness of space, which almost seems exactly like what this tiny creature was designed to do.