What was discovered?

A new microbe that can live on arsenic!  Since arsenic is a poison, this is a remarkable discovery...

not only do the microbes survive with arsenic in their environment, they actually USE the arsenic in the molecules inside their cells, including in their DNA, where it can do the job of phosphorus in the phosphates of the helical backbone!

How?

There are places in the world where plenty of arsenic is found - and not surprisingly, not many creatures are found there!

But, by taking a sample of mud from such a place in California, collecting some of the microbes which could grow there and then growing them on food containing ever increasing quantities of arsenic...

after many generations, the microbes still survived!

Examining the chemicals in their cells showed that the arsenic, which has similar chemical and physical properties to phosphorus, had actually replaced phosphorus!

Why is it important?

Until now, the 6 commonest elements needed to make the molecules inside cells of all living organisms on this planet were said to be carbon, hydrogen, oxygen, nitrogen, phosphorus and sulphur...

but now we know of microbes that can use arsenic instead of phosphorus!

This means that we need to be a bit more flexile in our thinking about what elements and molecules to look for when searching for new life on our planet and beyond!