concerns arise about arsenic-containing bacteria

To survive, microbes, plants, and animals all require six essential elements: 

1. oxygen, 

2. carbon, 

3. nitrogen, 

4. hydrogen, 

5. sulfur, &

6. phosphorus. 

But NASA astrobiology fellow Felisa Wolfe-Simon and her colleagues isolated a bacterium that, when grown with high arsenic concentrations and no added phosphorus, appears to replace some phosphorus with the chemically similar arsenic in key biomolecules, including DNA.

A startling discovery in and of itself, the finding became even more controversial because 

a NASA press announcement in December implied a connection to the search for extraterrestrial life.

arsenic, bacteria, & alien life

arsenic bacteria DNA structure as a clue in search for living organisms on other planets