LIVERMORE, Calif. - Arsenic - an element that triggers death for most Earthly life forms - is actually allowing for a bacterium to thrive and reproduce.
In a study that may prompt the rewriting of textbooks, a team of astrobiologists and chemists has found the first known living organism that can use arsenic in place of phosphorus in its major macromolecules. The new findings, published in the Dec. 2 Science Express, could redefine origins of life research and alter the way we describe life as we know it.
Oxygen, carbon, hydrogen, nitrogen, sulfur and phosphorous are the six basic building blocks of life on Earth. These elements make up nucleic acids, proteins and lipids - the bulk of living matter.
The new study by Lawrence Livermore National Laboratory and led by NASA and the U.S. Geological Survey has found that a bacterium isolated from Mono Lake may substitute arsenic for phosphorus to sustain its growth.
Mono Lake, located in eastern California, is an alkaline and hypersaline lake with high dissolved arsenic concentrations and is believed to have formed more than 760,000 years ago from neighboring volcanic eruptions.
Felisa Wolfe-Simon, a NASA astrobiology research fellow in residence at the USGS and the paper's lead author, has been studying possible arsenic based life forms at the lake for some time. Using samples from Mono Lake and a culture medium with reduced phosphorus levels, she showed that that a strain of Gamaproteobacteria can not only survive using arsenic but can grow as well.
"We know that some microbes can 'breathe' arsenic, but what we've found is a microbe doing something new - building parts of itself out of arsenic," Wolfe-Simon, said.
LLNL's Jennifer Pett-Ridge and Peter Weber were able to identify low concentrations of arsenic found in individual cells of bacteria and extracted DNA. NanoSIMS is a tool which allows precise, spatially explicit, elemental and is
|Contact: Anne Stark|
DOE/Lawrence Livermore National Laboratory