NASA research discovers life built with toxic chemical

[News_Editor]

NASA research discovers life built with toxic chemical

2010-12-03 03:42:55 GMT+7 (ICT)

WASHINGTON D.C. (BNO NEWS) -- NASA on Thursday announced that an astrobiology research the agency funded discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic.

The microorganism substitutes arsenic for phosphorus in its cell components. NASA said that the research has changed the fundamental knowledge about what comprises all known life on Earth. The tests were conducted in the harsh environment of Mono Lake in California.

"The definition of life has just expanded," said Ed Weiler, NASA's associate administrator for the Science Mission Directorate. "As we pursue our efforts to seek signs of life in the solar system, we have to think more broadly, more diversely and consider life as we do not know it."

The six basic building blocks of all known forms of life on Earth are carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. Phosphorus is part of the chemical backbone of RNA and DNA structures, which carry genetic instructions for life.

Phosphorus is considered an essential element of all living cells as well as a central component of the energy-carrying molecule in all cells and the phospholipids that form all cell membranes.

Arsenic is a chemical similar to phosphorus but is poisonous for most life in Earth. Arsenic disrupts metabolic pathways because its chemical behavior is similar to phosphate.

"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," said Felisa Wolfe-Simon, a NASA Astrobiology Research Fellow and the team's lead scientist. "If something here on Earth can do something so unexpected, what else can life do that we haven't seen yet?"

The microorganism, strain GFAJ-1, is a member of a common group of bacteria, the Gammaproteobacteria. Researchers were able to grew such microbes in the laboratory on a diet that was very lean on phosphorus and including generous helpings of arsenic.

When researchers removed the phosphorus and replaced it with arsenic the microorganisms continued to grow. Subsequent analysis determined that the arsenic was being used to produce the building blocks of new GFAJ-1 cells. The arsenic became incorporated into the microbes’ vital biochemical machinery, such as DNA, proteins and cell membranes.

The research team chose to explore Mono Lake due to its unusual chemistry, especially its high salinity, high alkalinity, and high levels of arsenic. The unique chemistry is a result of Mono Lake’s isolation from its fresh water sources for 50 years.

The discovery will impact ongoing investigations in many areas, including the study of Earth’s evolution, organic chemistry, biogeochemical cycles, disease mitigation and earth system research.

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