Microbes and Aliens

NASA researchers recently discovered a new microbe that can survive without one of the basic elements needed for life on earth. Could this organism be the key to finding life on other planets?

When NASA announced early last week that researchers had made an undisclosed astrobiology discovery that would impact the search for life in space, it sent ripples through the scientific community and popular culture alike. Speculation was rampant about what this discovery could portend. Some hoped the world was days away from meeting little green men from a distant planet.

In reality, the discovery was much closer to home.

In a press conference on Thursday, NASA researchers said they found a new microbe in Mono Lake in Northern California which substitutes phosphorus with arsenic, a toxic chemical, in order to grow and reproduce.

“It is terrestrial life, but not life as we know it,” said Mary Voytek, director of the astrobiology program at NASA headquarters and leader of the press conference’s panel discussion.

“All life that we know of requires carbon, nitrogen, oxygen, hydrogen, phosphorus and sulfur,” said Felisa Wolfe-Simon, the NASA astrobiology research fellow who led the experiment, in the press conference.

“We’ve discovered an organism that can substitute one element for another in its major biomolecules,” she said.

“The newly discovered microbe, strain GFAJ-1, is a member of a common group of bacteria, the Gammaproteobacteria,” the NASA website said.

The research was funded by NASA’s astrobiology program, Voytek said.

SUBSTITUTION REVOLUTION

The key to discovering the microbe was not to search far off in space, but to look in Earth’s backyard, Wolfe-Simon said.

“If you want to look for an organism that can substitute one element for another, you might want to think about where that particular element is abundant, and Mono Lake is abundant in arsenic,” she said.

Mono Lake, located just outside Yosemite National Park, contains three times the salt of seawater and has a pH level of 10, which is equivalent to bleach, she said.

“This seemingly inhospitable environment teems with life, like bacteria and algae and brine shrimp,” she said.

She said she had been thinking about the ability to substitute phosphorus with arsenic for a long time.

“The physical size of arsenic and phosphorus are very similar,” she said. “That chemical similarity lends insight into something.”

Researchers took mud from Mono Lake and placed it in a laboratory environment that lacked phosphorus, but was rich in vitamins and sugar needed for growth, she said. Scientists also added high doses of arsenic to the mud, she said.

“We found that not only did this microbe cope, or deal with the toxicity…but it grew and it thrived, and that was amazing,” she said. “Nothing should have grown.”

Then, researchers measured the total arsenic concentrations within the cells to determine what was occurring at the molecular level, she said.

“We found that the arsenic was associated with a band of genomic DNA,” she said.
Researchers determined that the microbe incorporated arsenic into the backbone of its DNA, rather than maintaining the normal phosphorus backbone, she said.

TO INFINITY AND BEYOND

Scientists said the discovery has changed common conceptions of what is required for life on Earth, and that it could potentially affect the search for extraterrestrial life as well.

According to NASA’s website, “The results of this study will inform ongoing research in many areas, including the study of Earth’s evolution, organic chemistry, biogeochemical cycles, disease mitigation and Earth system research. These findings also will open up new frontiers in microbiology and other areas of research.”

“It is not about arsenic, and this isn’t about Mono Lake,” Wolfe-Simon said. “It’s about thinking about life in a planetary context, and asking questions, simple questions, with a simple experimental design.”

“If something here on Earth can do something so unexpected, what else can life do that we haven’t seen yet?” she said. “We’ve cracked open the door to what’s possible elsewhere in the universe.”

ALIEN ACADEMICS

West, who will be teaching Astronomy 105, “Alien World,” next semester, said he most likely would incorporate the new finding into his class.

“We will be discussing many issues of habitability and the possibility of life in the universe,” he said. “These new results do alter our perspective about what is possible.”

“For our astronomy classes, it will just remind us to keep an open mind,” he said. “However, for the biologists, this result may lead to fundamental changes in their curricula if the result holds up.”

Students said they didn’t necessarily share the researchers’ enthusiasm.

“It’s all well and good, but it would have been cool to have been shaking hands with aliens next week,” said Samuel Taber, a College of Arts and Sciences sophomore. “Maybe I’ve just seen too many science fiction movies.”