EMBARGOED FOR Leave it to California to come up with creatures that could be from Mars. Leave it to scientists to make them green.
A new species of bacteria has been discovered thriving without oxygen in the harsh waters of northern California's Mono lake, where conditions perhaps resemble places on the red planet that might support similar life forms, scientists announced Wednesday.
A dye used in the laboratory to sort living things from dead stuff rendered the creatures green in an image released by NASA. Under a microscope, the bacteria look like miniature corkscrews winnowing through samples of the highly alkaline water in which they thrive.
Extremophiles
There is no solid evidence for life on Mars, so discussion of it is speculative. But on Earth in recent years, researchers have found several species of "extremophiles," microorganisms that exist in conditions most living things cannot tolerate.
The newfound extremophile, called Spirochaeta americana, swims in a high-mineral, salty environment where the pH can reach 10.5, compared to a range of 6.5 to 7.5 that is generally suggested for backyard hot tubs and swimming pools.
"The environment these bacteria inhabit would be distinctly inhospitable to many other life forms, including humans," said Elena Pikuta, a microbiologist at the University of Alabama in Huntsville.
Spirochaeta americana joins a growing list of organisms on Earth that don't mind extreme heat, cold, darkness or other awful conditions. They are ancient life forms that have endured most of what the planet can throw at them. Extremophiles have been found under Antarctic ice, around superhot volcanic vents, eating rock beneath the sea floor, munching on hydrogen and belching methane inside Earth's crust, and even in the waste from nuclear reactors.
Yet fragile
The new species was discovered in a laboratory by analyzing water and mud collected during a single day's visit to the lake. Outside their native habitat, the hardy creatures turn out to be surprisingly fragile.
"These extremely thin and graceful bacteria move with an elegant motion," Pikuta said. "Their cell walls are very delicate, and it is difficult to keep them alive for long periods in the laboratory."
It is primarily their ability to survive without oxygen that interests astrobiologists, those who study how and whether life might arise beyond Earth.
"Since other bodies of the solar system [planets and moons] lack our oxygen-rich atmosphere, microorganisms that thrive without oxygen are good candidates for astrobiology research," said Richard Hoover, an astrobiologist at NASA's Marshall Space Flight Center. "If, or when, we find life on other planets, our first discoveries will probably be microorganisms."
Hoover worked with Pikuta on the study, which was published in the May issue of the International Journal of Systematic and Evolutionary Microbiology.
Mono Lake is not like anything known on Mars. But there are is some common ground. Mono is the remnant of a much larger lake whose water level in the Pleistocene era was some 427 feet (130 meters) higher. Some scientists have speculated that depressions seen on Mars might be sites of former lakes.
Much of NASA's Mars program is currently geared toward finding places on the red planet where liquid water might exist. Water is one ingredient needed by all life as we know it. But even if there is liquid water on Mars, that does not guarantee life.
"Planets like Mars have conditions that would challenge the existence of highly organized multicellular organisms such as we find on Earth, but that doesn't mean these harsh places can't sustain microbial life forms," Hoover said. "By studying microorganisms found in Earth's extreme places, like Mono Lake, we can better understand how life might exist on Mars."
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