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[Chicago Astronomer Joe]

Mars May be Cozy Place for Hardy Microbes

A class of especially hardy microbes that live in some of the harshest Earthly environments could flourish on cold Mars and other chilly planets, according to a research team of astronomers and microbiologists.

Most stars in our galaxy are cooler than our Sun. The zone around these stars that is suitable for Earth-like temperatures would be smaller and narrower than the so-called habitable zone around our Sun. Therefore, the majority of planets would likely be colder than Earth.

In their study, the scientists tested the coldest temperature limits for two types of one-cell organisms: halophiles and methanogens. They are among a group of microbes collectively called extremophiles, so-named because they live in hot springs, acidic fields, salty lakes, and polar ice caps under conditions that would kill humans, animals, and plants. Halophiles flourish in salty water, such as the Great Salt Lake, and have DNA repair systems to protect them from extremely high radiation doses. Methanogens are capable of growth on simple compounds like hydrogen and carbon dioxide for energy and can turn their waste into methane.

The halophiles and methanogens used in the experiments are from Antarctic lakes. In the laboratory, the halophiles displayed significant growth to 30 degrees Fahrenheit (minus 1 degree Celsius). The methanogens were active to 28 degrees Fahrenheit (minus 2 degrees Celsius).

Although Martian weather conditions are extreme, the planet does share some similarities with the most extreme cold regions of Earth, such as Antarctica. Long regarded as essentially barren of life, recent investigations of Antarctic environments have revealed considerable microbial activity. “The Archaea and bacteria that have adapted to these extreme conditions are some of the best candidates for terrestrial analogues of potential extraterrestrial life; understanding their adaptive strategy, and its limitations, will provide deeper insight into fundamental constraints on the range of hospitable environments,” DasSarma said.

Source: www.physorg.com/news80537113.html

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I'm still under the contention that Mars harbors micro life today.

[Chicago Astronomer Joe]

Antarctic Microbes Handle Mars-Like Conditions

Lab experiments with primitive microbes taken from an Antarctic lake have shown that the hardy single-celled organisms can tolerate at least the warmest of the frigid temperatures found on Mars.

And they found that these species of microorganisms "huddled" together in colder temperatures to form a chemically linked unit called a biofilm. The finding marks the first time this phenomenon has been detected in the Antarctic species of so-called extremophiles.

The findings provide more evidence for the ideas that liquid found beneath Mars’ surface could harbor microbial life and that life could exist elsewhere in the solar system and galaxy, which is generally incredibly cold.

Hardy creatures

Scientists with the Maryland Astrobiology Consortium focused on two species of cold-adapted microbes. One, called Halorubrum lacusprofundi, is highly salt-tolerant. The other, Methanococcoides burtonii, can live without oxygen and thrives on methane. (H. lacusprofundi is a type of microbe that was discovered first in spoiled foods that had been salted for preservation).

Both microbes are types of Archaea, one of the three major types of life along with Bacteria (another class of microbes) and Eukaryotes (a group that includes animals, plants, fungi and Protists, e.g. paramecium, algae, protozoa and slime molds). Archaea might be able to survive in many places in the universe beyond Earth, including some of the more than 180 extrasolar planets detected in the past decade, or on their terrestrial moons.

The team, led by Shiladitya DasSarma of the University of Maryland Biotechnology Institute, part of the consortium, grew the microbes and found they survived and reproduced at 30 and 28 degrees Fahrenheit (about -1 and -2 degrees Celsius), respectively, just below the freezing point of water.

"We have extended the lower temperature limits for these species by several degrees," DasSarma said. "We had a limited amount of time to grow the organisms in culture, on the order of months. If we could extend the growth time, I think we could lower the temperatures at which they can survive even more."

More here: www.space.com/scienceastronomy/061031_st_mars_life.html

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All in good time.