Wednesday, August 08, 2007

Methuselah Germs

From a story on Fox News:

Microorganisms locked in Antarctic ice for 100,000 years and more came to life and resumed growing when given warmth and nutrients in a laboratory.

Researchers led by Kay Bidle of Rutgers University tested five samples of ice ranging in age from 100,000 years to 8 million years.

"We didn't really know what to expect. We knew that microorganisms were really hardy," Bidle, an assistant professor of marine and coastal sciences, said in a telephone interview.
The findings are reported in Monday's online edition of Proceedings of the National Academy of Sciences.

The researchers tested samples of the oldest known ice on Earth and had success at growing bacteria from the younger samples.

Microorganisms from the older ice didn't do as well, growing only very slowly. Some of the oldest microorganisms were watched for as long as a year, he said, compared to the week or so it usually takes to culture bacteria.

Calling the ice cores "gene popsicles," the researchers found evidence of some the most common bacteria still around, including firmicutes, proteobacteria and actinobacteria.

These are microorganisms that have been around a long time, Bidle said, "not something Earth hasn't seen before."

Bidle's researchers found that the DNA in bacteria deteriorates sharply after about 1.1 million years.

He said that after 1.1 million years the size of the DNA gets cut in half. In the oldest ice it consisted of just 210 units strung together. Normally the DNA of the average bacterium has about 3 million units.

One of the really cool things about bacteria is the ability of some of them to survive under unbelievably adverse conditions - boiling acid hot springs, deep-sea thermal vents, lithospheric inclusions, and hard vacuum.

I haven't had a chance to read the original article yet (God bless university on-line access!) If the reporter butchered something, I'll write a follow-up. As stated, however, this strikes me as a blow to the "life came to Earth from outer space" crowd. A million years isn't really that long if you are traveling across the galaxy on some space rock at 100 miles per second. It will only get you 537 light years/ megayear - a long way, but unlikely enough to get you from habitable planet to habitable planet, and then only with a 50% probability that your DNA is intact. That assumes that the phrase "the size of the DNA gets cut in half" is a half-life number. If it represents the mean of a bell-shaped size distribution, the likelihood of microbial viability gets a whole lot smaller. That doesn't include the likelihood of making it through the atmosphere unincinerated, etc. Remember, life arose on Earth very quickly after conditions became tolerable.

Looks like those trying to figure out how the Lord pulled it off might want to concentrate on terrestrial mechanisms.

Any old X-Files fans will, of course, be waiting for these experiments to unleash an extraterrestrial plague.