Bacteria: The Space Colonists What'sNEW



Conrad

On April 20, 1967, the unmanned lunar lander Surveyor 3 landed near Oceanus Procellarum on the surface of the moon. One of the things aboard was a television camera. Two-and-a-half years later, on November 20, 1969, Apollo 12 astronauts Pete Conrad and Alan L. Bean recovered the camera. When NASA scientists examined it back on Earth they were surprised to find specimens of Streptococcus mitis that were still alive. Because of the precautions the astronauts had taken, NASA determined that the germs were inside the camera when it was retrieved, so they must have been there before the Surveyor 3 was launched. Apparently, these bacteria had survived for 31 months in the vacuum of the moon's atmosphere. Perhaps NASA shouldn't have been surprised, because there are other bacteria that thrive under near-vacuum pressure on the earth today. Anyway, we now know that the vacuum of space is not a fatal problem for bacteria.

What about the low temperature and the possible lack of liquid water in space? The bacteria in the camera recovered from the moon would have suffered huge monthly temperature swings and the complete lack of water. Freezing and drying, in the presence of the right protectants, are actually two ways normal bacteria can enter a state of suspended animation. And interestingly, if the right protectants aren't supplied originally, the bacteria that die first supply them for the benefit of the surviving ones. English microbiologist John Postgate discusses this fact in The Outer Reaches of Life (1994) (2):

"When a population of bacteria dries out without a protectant, many of the cells break open and release their internal contents. Among these contents are proteins, gums and sugars, all of which are protective. If the population is sufficiently dense, so that significant amounts of protectant are released, material released from the majority which died first can protect a few of their surviving fellows. "Comparable considerations apply to death from freezing.... Protective substances such as glycerol are well known and widely used; they are called cryoprotectants. Bacteria frozen without such chemicals leak internal contents, among which are many substances that are cryoprotective."

Postgate says that bacteria have apparently survived for 4,800 years in the brickwork of Peruvian pyramids, and maybe even 300 million years in coal, using the drying strategy. He also describes bacteria that apparently survived for 11,000 years in the gut of a well-preserved mastodon, although in this case the colony may have continued to live and multiply using nutrients available in the carcass. Postgate gives several other examples of long-surviving bacteria, and he is careful to mention the possibility that some of the bacterial cultures may have been contaminated, so not all of the reports are necessarily reliable.

Some bacteria have another even more effective survival strategy: they form spores. Spores are bacterial cells in complete dormancy, with thick protective coats. In terms of our computer analogy, a bacterial spore is like a handheld calculator that has repackaged itself into its original protective shipping carton and turned itself off.

"The resistance of some bacterial cells to environmental destruction is impressive. Some bacteria form resistant cells called endospores. The original cell replicates its chromosome, and one copy becomes surrounded by a durable wall. The outer cell disintegrates, but the endospore it contains survives all sorts of trauma, including lack of nutrients and water, extreme heat or cold, and most poisons. Unfortunately, boiling water is not hot enough to kill most endospores in a reasonable length of time.... Endospores may remain dormant for centuries" (3).

Postgate concludes his chapter on spores, entitled "Immortality and the Big Sleep," by saying, "There may be much older spores out there, waiting for energetic microbiologists to revive them." And there were.



Ancient bee in amber

Thirty Million-Year Sleep: Germ Is Declared Alive!



Revived bacteria

Postgate, upon learning of this discovery, wrote an article for The Times of London that concluded as follows (6):

"... could life on this planet be descended from alien spores? ...Panspermia, the view that the seed of life is diffused throughout the universe, has been favored by a minority of thinkers since the Greek Anaxagoras in the 5th century BC. He, Arrhenius and Fred Hoyle may yet have the laugh on us doubters."

Conclusion

235

"Life manages very well without oxygen, evolving into flourishing communities of anaerobes. Acidity... presents no problem, as sulphur bacteria and their co-habitants illustrate, nor does a considerable degree of alkalinity bother alkophiles.... Water purity is a trivial matter: saturated salt brines support abundant bacterial life. And pressure is quite irrelevant, with bacteria growing happily in a near vacuum or at the huge hydrostatic pressure of deep ocean trenches. Temperature, too, presents little problem: boiling hot springs support bacterial life, and bacteria have been found growing at 112 C in superheated geothermal water under hydrostatic pressure; conversely, other types of bacteria thrive at well below zero, provided the water is salty enough not to freeze. And even if they do get frozen, many bacteria revive when their habitat thaws. Even organic food is not a prerequisite...."

There are bacteria that metabolize iron, nitrogen, sulphur, and other inorganic materials. There are bacteria today that can live without sunlight. Archaebacteria that can withstand extreme heat have been found thriving in oil reservoirs a mile underground (9). Some species of cyanobacteria are highly resistant to ultraviolet radiation. The only thing absolutely essential for bacteria to live, grow, and multiply is liquid water. We are confident that the early Earth had plenty of water. Scientists believe that concentration of water in the earliest atmosphere for which they have data, over four billion years ago, was far higher than it is today.