http://www.innovations-report.de/html/berichte/biowissenschaften_chemie/bericht-79435.html

"Researchers have investigated the peculiarities of microorganisms’ physiology and behavior in space on the “Mir” orbiting space station, and found that bacteria change significantly in extraterrestrial conditions...
Observations on board the “Mir” and “Photon 2” proved that microorganisms change even during short-term flights of 12-14 days. For example, streptomycetes changed their appearance (size, shape and outline of the colonies’ surface). The in-depth analysis also revealed genetic modifications of microorganisms. The number of their mutations does not increase, but some genes are disrupted. Some genes that are “dormant” on the Earth, begin to work, which generate the enzymes which damage structural materials."

Does this strike anyone else as possible evidence of a space-familiar ancestor? The bacterial species in question seem to have existing methods of dealing with the conditions of space, does this support panspermia as much as it seems to?

It just says to me that they are highly adaptable to different conditions, whichis why they can be found in harsh and widely varied conditions on earth.

hm; possibly. How quickly do individuals (as opposed to population) adapt to harsh conditions on the earth? Heat, Acidity, etc,etc?

We might equally ask why do some bacteria have a resitance to radiation far in excess of anything to be found on Earth other than in the heart of a nuclear reactor. That too suggests an extraterrestrial and extraplanetary origin.

Alternatively it is an intrinsic property of the actual resistance mechanism.

If that is so, does it appear to be triggered by all extreme environments? If the resistance mechanism was general in nature, and not due to exposure to a particular set of situations in the past, shouldn't it act similarly in all life-stressing environements?

This is very interesting information. You should consider updating the wikipedia article on Exogenisis.