The International Space Station Is Home To Potentially Dangerous Bacteria (sciencemag.org)
sciencehabit writes: There's a little known, dirty story about the International Space Station (ISS): It's filled with bacteria and fungi. A new study has found compelling evidence that microorganisms from human skin are present throughout the station, and some of the bugs could cause serious harm to astronauts.The most concerning finding was from the "high-efficiency particulate arrestance" (HEPA) air filter used in the ISS: 99.65% of the viable sequences they retrieved came from Actinobacteria. The Actinobacteria phylum includes Corynebacterium and Propionibacterium; each genus was found in the ISS samples at a high level, which is "problematic," say the researchers, because they both have species that are opportunistic pathogens. Astronauts who live in microgravity for prolonged periods also can have compromised immune systems.
By the time it reached end-of-life, the first space station became famous for hosting fungus mats of an unknown species:
http://www.straightdope.com/co...
From your link: "The fungal infestation came to light in 1988, when Mir inhabitants noticed that a porthole was obscured by what one alarmist described as "an unknown film that was spreading like some horror-movie scum." Closer examination revealed green-and-black encrustations behind control panels, inside air ducts, and in other nooks and crannies throughout the spacecraft. The stuff didn't literally eat metal and plastic but did give off corrosive chemicals such as acetic acid. Acetic acid is basically vinegar, so one doesn't want to become unnecessarily alarmed. Still, the acid pitted Mir's titanium, plastic, and glass, suggesting that the spacecraft's structural integrity might be threatened if the fungus were left unchecked."
It's not like putting a sliced tomato on the kitchen sink in a humid climate will prevent other parts of your kitchen from attracting any mold spores around. Bacteria and prokaryotes are mostly incapable of macrosopic movement (especially in air). They are also able to rapidly expand populations. Therefore, a "colonist" doesn't choose to move to the best spot, foregoing a worse one. They will try everywhere. If they gain a foothold, that foothold is likely to just unleash further colonists into the less hospitable, but still slightly viable, habitats.