The end of this excellent answer lead me to Wikipedia which linked to The blacker the better… especially in Chernobyl and Chernobyl Fungus Feeds On Radiation. One passage in 'blacker the better' caught my eye:

Melanized fungi actually seem to thrive in environments with high levels of ionizing radiation (ultraviolet, x and gamma rays), which is usually seen as very dangerous to life.

And then it goes on:

The walls of the damaged nuclear reactor of Chernobyl are covered in melanized fungi and they also are found living very happy on board of the International Space Station. Experiments showed that these melanized species of fungi seem to benefit from radiation, increasing their growth and germination.

Melanized fungi seem to be fungi which can produce a form of melanin, which may be able to derive some biological advantage (energy for synthesis or metabolism perhaps) from light or even radiation.

Have melanized fungi been found happy on the ISS? Is there anything written about this I could read? Any idea if they are gaining some biological advantage from higher radiation levels there? Were they there intentionally (part of an experiment) or did did they travel as common contamination or spores from Earth?

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    $\begingroup$ They have been found in troublesome abundance on MIR. Designers of ISS went to great lengths not to face that problem. $\endgroup$ – SF. Feb 24 '17 at 15:25
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    $\begingroup$ @SF. specifically melanized fungi, or fungi in general? $\endgroup$ – uhoh Feb 24 '17 at 15:32
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    $\begingroup$ I don't know. But they were thoroughly studied, there was a lot of species, the results of the study are out there. If I knew I'd post it as an answer. $\endgroup$ – SF. Feb 24 '17 at 15:42
  • $\begingroup$ @SF. Can you cite documentation about the MIR fungus problems? Sounds interesting. Seems like it should be an Answer here. $\endgroup$ – Basil Bourque Mar 3 '17 at 6:19
  • $\begingroup$ @BasilBourque: Wikipedia cites a couple sources in the relevant entry. $\endgroup$ – SF. Mar 3 '17 at 7:02

The experiment Growth and Survival of Colored Fungi in Space (CFS-A) - 12.07.16 showed that:

fungi can grow inside the space station and could decompose food and other organic materials in humid conditions. After exposure to air growth stopped, fungal hairs (filaments) developed within the food source and decomposed it by producing digesting enzymes. Submerged filaments don’t make spores, but fungi could still spread through direct contact. Dry spores remained living after 5 months in microgravity, with some fungi living longer than others. The data show that spores would grow well on salted food in space, and some species grow on iron surfaces covered with small quantities of carbohydrates.

One of the species used by the experiment was Ulocladium chartarum, which is a melanized fungi. You can see more on the results of the experiment at the link above. The experiment found that melanized fungi were indeed resistant to cosmic radiation to the degree that radiation was not found to affect their growth, instead microgravity was the main inhibitor. I did not see anything about radiation providing any advantage, but it was at least not an obstacle.

The experiment page also includes a picture of an actual contamination (of what appears to be melanized fungi) on one of the interior panels of the ISS. The caption says that the crew has weekly sessions to clean such surfaces.

ISS contaminated interior panels

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  • $\begingroup$ Yikes!! I'm starting to sneeze just looking at it. $\endgroup$ – uhoh Mar 1 '17 at 16:29

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