Wont micro-organisms quickly adapt and start producing UV resistant strains?

The germicidal effect is a function of the DNA being directly affected by the UV rays and breaking apart. Very few organisms exist that could adapt, this would require external shells, skin etc, not typically found in microorganisms.

	▲	jiehong an hour ago \| parent [-]
		Tardigrades and organisms ables to survive space by having more efficient DNA repair mechanisms. Unlikely for most organism, true

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VMG 4 hours ago | parent | prev | next [-]

There is a giant orb in the sky that emits UV and has for billions of years.

I think the microbes are still trying to figure this one out.

	▲	Qem 4 hours ago \| parent \| next [-]
		> I think the microbes are still trying to figure this one out. They mostly figured it out a couple billion years ago. Cyanobacteria oxidized Earth's surface until the atmosphere was flooded with molecular oxigen, that gets turned to ozone in the stratosphere, filtering most UV. Pretty large engineering feat for a bunch of microbes.
	▲	mahrain 4 hours ago \| parent \| prev [-]
		You are correct, however most of the harmful rays get filtered out in the upper atmosphere. Far-UV doesn't reach Earth, only UV-A and small amounts of UV-B (if the ozone layer is more or less intact that is!).

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ljsprague 4 hours ago | parent | prev [-]

I also wonder about stuff like this. I think some things are just a bridge-too-far for organisms to evolve protections against. For instance, are we worried about using too much bleach? Or stepping on cockroaches?

	▲	kijin 3 hours ago \| parent [-]
		There are radiotrophic fungi that thrive in Chernobyl, so I wouldn't hold too much hope for UV either. It probably won't be able to penetrate a decent biofilm.