They can, but it's self-limiting in that all you're really doing is supplying an evolutionary pressure that results in UV-tolerant fungi/pathogens.

I once toured a (large) malting works where the soak-tanks are bathed in UV all the time (except when humans need to enter the room) and harsh chemicals are employed constantly to limit fungal and bacterial growth. They are still unable to eradicate those pathogens and suffer constantly from infection problems.