http://aac.asm.org/cgi/content/full/50/11/3839?maxtoshow=&HITS=10&hits=10&RESULT
FORMAT=&fulltext=biofilms&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT

But there is a way, if Cryptococcus neoformans is typical:

http://aac.asm.org/cgi/content/full/50/6/2132?maxtoshow=&HITS=10&hits=10&RESULTF
ORMAT=&fulltext=biofilms&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT

Note that the fungi in biofilm is pretty much immune to gamma rays.
It takes a -riggin Alpha emitter to can it.

I have considered coating the biofilm with iron nanoparticals and then
activating them with an MRI.
It would cook the bugs, but control would be tricky.