On the subject of killing microorganisms that may be lurking on old
piano rolls.

I once purchased a Bruder fairground organ that had a bad case of
active woodworms.  I found a moving and storage company that had a
large sealed room.  They would spend the week putting things in the
room that needed to be fumigated.

On Friday afternoon they closed the room and flooded it with cyanide
gas and left it until Monday.  Being a gas, rather than some sort of
spray, it penetrated thoroughly and killed absolutely anything and
everything alive both in and on the objects in the room.

Bruce Miller
Issaquah, WA