Ye olde trick of the trade for fungus. Place the lens on a flat surface, get an angle-lamp and lower the bulb to about 6" above the lens. Switch on the angle-lamp and cook the lens for a few hours which will kill off the fungus. Just keep an eye on it to make sure nothing catches fire. Usual disclaimers with this post but we use to use it in a photographic store I errrrm worked at