50% hydrogen peroxide (3% is the usual household strength, I have 10% here and dilute it down with destilled water)
50% ammonium hydroxite (25% - 32% household ammonia)
that was the mix Zeiss once even had on their webside but it's gone.
a good guide:
How to Remove Fungus from a Lens
Hydrogen peroxid is very important to crack fungus-cells!
In households a mix of hydrogen peroxid, vinegar, borax and water is very good and without hydr.per. the solution cannot penetrated deep enough
and thus the fungus survives and returns
The difficulty can be coatings but I would never risk to keep a lens with possible spores with other lenses
and thus this means thorough cleaning of everything, not just a bit of glass.
There are many different opinions and I don't claim to be a specialist.
Lets see... a SMC M50/1,4 has to be cleaned in few days. It is in a completly different room so it can't infect any other lens.
Maybe too careful, but I'd rather be too carefull than careless!
But I think this question does not belong into this section, there are others or just a new thread?