Disinfectant for tissue culture?

[Henry Kuska]

    I am a retired chemist who is trying to do rose plant tissue culture 
at home in a sunroom-greenhouse.  I use a microwave oven for 
sterilization and a fishtank turned on its side as a clean area.  
Needless to say I get more contamination than I would like.  Is there a 
chemical that I could add to the solution to kill the mold but not bother 
the plant tissue?