You may find that the liquid medium was contaminated or your plate used to streak out your yeast strain contained contaminants. Check your other media bottles to determine if your problem is with the autoclave step of sterilization. Also inspect your inoculum plate to determine if any colonies have a different color or shape which may indicate a contaminating organism. Table of Contents I did a transformation and got a lot of fungus all over my plates. You probably have an infection in your plate storage cold room.
Most cold rooms are cold and dark and ideal for fungus growth.
Inspect your cold storage facility and disinfect if necessary. If your bait or reporter does not show auto-activation you are ready to proceed. Determine the amount of library DNA that most effectively gives the number of transformants needed to cover your library. If necessary the transformation reaction can be scaled up to 120 x. Under conditions of high DNA concentration many yeast cells take up more than one DNA molecule.