Well that does it. All three jars are contaminated and now there is green mold growing on my stock mycelium :( The hydrogen peroxide helped, but in the end there was simply too much competition.
The first two jars were doomed from the beginning since the fungus gnats were able to get past the screening. The third jar's demise is a bit puzzling. I wonder if perhaps the sterilization process was not long enough. No, the mold mycelium first appeared at the top of the jar on top of the cardboard barrier. So I guess the mold spores were introduced as I transferred the mycelium to the jar and started growing before coming in contact with the hydrogen peroxide. Next time I will take more care and perform the transfer in an environment with fewer contaminants floating about.
I stated there would be pictures, but I decided to wait until I have healthy mushroom mycelium.
O well, on to something new.
I was reading up on liquid culture and was intrigued. The process involves the growth of mycelium in a nutrient enhanced jar of water. Within a week, week and a half, the mycelium should be ready to transfer to the growing medium (substrate).
The bags of beech mushroom mycelium are still white and fuzzy, but not growing into the coffee grounds. To date there is no visible sign of contamination.