All hope is not lost, but time is of the essence!!!
Make a water/hydrogen peroxide mix and spray down the substrate really well, being careful not to leave any standing water.
This is by no means a guarantee unfortunately, but using this mix has helped stave off any potential intruders in my crops, and I think it would help kill whatever that is while preserving your cake for growth.
Here's a good piece of info I regularly use from the Shroomery.
http://www.shroomery.org...-of-the-mushroom-cultureGood luck!
"We speak of Time and Mind, which do not easily yield to catagories. We separate past and future and find that Time is an amalgam of both. We separate good and evil and find that Mind is an amalgam of both. To understand, we must grasp the whole." -Isaac Asimov
"You will not be punished for your anger, you will be punished by your anger." -Buddha
"I must not fear. Fear is the mind killer. Fear is the little death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when my fear is gone I will turn and face fear's path, and only I will remain." -Paul Atreides, while being tested with the Gom Jabbar by the Reverend Mother Gaius Helen Mohiam