I'm cleaning up some PS Mexicana Chicon Nindo on MAE agar. The source of my spores was from a swab so I knew that I'd have some cleanup work on my hands.
I did the swab to four plates. Two of the four swab plates had less contams then the others so I transferred those two plates to four plates each which was transfer #1. From those eight plates one was less contaminated the the others so I transferred that plate to eight plates for transfer #2. I'm currently still on transfer #2 and average contam rate is the same as transfer #1. I've got one plate that is less contaminated than the others. I still have the majority of all of these plates on hand.
In between transfer #1 and transfer #2 I made my batch of eight MAE plates and incubated them for seven to ten days at 70-80F to ensure that there was no growth and I had confidence in my jars and sterilization times. After that period nothing was growing on any of the plates so I proceeded.
I keep having a contamination that starts the edge of my jars then works it's way towards the center of the plate where the agar wedge transfer is. I assume that this is bacteria but I'm no contam expert. Any ideas?
Any guidance or input on how you would proceed? I don't mind doing transfer after transfer at this point but figured to reach out.
I can obtain some antibacterial agar. I'm also thinking about pressure cooking some of the MAE agar I already have in a beaker and pouring a thin layer over the plates that I've done transfers from so far, two from swab, one from T#1, and one from T#2. I've heard that the mycelium will pop up through the thin agar layer after a few days and the heat of the agar and suffocation slows the bacteria down during that time. Then do a transfer from the mycelium that pops through hopefully not taking any of the thin layer of agar with.