I had that happen to me but I thought the mycelium was dead so I threw them out.

Extreme condensation from the water evaporating from the petri. If you don't move them at all youll be alright I moved one or two and the condensed water fell on the agar w/some bacteria that wreaked havoc.

oh well nothing more to post.

Hrm, I'm wondering, are you using petri dishes in the fridge, or test tubes? Test tubes are air tight, and it's not just the temp, but also the lack of air.

Petri dishes !=good for long term storage.

Oh yea, is your fridge cold enough? Freezer is not a good idea for living mycelia... it's likely that it will kill it. Especially when you consider the enviroment that Ps.'s grow in. (Though it is *possible* for it to live)

Correct storage temp is 35-40F (2-4C)
Stamets advises re-growing/fruiting a
strain every six months to avoid problems
with strain degeneration or lack of fruiting
ability.

Oil Imersion

Add a thin layer of mineral oil over the live mycelium after it has been established in a test tube (slant). Mineral oil is non-toxic to mycelium and greatly reduces the myceliums metabolism and inhibits evaporation from the agar base. The culture is stored at 37-41F. A study started in 1979 proved that 30 wood loving species were preserved in oil for 27 years and then fruited. To reactivate, slants are inverted (upside down) so the oil would drain off and then incubated at 77F. Within three weeks each slant showed signs of renewed growth. Other studies have concluded that definate degeneration is seen after 5 years. Whilst 2.5 years showed abilities similar to the day it was preserved.

Stamets also mentions immersion into liquid nitrogen (EXPENSIVE!!!) also innoculation of horse manure/straw compost, kept at 36-38F.

Oh yea, when using test tubes, prior to letting the gell, put them sideways so they slant, when they gell that will give more surface area to work with.

(Hrmm... I think the test tubes with caps are called slants. But I know what you're talking about and those are the ones I got in the mail. I use the test tubes with caps which my gf who used to work at a lab calls slants... dunno)