I've been following this thread closely as I have the same questions regarding storage, specifically storage of the yeast I've captured off of juniper berries:
https://www.homebrewtalk.com/f163/can-i-culture-yeast-juniper-berries-169156/ I have saved a yeast vial of the "mother" yeast, (that is to say the initial yeast that grew from the first starter) washed and stored in the refrigerator. I am seeing that yeast is alot tougher than alot of people give it credit for, I mean doesn't/didn't all yeast initially exist in nature, in some cases freezing for months, thawing, freezing again numerous times then surviving through 100F temps for months etc, etc only to repeat the process again all the while reproducing more cells and new generations.
Which brings up another question; If you store a certain yeast in freezing temperatures that naturally existed in a tropical environment, Aren't all the surviving yeast likely to be mutated is some way from the original? We have no way of knowing where or when most of the commercially available yeast comes/came from, nor how much mutation it's gone through, nor what generation it is, etc, etc. We only know what properties/effects it's suposed to impart to our brew.
My point is this; Whenever a human uses or stores yeast, it will likely mutate in some way. I keep trying to find some inexpensive way to store my juniper yeast dry and in a manner which will not allow it to mutate, after a few days of deduction/procrastination I have realized that it (Or some form of it) is already stored on all the juniper berries on all the trees in the hundreds of acres of BLM land in Colorado and I'm certain other states. I should stop worrying about it and stop trying to control it, when I run out or it becomes mutated or unviable I will simply trek out and pick some more berries.
I will still use commercial yeast for certain brews assuming the juniper yeast doesn't work in some manner for certain styles (still testing). But when I do find it has failed ( I already know it's alcohol tollerance is ~15%) in some way, that allows me to search for another naturally occuring yeast that will not fail under those circumstances, that's what I find exciting, in the yeast world anyway.
Wow, long post, I guess you all know me now . . . . in a yeast-shell.
Keep on yeasting my friends