There is a book that says to store Bacillus spores in 50% glycerol at -70 degrees Celsius (doesn't mention if the 50% is final concentration or not). But from what I know, the cells themselves can be stored in any % glycerol as long as the final glycerol concentration is 15% (v/v) at -80 degrees Celsius.
Is there a difference between preserving spores and cells? Because the book said to preserve the cells at a certain glycerol concentration and the spores at a different glycerol concentration.
Also, say I scrape some B. subtilis out from the cryovial for reuse, and they are frozen. Do I wait for the scraped cells to thaw and then plate them, or plate them while they are still frozen?
And if I want to sporulate these cells, should I recover these frozen cells by plating and incubating overnight, or can I just drop them directly into the sporulation medium? I want to get the details down properly.