I enjoy making fermented foods, one of them is natto, which is cooked soybeans fermented with B. subtilis.
I usually buy the B.s. spores online, but they are somewhat expensive and often hard to find. (At least in central Europe.)
One way of going around this is to freeze some natto from a batch, and use it to inoculate the next batch.
Just out of curiosity, I'd like to create an inoculation material similar to the one I can get on-line.
So, I'd like to create a dry, powdered material containing a large number of B. subtilis endospores.
Drying the fermented soy is trouble some because of the high oil, fiber, etc. content. I think it'd be too bulky and spoil easily.
I imagine I'd need some growing medium (I can work with agar plates if necessary as long as I can prepare the medium at home)
Than I'd need to incubate the culture so the B.s. can multiply rapidly, and than - I imagine - I'd need to create an environment facilitating endospore formation.
Once that's done, I could - probably - just dry and grind the medium.
So, what the growth medium and the incubation environment for the growth / spore formation stages should be?
Many thanks in advance.