how to separate spores from vegetative cells?

[Chris Michiels]

We want to prepare spore suspensions of Bacillus subtilis that are 
(virtually) free of vegetative cells. Since we want to study spore 
germination, the method should not interfere with germination. For 
instance, we do not want to use heat or lysozyme to kill the vegetative 
cells, because these treatments can activate the spores.
Is density gradient centrifugation a possibility?
Thanks for any suggestions.

Chris Michiels
Lab. Food Microbiology
K.U. Leuven
Belgium