Hi Maria,

In our work with anaerobic spores we suspended grown cultures from solid media in clean water and the culture was incubated for sporulation. The only purification we have applied was filtration over 8 um sterile filter to remove larger particles.

I hope this response answers your question?

Regards

Wim Hijnen 

I have used Percoll and Histodenz in the past.

Hello Maria, while I was working on Clostridium perfringens spore isolation, we used a protocol that has been used for B. subtilis spore isolation and purification. You can check the method part of the paper: 

http://jb.asm.org/content/early/2016/04/05/JB.00212-16.abstract