1. Centrifuge spore suspension at 300 G for five minutes to form a spore pellet which contains two strata, the upper supernatant fluid and the lower stationary phase containing most of spores.
  2. Transfer supernatant fluid to another tube using a pipette, and resuspend lower stationary phase using sterile water.
  3. Centrifuge supernatant for five minutes at 300 G to pellet the spores, and again transfer supernatant fluid to another tube and resuspend the lower stationary phase. 
  4. Repeat procedure three times.
  5. Combine resuspended lower strata created from each centrifugation to yield a spore suspension with a purity greater than 99 % (Cole, 1970).