examination under light microscopy. Once sporulation had
reached at least 95%, the plates were flooded with sterile
distilled water and the growth was scraped off with a sterile
swab in order to collect the spores. Spores were washed three
times in distilled water and separated by centrifugation (13,000
g, for 5 min), and then stored in distilled water at 20 C until
use. The spore concentration was determined by serial dilution
and viable cell count on TSA.