2.1. Preparation of spore crops
For each strain, a bead was removed from the cryovial using a
sterile plastic inoculating needle and transferred to cooked meat
medium þ 1% glucose (Oxoid, code CM 0081B) (Oxoid, Basingstoke,
UK). The cooked meat medium was incubated at 30 C for 48 h
under anaerobic conditions. After incubation, 100 ml of the cooked
meat medium was added to 10 ml of trypticase peptone glucose
yeast extract (TPGY) medium (Reddy, Tetzloff, & Skinner, 2010) and
the broth was incubated anaerobically at 30 C for 24 h. The culture
(all 10 ml) was transferred into 90 ml TPGY medium and incubated
anaerobically at 30 C for 48 h. The whole 100 ml of culture was