FIG 2.

BoNT/E protein and toxicity levels in the starting (mid-exponential-phase) broth cultures of C. butyricum type E strains ISS-21 and ISS-190 and in the cultures after 24 h of incubation under AN or AE conditions. BoNT/E protein levels (ng/ml) were measured by ELISA (histogram bars); BoNT/E toxicity levels (mouse lethal dose [MLD]/ml) were assayed by mouse test (symbols). Data are the mean values from two independent experiments for each strain, with samples assayed in duplicate in each ELISA. Columns that do not share the same letter are statistically different according to Student’s t test (P < 0.05).