FIG 1.

Growth of neurotoxigenic C. butyricum type E strains ISS-21 and ISS-190 under anaerobic (AN) or aerated (AE) conditions. (A and B) Growth curves of strains ISS-21 (A) and ISS-190 (B) were generated by measuring the OD₆₀₀ values. The number of viable cells (symbols) was determined in the starting (mid-exponential-phase) broth cultures and after a 5-h incubation under AN or AE conditions. (C) At the end of the experiments, foam was visible in the AN broth cultures but not in the AE broth cultures. (D) Net growth of the C. butyricum type E strains ISS-21 and ISS-190 at different initial bacterial densities after a 5-h incubation under AN or AE conditions. Under AE conditions, net growth was observed only when the initial densities were >10³ cells/ml. The errors were calculated by determining the standard deviation from the mean for three independent experiments for each strain. *, P < 0.05 according to Student’s t test.