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The effect of human bile juice and bile salts (sodium cholate, sodium taurocholate, sodium glycochenodeoxycholate and sodium chenodeoxycholate) on growth, sporulation and enterotoxin production by enterotoxin-positive and enterotoxin-negative strains of Clostridium perfringens was determined. Each bile salt inhibited growth to a different degree. A mixture of bile salts completely inhibited the growth of enterotoxin-positive strains of this organism. Human bile juice completely inhibited growth of all the strains at a dilution of 1:320. A distinct stimulatory effect of the bile salts on sporulation was observed in the case of C. perfringens strains NCTC 8239 and NCTC 8679. The salts also increased enterotoxin concentrations in the cell extracts of the enterotoxin-positive strains tested. No effect on enterotoxin production was detected when an enterotoxin-negative strain was examined.

C. perfringens enterotoxin shortened the lag phase and time of onset of sporulation of the same organism in a dose-dependent manner. The toxin stimulated macromolecular synthesis of pre-exponential phase cells.

Inclusion bodies (IB) synthesized during sporulation and enterotoxin formation by Clostridium perfringens were isolated. Sporulating cells were lysed by sonication in the presence of protease inhibitors. IB were isolated by centrifugation in linear gradients of sucrose, sodium bromide or sodium diatrizoate and banded at buoyant densities of 1.33–1.36 g/cm3, 1.30–1.34 g/cm3 and 1.33 g/cm3, respectively. Isolated IB were treated with detergent to remove attached cell membrane. They ranged in size from 0.5–1.4 μm long and from 0.2–0.5 μm wide. They were found to be serologically related to purified enterotoxin.