[Inhibition of enteropathogens by Clostridium butyricum MIYAIRI 588]

The inhibitory effect of Clostridium butyricum MIYAIRI 588 against various enteropathogens was investigated in mixed cultures. It was observed that C. butyricum M588 inhibited the growth of Vibrio cholerae O1, V. cholerae non-O1, Aeromonas hydrophila, and Shigella flexneri. Considering that the interaction between C. butyricum and Shigella is especially important because of their proliferation site in the lower intestine, further examinations were carried out on Shigella in particular. Results were as follows: 1) In BHI broth culture of Shigella, the pH of culture fluid went down to 5.2, but the growth of Shigella was not inhibited. 2) In the mixed culture of Shigella and C. butyricum, the growth of Shigella was inhibited, nevertheless the pH of the culture fluid was 5.6. 3) In the mixed culture with phosphate buffered BHI maintaining the pH higher than 6.0, the growth of Shigella was inhibited. 4) In case of pure culture of C. butyricum in BHI broth, the pH of culture fluid indicated 5.5, and Shigella failed to grow in the cell free culture supernatant. 5) The growth of Shigella was not inhibited in the culture supernatant when the pH was adjusted at 7.2. These results suggested that the inhibition of Shigella in the mixed culture with C. butyricum was not due to a single factor such as pH or fatty acid etc. but due to multifactors including live cells of C. butyricum.